This article presents the results of research of processes of deformation and destruction of asphalt concrete
pavements under cyclic loads. As the ground for such approach to estimation of the asphalt concrete properties served
the proof that regardless of the composition and structure of asphalt concrete with an equal amount of elastic (viscoplastic)
bonds possess the same relaxation ability. This situation is a significant feature of the behaviour of asphalt concrete,
which opens the way for the development of certain approaches to the analysis of their properties, evaluation of
reliability and durability. The promising methodology for the comparative assessment of fatigue and cyclic durability
of asphalt concrete by exploring the complex set of elastic and viscoplastic bonds in their structure depending on the
temperature, magnitude, and modes of action of the loads is proposed in the presented work. In the future, the establishment
of patterns of behaviour of asphalt concretes with the same set of elastic bonds is allows to optimize compositions
based on the principles of temperature-structural analogythat is relevant in studying fatigue and cyclic durability
as well as low-temperature crack resistance and shear stability.
This paper aims to develop frost-resistant concretes, and investigate their pore structures and freeze–thaw damage mechanism. The frost-resistant concrete mixtures are designed by using rubber particles and nano-SiO2 to partially replace sands. The chord lengths, specific surface areas, contents and spacing coefficients of the pores in the designed concretes are measured and analyzed. The results show that concrete mixture incorporated with 5% silanized rubber and 3% nanosilica shows good synergetic effect by considering both mass loss and relative dynamic modulus of elasticity (RDME). The freeze–thaw damage degree of the concrete could be reduced by adding high elastic rubber particles, due to filling and constraining pores, and resulting in better uniform pore distribution and smaller pore spacing coefficient. Furthermore, the correlations between frost resistance and pore are analyzed and proposed.
A CuO/bentonite composite photocatalyst was prepared to fully utilize the adsorption capacity of bentonite and the photocatalytic activity of CuO. CuO and bentonite were chosen as a photocatalyst due to the excellent optical property of CuO and large specific surface area of bentonite, together with their high stability and low production cost. The sample was characterized by XRD, SEM, and BET. The effects of several factors on degradation process were investigated such as dosage of H2O2, irradiation time, pH of the solution, and dosage of catalyst. The optimum conditions for decolorization of methylene blue solution by CuO/bentonite were determined. Under optimal conditions, the decolorization efficiency of methylene blue by a 1.4% CuO/bentonite (400 °C) composite photocatalyst under visible irradiation at 240 min reached 96.98%. The degradation process follow edpseudo-second-order kinetics. The photocatalytic mechanism is discussed in detail. This composite structure provides a new solution to the cycle and aggregation of the photocatalyst in water.
This article presents the results of studies to optimize the composition of water dispersion of epoxy resin for the modification of RAP cold recycled mixes. The resulting water dispersion is easily combined with the bitumen emulsion and can be easily applied in the preparation of cold mixes. This kind of modification will significantly improve their reliability and durability and to closer in magnitude to the properties of hot asphalt concrete widely used for the construct of road pavements. In order to improve the efficiency of the modification process, the process of emulsification of epoxy oligomers in the presence of nonionic surfactants and further application of the obtained dispersions as a component of bitumen emulsions used for the preparation of RAP cold recycled mixes is justified. This kind of integrated approach to the selection of the composition of water dispersion of epoxy resin provided a higher level of its interaction in the formation of elastic and viscous bonds of increased strength in the formation of the structure of composites based on asphalt, bitumen emulsions and cement.
The use of thermal insulated decorative panel materials with low thermal conductivity and high flame retardance is a key step toward energy-saving buildings. However, traditional thermal insulation materials are always highly conductive and inflammable, which restricts their application for new buildings. This study aims to prepare the non-combustible, cement-based EPS mixtures with thermal conductivity lower than 0.045 and density less than 140 kg/m3 and characterize it with mechanical, thermal, and flame retardant properties. The effect of particle size, Silica coated and content of EPS on the physical, mechanical, thermal, and combustion performance are conducted in this paper. The comprehensive indoor tests including density, water absorbing, softening coefficient, compressive strength, tensile strength, moisture susceptibility, thermal conductivity, and scanning electron microscopy (SEM) along with combustion performance are reported to evaluate the effects of several variables on the investigated cement-based nonflammable EPS (CEPS)mixtures. The results show that small and gradation EPS particles significantly improve the comprehensive performance of mixtures. In addition, Silica coated ESP significantly improve the flame retardance of mixtures while reduce the mechanical characteristics slightly. These results contribute to the selection of appropriate materials to enhance the thermal insulation, flame retardance and mechanical properties of CEPS.
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