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Roller-compacted concrete (RCC) is a dry, zero-slump concrete prepared from the same ingredients as conventional cement but with a lower cement percentage. It is frequently compacted in the same way as dirt is. RCC is utilized chiefly to build massive structures such as dams and vast horizontal surfaces like highway foundations. Because of the low cement concentration, it slows the rise of temperature in mass concrete and decreases thermal strains. However, this paper analyzes the possibility of a chemical link forming between functionalized Multi-Wall Carbon Nanotubes and Nano-alpha Alumina in Roller-Compacted Concrete (RCC) structure using spectroscopic analysis. Various characterization methods, including X-ray diffraction patterns, Fourier-transform infrared (FT-IR) spectrometry, and scanning electron microscopy (SEM), were employed to analyze the nanocomposite's interaction. Based on X-ray diffraction pattern results, Multi-Wall Carbon Nanotubes (MWCNT) peaks show that the powder is amorphous, but it becomes crystalline when combined at high temperatures. The X-Ray diffraction (XRD) profile of the carbon nanotube-doped alumina sample reflects the leading share of Al₂O₃, with angles and diffraction plates of Al₂O₃ being the same as α- Al₂O₃ orthorhombic crystalline phase owing to the low carbon concentration. Besides, scanning electron microscope analysis revealed that α-Al2O3 powder samples without MWCNT and containing MWCNT have a shell state that the doped sample tends to be spherical.

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This work describes the production and morphological, structural, and magnetic characterization, as well as the electromagnetic shielding properties of polymeric based composites reinforced with different ratios of magnetite and carbon black. This kind of composites are used not only for the manufacture of electronic elements such as shape memory polymers, sensors and transducers, but especially for the production of electromagnetic shielding materials in both passive defense and civil construction applications; Buildings, vehicles or airplanes.

The melt mixing method and vulcanization procees was followed for the manufacture of the composites.Composite materials with natural magnetite and synthetic magnetite have been considered separately. Reinforcements fillers were added in different ratios. The morphological analysis carried out by FESEM demonstrates the differences in size and shape of the fillers.Through the Raman and XPS spectroscopy the  interface matrix-fillers was studied. The magnetite content, as well as its source, directly affect the magnetic behavior of the composites. The electromagnetic shielding properties were evaluated in the X band of frequency (8-12 GHz) and K band (18-27 GHz), with attenuations greater than 34 dB for the composites with the highest amount of magnetite. 

Abstract

Epoxy resin composites inherent brittleness and poor crack resistance make necessary some form of toughening. Recently, several types of nanoparticles are being incorporated due to their theoretical high stiffness and strength. However, the addition of tougheners to the entire matrix resin could lead to a decrease in in-plane mechanical properties and to an increased viscosity of the system, being reduced the processing ability of matrix resin. Moreover, a homogeneous dispersion of these nanoparticles is still a problem. Thermoplastic nanofibrous structures can tackle these problems. They offer a solution for the dispersion issue, since they can be readily embedded in the resin and incorporate a nanosized phase in the composite. These nanofibres also do not increase the viscosity of the resin. Moreover, due to their macro scale length, no health hazards are involved in the production and use of these nanofibres.

This paper investigates the effect of electrospun nanofibrous veils made of polyamide 6 modified with TiO2 nanoparticles on the properties of a carbon fibre/epoxy composite. The nanofibres were incorporated in the carbon fibre/epoxy composite as stand-alone interlayered structure during a vacuum infusion process. The effect of positioning these veils in different composite positions has been investigated. Incorporation of polyamide nanofibers increases the stress at failure and the Young’s modulus. Furthermore, mode I tests showed a slight improvement. When TiO2 modified veils are incorporated in the composite, similar mechanical properties were obtained, but new antibacterial properties were achieved when irradiated with UV light widening the application area of these composites.

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The diffusion or permeability of ions or gases through the cement matrix is key in the degradation of reinforced concrete for marine applications. The delay in ion diffusion has been an important approach to extend the life of this type of materials. In this work it is detailed how reduce degradation of cement mortar using nanotechnology. The addition of nanoparticles to the cement paste has important implications for the hydration and microstructure, reducing porosity and improving mechanical properties. In this study, different nanoparticles have been used to reduce the porosity of mortars evaluating this improvement by means of electrical resistivity measurements. It is perfectly established the porosity reduction with the increasing of electrical resistivity. Reduction of porosity minimises the intake of aggressive agents into the mortar in a meaningful way, retarding the corrosion of metal reinforcement. Nanoparticles addition (<10%) within cement mortar have allowed to increase the electrical resistivity in up to 112% regarding to control sample, without modifying of mechanical properties.       

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