Documents published in Scipedia

• Analysis of the Repassivation of Corroded Bars in Cementitious Materials Subjected to Realkalisation

  G. R. Meira, P. R. R. Ferreira, A. A. Meira

  DBMC 2023.

  
  

  Abstract

  The effect of concrete realkalinisation on reinforcement repassivation was evaluated by means of electrochemical measurements considering different previous corrosion degrees of reinforcements and different environmental conditions. Reinforcements obtained from a real concrete structure which were activated due to concrete carbonation were used for this purpose. Five different corrosion degrees were considered. All these reinforcements after being classified, were embedded in fresh mortar specimens and were cured in wet chamber for 7 days. After that, they were sequentially subjected to two different environmental conditions; laboratory environment (65% of relative humidity) and 80 % of relative humidity environment. Along all the testing period, reinforcements were monitored on corrosion potential and instantaneous corrosion current density by linear polarisation measurements. Results show that as the previous corrosion degree increases it becomes harder to reach the repassivation condition for reinforcements. This shows that the effectiveness of concrete realkalisation on reinforcement repassivation depends on the previous corrosion degree of reinforcements. The influence of the relative humidity was not significant under the experimental conditions adopted in this work.

  Abstract
  The effect of concrete realkalinisation on reinforcement repassivation was evaluated by means of electrochemical measurements considering different previous corrosion degrees [...]

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• Durability Assessment and Maintenance Planning of Concrete Structures in Ningbo-Zhoushan Port Main Channel Sea Link Project

  L. Li, K. Li

  DBMC 2023.

  
  

  Abstract

  This paper performs the durability assessment and maintenance planning of concrete structures during construction phase in the ongoing Ningbo-Zhoushan Port Main Channel (NZPMC) sea link project with a service life of 100 years. The background of this project is first introduced and the durability design at preliminary study phase is recalled; the chloride-induced corrosion of reinforcement steel was considered as the most critical process that controls the design. Then, the durability model for assessment is established for this durability limit state and the statistical properties of the model parameters are given. From the collected data on the concrete cover thickness and modified chloride diffusion coefficients, the statistical properties of these parameters are updated. With the design options adopted in design phase and the updated parameter properties, taking one non-navigable bridge as an example, the achieved reliability levels and failure probabilities are calculated for structural elements under different exposure conditions by using full probabilistic approach. On the basis of the achieved reliability level of durability, a preliminary maintenance planning is performed for the concrete elements in the concrete structures, and the corresponding recommendations are given.

  Abstract
  This paper performs the durability assessment and maintenance planning of concrete structures during construction phase in the ongoing Ningbo-Zhoushan Port Main Channel (NZPMC) [...]

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• Damaged Swedish Buildings

  P. Wallentén, S. Olof Mundt-Petersen, K. O. Anders Joelsson, M. Kläth

  DBMC 2023.

  
  

  Abstract

  Damages with a negative influence on the indoor environment often become linked to high costs. Detailed facts about buildings with damages need to be collected and analyzed in order to be able to reduce the number of damages. This paper presents basic facts, such as design, property ownership and year of construction in buildings where 1105 damages were found. In general, the study gives qualitative indications and cross-comparing to other parameters considering damages and causes of damages needs to be done to obtain better results. Buildings with indoor air ventilated or heated crawlspaces have less damages compare to non- or outdoor ventilated crawl spaces. Damages are more common in buildings with poor exterior insulation in the foundation or a no-drainage and poorly ventilated cladding. In the buildings in the study, schools and local authority owned buildings have a high frequency of damages. A higher number of damages were also found in condominium association owned multi-family houses compared to public tenancy owned multi-family houses.

  Abstract
  Damages with a negative influence on the indoor environment often become linked to high costs. Detailed facts about buildings with damages need to be collected and analyzed [...]

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• Classification Systems for the Built Environment: A Cornerstone for the Long-term Performance Analysis

  C. Serrat, V. Royano, V. Gibert, J. Rapinski

  DBMC 2023.

  
  

  Abstract

  In the long-term performance analysis of the built environment, classification systems are seen as a key consideration. When classifying residential building objects, characteristics such as accuracy, exhaustivity, and consistency are required. It is noticeable that while organizations around the world are working to develop an internationally agreed standard classifier, the use of national classification systems remains widespread. Therefore, this paper focuses on reviewing the most popular classification systems such as CoClass, Uniclass 2015 and OmniClass®, among others, and discusses their strengths and weaknesses, in order to be useful both to the research and technical communities. Based on this, two main contributions are derived. On the one hand, the paper points out that there is no international consensus to use a common classification system. On the other hand, some recommendations are given and illustrated to meet the challenges of classifying existing buildings, in particular under a functional assessment approach.

  Abstract
  In the long-term performance analysis of the built environment, classification systems are seen as a key consideration. When classifying residential building objects, characteristics [...]

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• Causes of Damages in Swedish Buildings

  S. Olof Mundt-Petersen, P. Wallentén, I. J. Edskär, K. O. Anders Joelsson

  DBMC 2023.

  
  

  Abstract

  Damages, failures and functional defects in buildings create high cost for the owner and the society. It is important to determinate the causes of damages in order to limit the costs. This paper presents the causes of 1105 different damages from a technical perspective from 265 real damage investigations. In general, the results show that; 1. Rain and snow was the most common moisture source cause damages, 2. The number of damages caused by wet concrete and PVC or linoleum flooring may be overestimated. 3. A significant number of damages were caused in details where different materials connect to each other, 4. A high number of damages were linked to wear and tear and poor maintenance. 5. Causes of damages occurs in all phases of the building process but most of them were deemed to occur in the management and on-site construction phase. 6. Most of the damages were caused by building owner or their facility trustees.

  Abstract
  Damages, failures and functional defects in buildings create high cost for the owner and the society. It is important to determinate the causes of damages in order to limit [...]

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• Assessment of the Impressed Current Cathodic Protection System after 4 Years Operation: Evolution Over Temperature and Time of the Applied Current and Tension on Anodic Zones of the Saint-Cloud Viaduct (France)

  J. Ducasse-Lapeyrusse, V. Bouteiller, O. Lesieutre, E. Marie-Victoire, M. Bouichou, G. Damien, V. Martinet, C. Annede-Villeau

  DBMC 2023.

  
  

  Abstract

  This paper presents the feedback of the Impressed Current Cathodic Protection (ICCP) system implemented on a road bridge, the Viaduct of Saint-Cloud, constructed in the 1970s in France. After a test trial in 2012, the full-scale ICCP system was energized in 2018. It consisted of 44359 discrete titanium anodes implemented on the lateral segment webs on both sides of the Viaduct, distributed in 212 anodic zones on one side and 153 anodic zones on the other side. The four years monitoring data include the variations of the applied current and tension on anodic zones, their polarization, etc. This paper focus on the global resistance of the circuit for the different anodic zones. The circuit resistance shows first the influence of the temperature. The differences between anodic zones and their evolution over time also bring more information about the environment of the anodes and the reinforcements. The analysis of the response of the circuit reveals the heterogeneity of an actual and large-scale ICCP system and provides important feedback to an appropriate ICCP design for durable cathodic protection.

  Abstract
  This paper presents the feedback of the Impressed Current Cathodic Protection (ICCP) system implemented on a road bridge, the Viaduct of Saint-Cloud, constructed in the 1970s [...]

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• Analytical and Experimental Service Life Assessment of Ningbo-Zhoushan Port Main Channel Sea Link Project

  L. Li, K. Li, R. Torrent

  DBMC 2023.

  
  

  Abstract

  The Ningbo-Zhoushan Port Main Channel (NZPMC) sea link is one of the most important projects undertaken by the People's Republic of China. The main factors that determine the service life of these marine structures, exposed to chloride-induced corrosion, are the "penetrability" and thickness of the concrete cover that protects the steel reinforcement. In an initial design phase, these factors are defined by modeling the penetration of chlorides with analytical tools (based on the Duracrete approach). In the construction phase, data are collected from the in-site laboratory for concrete chloride diffusivity, and from non-destructive tests for the concrete cover thickness and air permeability for the prefabricated bridge piers. On the basis of these data, two model-based approaches are used to predict the service life of the bridge. The first model is an analytical one based on the solution of Fick’s 2nd diffusion law, for chloride ingress into concrete using the corrosion initiation as durability limit state.The second model uses the “Exp-Ref” model, using the concrete cover thickness and air permeability as input parameters and calibrated by the EuroCode specifications on structural concretes in marine environments. Both approaches use Monte-Carlo simulations and consider the statistical properties of the input parameters. A comparison of the analytical and experimental predictions is made, showing compatibility with 100 years of service life. The convenience of verifying the analytical predictions with those obtained from site experimental data is discussed.

  Abstract
  The Ningbo-Zhoushan Port Main Channel (NZPMC) sea link is one of the most important projects undertaken by the People's Republic of China. The main factors that determine [...]

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• An In-situ Method for Assessing the Kinetics of Acid Attack on Iron-richAlkali-activated Materials

  Z. Yu, R. Oliveira-Silva, E. De Oliveira, N. Wen, Y. Pontikes, D. Sakellariou

  DBMC 2023.

  
  

  Abstract

  In iron-rich alkali-activated materials (AAMs), iron is present in both the ferrous and ferric states. Fe3+ is considered to be present in a silicate network and the dissolution of Fe3+ under acid attack can be taken as an indication of the deterioration of the AAMs framework. Conventional methods for evaluating the acid resistance of AAMs are based on the durability standards for OPC concrete with indicators such as mass change and dimensional change, or by measuring the corroded depth. All of these methods are measured based on solid samples and many samples have to be prepared to obtain different points in a time profile. Here we propose nuclear magnetic resonance (NMR) relaxometry measurements as an in-situ method for the direct determination of dissolution kinetics of Fe3+ ions in an acid solution with high temporal resolution. The leaching kinetics of iron-rich AAMs in (sulfuric) acid can be described by the Real Physical Picture (RPP) kinetic model, which was originally used to describe the gas-solid interaction. The fitting results show that the leaching process is controlled by chemical reactions at the beginning and by diffusion over time.

  Abstract
  In iron-rich alkali-activated materials (AAMs), iron is present in both the ferrous and ferric states. Fe3+ is considered to be present in a silicate network and the dissolution [...]

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• Experimental Study of the Development of Stresses in Prestressing Strandsunder Different Environments

  D. Xu, C. Chen, Y. Zhao

  DBMC 2023.

  
  

  Abstract

  This paper presents findings from an experimental study on the effects of different environmental factors on post-tensioned prestressed concrete beams. The study included four different environments: outdoor shielded, drying-wetting cycles with tap water, drying-wetting cycles with NaCl solution, and drying-wetting cycles with NaCl solution and energized longitudinal rebars. A vibratingstring anchor cable dynamometer was used to measure the stress variation in prestressing strands. The results indicate that ambient temperature affects the trend of stresses in the prestressing strands. The increasing humidity caused by drying-wetting cycles and increasing salinity caused by NaCl solution led to the expansion of the concrete and increased stresses in the prestressing strands. Additionally, the corrosion of longitudinal rebars caused by the impressed-current accelerated corrosion method results in concrete damage and cracking, and continuously decreases the stresses in the prestressing strands. The study is ongoing, and further observations and reports will be made to evaluate the effects of different environmental factors on stresses in prestressing strands of post-tensioned beams.

  Abstract
  This paper presents findings from an experimental study on the effects of different environmental factors on post-tensioned prestressed concrete beams. The study included [...]

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• Exploring Moisture Performance of Two Distinctive Solid Bricks underCurrent and Future Climate in London

  B. Xu, S. Zhang, T. Cambray, V. Marincioni

  DBMC 2023.

  
  

  Abstract

  The increasing concerns surrounding climate change have raised apprehension about the heightened frequency and intensity of extreme weather events, globally as well as in the UK. Historic solid brick buildings, due to their construction materials and prolonged exposure to changing climate conditions, are vulnerable to the impacts of climate change, resulting in increased moisture risks that undermine their durability. Understanding the moisture behaviour of solid bricks facing climate change is therefore significant. This study aims to investigate the moisture performance, with a specific focus on moisture content, of two distinct types of bricks: handmade bricks from the 19th century and more recent – early 20th century - bricks, under current and future climate scenarios in London. The results reveal that the more recent bricks can have greater susceptibility to climate changes, providing valuable insights for the implementation of effective moisture control strategies and informed decision-making in the retrofitting of solid brick buildings in the UK.

  Abstract
  The increasing concerns surrounding climate change have raised apprehension about the heightened frequency and intensity of extreme weather events, globally as well as in [...]

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