Applied Mechanics and Materials Vols. 368-370

Abstract: This study employed Taguchi method to identify key factors influencing the protection provided by the surface treatment of reinforced concrete structures. We evaluated the protective characteristics of silicate concrete sealer (SCS) as well as its underlying mechanisms. An L12 (2⁷) orthogonal array was produced using seven control factors and two levels to obtain the necessary data from only twelve experiments. Tests were performed to evaluate compressive strength, water absorption, and permeability. The major factors influencing the effectiveness of SCS included the water-binder ratio of the substrate, cumulative curing time of the sealer, content of pozzolanic material, and type of sealer materials. XRD analysis and SEM observation revealed the composition and efficacy of SCS in protecting concrete. The SCS reacted chemically with the cement hydration product Ca (OH)₂ and filled the pore structure with C-S-H gel, which succeeded in greatly improving the mechanical properties of the concrete.

Abstract: Liquefaction of saturated sands remains an important topic in Geotechnical earthquake engineering. Amongst various review measures available,the use of CFG Column and stone columns Composite foundation to prevent liquefaction can achieves good results. In this paper, a detailed review on effectiveness of densification, drainage and reinforcement of CFG column and stone columns Composite foundation for the resistance of soil liquefaction during earthquakes is presented.

Abstract: The concrete building protection materials is widely in the hydraulic and bridge engineering. In the external environment, water, chloride ion, deicing salt and freeze-thaw cycle is the greatest enemy of the concrete builidng , leading to concrete corrosion damage. we found that silane materials is an efficient materials for building protection ，water absorption rate of silicone protected specimens is no more than 0.004 mm/min^0.5and the chloride diffusion coefficient was clearly reduced. The silane can penetrate into a few centimeters below the surface of the concrete structure to provide long-term protection. So the silane materials is considered the most suitable for concrete protection.

Abstract: During the long term service, concrete deterioration will occur due to erosion circumstance, load or unload condition, which will have negative effect on its security and durability. This article mainly discusses the effect of cement-based permeable crystallization material on compressive strength, rebound putative strength, carbonization performance, chloride permeability, and frost resistance of deterioration concrete. The result has shown that cement-based permeable crystallization material can effectively improve the strength, carbonization resistance performance and chloride resistance ability, but for the frost resistance is not obvious. We also analyze the function mechanism of the cement-based permeable crystallization material through ESEM observation.

Abstract: The effect of nitrite on steel corrosion induced by sulfate in three simulated concrete pore environments has been investigated by means of half-cell potential, linear polarization resistance and visual examination, as well as sulfate-induced corrosion is compared with chloride-induced corrosion. The results indicate that with the presence of nitrite, sulfate-induced corrosion can be inhibited effectively. Sulfate threshold level increases with the increasing of nitrite concentration and highly alkaline environment plays an important role in assisting nitrite to inhibit sulfate-induced corrosion. Chloride-induced corrosion is more prone to initiate than sulfate-induced corrosion in highly alkaline environment but in neutral environment, when nitrite content is equal to or less than 0.053mol/L, sulfate-induced corrosion is more likely to occur than chloride-induced corrosion.

Abstract: The influence of nitrite concentration on the linear polarization curves of steel, Tafel slope and Stern-Geary constant B have been investigated in three different pH environments simulating the highly alkaline environment, carbonated environment and neutral environment that really existed on the surface of steel in concrete. The results indicate that when the steel is in passive state, the presence of nitrite has little influence on anodic/cathodic polarization curves and Stern-Geary constant B; but when the steel is corroded, the presence of nitrite not only reduces the current density of anodic polarization curve but also decreases the value of Stern-Geary constant B. If this influence is not considered in practical corrosion measurement, the corrosion current will be overestimated.

Abstract: Concrete is one of the oldest building materials known to humankind. From 1824, with the advent of Portland cement, concrete assumed a prominent place among the construction materials, due to large amounts of strength, durability and versatility it offered compared to other products, allowing the molding of various forms architectural. Until the early 80s, the concrete remained only as a mixture of cement, aggregates and water, however, in recent decades, due to the development of new techniques and products, the concrete has been undergoing constant changes. The concrete with lightweight aggregates have been used since the beginning of the last century, with low values of density (< 2000 kg/m³), demonstrating the great potential of using this material in several areas of construction ^[. With the objective of analyzing the influence of the consumption of cement in conventional concrete and light, were molded, tested and compared body-of-evidence containing two different amounts of cement consumption: a) 350 kg/m³ and b) 450 kg / m³. The results were compared with those obtained by other researchers, as well as with [ and [.

Abstract: Small sized specimen of cement concrete pavement structure was prepared indoors. By utilizing the dynamic signal tester and obtaining the vibration frequency domain signals through the falling-ball vibration impact test method, the attenuation rules of the vibration response of the pavement structure were analyzed and the effects of the flexible functional layer on the vibration-reduction and energy-absorption were studied. The results showed that, after compared with the normal flexible functional layer, the flexible functional layer incorporated with rubber powder resulted in the pavement structure having the better capacities of vibration-reduction energy-absorption and impact resistance. Accordingly, the rupture failure of the cement concrete pavement induced by vehicle load can be reduced.

Abstract: Through a series of mechanical properties experiment of recycled asphalt mixture composed of waste asphalt mixture 20% and different content of rubber powder, the paper analyzes and compares the elasticity, tensile strength and bending strength of asphalt mixture and recycled asphalt mixture, concluding that recycled asphalt mixture that mixed with crumb rubber content of 20% can completely replace the new asphalt mixture in the application. It has great significance for the future to recycling waste asphalt mixture in the highway.

Abstract: Upon large demands from southwest of China where a large number of hydropower stations are schemed or under construction with presence of a variety of aggregates, it is of necessity to launch a comprehensive investigation on influence of aggregates on properties of concrete which was rarely reported before. Four types of aggregates selected from different construction sites were used to conduct tests, and results indicated that water absorption of aggregates exhibited a consistent rising tendency over 180 days and it had close relationship with autogenously shrinkage of concrete which varied in the manner that high water absorption of aggregates produced more obvious shrinkage. With employment of advanced temperature and stress machine, concrete made with diorite and basalt was rated better than limestone and natural granite concrete in crack resistance based on comparison of cracking temperature and thermal impact according to RILEM TC119.