Scipedia: Documents published in 2020

Reduction of Saturn Orbit Insertion Impulse using Deep-Space Low Thrust

Roberto Flores — Tue, 27 Oct 2020 12:31:02 +0100

Orbit insertion at Saturn requires a large impulsive manoeuver due to the velocity difference between the spacecraft and the planet. This paper presents a strategy to reduce dramatically the hyperbolic excess speed at Saturn by means of deep-space electric propulsion. The interplanetary trajectory includes a gravity assist at Jupiter, combined with low-thrust maneuvers. The thrust arc from Earth to Jupiter lowers the launch energy requirement, while an ad hoc steering law applied after the Jupiter flyby reduces the hyperbolic excess speed upon arrival at Saturn. This lowers the orbit insertion impulse to the point where capture is possible even with a gravity assist with Titan. The control-law algorithm, the benefits to the mass budget and the main technological aspects are presented and discussed. The simple steering law is compared with a trajectory optimizer to evaluate the quality of the results and possibilities for improvement.

Cambios en la estructura narrativa de las series de Netflix. El caso de Mindhunter

Adrià Naranjo — Tue, 27 Oct 2020 10:23:02 +0100

Abstract:

This paper examines the impact of Netflix simultaneous release on the narrative structure of Mindhunter (2017Today). The analysis of its first season shows that it adopts a structural model unconstrained by the procedural format formula, and that the season is conceived as a feature film that develops a complex main character. Simultaneous release impacts in cliffhangers and episodic plots too, as they become less prominent.

Resumen:

Este artículo aborda el impacto del estreno simultáneo de Netflix en la estructura narrativa de Mindhunter (2017-Hoy). El análisis de su primera temporada muestra que adopta un modelo estructural libre de la fórmula del formato procedimental, y que se concibe la temporada como un largometraje que gira entorno al desarrollo de un personaje complejo. El estreno íntegro, además, hace que el cliffhanger o las tramas episódicas pierdan protagonismo.

Monitoring and support optimization analysis of surrounding rock pressure and initial supporting stress in deep-buried soft rock tunnel

RUIFENG LI — Sat, 24 Oct 2020 09:29:37 +0200

Attempting at the problems of surrounding rock pressure and initial supporting stress of deep-buried soft rock tunnel, a soft rock highway tunnel project in Northwest China was monitored on-site for surrounding rock deformation, surrounding rock pressure, initial stress and other items.Discuss the deformation laws and stress characteristics of surrounding rock and steel arch at different construction stages, and compare and analyze the deformation control effect of surrounding rock with different initial lining thickness, different initial elastic modulus and different anchor length through numerical simulation.The results show that the excavation stage of the upper step is a stage where the pressure and deformation of the surrounding rock increase rapidly. The steel arch support is mainly compressed, and the average stress can reach more than 50% of the peak value within 5 days. The stress is mostly higher than the measuring point of the lower step. The initial steel frame support of the upper step and the middle step bears a greater load. The excavation of the upper middle step should be "passed quickly and supported in time", and the construction should adopt The “letting first,then resisting” method appropriately increases the reserved deformation of the surrounding rock to relieve the support stress of the primary steel frame. When the deformation of the surrounding rock and the growth rate of the surrounding rock pressure slow down, the secondary lining can be applied in advance. The research results can provide reference and reference for the design and construction of similar tunnel projects.

Exposure of Belt and Road Economies to China Trade Shocks

Scipedia content — Wed, 14 Oct 2020 16:26:00 +0200

The Belt and Road Initiative seeks to deepen China's international integration by improving infrastructure and strengthening trade and investment linkages with countries along the old Silk Road, thereby linking it to Europe. This paper uses detailed bilateral trade data for 1995-2015 to assess the degree of exposure of Belt and Road economies to China trade shocks. The econometric results reveal that China's trade growth significantly affected the exports of Belt and Road economies. Between 1995 and 2015, the magnitude of China's demand shocks was larger than that of its competition shocks. However, competition shocks became more important in recent years, and were highly heterogeneous across countries and industries. Building on these findings, the paper documents the current degree of exposure of Belt and Road economies to China trade shocks, and discusses policy options to deal with trade-induced adjustment costs.

Document type: Book

Traffic, Air Pollution, and Distributional Impacts in Dar es Salaam: A Spatial Analysis with New Satellite Data

Scipedia content — Wed, 14 Oct 2020 16:13:46 +0200

Air pollution from vehicular traffic is a major source of health damage in urban areas. The problems of urban traffic and pollution are essentially geographic, because their incidence and impacts depend on the spatial distribution of economic activities, households, and transport links. This paper uses satellite images to investigate the spatial dynamics of vehicle traffic, air pollution, and exposure of vulnerable residents in the Dar es Salaam metro region of Tanzania. The results highlight significant impacts of seasonal weather (temperature, humidity, and wind-speed factors) on the spatial distribution and intensity of air pollution from vehicle emissions. These effects on the metro region's air quality vary highly by area. During seasons when weather factors maximize pollution, the worst exposure occurs in areas along the wind path of high-traffic roadways. The research identifies core areas where congestion reduction would yield the greatest exposure reduction for children and the elderly in poor households.

Document type: Book

The ecological impact of transportation infrastructure

Scipedia content — Wed, 14 Oct 2020 15:42:08 +0200

There is a long-standing debate over whether new roads unavoidably lead to environmental damage, especially forest loss, but causal identification has been elusive. Using multiple causal identification strategies, this paper studies the construction of new rural roads to over 100,000 villages and the upgrading of 10,000 kilometers of national highways in India. The new rural roads had precise zero effects on local deforestation. In contrast, the highway upgrades caused substantial forest loss, which appears to be driven by increased timber demand along the transportation corridors. In terms of forests, last mile connectivity had a negligible environmental cost, while expansion of major corridors had important environmental impacts.

Document type: Book

Rural Roads and Local Economic Development

Scipedia content — Wed, 14 Oct 2020 15:35:11 +0200

Nearly one billion people worldwide live in rural areas without access to the paved road network. This paper measures the impacts of India's $40 billion national rural road construction program using regression discontinuity and data covering every individual and firm in rural India. The main effect of new feeder roads is to allow workers to obtain nonfarm work. However, there are no major changes in consumption, assets or agricultural outcomes. Nonfarm employment in the village expands only slightly, suggesting the new work is found outside of the village. Even with better market connections, remote areas may continue to lack economic opportunities.

Document type: Book

Phrasal verbs in general english and traffic engineering and their serbian equivalents

Scipedia content — Wed, 14 Oct 2020 14:55:45 +0200

Document type: Part of book or chapter of book

Commercial arrangements and liability for crossing pipelines power cables and telecom cables connectors on the seabed

Scipedia content — Wed, 14 Oct 2020 14:44:20 +0200

Document type: Part of book or chapter of book

Societal issues and environmental citizenship

Scipedia content — Wed, 14 Oct 2020 13:59:45 +0200

This chapter investigates the role of Environmental Citizenship within the twenty-first-century societal issues of human activities - urban development, transport systems, tourism, and cultural heritage. The first part of the chapter analyses the relationship between Environmental Citizenship, urban development, and cultural landscapes. Cities are home to the majority of the worlds population and are responsible for most of the resource consumption and waste production, which places them in the focus of Environmental Citizenship discourses. The issues of urbanisation and Environmental Citizenship are followed by issues of sustainable transport that, among others, have a goal of reducing transport disadvantage of marginalized social groups. Cultural heritage is identified as a new fourth pillar of sustainable development (along with environment, economy and society), and its role in Environmental Citizenship is explored. Sustainable tourism is reviewed using new approaches that have adopted elements of Environmental Citizenship and were introduced as a reaction to unsustainable mass tourism. Finally, the chapter presents certain practices of Environmental Citizenship within the investigated fields of expertise that could be promoted and implemented elsewhere. Document type: Part of book or chapter of book

Balancing competing interests when building marine energy infrastructures the case of the nord stream pipelines

Scipedia content — Wed, 14 Oct 2020 12:52:32 +0200

Document type: Part of book or chapter of book

Maize price volatility: does market remoteness matter?

Scipedia content — Wed, 14 Oct 2020 12:48:41 +0200

This paper addresses the role of market remoteness in explaining maize price volatility in Burkina Faso. A model of price formation is introduced to demonstrate formally that transport costs between urban and rural markets exac¬erbate maize price volatility. Empirical support is provided to the proposition by exploring an unusually rich data set of monthly maize price series across 28 markets over 200413. The methodology relies on an autoregressive conditional heteroskedasticity model to investigate the statistical effect of road quality and distance from urban consumption cen¬ters on maize price volatility. The analysis finds that maize price volatility is greatest in remote markets. The results also show that maize-surplus markets and markets bordering Côte d'Ivoire, Ghana and Togo have experienced more vola¬tile prices than maize-deficit and non-bordering markets. The findings suggest that enhancing road infrastructure would strengthen the links between rural markets and major consumption centers, thereby also stabilizing maize prices. (Résumé d'auteur)

Document type: Book

Evaluation of the performance of ballasted railway structures subjected to high-speed train loads by the Discrete Element Method

Joaquín Irazábal González — Fri, 09 Oct 2020 13:00:03 +0200

Conventional and high-speed train lines are being constructed all over the world with the objective of improving the mobility of both people and goods. Most of these infrastructures are built with railway ballast, a granular material whose main functions are resisting train loads and facing climate actions. The growth in popularity of railway infrastructures has led to an increasing interest in the development of numerical models to evaluate their performance and improve their maintenance. To this respect, the Discrete Element Method (DEM) is an approach that considers the discontinuous nature of granular materials, such as railway ballast. Moreover, it can also be used to compute the behaviour of continuum materials, such as rails and bearing plates, applying the so-called bonded DEM. The code used is developed within DEMPack, a specific software tool for modelling physical problems using the DEM. After evaluating the different geometrical alternatives for representing railway ballast and considering the high amount of material involved in the full-scale tests (more than 130,000 particles) the calculations were carried out using the most efficient option, spheres with rolling friction. This geometrical simplification is not suitable for small-scale tests, however, previous analysis showed that it is accurate enough for reproducing the macroscopic behaviour of the ballast layer. The numerical results correctly capture the effect of changing several parameters such as ballast compaction, inter-particle friction or grain size. It can be concluded that the DEM increases the possibilities for analysing innovative solutions aiming to improve ballasted tracks design, maintenance and performance, since real case-scenarios can be studied with enough accuracy and feasible time.

Revista Gaceta Técnica. Editorial. 21(2), 1-3, julio-diciembre, 2020 ISSN 1856-9560 (Impreso) ISSN: 2477-9539 (Internet) Depósito Legal pp 1999907LA22 ppi201602LA4730

Luisa Casadei — Thu, 08 Oct 2020 22:38:16 +0200

PROPUESTAS DE CONECTIVIDAD DEL CASCO HISTÓRICO DE BARQUISIMETO CON OTROS SECTORES DE LA CIUDAD PROPOSAL FOR BARQUISIMETO´S HISTORICAL CENTER´S CONNECTIVITY WITH OTHER SECTORS OF THE CITY

Luisa Casadei — Thu, 08 Oct 2020 22:38:12 +0200

A series of urban proposals is presented below, designed to connect the historic center of the city of Barquisimeto in Venezuela, with other sectors of the city. Large buildings where different legislative, administrative and judicial bodies of the Lara State operate in an area surround Works of great architectural and historical value dating from the 19th century stand out, with touches of modernity since it. The proposals involved correspond to the design of super blocks, a network of bicycle lanes, a university transportation system called UCLA University Route, and a large historical library. All this in order to achieve connectivity not only from a spatial point of view through mobility systems, but also through the emotional connection of the citizen to that sector, achieving that attachment or sense of belonging.

EVALUACIÓN DE DESPLAZAMIENTOS EN EDIFICIOS DE HORMIGÓN ARMADO PARA EL FUNCIONAMIENTO DE ANTENAS 5G EN CHILE ASSESSMENT OF DISPLACEMENTS IN REINFORCED CONCRETE BUILDINGS FOR THE OPERATION OF 5G ANTENNAS IN CHILE

Luisa Casadei — Thu, 08 Oct 2020 22:38:09 +0200

The imminent emergence of 5G networks in the Chilean telecommunications market has made it essential to anticipate the possible imbalances that these could reach when any of the earthquakes that repeatedly strike the country occurs. To do this, a methodology based on conventional linear elastic analysis, both spectral modal and time-history, has been formulated to estimate the induced displacements for two different levels of strong ground movements, based on seismic records obtained in the subduction zone. The results obtained have served to obtain fairly adjusted analytical expressions, formulated from a single system variable, the height of the level, so that they can be used to quickly estimate the lateral displacements of the 5G antennas that will be networked, by personnel who has no training in structural dynamics, but who will be in charge of making the adjustments in the 5G network nodes.

ANÁLISIS DEL CONGESTIONAMIENTO VEHICULAR PARA EL MEJORAMIENTO DE VÍA PRINCIPAL EN GUAYAQUIL-ECUADOR ANALYSIS OF TRAFFIC CONGESTION FOR THE IMPROVEMENT OF A MAIN ROAD IN GUAYAQUILECUADOR

Luisa Casadei — Thu, 08 Oct 2020 22:38:06 +0200

In Guayaquil-Ecuador, Av. Pedro Menéndez Gilbert is a main road with a designed capacity of 9000 vehicles/h, currently presenting traffic congestion problems, which affects its users. In order to propose possible solutions to the mobility problem, the research carried out aimed to analyze alternatives that would improve the level of service. The data collection method consisted of observation, with fieldwork at the entrance and exit intersections of a 900-m-long section. Manual counts and vehicle categorization were carried out for one week, as well as counting the distribution times of the traffic lights. The intersections were characterized in their geometry, traffic flows and traffic light system. Based on a previous study, a 5-year increase from 135,170 vehicles to 190,424 vehicles was projected. It was found that the main causes of congestion are the distribution of the alternating times of the signal cycle, and the blockage that occurs by the Metrovía feeder and collector buses. It is concluded that the main solution is the updating and proper adjustment of the traffic light system, as well as the opening of a pre-existing exit road, prior to the intersection, and control of the blockage produced by the Metrovía units.

PROPUESTA DE UN PLAN ESPECIAL URBANO PARA LA ZONA MACROSECTOR CENTRO DE BARQUISIMETO, ESTADO LARA PROPOSAL OF A SPECIAL URBAN PLAN FOR THE MACROSECTOR ZONE IN THE CENTER OF BARQUISIMETO, LARA STATE

Luisa Casadei — Thu, 08 Oct 2020 22:38:02 +0200

This article is about the elaboration of a special plan for a zone of the Macrosector Center of Barquisimeto, derived from a situational analysis of the urban structure, social organization, resident population, roads and requirements of urban equipment. Elements of both traditional and strategic planning were combined in a complementary way. In order to create an urban, organized, planned and sustainable space, where the needs and requirements of its inhabitants are covered in the economic, social and cultural aspects, and where their rights and duties as citizens are promoted both today and in the course of the next ten years. The proposed strategic guidelines seek to promote the execution of the action program over time and identifying the public, private or social organizations that will lead each action. This study ends with a proposal that is specified in two housing projects in accordance with the urban environment and current urban regulations.

Editorial

Luisa Casadei — Thu, 08 Oct 2020 22:28:16 +0200

Proposal for Barquisimeto´s historical center´s connectivity with other sectors of the city

Luisa Casadei — Thu, 08 Oct 2020 22:28:13 +0200

Assessment of displacements in reinforced concrete buildings for the operation of 5G antennas in Chile

Luisa Casadei — Thu, 08 Oct 2020 22:28:09 +0200

Analysis of traffic congestion for the improvement of a main road in Guayaquil-Ecuador

Luisa Casadei — Thu, 08 Oct 2020 22:28:06 +0200

Proposal of a special urban plan for the Macrosector zone in the Center of Barquisimeto, Lara State

Luisa Casadei — Thu, 08 Oct 2020 22:28:02 +0200

Towards the Virtual Wind Tunnel for civil engineering applications

María Jesús Samper — Tue, 06 Oct 2020 14:19:06 +0200

This monograph develops a numerical tool (the Virtual Wind Tunnel, VWT) for the
reso-lution of problems involving fluid flow around structures. Due to the limitations
that traditional methods may have in this context, the VWT is based on the use of fixed
mesh technologies (CutFEM-type) combined with an implicit representation of the
embedded bodies.
One of the main contributions of the monograph is the use of such fixed mesh methods to
solve lightweight thin-walled structures problems. Hence, two embedded formulations
capable of representing the flow around bodies with and without internal volume are
proposed. The first one results in a simpler implementation and lower computational
effort but can only represent a slip behavior of the wall. The second one gets rid of such
limitation by including a Nitsche imposition of the Navier-slip condition, thus allowing
modelling any wall behavior as a wall law would do.
The applicability range of the VWT includes the fluid–structure i nteraction problem
(FSI). To that purpose an improvement for the boundary condition imposition of the
FM-ALE algorithm mesh motion problem is also proposed. Moreover, the implementation,
which has been conceived to be easily extended to any other coupled problem, is
also treated.
The validation of the technologies within the VWT includes multiple theoretical test
cases as well as feasible industrial applications. Among these, the FSI analysis of a
4-point tent during a strong wind episode deserves to be highlighted as it showcases the
achievement of the initial objective of the monograph.

Hempcrete Buildings: Environmental Sustainability and Durability of Two Case-studies in North and South Italy

Scipedia content — Tue, 06 Oct 2020 10:02:45 +0200

In the framework of Circular Economy policies aimed at reducing the consumption of raw materials, shives, as an agricultural by-product of hemp cultivation, have gained a renovated life in the construction sector. Its excellent thermal insulating properties permitted the development of new building materials to be used in various executive technologies. When shives are mixed with a mineral binder such as lime or cement, the mixture is usually referred to as hempcrete. In Italy, the use of hempcrete and the development of new production chains and implementation techniques dates back only to about the last decade, while other European countries have more long-lasting experiences (90s). In order to assess the potential benefits of hempcrete in the construction sector, its environmental performances were evaluated using the LCA methodology, by comparing four non-loadbearing representative walls, one made with hempcrete blocks and the others with more “traditional” materials.

This research constitutes a solid basis for the development of future guidelines and/or regulations at national and international level in order to guarantee the maximum diffusion of this type of product. Then, a study has been carried out regarding the functionality of hempcrete blocks in masonry, layered with finishing plaster made of fine hemp shives, to evaluate the in-situ hygrothermal building performance. In particular, measurement methods were developed and analysis were carried out on two houses, one in northern Italy and one in southern Italy, and precisely in Sicily, focusing the study on the performances of the walls subjected to warm Mediterranean climates. Indeed, the literature on masonry behavior in hot Mediterranean climates is much scarcer than in cold climates.

Grain Size Analysis of Class C Fly ash Used for Aluminium-Silicate Binders

Scipedia content — Thu, 01 Oct 2020 09:30:14 +0200

Concrete structures are constantly moving in the direction of improving the durability. Durability depends on many factors, which are the composition of concrete mix, the usage of additives and admixtures and also the place, where material will work and carry the load. Taking into account that the consumption of cement on the globe gives way only to the consumption of drinking water, the issue of concrete technology begins to take on an economic and ecological aspect. Mentioned above the aspect of durability is strictly connected to economy. Due to huge amount of greenhouse gasses produced in the process of calcination, the ordinary Portland cements are responsible for even 8% of anthropogenic carbon dioxide production. This paper is focused on properties of materials known as green binders. They can be used to produce aluminium-siliceous binders and green concretes which can also be known as geopolymer concretes. Often used in construction industry, class F fly ashes are also good substratum also for aluminium- siliceous binders. Nevertheless amount of available class F fly ashes do not give the possibility to replace ordinary cements by aluminium-silicate one produced from this type of ash. This raises the need to look for replacement solutions for the substrate of the new green adhesive. As the substrate of new eco-binders there were used fly ash which came from coal and high calcium ash from the burning of lignite, called class C fly ashes. However not processed one, cannot compete with Portland cements due to durability. It surely depends on many aspects of polymerization process, which are for example maturation environment, concentration and type of alkaline activator, but the most important are parameters of fly ash substrate. This is because main attention was paid to granulation of examined class C fly ashes which have been subjected to a grinding process involving milling in a magnetic mill and subjected to ultrasonic waves. The analysis of grain change was presented in the aspect of the possibility of increasing the strength and durability of the cement material.

Prescription of Maintenance Interventions by the New Generation of Eurocodes for Climate-Change Resilient Structures

Scipedia content — Mon, 28 Sep 2020 12:59:00 +0200

The new generation of structural Eurocodes will include climate change adaption measures in order to enhance the climate resilience of infrastructures across Europe. This paper discusses the impact that climate change might have on reinforced concrete structures subjected to corrosion, and the associated challenges of the standardisation of adaptation measures. A resilience-based framework is proposed for the adaptation of structural codes to climate change-induced actions. Such an approach aims to provide the required adaptive capacity to the new structures in order to be able to respond to the uncertain future minimising the investment under unlikely scenarios. In that way, the strategy can be summarised as a climate change-adapted design plus an in-design maintenance plan. Future actions, such as mapping the future climate-related drivers of corrosion, the determination of the design values of these drivers, and the prescription of maintenance activities, should be further investigated. Although this paper focuses on the new structures that will be designed with the new codes, some of the insights can be extrapolated to the existing structures.

Failure Analysis of a Total Damage by Hail Impact of an External Thermal Insulation Composite Systems

Scipedia content — Mon, 28 Sep 2020 12:58:54 +0200

A hailstorm has heavily damaged a glass fibre mesh reinforced mineral render of an externally insulated composite system (ETICS) of a family house. While a neighbouring house of identical design and of the same age showed only minor defects, for the house under investigation it was a total failure of the render. Material probes were taken from the damaged façade and analysed physically and chemically. Before renovation, the hail resistance of the façade was determined with a unique artificial hail impact test method: Clear ice balls were shot against the façade with the help of a launcher, where the kinetic energy of the projectile can precisely be controlled. The type of damage due to natural hail could be reproduced. The impact energy needed to cause a damage similar to the one caused by the natural hail was determined. The hail impact damage was also identical to results from hail testing performed in the laboratory on similar systems. Since the amount of rendering material on the façade was not according to standards of the Swiss Society of Engineers and Architects - it was by far too thin - specific laboratory tests were performed with specimens not only made of similar materials but also with a comparable thin render layer. By systematic variation of the projectile size and its velocity, the impact parameters were studied and correlated to the type and extent of the hail impact damage. A threshold, associated with the first appearance of full circle cracks in the render, was found to be a kinetic energy of 2.5 J. The assessment of a supposed thickness effect and an effect of doubling the reinforcement on the hail impact resistance and the effect of the age of the façade however was a challenge. The methodological limitations given by the circumstances and the approach used are discussed in this paper.

Hygrothermal Regulation of Brick Masonry of Nanjing City Wall by Plants

Scipedia content — Mon, 28 Sep 2020 12:58:47 +0200

Nanjing City Wall, one of the most important cultural heritages in China, has been damaged in a natural environment for centuries. Plants can be a candidate to regulate the micro-environment and mitigate the influence of local climates, which cannot be easily controlled by human efforts. Therefore, we examined the potential of the roadside trees along the City Wall to buffer the hygrothermal cycles that can deteriorate the City Wall. We surveyed the deteriorated state and measured the temperature and moisture content of the City Wall. Measured results showed smaller temperature fluctuation at shaded surface than the unshaded with a maximum temperature difference of 10.9 ℃ in summer. The measured water content decreased with height. A coupled two–dimensional hygrothermal ‘City Wall–plant’ model was proposed to clarify the influence of the roadside trees on the hygrothermal distribution of the City Wall. The proposed city wall-plant hygrothermal model could predict the surface temperature and water content well.

Prolonging the Durability and Conservation of Historic Materials by Microclimatic Monitoring in the Archaeological Areas

Scipedia content — Mon, 28 Sep 2020 12:58:41 +0200

Many factors have to be considered for the correct conservation of cultural heritage, in particular, the exposition of the object/site to open air, as the archaeological sites have. The risk factors can be intrinsic (durability of materials, construction and decorative techniques) and extrinsic (environmental and microclimatic conditions). The consideration of the conservation issue regarding the second has to take into account the effects the microclimatic parameters on the objects and the variation of microclimate for the use, as well as the modification due to the improvement of accessibility, safety and installations (for example plant and architecture addition/modification). In fact, the main objective of the conservation/fruition of the archaeological areas is achieving the project choices most integrated, functional and adequate to meet the needs of conservation. Monitoring and diagnostics are a necessary condition to be able to correctly define the design choices. The proposed contribution aims to specify how monitoring the microclimatic values play a fundamental role in the whole process of conservation, since the early study to the management of the site, to ensure the greater conservation and durability of the material and, ultimately, the best fruition at present and in the future.

Gold Leaf Murano Glass Piastras‘ Performance in the Trencadís Catalan Modernism Mosaic: Recognition of Primary Alteration Patterns

Scipedia content — Mon, 28 Sep 2020 12:58:35 +0200

Gold leaf Murano glass is a unique product that over the centuries, especially during Byzantine period, has been used as facing forming big flat or curved mosaics that result in an architecture full of light and symbolism. This product is presented in a format of squared piastras with the same approximate dimensions that the gold leaves ones have (8x8 cm). Piastras are cut in smaller squares (1-1,5cm) in order to obtain the tiles that form mosaic’s cladding. This cladding technique was incorporated during Catalan Modernism. Through this technique, beautiful pieces of tesseras of gold leaf Murano glass combined with others of opaline glass. In order to overcome the artistic challenges from this architectural movement, new mosaics were placed outdoors in order to shine by the incident sun beams and the square tiles were replaced by irregular tiles that form polygonal meshes capable of coating double curvature surfaces with great elegance. This location and prolonged exposure to the weather cause, over time, a deteriorated appearance, despite being composed of great resistant materials such as gold and glass. Studies oriented to know the phenomenology of this deterioration are being carried out and its impact on the expected durability of this coating. Being a handmade product and completely manual execution, the first studies have aimed to identify the primary anomalies that are originally generated in the different layers of this product at the time of manufacture, transport and handling. Knowing these primary anomalies must allow to prevent their occurrence and reduce their incidence in the manifestation of so-called secondary anomalies. All this in order to prolong the useful life of this appreciated architectural cladding.

A Vector Scale of Severity of Damages in Buildings

Scipedia content — Mon, 28 Sep 2020 12:58:29 +0200

In the context of the existing buildings, along the recent years the concept of maintenance has changed from corrective maintenance to preventive maintenance, which is based in part on periodic inspections. There is ample evidence that preventive maintenance is more efficient than corrective maintenance, since severe deteriorations that may represent danger to people are avoided, and also money is saved. To make periodic inspections of the buildings is useful to quantify the extent to which deficiencies are severe or not, in order to facilitate decision making and prioritize therapeutic interventions. To this purpose many scales have been used and are used to assess the degree of gravity of the damages in constructive elements. But it is important to say that there is no common consensus and these scales are different between them according to the study to which they belong. Thus, the main goal of this article is to propose a methodology for calculating the degree of severity of damages in buildings, which is of widespread use. This calculation method, which is in distribution and in scalar, lets to calculate the severity index of systems and of the entire building, and it is easy to use and flexible.

A 3D Model for Building Condition Assessment

Scipedia content — Mon, 28 Sep 2020 12:58:23 +0200

The aim of the paper is to analyze practical aspects with use of 3D Model for accurate building condition assessment. Use of fully interactive visualization methods from a technical condition assessment platform going to be, especially taking into consideration current COVID-19 scenarios, a very supportive tool for the massive inspection of building stocks, particularly in big residential areas. The authors present the approach based on high-performance images that were captured by Unmanned Aerial Vehicles (UAVs). The next step is the generation of a 3D model and orthophotos of building facades. The graphical information together with tables of attributes will allow the interactive geo-referenced management and assessment, that is proposed as a form of interactive cooperation. The idea of this approach corresponds widely with the Building Information Modeling aims. The authors introduce the methodology, stages of the inventory and follow-up process carried out within the platform requirements together with advantages of the visualization techniques, basing on a particular case study. Technical details about the information system and the analysis connected with the visualization utility will be presented and illustrated.

A Nonparametric Statistical Model for the Selection of Significant Variables Acting in the Deterioration of Built Façades

Scipedia content — Mon, 28 Sep 2020 12:58:17 +0200

Serrat and Gibert (2011) introduced the use of survival analysis techniques for the study of time-to-failure in the facades of a building stock. Those techniques have been implemented in a predictive system that incorporates the inspection methodology together with the statistical methodology. The system proposes a network of urban laboratories for building research analysis and information with the aim of modelling the degradation time based on the information from all the cities participating in the project, from a multiscale perspective. The approach is population based, that is from the manager of the building stock point of view, in order to obtain information on the evolution of the stock across time, and to help the manager with decision making process on global maintenance strategies. However, for an efficient decision making it is crucial to determine those covariates -like materials, morphology and characteristics of the facade, orientation or environmental conditions- that play a significant role in the progression of different failures along the façade service life. The proposed platform also incorporates an open source GIS plugin that includes survival and test moduli that allow the investigator to model the time until a damage when taking into account the variables collected during the inspection process. The aim of the paper is to introduce the methodology and the modelling strategy for the deteriorating process of an urban front. The contribution will be illustrated with a case study located in the city of L’Hospitalet de Llobregat (Barcelona, Spain) in which more than 14,000 facades have been inspected and analyzed.

Structural Reliability of Bridges Made with EAF Concretes

Scipedia content — Mon, 28 Sep 2020 12:58:11 +0200

The development of sustainable concretes is becoming an emerging issue in civil construction sector. The use of Electric Arc Furnace (EAF) slag aggregates in the production of concretes is one way to fulfill sustainability goals. Past research demonstrated a significant increase of mechanical properties of EAF concretes when compared with ones made with natural aggregates (NA); however, at the same time, their use implies also an increase of self-weight loads. The present contribution aims to investigate the reliability of structural systems realized with EAF concretes, with special emphasis to bridge structures. Two different bridge types, considered as case-study examples, are designed considering ordinary concrete mixes, and subsequently, a reliability analysis is run for each EAF concrete class in order to investigate the variation of structural safety margins related to the use of the sustainable EAF concretes in replacement to the ordinary NA concrete mix.

Carbonation Effect on the Chloride Profile

Scipedia content — Mon, 28 Sep 2020 12:58:05 +0200

In natural marine exposures, the chloride profile may have a maximum in the concrete surface (surface concentration) or this maximum may appear some mm or even centimeters, in depth. This fact has been attributed to a) a “washing effect” due the continuous action of the sea water, b) the wet and dry “convection” induced by the action of the sea water waves c) the leaching of the hydroxide ions or d) the carbonation of the external layer of concrete. In a test in the laboratory, the profile resulting in a diffusion chloride test in most of the cases presents the maximum in the surface of the specimen but seldom has this maximum beyond the surface. This behaviour in natural and in laboratory conditions, although noticed, has not been satisfactorily explained. The author has addressed the problem in a previous communication. In present one shows evidences on the role of the carbonates/bicarbonates in the water of the testing solution. It can be deduced from the analysis of the profiles obtained with de-carbonated solutions that the carbonates/bicarbonates ions compete with the chlorides in the binding with the hydrated cement phases, which results in a modification of the chloride profile and a different diffusion coefficient. The maximum seems to be produced by the higher mobility of the chloride with respect to the carbonate/bicarbonate. The bound chlorides are displaced by the carbonation and the free chlorides move inside forward. In the external parts less total chlorides are noticed because the free chlorides are function of the bound chlorides.

Fire Properties of Novel Cellulosic Material Modified with Expandable Graphite

Scipedia content — Mon, 28 Sep 2020 12:57:59 +0200

Expandable graphite (EG) is an intumescent additive known to improve fire properties of various materials. Intumescent fire retardant (IFR) based on EG is a protection method for flammable materials taking the attention of researchers in the past few years (Xie et al., 2000). New studies indicate that EG is a good source of carbonization agent for effective and environmentally friendly intumescent systems (Feng et al. 2013). Although EG is used in a growing number of IFR systems as a blowing agent that will suppress flammable gases up to 75%, while reducing the flame spread index, its application to cellulosic material is not so popular in the cellulose industry today (Krassowski et al., 2012). The current study focuses on flammability, concerning cellulose modified material(CMM). The objective of this work was CMM encrusted with EG. The general aim of the research was to determine its basic fire resistance properties. The scope of the research included measurement of the following parameters: time to ignition (Ti), time to flame out (Tf), total heat peak (THR) and mass loss (ML). Samples of CMM sheets were manufactured with the use of hydropulper and rapid-koethen devices. Two types of EG (i.e. ES20 C200 and ES100 C10) were used. Sodra Black Cellulose fibres (700 kg/N3) was used in this experiment. Cellulose milling time was 30 min. and drying time of 40 min. The drying temperature of the final sheets was controlled and kept at 930C to avoid graphite activation. Final sheets were conditioned at room temperature at 200C and relative humidity 60%. With heat flux of 35 kW/m2 , all samples were tested on MLC apparatus. The addition of EG was found to increase the flame retardant effectiveness of cellulosic material. Although Ti for all CMM species were lower than that of control samples, this fact actually favored the promotion of char forming, which led to a longer combustion process for all CMM.

Preventing Damage by Updating Moisture Control Standards

Scipedia content — Mon, 28 Sep 2020 12:57:53 +0200

Despite progress in moisture control analysis, repairing moisture damage is still a considerable cost factor in the building sector. While there are many reasons for the lack of improvement during the last decades, inadequate moisture control standards are certainly also to blame. In many countries, interstitial condensation calculations according to Glaser are the sole means for assessing moisture control design, neglecting other important moisture loads such as driving rain, construction moisture and air infiltration. To overcome this lopsided focus on vapour diffusion, the update of the German moisture control standard has restricted the applicability of the Glaser method and introduced a normative Annex on performance evaluation by hygrothermal simulation. Recently, a new project has started to develop advanced models helping to evaluate the simulation results. Currently, it is already possible to assess the risk of mould growth, rot, and critical moisture accumulation by methods referred to in this standards. Also addressed in the standard is the selection of critical indoor and outdoor boundary conditions. Thus, it is officially encouraged to perform hygrothermal simulation, giving architects and engineers the chance to design more moisture tolerant and ultimately more durable constructions. Considering the necessity to reduce the carbon footprint of buildings, the application of hygrothermal simulation provides the opportunity to use more innovative renewable and recycled materials that could not adequately be judged by the Glaser method. Another benefit presents the analysis of construction resilience in case of natural disaster such as flooding or extreme rain events.

The Structural Strengthening of a Masonry Heritage Shop House using Glass Fibre Based Materials

Scipedia content — Mon, 28 Sep 2020 12:57:47 +0200

A two-storey masonry pre-war shop house in Taiping, Malaysia was badly affected by construction being undertaken at an adjacent lot. The building was in a serious state of disrepair and on the verge of collapse at the time of the investigation and temporary propping and a stoppage of adjacent works had to be imposed. For the remedial intervention a rapid approach was critical with materials and methodologies selected to incur minimum additional impacts on the building in terms of physical works and with flexibility on site. Several innovative techniques developed for the structural intervention of masonry buildings was considered. In this case the masonry wall cracks were repaired by a stitching method using the glass fiber rod maperod g which was considered a suitable material due to the compatibility of modulus of elasticity (40,800N/mm2) to the lime mortar, having good tensile strength of 760 N/mm2 to help bridge the cracks in case of further movement and is also corrosion resistant and will remain protected in future even though it is embedded in a highly porous masonry substrate. The materials used were easily transportable, flexible (ie) could be prepared to requirements on site and could be delivered to site quickly despite this being imported. The approach taken resulted in a rapid reinstatement of the building, minimised the risk of losing heritage features and matched the client’s overall objectives. The paper provides details of the approach taken and the basis for the remedial intervention.

The Business Case for Re-Usable Buildings - Business Models, Systems Diagnosis and Case for Action

Scipedia content — Mon, 28 Sep 2020 12:57:41 +0200

This paper presents the results of a pathfinder project on re-usable buildings which was part funded by Climate- KIC, supported by the EIT, a body of the European Union. It places reusable buildings in the context of sustainability generally, and specifically within the general theme of circular economy transition. It includes a brief summary of the literature review undertaken, focussing on challenges and benefits to the business case for adoption of reusable buildings.

Innovative Environment-Friendly Interior Finishing Technologies Resistant to Mold Growth

Scipedia content — Mon, 28 Sep 2020 12:57:35 +0200

Excessive mold development in interior spaces can be the cause of health problems in their users, as well as of a decrease in the comfort of use of internal spaces. The aim of our study was the development of a service that can ensure the long-term elimination of the cause and effects of mold in buildings by using new compositions of materials and finish application techniques. For this purpose, the most mold-resistant variants of construction material compositions and the technology of their application were selected. The study features an analysis of 18 variants of samples taken from climatic boards with various building finishes, which were tested for resistance to three species of mold: A. versicolor, Ch. globosum and P. funiculosum, under different climate and humidity combinations. The results of the study pointed to the most effective anti-mold technology. One comprehensive solution that can improve the conditions of the use of interior spaces is an external wall interior thermal insulation application system that employs silicate and lime sheets.

Predominant Climate Exposure Strains - Thermal Degradation Testing Compared to Historical and Future Climate Scenarios

Scipedia content — Mon, 28 Sep 2020 12:57:29 +0200

The service life of a building or structure is often presumed to be 60 years. Products usedin the building envelope are often covered by a facade material on the exterior side. Hence, the failure of these products is not easily observable, and the repair or replacement is normally not technically nor economically feasible. Thus, these products are expected to endure the entire estimated lifetime of the building. Service life prediction of these products is based on accelerated ageing tests, whose aim is to measure future possibilities of materials‘ durability under their expected service life. Preliminary calculations of acceleration factors are discussed and related to historical and future climate scenarios for a dataset from Calgary, Canada. The changes in temperature threshold values for this dataset is significant. Relating the measured values to a duration of a typical accelerated durability test indicates that the test duration is sufficient for a service life of 102 years according to historical climate, but only 52 years taking into account an assumed climate change.

Sustainability and Maintainability of High Rise Vertical Greenery Systems (VGS): its Lessons and Assessment Scoresheet

Scipedia content — Mon, 28 Sep 2020 12:57:23 +0200

Vertical Greenery Systems (VGS) applied on building has proven economic, environmental and social benefits which made it one of the widely accepted green building design strategies to support sustainable development. However, incorporating vertical greenery systems into innovative facades generates maintainability challenges. This paper highlights the best and good practices Design for Maintainability scoresheet, as well as the VGS defects and issues. The Design for Maintainability (DfM) assessment scoresheet will be beneficial in assessing and avoiding potential VGS defects leading to its maximum performance, longevity and sustainability. This research has established a list of best practice guidelines and measures with weighted scoring system for evaluating the maximum performance and efficient maintainability of VGS applications on facades while minimizing cost, risks, negative environmental impacts and consumption of matter/energy. The paper’s contribution will be the improvement of the designers’ decision making process, expanded library on vertical greenery systems defects as well as the importance of integrating maintainability of high-rise VGS facades in tropical conditions during its design inception.

Sulfate Resistance of Blended Cements (Limestone Illite Calcined Clay) Exposed Without Previous Curing

Scipedia content — Mon, 28 Sep 2020 12:57:16 +0200

Durability in aggressive environments is an important factor to extend the service life of concrete and the use ternary blended cements (limestone filler + calcined clays) can contribute to this purpose. In sulfate environments, the effects of supplementary cementing materials depend on the concentration, Portland cement and the progress of hydration reactions. Low level of limestone filler replacement influences the stabilization of AFt due to formation of monocarboaluminate, but high replacement increases the effective w/c and the capillary porosity promoting sulfate penetration. The use of active pozzolans suppresses the sulfate attack by minimizing both ettringite and gypsum formation. It is generally assumed that curing prior to sulfate exposure should be extended to allow the development of the pozzolanic reaction and subsequent reduction of portlandite content, pore size structure refinement and permeability reduction. However, in most field applications, concretes exposed to sulfate attack are cast in situ and thus, these are exposed to sulfate since early ages. This paper evaluatesthe sulfate resistance of an illitic-calcined clay and limestone filler when the cement is exposed immediately to aggressive environments. In this paper, the external sulfate resistance of blended cements containing 30% replacement of limestone filler and/or calcined clay (C30F, C30CC and C15F15CC) are analysed. Two different calcined clays from Buenos Aires, Argentina were selected. Mortar prisms and cement paste cubes were fabricated and exposed to a sodium sulfate solution after 2 days. Comparison ofsulfate resistance was based on the expansion, mass variation, visual appearance and compressive strength . Furthermore, the evolution of microstructure of blended cements exposed to sodium sulfate solution was characterized by XRD tests on the external surface and the core of cementblended pastes.

Detailed Modelling of the Masonry Unit-Mortar Interface Using Hygrothermal Simulation

Scipedia content — Mon, 28 Sep 2020 12:57:10 +0200

Hygrothermal models are important tool for assessing the risk of moisture-related decay mechanisms in historic masonry structures. However, there are significant uncertainties in the process related to material properties, boundary conditions and quality of construction that effect confidence in the model’s predictions compared to measured values. This paper examines one potential source of uncertainty; the imperfect nature of mortar joints inmasonry walls, exemplified by such things as open joints, hairline cracks and imperfect bonds at the interface between mortar and unit. These are rarely considered in hygrothermal modelling in detail, where perfect interfaces are typically inferred. The premise is that at this interface, liquid transport behaviour is more similar to that of a fracture than that of a bundle of capillaries. These fractures of varying heights (or aperture) can affect transport into and out of the plane of the wall (perpendicular plane) and impede the liquid transport between mortar and the masonry unit (in-plane). This could lead to the “effective” moisture transport being different than what would be predicted using measured bulk material properties. A more detailed method for modelling this interface, borrowing techniques from the field of geohydrology is presented which demonstrates the effect that detailed modelling of the mortar joint has on moisture transport in masonry. A brick wall with cement mortar is studied. A twodimensional hygrothermal model was created to demonstrate the effect of increased liquid conductivity into the wall cause by fractures.

Improving Frost Durability Prediction based on Relationship between Pore Structure and Water Absorption

Scipedia content — Mon, 28 Sep 2020 12:57:03 +0200

In North America, clay bricks are qualified as durable if they meet either the ASTM C216 or CAN/CSA A82.1 standard. Although these standards are widely used in North America, they have not been linked with pore Structure (PS). Furthermore, moisture content and pore structure (PS) are two significant parameters that influence the performance of clay bricks during the freezing-thawing process. Thus, finding a relationship between them will lead to a quick assessment of water absorption (WA) and knowing their effect on frost resistance (FR). This work aims to investigate the relationship between PS and WA of clay bricks. Five different types of clay bricks were examined. WA of brick samples was determined according to the CAN/CSA A82.1 standard. Mercury Intrusion Porosimetry (MIP) was used to determine the total porosity and pore size distribution (PSD). The variation of 24-h cold water absorption (CWA) among samples of each type of brick was analyzed and each type of brick was divided into three groups according to their 24-h CWA: low - medium - high. The PSD of bricks was also divided into several ranges based on the pore size. The results indicated that some types of brick have a wide variation in 24-h CWA, which could affect the frost resistance evaluation. The strong relationship between WA and PSD was found, which could be used as a base for determining 24-h CWA.

Identifying the Possibility of Using Unmanned Aerial Vehicles in the Process of Construction Projects Implementation

Scipedia content — Mon, 28 Sep 2020 12:56:57 +0200

Nowadays, dynamic progress in the field of modern technologies influences the development of unmanned aerial vehicles. The potential application area of this type of technology is constantly growing. The equipment is available to almost everyone and its use isbecoming ever easier. The aim of the article is to present the possibility of using unmanned aerial vehicles in construction projects, for economic and time reasons, as well as to perform work in places that are inaccessible or too dangerous for humans. The article is the result of literature research, expert opinions and author‘s own analyses. The article draws attention to the fact that unmanned aerial vehicles may have a number of applications and unlimited possibilities. The use of modern technologies enables the flight at different heights and within a radius of many kilometers. Due to the fact that they are equipped with various types of cameras, they constitute a useful observation tool in various projects. The article presents thermal imaging tests in the area of construction and indicates that the value of energy consumption depends mainly on the effectiveness of insulation - increase in thermal insulation, while the effective way of their diagnosis is the use of thermal imaging camera. The authors of the article conduct research on a wide range of applications of unmanned aerial vehicles in construction projects.

FRP Reinforcement for Concrete Frame Buildings at Mexico City Around 1900 to 1960

Scipedia content — Mon, 28 Sep 2020 12:56:51 +0200

Mexico City is located at a seismic region with a complex soil. That condition had an impact on buildings and their conservation; it requires to know their structural state to control strain and cracks that could cause severe damages. To accomplish that objective this research contemplates the evaluation of concrete elements to propose an alternative to restraint antique concrete deformations using FRP system.

Proven Performance: Aged TPO Field Study

Scipedia content — Mon, 28 Sep 2020 12:56:44 +0200

New thermoplastic polyolefin (TPO) roof membranes have been extensively analyzed in laboratories, roof exposure farm fields, and under accelerated weathering conditions. The ASTM International material standard specification for TPO membranes has been regularly improved since its inception to incorporate more demanding tested-product performance, including requirements for accelerated weathering and aging. Industry data on the aged performance of TPO roof membranes to date has largely been based on laboratory work, regional studies, and anecdotal case studies of TPO roofs, predominantly those that have been improperly designed and/or installed, and membranes with retired formulations that resulted in premature failure. Today, there are TPO roofs in the United States that have been in service for nearly 20 years. This paper will review the long-term performance of a large sampling of TPO roof membranes installed throughout the United States by evaluating thickness, flexibility, inspection under 7X magnification, aged seam strength, and repair weld adhesion. The intent of this study was to evaluate 1) field-aged TPO roof membrane performance and 2) the ability to repair field-aged TPO roof membranes.

The Influence of Injection Agents Applied for Carrying out Secondary Horizontal Damp Proof Courses on Masonry Mortar Properties

Scipedia content — Fri, 25 Sep 2020 13:22:30 +0200

In the article, a comparative analysis of the effects of selected substances applied to create secondary horizontal damp proof courses of masonry walls by means of the chemical injection method on the properties of masonry mortar was carried out. Particular attention was given to the influence of impregnation on the hygric properties of mortar. The resistance to destructive factors accompanying the dampening of masonry wall structures was also subjected to observation.

Durability in Marine Environment of High-performance Concrete with Electric arc Furnace Slags and Cupola Slag Admixture

Scipedia content — Fri, 25 Sep 2020 13:22:23 +0200

Obtaining new building materials that are more environmentally friendly than the traditional and that guarantee an optimal response to the most demanding conditions, is one of the greatest challenges in the science of materials. The use of electric arc furnaces slags (EAFS) and cupola slag (CS) to produce a structural self-compacting concrete (SCC), involves the valorization of industrial byproducts that often end up in landfill and avoid the extraction of a natural resource. The potential qualities of these wastes make them desirable for the production of high quality concrete. Highperformance concrete mixes are designed taking advantage of the high stiffness, the peculiar geometry and the high strength of the EAFS, as well as the high pozzolanicity of the cupola slag. There are great benefits at the mechanical level with its use, but it is necessary to know more about its durability. Different mixes using basalt aggregates and silica sand are used to compare the effects of using EAFS and cupola slag admixture in mixes that have been subjected to durability tests. These tests consist of the determination of chloride ion penetration and protection against reinforcement corrosion after 10 months of exposure in tidal race. The comparisons made after subjecting the different mixes to these tests allow to conclude that chloride ions penetrate almost twice with EAFS than with natural aggregates, while no corrosion of the bars has been shown in any of the mixes.

Study of Autogenous Self-Healing in Different Mortar Formulations

Scipedia content — Fri, 25 Sep 2020 13:22:15 +0200

Autogenous self-healing of cement-based materials is a topic of current interest. This research evaluates autogenous self-healing in four types of mortars based on Portland Cement, one containing CEM II and the other 3 formulated with CEM I and different additions: fly-ashes; nanosilica and hydraulic lime. The evolution of longitudinal cracks caused by a point load has been evaluated measuring the water absorption by capillarity and studying the evolution of the crack by optical microscopy. Besides the mortar composition, it has been evaluated the effect of the environmental conditions on the crack repair. The different specimens were exposed to three different environments: water immersion, curing chamber at 20 ± 2°C and 95 ± 5% of relative humidity (RH) and the laboratory at 25 ±5°C and 65% ± 5% RH. The results obtained allow us to establish that constant hydration is an essential factor for the development of self-healing mechanism. If the samples are kept in water immersion self-healing occurs no matter the additions of the mortar formulation. Size of the crack is also an important factor to allow self-healing. The product formed during selfhealing to fill the crack is mainly calcium carbonate.

Application of Pro-Ecological Building Technologies in Contemporary Architecture

Scipedia content — Fri, 25 Sep 2020 13:22:09 +0200

Structural and material solutions of modern buildings are an important element of considerations in accordance with the idea of sustainable design, in which the aim is to minimize their negative impact on the environment. These searches turn towards low-tech technology, which uses natural and low-processed materials, which are possible to obtain in selected locations. Construction in the raw earth technology is a modernization of the traditional technology, in which it is possible to apply pro-ecological values associated with the used material. The paper presents research on insulation properties of walls in an experimental earth building located in Pasłęk in Poland. The aim of the research was to determine the potential of the applied raw earth technology in a local climate. The accepted design assumptions were verified due to the effects achieved in the empirical research on the thermo-humidity conditions in an experimental building. On the basis of the conducted research with the use of specialized tools, the positive and negative sides of the selected technology and building material were determined.

Microstructural Evaluation of Durability of Different Cementitious Mixtures in Microbial Induced Corrosion Environments

Scipedia content — Fri, 25 Sep 2020 13:22:02 +0200

Sound and durable concrete mixtures are essential in environments where microbial induced corrosion (MIC) is a concern. In this study three concrete mixtures prepared with different binders (ordinary portland cement (OPC), calcium aluminate cement (CAC) and alkali-activated cement (AAC) were petrographically examined after exposure to laboratory-controlled MIC conditions. Analytical techniques included reflected light microscopy, polarized and fluorescent transmitted light microscopy (FLM) and scanning electron microscopy equipped with an energy-dispersive X-ray spectrometer (SEM/EDX). SEM/EDX analyses obtained from the same areas provided information on chemical and mineralogical alteration, while quantitative image analysis with FLM affords an opportunity to quantify the variation in capillary porosity of the paste within alteration zonation. The microscopic observations indicate that the change in normalized capillary porosity coincide broadly with different alteration zones, which are in turn dependent on the type of binder. The OPC concrete shows the greatest deterioration where the paste is largely replaced by gypsum and high capillary porosity is lined to leaching of a calcium. The formation of ettringite densifies the paste and lowers the capillary porosity inboard of the gypsum zone in the OPC concrete. The CAC and AAC mixtures show better resistance to leaching than the OPC mixture, which explains their superior resistance to MIC. These findings are consistent with independent macroscopic observations that indicate the OPC mixture deteriorated more rapidly and severely than the CAC and AAC mixtures.

Assessment of Moisture Response and Expected Durability of a Heritage Masonry Building Subjected to Projected Future Climate Loads of Ottawa, Canada

Scipedia content — Fri, 25 Sep 2020 13:21:42 +0200

As part of the Canadian government‘s recent drive to the "on Greening Government" initiative, heritage buildings forming part of the parliamentary precinct in Ottawa, Canada are to be retrofitted in the coming years to help reduce energy usage and decrease greenhouse gas emissions associated with heating and cooling. Increasing levels of GHG concentrations over time has the potential to raise the mean global temperature by +3.5 degrees. The predicted impact on Ottawa‘s climate will be significant, increasing precipitation annually by 14.4% and decreasing the January winter design temperature from - 25º C to -11.7º C or 53%. In this paper, the moisture response of a heritage building located in Ottawa, Canada is determined from results of numerical simulations when subjected to both historical and projected future climate loads. Various insulation strategies for masonry wall systems were assessed. The objective was to decrease the energy demand associated with heating and cooling by applying insulation on the interior face of the masonry. Using future climate loads, results from hygrothermal modeling showed that although the climate change model produces higher volumes of annual precipitation, no deleterious levels of moisture build-up were observed in the wall system. In fact, moisture levels remained relatively consistent, irrespective of the insulation type applied to the interior face of the walls. Moisture content for all scenarios was well below critical saturation of the masonry materials. The warming climate has a dramatic effect by reducing the number of hours below freezing experienced by the interior brick wythe when interior insulation is applied. From the hygrothermal analysis, it was concluded that the warming temperatures will substantially reduce the number of hours the interior wythe of masonry experiences freezing temperatures which in turn, reduces the potential for freeze-thaw damage to the masonry. The interior application of moderate levels of insulation should therefore be considered for retrofit measures for this heritage building, located in Ottawa, Canada, without increasing the risk of damage to the wall.

Experimental Verification of the Theoretical Aging of Vacuum Insulated Panels

Scipedia content — Fri, 25 Sep 2020 13:16:17 +0200

Vacuum Insulation Panels (VIPs) encompass a higher thermal resistance per unit of thickness compared to any other kind of insulation. However, their aging has often shown some critical concerns among stakeholders. To support the broader use of VIPs in the building sector, a comprehensive analysis of the physical properties of VIPs and in particular of their thermal conductivity over longperiods is required. This research investigates the effect of the temperature and relative humidity on the service life and thermal conductivity of VIPs. The scope of this study is to validate existing aging models for VIPs. First, the experimental results of the thermal conductivity for five VIPs both in pristine and in laboratory-accelerated conditions are described. Then, an analytical aging method is employed to validate the collected data. Results show that the aging has a more significant impact on the performance of VIPs with a core of fiberglass-core than with VIPs with a core of fumed silica.

Electro-Desalination of Sandstones With Cracks

Scipedia content — Fri, 25 Sep 2020 13:16:10 +0200

Historical stone monuments and buildings are lost due to salt induced decay. This paper deals with a method, electro-desalination (ED), in which an electric DC field is applied to the infected stones. The method utilizes that ions are transported (electromigrating) in the pore solution in the electric field. In the experimental work here, sandstone prisms were spiked with NaCl to high concentrations prior to ED. During the application of current, the Cl ions are electromigrating into a poultice at the anode, and Na ions into a poultice at the cathode. Damaged stones are often fragile and cracked, and the focus of this paper is to investigate experimentally if the salts are removed effectively from the stone parts next to a crack. In the lab experiments performed, a crack was cut half through the rectangular sandstone prisms perpendicular to the electric field. The results showed no delay on the ED processfrom the crack. All through the stone, very low concentrations of Na and Cl were reached. The concentration were even lower than the concentrations before the spiking. This finding of effective desalination around a crack is important, as it means that during ED, the poultice with electrodes can be placed around the cracked and fragile surfaces, and thus further damage from physical contact between poultice and fragile stone can be avoided.

Assessment of Building Resistance to Accidental Actions in the Social Aspect of Sustainable Construction

Scipedia content — Fri, 25 Sep 2020 13:16:02 +0200

In the article is considered one of the categories of social aspect of sustainable construction as specified in the standard EN 16309:2014 - namely: safety and security. The authors analyzed the component of the above-mentioned category with a subcategory called: resistance of buildings for accidental actions. The assessment criteria are: earthquake resistance, explosion resistance, fire performance and traffic impacts. A model of building‘s assessment of random interactions is presented, which will allow to make comparisons of the object‘s safety in the investigated ranges with other residential buildings, as well as with a reference building.

A Framework for Installation Impact Analysis on Building Performance

Scipedia content — Fri, 25 Sep 2020 13:15:54 +0200

Product installation during the construction process impacts the overall performance and durability of a building. However, when the building construction industry fails to address installation quality the product performance is affected. This research explores the importance of optimized product installation and how it affects product performance. During the installation period, standard product performance can be affected by the information known about the product and the amount of time put into the assembly of the product. The building products can vary from insulation, A/C units, water heaters, etc. An installers‘ workmanship can impact standard product performance if they have limited knowledge about the product and its operational functionality. The products‘ prescribed functionality could be altered due to less than standardized installation practices. Improper installation of a product can lead to major deviations in performance that can increase maintenance costs over the lifetime of the product in addition to adverse effects of the product during its normal life cycle. Labor sensitivity is an underrepresented aspect of building construction that contributes to the problem of energy inefficiency. The goal of this work is to develop a metric that can quantify how relatively sensitive a building product and overall building performance is to the efforts of time and knowledge, specifically during the installation process. From this metric, the impact of installation on performance for different products can be compared through numerical values, highlighting products that require special care during the installation process to ensure desired performance.

Practical Application of Low-Cost Sensors for Static Tests

Scipedia content — Fri, 25 Sep 2020 13:15:47 +0200

Structural Health Monitoring (SHM) is essential to assess the accuracy of durability predictions of structures. Using low-cost sensors on structural evaluation has gained significant attention compare to high-cost sensors. Although these may not be as accurate and sensitive as the expensive electronic devices, with efficient code and right use, there is a possibility of getting useful information from them. These sensors can vary based on their functionality and the measurements they provide. For example, one is highly sensitive to the light of its environment while the other kind would give different results in different temperatures. In this paper, three different displacement measuring sensors have been studied. An ultrasonic sensor (HC-SR04) and two different types of laser sensors (VL53L0X and VL53L1X) are investigated in the paper. An Arduino Mega has captured their measured data, and a raspberry pi has made the acquisition. Not only issues regarding coding and placing of these sensors have been presented ultimately, but precise solutions for the aforementioned problems as well as an efficient way of assembling all the sensors are also presented in this paper. The data generated from these electronic devices can be used for Structural Health Monitoring applications.

Evaluation of Tortuosity in Cemented Sand Using X-Ray Computed Microtomography

Scipedia content — Fri, 25 Sep 2020 13:15:40 +0200

Cemented sand is a common way for soil stabilization or ground improvement. Tortuosity is an important parameter that has a significant impact on flow and transport characteristics of porous media and related to permeability and diffusion coefficient. This study aims to quantitatively investigate the tortuosity of the cemented sand with different cement content using X-ray computed tomography (CT) based random walk simulation. The cemented samples were scanned using microCT and converted to 3D pore space through image processing. Random walk simulation was applied to the reconstructed 3D pore space to calculate the tortuosity. Higher cement content gave an increase in tortuosity and a decrease in porosity. This indicates that the addition of cement makes pore space more tortuous and decreases both permeability and diffusion coefficient which are being treated as important parameters for durability of construction materials.

Understanding the Reactivity of Dicalcium Silicate by Density Functional Theory

Scipedia content — Fri, 25 Sep 2020 13:15:33 +0200

Ordinary Portland Cement (OPC) is a mixture consisting of various phases. Because of mineralogical complexity, the relationship between chemical reactivity of the mixture and each individual phase is still unanswered question. In this study, computational method based on Density Functional Theory (DFT) was applied to investigate the chemical reactivity of different polymorphs of dicalcium silicate crystals. At first, computationally generated dicalcium silicate crystals were geometrically optimized to achieve targeted convergence criteria for computing the total internal energy, lattice parameters, and atomic arrangement at 0K. The simulations performed explain well the thermodynamic stability as well as the synthesis temperatures of the different polymorphs of dicalcium silicate.

Quantifying Thermal Performance of the Building Envelope - Beyond Common Practice

Scipedia content — Fri, 25 Sep 2020 13:15:26 +0200

Performance metrics serve as useful tools and indicators for many applications. For the building industry, various metrics exist; typically, these metrics do not assess the whole building performance. Instead, these represent separate components or heat transfer mechanisms of a building like R-value, U-factor/value, and airtightness. The mechanisms defined under these metrics all contribute significantly to the overall thermal performance of a building but will rarely act independently. There are metrics that account for the overall energy performance of a building, such as Energy Use Intensity (EUI). However, these metrics tend to be highly influenced by how the building is operated and used. There are also metrics which provide assessment on a relative basis. These indices are based upon comparison to a baseline, which complicates meaningful metric-based energy analyses. This paper presents a performance metric developed to account for various thermal properties and behaviors of a building. The metric accounts for all the relevant mechanisms that influence heat losses and gains in buildings and is thus directly related to the energy performance. In addition, the metric is designed to comprise air infiltration and allows users to account for workmanship quality, and imperfections of the building thermal resistance due to penetrations and other installations. This paper will describe how the metric can be applied for various building types and in different climates.

Behaviour of Surface Chloride Concentration in Concretes Subjected to Field Exposure in Marine Atmosphere Zone

Scipedia content — Fri, 25 Sep 2020 13:15:18 +0200

Surface chloride concentration (Cs) is one of the parameters that feed models used to simulate chloride ingress into concrete. Therefore, understanding its behaviour over time is important for a more accurate forecasting. This work is part of a larger researcher project that aims to analyse the transport of chlorides into concrete in marine atmosphere zone based on long-term field exposures. The present paper focuses on the behaviour of Cs along 12.5 years. Prismatic concrete specimens with three different mixtures were exposed at places located at four different distances from the sea. Climatic variables and chloride deposition on the wet candle were parameters used to characterise the environment. Periodically, samples from concrete surface were extracted from the specimens and chemically analysed. Results show that Cs increases along the years and suggests a tendency of stabilisation over time, although this level could not be reached in the present exposure period. The relationship between Cs and chloride deposition rate on the wet candle was analysed and it was observed that the function {\textstyle C_{s}=C_{0}+k_{c}s.(Dac)^{n}} is the one that best fits to experimental data.

Multiple-Criteria Cost Analysis for Simulated Life Cycle of Office Building

Scipedia content — Fri, 25 Sep 2020 13:15:12 +0200

The article presents an office building life-cycle estimating possibility with the use of multiple-criteria evaluation and simulations modeling techniques. The first part describes the life cycle of an office building with a focus on the places where it is necessary to make strategic decisions. These decisions are most often associated with (the incurring of) high financial costs. It is, therefore, necessary to choose a tool supporting the decision-making process. Presents for evaluation several criteria were developed, a number of which concern office buildings. It should be remembered that the multiple-criteria assessment means not only the criteria but also weights which are assigned to them. The article discusses different ways of assigning weights to criteria, e.g. the Simos method. The use of several different methods of multiple-criteria evaluation was suggested, for example the method of weighted sum, the ideal point method and the entropy method. The analysis was based on simulation models. The full cost model was built in MS Excel. For modeling the Crystal Ball software was used. The software applied allowed not only to determine confidence in the selected scenarios, but also to point to the criterion or factor which has the greatest impact on the final result. Such information can be obtained through the use of sensitivity analysis.

Environmental Monitoring System Based on Low-Cost Sensors

Scipedia content — Fri, 25 Sep 2020 13:15:04 +0200

Temperature and humidity measurements provide useful information on multiple areas of civil engineering application such as Structural Health Monitoring (SHM), Structural System Identification (SSI) and structures rehabilitation. Majority of the existing commercial systems are so costly and also these measurement paradigms need many reference spots for a full-scale structure. The aforesaid paradigms are based on collecting data through smart devices, transferring information to each other and in the final stage processing the obtained information collaboratively through cloud computing or the others technologies. Taking into account the above information and obstacles, utilizing the Open Source Platforms (OSP) microcontrollers like Arduino as well as low cost sensors are attracting more and more attention. This paper gives a comprehensive information about the most determinant aspects of the aforementioned kits in terms of their pros and cons, installation procedure, communication protocol, number of the required connections and specific characteristics of the data acquisition system.

A Comprehensive Description of a Low-Cost Wireless Dynamic Real-Time Data Acquisition and Monitoring System

Scipedia content — Fri, 25 Sep 2020 13:14:57 +0200

Nowadays, low-cost sensors and acquisition devices have been emerging as an obvious solution to many innovative applications such as Structural Health Monitoring (SHM) systems. In this paper, issues regarding dynamic data acquisition, as well as their respective solutions, are presented. Moreover, a comprehensive description through-out an inexpensive sensor network system using opensource hardware for a real-time acceleration data acquisition has been presented. The platform consists of an accelerometer, an Arduino board, and a computer as a data recorder and presenter. Data is recorded through an efficient microcontroller code that can provide a considerable reading frequency (up to 300Hz). Using Python, instant acceleration recording for all the three axes has been done. It is shown how the performance of the proposed system is efficient for the field of SHM systems.

Integration of Durability Data of Construction Elements Within a BIMBased Environment

Scipedia content — Wed, 23 Sep 2020 16:10:50 +0200

Fabric Reinforced Cementitious Matrix (FRCM) and Composite Reinforced Mortar (CRM) systems are used as Externally Bonded Reinforcements (EBR) in civil and historical construction. These materials are made by fibrous reinforcement, in forms of dry (FRCM) or cured (CRM) meshes embedded in a cementitious/hydraulic lime matrix. At present, this technology is considered very promising in the field of structural strengthening, retrofitting and repair existing structures. This is true especially in those cases of masonry and historical buildings, due to the specific criteria of conservation and compatibility with the substrate that need to be fulfilled. These materials, in fact, results more compatible with masonry substrate because of the inorganic matrix, instead of polymeric resin used for the well-known FRP systems (Fiber Reinforced Polymers). The recent use of these new materials in civil engineering needs appropriate and complete guidelines, that regard not only the design aspects but also the durability features. This paper presents the results of a large experimental program focused on the durability of FRCM and CRM systems and their single components, in different alkaline environments. For the whole experimental campaign, the samples have been immersed into three different alkaline solutions, for four exposure times (500, 1000, 2000 and 3000 hrs). In addition, in order to study the different accelerating effects due to temperature, three different temperatures were maintained during the ageing periods: 23°C, 40°C and 70°C. The results about the mechanical characterization of residual properties are discussed in order to highlight the influence of alkaline environments on the mechanical properties of single elements and the whole strengthening systems that were tested herein.

Residual Strength and Durability of Glass Fiber FRCM and CRM Systems Aged in Alkaline Environments

Scipedia content — Wed, 23 Sep 2020 16:10:01 +0200

Durability Evaluation of Hemp Fibers and Recycled Aggregates Concrete

Scipedia content — Wed, 23 Sep 2020 15:42:13 +0200

Hemp and Recycled Aggregates Concrete (HRAC) is a sustainable concrete where coarse aggregates are partially replaced with industrial hemp fibers and recycled concrete aggregates (RCA). This replacement has two main benefits: it saves on natural resources and it recycles and reuses waste material. Previous studies showed that the mechanical performance of HRAC is satisfactory. On the other hand, concrete’s durability is also an important criterion to evaluate concrete’s performance and HRAC’s durability can be affected by the presence of both RCA and hemp fibers in the concrete’s alkaline environment. This paper aims at investigating the durability of HRAC concrete mixes by comparing the mechanical performance of HRAC specimens at the ages of 2 and 28 days. Furthermore, the performance of HRAC under freeze/thaw cycles is evaluated and compared to that of regular concrete. Results showed that the mechanical performance of HRAC improves at older age and the resistance of HRAC mixes to freeze-thaw cycles is similar to that of control mixes.

Financial Management of Construction Companies

Scipedia content — Wed, 23 Sep 2020 15:42:07 +0200

The objective of financial management of construction companies is to generate profit and provide financial stability. Financial stability is provided by managing the amount of both fixed and current assets, the amount of equity and external capital. Therefore, in order to reach the objective of financial management, it is necessary to comply with the basic financial rules. In the framework of nationwide analyses of economic indicators for different industries, there is data published on the website of the Ministry of Industry and Trade, which, however, apply to all construction companies. For this reason, the authors of the article focused on individual subcategories of construction companies (small, medium and large), which are defined by turnover, assets and number of employees. The research studied whether these subcategories fulfil all or part of the basic financial rules, including the following rules: golden rule of risk equalization: the ratio of own and external resources should be in the ratio of 1:1, golden balance rule: fixed assets should be covered by long-term resources; golden "pari" rule: fixed assets should be covered by equity. The research also monitored the structure of assets, i.e. the ratio between fixed and current assets and was based on elementary methods of financial analysis (vertical and horizontal methods). The outputs of the paper will be further used for the next step of the research, which will focus on tax optimization of individual categories of construction companies in relation to financial management of fixed assets.

The Future Climate Moisture Susceptibility of Wall Assemblies: Analysis Based on Monte Carlo Simulation Using a Simplified Deterministic Hygrothermal Simulation Model

Scipedia content — Wed, 23 Sep 2020 15:42:01 +0200

A newly developed generic algorithm to assess moisture susceptibility of simplified wall assemblies has been developed within the CIB-W080 WG 2. This group is focusing on guidelines for design for durability of building envelopes. The algorithm is implemented in a publicly available Matlab code. A simplified wall assembly consisting of up to four material elements is considered. Optional vapor retarder and thermal resistances are located between the elements. In this paper modelling of a ventilated cladding is implemented. Using the simplified numerical model, a probability‐based risk analysis using the Monte Carlo method is demonstrated. The risk assessment of the wall assembly considers the interior and exterior climatic load. The moisture transport mechanism accounted for in the analysis is diffusion. The rain load is assumed to be transferred directly to a chosen outer susceptible material element in the construction. An insulated wooden wall structure is analyzed and the probability distribution of the time of wetness is presented for cases using sequence of 31 consecutive climatic years, randomly varying indoor moisture excess, indoor temperature and driving rain leakages.

Numerical Strategy to Simulate Seawater Ingress in RC Concrete Blocks Exposed to Wetting-Drying Cycles in Field Conditions During 19 years

Scipedia content — Wed, 23 Sep 2020 15:41:55 +0200

Numerical results are compared to experimental data on concretes exposed in field conditions for 19 years and subjected to wetting/drying cycles in seawater after a couple of curing days. They were obtained thanks to a hydration model assuming fully hydrated concretes (19 years of curing time) and a reactive transport model in saturated conditions taking into account precipitation/dissolution of minerals and their kinetics and adsorption of ionic species on C-S-H. Numerical results show surprisingly rather good results, especially for concretes with fly ash. For OPC, although model considers average bulk porosity modifications, the experimental apparent diffusion coefficient increases much more. For concretes with silica fume, numerical results also show underestimations of total chloride content also experimental apparent diffusion coefficients are constant. Analysis of hydration calculations show that concretes are not fully hydrated after 19 years. Additional chloride content from reactions between anhydrous phases and chloride ingress may appear.

Bio-Based Building Materials-How to Unravel the Role of Material Characteristics on Fungal Susceptibility?

Scipedia content — Wed, 23 Sep 2020 15:41:48 +0200

Bio-based materials are gaining importance in the building industry, as the focus on sustainability and life-cycle-assessment has increased substantially over the last decade. Wood and wood-engineered products as well as insulation materials made from cellulose, wood, flax, hemp, etc. are increasingly used. These materials are made from renewable resources and with considerably lower energy consumption than various other building materials, such as insulation polymers, steel and concrete. As steel can corrode and concrete can rot, so can bio-based building materials degrade over time when exposed to those conditions that favour decay. Since fungi cause not only aesthetical degradation, but can also severely compromise the structural integrity of a building component this is critical for any service life approach. Consequently, a proper understanding of the fungal susceptibility of bio-based materials is needed, both for optimal application of bio-based materials as for the design of new materials. Based on a combination of tests we try to unravel the role of the material‘s chemical components, structure and moisture dynamics on its fungal susceptibility, as well as the interaction between those material characteristics. In a first test set-up, the ‘paste test‘, the material‘s structure is removed and fungal growth is assessed over time in 2D, with only the material‘s chemical components playing a role. In the second test set-up, the ‘X-ray CT test‘, fungal development is assessed nondestructively in 3D with X-ray CT, giving an indication of moisture production and distribution over time, in relation to the material‘s structure. By comparing the results, we have a better idea of how much each material characteristic influences fungal susceptibility. This knowledge can then be used for optimising fungal testing of bio-based materials, ensuring optimal application and providing the building industry with the confidence they need to pave the way to a more sustainable future.

On Bio-Deterioration of Solar Reflective Materials: An Innovative Experimental Procedure to Accelerate the Ageing Process of Surfaces

Scipedia content — Wed, 23 Sep 2020 15:41:40 +0200

Solar reflective materials are one of the most efficient solution to the urban heat island effect, according to which temperatures, in urban areas are significantly higher than those in the surrounding rural areas. Solar reflective materials (SRM) are characterized by the ability to reflect solar radiation in the whole wavelength spectrum remaining cooler under the sun. The importance of radiative properties focused the attention more on SRM subjected to aging processes instead of the new products. According to this, several standards are, nowadays, available to investigate natural (ASTM G7, ANSI CRRC/S100) and accelerated (ASTM D7897) aging. Unfortunately, these standards do not take into account the presence and the growth of microorganisms such as algae and cyanobacteria, which can be responsible not only for the decrease of radiative properties against time, but also for the decay of physical and chemical properties of SRM themselves. This study outlines an experimental procedure to accelerate natural bio-deterioration of building materials through a laboratory test. Two types of SRM have been involved, studying their thermal properties before and after the bio-deterioration accelerated treatment. The methodology involves the use of a Temporary Immersion System (TIS bioreactor), which is based on the temporized soaking of materials samples with a liquid growth medium inoculated by selected species of algae or cyanobacteria. The system promotes a homogeneous contact between the materials surfaces and these microorganisms blowing sterilized air into the medium inside the bioreactor chamber. Within three weeks into TIS bioreactor, materials samples have shown large areas of biofilm deposition on themselves. The experimental procedure, hence, confirms the capability of the system to optimize environment conditions where the growth of microorganism and their interactions with materials results accelerated. Very high attention is given to the aim to make the procedure repeatable. For this proposal, all the variable factors are minimized, maintaining constant the environmental condition and working on sterility in order to do not contaminate or alter the growth inside the bioreactor.

Analysis of Change of Physical Properties of Organic Repair Products due to Fire Exposition

Scipedia content — Wed, 23 Sep 2020 15:41:33 +0200

Organic repair products for concrete can be exposed to accidental incidents, like fire. The increase of temperature produces a modification in some of their properties. In general, these types of repair products have organic fibers to increase their tixotropic properties, but they are more sensible to the high temperature than the Portland cement or aggregates. In order to analyze the behavior of organic repair mortars with temperature three types of repair mortars are studied. These repair products have the organic components composed by acetate fiber of polyvinyl like Vinyl Acetate Acrylate (VAA), Copolymer of Vinyl Acetate Vinyl Versatate (VeoVA) and Acrylic polymers fibres. The repair products are tested increasing the temperature from 1.7ºC /min until 200ºC, 400ºC or 600ºC respectively during 20 minutes. After that, the samples are cooled in four different cooling conditions two of them slow and two others fast, and with and without oxygen. These conditions are used in order to simulate the different conditions that can occur during the cooling after fire. After the testing the visual aspect, the color and brightness and the open porosity is analyzed in each condition of test. In this work the relationship between the temperature of exposition, the cooling conditions and the change in some physical properties are studied.

Pore Refinement Action of GGBFS and Fly Ash on the Primary and Secondary Capillary Imbibition Rates of Concrete

Scipedia content — Wed, 23 Sep 2020 15:41:27 +0200

Capillary imbibition is a transport phenomenon occurring in concrete structures exposed to weathering, frequently in direct connection with the resistance against different deterioration processes. This property depends on the volume and connectivity of pores. For ground granulated blast-furnace slag (GGBFS) and fly ash blended concrete mixes, the pore refining action of these supplementary cementitious materials plays a positive role in the disconnection of the capillary porosity and consequent reduction of the capillary imbibition rate. Moreover, for this particular transport process, primary and secondary transport rates can be defined in connection with different driving mechanisms. This allows a complementary description of the pore structure of concrete. In this paper, blended concrete mixes were prepared by substituting 20, 40 and 60 % of OPC by GGBFS, and 20, 30 and 40 % of OPC by fly ash. The pore structure of these concretes is assessed by water absorption under vacuum and mercury intrusion porosimetry after curing periods of 28 and 90 days. Long-term capillary imbibition tests were also performed and primary and secondary imbibition rates are computed by a novel approach that considers their linear evolution with the fourth root of time. Results show the refinement action of GGBFS and fly ash by a softening in the transition stage between the primary and secondary imbibition periods. A low water flow rate is consequently correlated with the increased tortuosity of samples.

Mechanical and Environmental Behavior of Cement Mortars Containing Ladle Furnace Slag

Scipedia content — Wed, 23 Sep 2020 15:41:21 +0200

At present, steel production is mainly done in basic oxygen furnaces (BOF) and electric arc furnaces (EAF) (Pauliuk, S. et al, 2013, Morfeldt, J. et al, 2015). According to the statistics, it is expected that the use of electric arc furnaces to supply the demand for steel will prevail. In 2017, in Europe, 41% of steel was produced in electric arc furnaces, while in Spain, according to the Union of Steel Companies (UNESID, 2016), the percentage was almost 66% in 2016. In 2016 the European Union generated approximately 18.4 Mt of slag (black and white), of which 1.5 Mt was produced in Spain. In other words, the amount of white slag produced was about 286 thousand tons, approximately between 20 and 30 kg of slag per ton of steel (UNESID, 2016, Euroslag, 2016). Refining slag (white slag) is the second most abundant waste in steel production, and, to date, its final destination is still the landfill. This study has used ladle slag from refined steelworks, as a replacement for cement in different proportions (0, 25, 50 and 75%), for the manufacture of mortars. A broad characterization of the ladle slag has been carried out, as well as determining the mechanical, durable, and environmental properties of the manufactured mortars. The results show that using the ladle slag as a replacement for cement produces a decrease in compressive strength, but the expansion behavior remains below the stability limit. It also has been seen that the slag incorporated into mortars, evaluated by leaching test at 28 days, shows inert material behavior.

In-Situ Tests on Silica Aerogel-Based Rendering Walls

Scipedia content — Wed, 23 Sep 2020 15:41:11 +0200

In this paper, two aerogel-based renders are characterized based on in-situ testing of walls prototypes. The in-situ tests to assess the mechanical performance are: pull-off, surface impact tests and compressive strength on collected samples. The physical performance includes the water resistance and thermal conductivity coefficient. The tests carried out to assess water-resistance are: Karsten tube, moisture meter and capillary water absorption of collected samples. The thermal performance was tested based on infrared thermography and thermal conductivity transient method. The combination of these in-situ tests allowed a better performance characterization of the aerogelbased renders and characterized the applied renders. These results were carried out under two national research projects (Nanorender and P2020 PEP).

Out-Of-Plane Displacements Determination Based on the Analysis of Point Clouds from TLS Using the M-Split Estimation

Scipedia content — Wed, 23 Sep 2020 15:41:03 +0200

Building structures are exposed to the impact of various forces and natural phenomena. Earthquakes, heavy rains, displacements of land surrounding the building can have a significant and negative impact on the elements of buildings or entire construction objects. Terrestrial laser scanning technology can be successfully used to obtain data on changes in the structure of an object. This papier discusses the use of TLS as a measurement method for obtaining information on displacements and deformations that have occurred after heavy downpour. As a result of the rapid rain, the ground displacement occurred, which in effect led to damage to the retaining wall. The terrestrial laser scanning was used to measure the area covered by the displacements and the M-split method to model the obtained data.

Identification of Defects and Hazards in Structures Based on the Point Cloud Using the OptD Method

Scipedia content — Wed, 23 Sep 2020 15:40:54 +0200

Structural changes taking place in buildings and structures due to the passage of time are a normal phenomenon. However, the building objects are also adversely affected by atmospheric conditions or violent natural phenomena. Every year, our surroundings are increasingly attacked by extreme weather phenomena such as: floods, hurricanes, heavy storms with rain or extreme heat. Such phenomena are natural elements of nature, however they significantly interfere in the technical condition of the building. They often cause measurable economic losses: flooding, cracks, construction displacements and even their total destruction. At the time of estimating losses, calculating the costs of repair, and then making decisions about the method of restoration, a helpful tool can be laser scanning: terrestrial, airborne or mobile, depending on the character of the object and the size of the disaster. The paper presents an identification of defects and hazards in structures based on the point cloud using the OptD method.

Airborne Algal Growth on the Roofs of Membrane-Structured Residences in a Cold Areas of Japan

Scipedia content — Wed, 23 Sep 2020 15:40:45 +0200

Discoloration of building facades due to airborne algae is observed in our surroundings. The growth conditions of these algae are not fully clear yet, and efficient preventive measures have not yet been determined. This study was aimed at investigating the influence of ambient environment and building structure on algal growth. A residential building in the cold region of Japan was surveyed. The roof was a multilayered structure consisting of a semi-transparent film, an air layer, an outside insulation layer, and was supported by rafters. The soiled state was visually observed and recorded through pictures, and seemed to be particularly increased in autumn. Several black stripes appeared on the northeast (NE) roof four months after its cleaning. The soiling first appeared on the film backed by the rafter, and then extended to the film backed by the air layer. It rarely appeared on the southeast roof. The roof-surface temperature was measured and a stripe-shaped distribution was observed. The temperature of the film with rafter was higher and lesser than that of the film with the air layer during the night and in the early morning, respectively. Although condensation occurred nightly, its frequency showed no orientational difference. Algae can die when exposed to a temperature higher than 40 °C. The southwest roof had the longest period of a surface temperature over 40 °C, while the northwest (NW) roof had the shortest period of this surface temperature. These measurements corresponded well to the survey results according to which soiling mainly occurred on the NE and NW sides of roofs. The time for algal growth was estimated assuming that algae can grow at surface temperatures between 0 and 40 °C.

Mobile Augmented Reality Application Supporting Building Facades Visualization

Scipedia content — Wed, 23 Sep 2020 15:40:38 +0200

The use of mobile devices such as smartphones still increases over last years. Smartphone hardware capabilities are comparable with average personal computers. Thanks to the increasing computing power, their application is focused on more and more sophisticated and complex tasks. These includes among others augmented reality (AR) applications, which support precise GNSS localization and use signals from such devices like accelerometer or gyrocsope. They are able to create interactive, immersive real-time visualisation of any kind. The article presents a prototype Mobile Augmented Reality (MAR) Application for visualization of the building facades. It allows to support the original look of the building with the additional information from database. Software of this kind, can be used for overviewing, inspecting or work planning carried out on the facade of the building. As a part of the test, a prototype of the MAR application for Android has been prepared. Rest of the solution components have been presented in form of a concept, implementation of which is planned in near future. Basic technical assumptions are already developed, but details may change. The paper mentions also some important AR problems, especially positioning in urban environment and accurate registration of digital objects in the real world.

Permeability of Ultra-Fine Reactive Fly Ash applied to Cement-Based Composites

Scipedia content — Wed, 23 Sep 2020 15:40:28 +0200

This study explores the permeability of the partial replacement of cement using ultra-fine reactive fly ash (URFA) and silica fume. URFA is an industrial by-product from thermal power plants and it has a smaller spherical particle size (0.1 µm to 10 µm) than the general fly ash. The fixed water-to-binder ratio was 0.45 and the replacement of cement was used as 5% and 10%. The combinations of URFA and silica fume in composites were used as 5% URFA plus 5% silica fume and 8% URFA plus 2% silica fume. The results show that the inclusion of URFA was enhanced to increase the workability, and help to produce pozzolanic reaction and C-S-H colloids. The colloids were filling the pore structures to increase the compactness of specimen, which is consistency with the increased the compressive strength and reduction of the dry shrinkage. It also was reduced the chloride ion penetration and non-steady state migration coefficient, which is helpful for improving the mechanical properties and permeability. The composites with 10% URFA had a better performance. For blending specimen, it was also a tendency to improve mechanical properties and permeability; and the combination of 5% URFA and 5% silica fume in composites enhanced better performances.

Evaluation of Economic Efficiency of Territory Development

Scipedia content — Wed, 23 Sep 2020 15:40:20 +0200

The article deals with the analysis of background resources for the evaluation of socioeconomic impact methodology elaboration of the territory development in the field of commercial, service and residential properties, mixed constructions and multifunctional buildings in the first phase of their life cycle. The research team investigated the possibilities of using the information and procedures for the evaluation of socio-economic impacts of the territory development. Relevant data for the evaluation was identified and analysed on the research sample of 12 major urban districts of the city of Brno. Technical and social parameters that appeared relevant for the economic evaluation of the surveyed location development were identified based on the available data on individual territories. The first identification step was their description. Subsequently, suitable metrics for their evaluation were examined. Findings about what socio-economic impacts these locations create in the field of interest and whether these impacts are efficient in terms of their functioning represent the output of the paper. This includes determining the overall economic efficiency of the implementation phase of their life cycle. This output then forms base for the future research focusing on the possibility of including other variables that shall focus on the operational phase of the life cycle and extend the assessment to a wider timeframe.

A Methodology for Assessment of Building Assembly Air Leakage Moisture Response, Condensation Risk, and Expected Durability When Subjected to Projected Future Climate Loads

Scipedia content — Wed, 23 Sep 2020 15:40:12 +0200

It was determined that the ability to assess the required performance of an air barrier assembly could now be supported using modern computational hygrothermal simulation techniques coupled with historical and future climate data and the new durability methodology developed as part of the updated 2019 CSA S478 Guideline for Durability of Buildings.

A Joint Inversion Approach of Capacitive and Resistive Measurements for the Estimation of Water Saturation Profiles in Concrete Structures

Scipedia content — Wed, 23 Sep 2020 15:40:05 +0200

Concrete is a construction material that is well known for its durability. However, it is exposed to environmental attacks that lead to the penetration of aggressive agents such as water and chlorides, thus, threatening its durability and service life. Within this context and exploiting the sensitivity of the electromagnetic properties of concrete to its water content, the literature suggests determining water saturation profiles using non-destructive techniques. For instance, measuring the electrical resistivity at several points of the surface of the concrete structure can lead to an estimate of the resistivity depth profile. Then, after a calibration step, the water saturation depth profile can be obtained and the durability can be assessed. Similarly, the water depth profile can be assessed by dielectric permittivity measurements. In this paper, we propose a new inversion scheme based on the combination of both resistive and capacitive measurements: resistivity and permittivity measurements are inverted jointly to estimate the water saturation profile in concrete. Numerical experiments with simulated data show that information gathered from the two measurements enriches the inversion process, leading to the determination of more reliable water saturation profiles.

Synthetic Resin Reinforcement of Timber Joints Deteriorated by Termites

Scipedia content — Wed, 23 Sep 2020 15:39:58 +0200

Timber has been widely adopted as a global structural material. However, timber sometimes deteriorates due to various factors such as termite infestation, which may reduce its strength and durability. It is difficult to ascertain the degree of deterioration of timbers by visual inspection because deterioration by termites causes severe damage to the inner parts of the timber. Therefore, the damage is often discovered after the deterioration progresses. The restoration and refurbishment method currently implemented is removing the degraded parts and partially replacing them with new healthy wood. Although it is as desirable to reinforce the original part as it is to restore its strength, especially for historical timber structures, this approach has not yet been put into practical use. This study investigates the possibility of restoring timber deteriorated by termites with little changes in its appearance by using resin filling. Deterioration by termites occurs at the base of the timber. Therefore, the specimen is assumed to be the joint of a foundation and column. First, the deteriorated specimen was filled with epoxy resin, and then, the effectiveness of the filling was confirmed by a nondestructive test method using ultrasonic pulse velocity. Finally, shear strength test was performed for the joint. As a result, ultrasonic velocity significantly increased because of the resin filling. The strength of the specimen filled with epoxy resin was restored and was close to the strength of a healthy one. It was confirmed that this strengthening method with resin filling was useful for improving the structural performance of timber deteriorated by termites with little change in appearance.

Impact of Portland Cement Content on Alkali Activated Bottom Ash

Scipedia content — Wed, 23 Sep 2020 15:39:50 +0200

This study explores the behavior of blended mortars of low reactive bottom ashes (BA) and ordinary Portland cement (OPC) in an alkaline solution. Mortar mixtures incorporating OPC with different replacement levels (0% to 30% mass) were studied. Isothermal conduction calorimetric analysis was studied and 28-and 60-day mechanical strength values were found. SEM images was used to identifies porosity structures at 28-day. Water absorption was also investigated. The results revealed different behaviors to low (OPC 2.5 and OPC 5) and moderated (OPC 10 and OPC 30) OPC content. Increase in percentage of Portland accelerated hydration kinetics. There is a second peak formation for moderated OPC content, associated with C-A-S-H gel formation. The partial replacement of bottom ash by OPC tend to reduce the absorption. There is a slower initial water absorption to low OPC content. This behavior is due the higher unreacted BA content, that works as a filler. Otherwise, the increase of water absorption for OPC content is due to the coexistence of Portland cement hydrates and alkali activated reactions.

Building Circular Economy: a Case Study Designed and Built Following a BIM-Based Life Cycle Assessment Approach

Scipedia content — Wed, 23 Sep 2020 15:39:42 +0200

The awareness of the environmental impact of buildings during their entire whole life cycle has seen a growing interest in recent years. In fact, as buildings become more energy-efficient, life cycle impacts become increasingly important. Investors in the building sector are becoming aware of the direct and indirect benefits of a design process that enables the control of the impact of the building, ensuring the higher quality, intrinsic value of materials under a circular economy point of view. The durability is, together with reusability and recyclability, one of the main characteristics of construction materials. In this framework, the purpose of this paper is to describe a BIM-based approach to life cycle assessment (LCA) from the initial stages of the design of the Socrates Building in Viladecans. For this scope, a digital model in the TCQi GMA software was created to assist in the evaluation, optimization, and comparison of different design and construction alternatives. An integrated project delivery contract was adopted. These aspects altogether showed the potential of increasing the real estate value and the profitability of the building. This paper discusses problems that emerged during the digital project management, assessing criticalities and opportunities.

Laboratory Vs Field Performance of Innovative Thermal Insulating Plasters

Scipedia content — Wed, 23 Sep 2020 15:39:35 +0200

Thermal insulating plasters and renders are becoming a popular solution for the energy retrofit of existing and historic buildings because of their suitability/compatibility with the existing masonry supports. However, as for most of the insulating products, the actual performance of these materials might significantly differ from the one determined with simplified methods (EN ISO 6946 standard) that are commonly adopted by the designers. In this study, an overview of the latest Authors researches that involve three different thermal insulating plasters, containing respectively perlite, vegetal and aerogel aggregates, are presented. The developed plasters were characterized in the laboratory and successively applied in three demonstration buildings. From the in-field thermal monitoring activities, all the analysed thermal insulating plasters showed a decrease in the thermal performance between 25 and 30% if compared to the laboratory measurements.

Selecting Criteria for Assessing "Environmentally-Friendly" Material Options in Construction: Part I

Scipedia content — Wed, 23 Sep 2020 15:39:28 +0200

One of the design team‘s tasks is assuring that their project has a low negative impact on the environment. This comes from regulations as well as expectations of direct benefits (reduction of operating cost, the project‘s improved image in the eyes of the public, etc.). To fulfill this task, one needs to define criteria for assessing the design options. These are to correspond to the individual qualities of the project, and they should be significant and possible to assess. The paper, divided into two parts, presents a review of the literature concerning the criteria for the assessment of design solutions defined as "green" or "environmentally friendly". Part I presents the method of the analysis and investigates into the number and type of criteria adopted in the sample of papers being the object of analysis. Part II focuses on the ways of defining criteria values, weights, and methods of multicriteria assessment.

Biomimetic Antifreeze Polymers: A Natural Solution to Freeze-Thaw Damage in Cement and Concrete

Scipedia content — Wed, 23 Sep 2020 15:39:22 +0200

Ice is one of the few substances on Earth that expands when it freezes. Consequently, this phase change causes damage to porous cementitious materials that absorb water and undergo freezethaw cycling. Inspired by nature, the objective of this work is to characterize biomimetic antifreeze polymers (BAPs) that explicitly mimic the behavior of antifreeze proteins (AFPs) and antifreeze glycoproteins (AFGPs) naturally found in plants, fish, insects, and bacteria for use as a concrete additive. The ultimate goal of this work is to enhance the freeze-thaw durability of ordinary portland cement (OPC) concrete without the use of traditional air entraining agents (AEAs). This work will highlight recent research that has shown that small additions, less than 0.1% by wt. of cement, of BAPs that exhibit ice recrystallization inhibition (IRI) activity can mitigate freeze-thaw damage in OPC paste and concrete while entraining less than 3% air.

Integrating Self-Sensing in Self-Healing Concrete: Towards a Biomimetic Approach to Repair

Scipedia content — Wed, 23 Sep 2020 15:39:14 +0200

Material degradation of our civil infrastructure is inevitable, and regular maintenance is required to mitigate against failure during the service-life. However, understanding and knowledge of composites is now leading to the creation of concretes with autonomic self-healing capabilities. This development will transform our infrastructure by embedding self-immunity and resilience so that structures evolve over their lifespan enhancing durability and serviceability, improving safety and reducing maintenance costs. Research in the UK under the auspices of Resilient Materials for Life (RM4L) has developed a suite of multiple-scale biomimetic self-healing concretes that can adapt and respond to damage without external intervention. This paper discusses the development of bacteria to precipitate calcite in cracks in concrete. Whilst bacteria-based healing is possible through several pathways, it is only now that a better understanding is permitting the optimization of the process. There are two key technologies for including bacteria healing in concrete: (i) encapsulation and (ii) vascular flow networks. Vascular flow networks permit continuous unlimited delivery of healing agents to internal areas of damage, facilitating repair on a reoccurring basis. However, in order to use them effectively human intervention is required to identify cracking and trigger healing processes. A more biomimetic approach is to provide the concrete with a form of self-sensing capability to enable it to initiate crack healing itself. Research using PZT sensors to detect cracking is described.

Concrete: Limit States and Sustainability

Scipedia content — Wed, 23 Sep 2020 15:39:07 +0200

The structural design of concrete structures has to result in qualities ensuring ordinary structural safety and serviceability, together with durability. Recently, it has become necessary to pursue sustainability as well, and rather newly the issue of resilience has also appeared. It is now apparent that the effects of mechanical load, environmental load and even social coherence need to be reflected and included in the formulation of limit states. This is a complex matter involving the factors of time, service life, degradation effects, modelling, probability analyses, limit states, costs and other phenomena. It has not yet been completely understood, albeit several notions in this context are contained in different codes and regulations, e.g. EN 1990, EN 1992, ISO 13823:2008, ISO 16204:2012, fib MC2010 and fib MC2020 (currently under preparation by the fib committees). According to fib Model Code 2010, the design method most commonly used for concrete structures today is performance-based. Sustainable target value design can be briefly expressed as the comparison of sustainable capacity vs. sustainable impacts. This requires the formulation of a new class of limit states – apart from those of the engineering (or structural) type, also sustainability limit states now need to be specified. The presented contribution briefly mentions traditional and durability limit states, discussing their variants and context, and then concentrates specifically on the formulation of limit states for concrete sustainability at material level. It also presents some examples which apply a full probabilistic approach.

Impact of Climate Change in Building Envelope Design: The Performance to Withstand Mould Growth

Scipedia content — Wed, 23 Sep 2020 15:39:00 +0200

Mould growth is a biodeterioration phenomenon that jeopardizes the integrity, functionality and durability of building envelopes. The performance to withstand biodeterioration depends on the critical hygrothermal conditions inside the envelope. These conditions are subject to the configuration of building envelopes, and climate exposure, accounting for both the outdoor weather and indoor environments‘ conditions. These critical conditions are likely to intensify in response to the changing climate, and hence, modification and adaptation of the envelopes‘ configuration will be required. An understanding of the implications of envelope configurations‘ choices is required to set up guidelines for forthcoming building envelope design. Parametric analyses are a potent source of insight to investigate how the input parameters influence the desired outcome. In light of this, a parametric analysis is carried out to investigate the performance of three building envelopes to withstand mould growth. The impact of climate change in the performance evaluation is accounted for by employing both historic and future climate change scenarios in which the global climate temperature change is forecast to be 3.5º C. Input parameters related to the simulation of mould growth are also investigated. Recommendations to current building envelope design guidelines are drawn for the performance evaluation to withstand mould growth

An Experimental Study on the Thermal Conductivity of Concrete Containing Coal Bottom Ash Aggregate

Scipedia content — Wed, 23 Sep 2020 15:38:53 +0200

Thermal conductivity plays a significant role in efficient energy usage, especially in the construction field. Low thermal conductivity is preferable because lower thermal conductivity will increase the thermal insulation provided by the concrete and reduce the heating and cooling costs for residential and commercial buildings. To accomplish this goal, porous materials can be considered for use in concrete. Additionally, researchers have had challenges producing high-strength concrete with low thermal conductivity. Therefore, this study aims to investigate the effects of replacing crushed fine aggregates with coal bottom ash (CBA) on the thermal conductivity and mechanical properties of high-strength concrete. The concrete properties, including unit weight, compressive strength, and thermal conductivity, were measured. The experimental results revealed that the thermal conductivity of the CBA concrete decreased as the unit weight of the CBA concrete decreased, and the thermal conductivity also decreased as the compressive strength decreased. Finally, the relationships between the thermal conductivity, unit weight, and compressive strength of the CBA concrete were also examined.

Durability Studies on Fiber-Reinforced Siderurgic Concrete

Scipedia content — Wed, 23 Sep 2020 15:38:46 +0200

The construction sector is clearly one of the most pollutant at a global level and its consumption of natural resources is also enormous. Over recent years, heightened awareness of this issue within the construction sector has motivated changes within its working practice,seeking to reduce its environmental impacts and to mitigate the effects of climate change. The consumption of natural resources can be reduced in very different areas and special attention has been given to the substitution of Natural Aggregates (NA) in concrete design by replacing those aggregates with various waste coproducts. Siderurgic concrete is the name given to concrete manufactured with siderurgical aggregate from the steel-making industry. In this paper, test results on fiber-reinforced siderurgical concrete are reported. The concrete is manufactured with approximately 50% Electric Arc Furnace Slag (EAFS) aggregate by volume, for use in pavement applications. Steel and polypropylene fibers, amounting to approximately 0.5% by volume of the concrete mass, are also added to the mix. The durability properties of this concrete type are analyzed through freeze/thaw and moist/dry tests. Furthermore, the long-term behavior of the concrete is explained through its internal structure, using Mercury Intrusion Porosity (MIP) and low-vacuum Scanning Electron Microscopy (SEM) analyses. The results add further weight to the feasibility of using EAFS in replacement of NA in fiber-reinforced concrete for pavement construction.

Relationships between Outside and Interior Appearance Inspection and Actual Bio-Deterioration of Structural Members in Existing Wood Houses

Scipedia content — Wed, 23 Sep 2020 15:38:40 +0200

The inspection of the used house which is necessary to be evaluated is carried out without removal of the interior or exterior finishing materials. However, where the interior or exterior appearance was degraded, there was not always a bio-deterioration of the wooden structural member in the existing wood houses. Therefore, the interior or exterior appearance of the 103 used wood houses were inspected and the bio-deterioration of all wooden structural members were investigated after removal of the finishing materials. Then, the relationships between the appearance degradation and the actual bio-deterioration of the wooden structural members in the used wood houses were studied. The results were summarized as follows: 1) The bio-deterioration of the wooden structural members were found much on 1st story rather than 2nd story, in the elder building age, in case of short eaves and in case of low foundation. The issues known experience empirically were verified numerically. 2) The tendency of the appearance degradation occurrence were the same as the tendency of the biodeterioration partially, but didn’t match it entirely. 3) About 90 % of the portions whose interior or exterior appearance were degraded didn’t have the bio-deterioration of the wooden structural member. 4) The ratio of the portion with the bio-deterioration of the wooden structural member without appearance degradation were only 1.6 %.

Viability of Production and Application of Concrete with Addition of Fibers of Polyethylene Terephthalate (PET) Bottles for Construction

Scipedia content — Wed, 23 Sep 2020 15:38:33 +0200

Concrete is the main material used in the construction industry not only for the ability to produce infinite variety of shapes for precast forms and for its characteristics of high resistance to compression, but primarily for their low manufacturing cost. Nonetheless, the production by mixing cement, fine aggregate, coarse aggregate and water, using natural raw materials such as stone, sand and water, despite being plentiful, represent the consumption of millions of tons of natural resources. Thus, the continuous search for new solutions is fundamental in order to not only further lower the manufacturing costs of this essential component in construction, but also to seek alternative materials, those of origin in processes of sustainability