Advanced Materials Research Vols. 168-170

Abstract: This paper studied the compound modified asphalt which was made of crumb rubber modified asphalt, and some chemical modifier were added.The experimental shows the performance of this kind of modified asphalt .The proper parameters and ratios can be used to improve level of the using of crumb rubber modified asphalt.

Abstract: Cemented soil resistivity is one of its inherent properties which can be used to detect its unconfined compressive strength and polluted state. But the cemented soil resistivity is macroscopic showing of its microstructure conductivity. Its resistivity closely relates with resistivity of various material components, such as soil porosity, cement mixing ratio,etc. So further researching the electrical model of cemented soil is great significance. This paper introduces the existing cemented soil electrical model(Komine model). Then based on the microstructural observation of the SEM images of cemented soil, the problems of Komine model are pointed out. Furthermore a more reasonable microstructure is proposed. The new electrical model of cemented soil is set up on three hypotheses. This new model is composed of parallel structure and series structure. Some soil particles surrounded by the hydration products such as CSH or CASH connect with pore water parallel to form the series structure. The hydration products that continue to harden to form the cemented soil skeleton connect with soil particles and pore water to form the parallel structure. The new electrical model of cemented soil can explain better electrical conductive mechanism of cemented soil materials.

Abstract: The effect of different quantity of air-entraining agent on the impermeability of cement-based materials are studied in this paper. Impermeability test and mercury intrusion porosimetry (MIP) method were used to characterize the impermeability and pore structures. The fractal dimension is used to describe the characteristic of pore structure and calculated by the data of MIP experiment. The result shows that owing to the improvement of pore structure, the impermeability performance of the cement-based composites is noticeably enhanced when air-entraining agent is added with appropriate quantity.

Abstract: The unconfined compressive strength, deformability and water stability of clay soil consolidator were investigated; the results were compared with those of cement and lime. The results indicated that the strength, water stability and resistant to deformability of stabilized soil containing the consolidator were prior to those of cement and lime. Moreover, the stabilization mechanism of the consolidator was descried.

Abstract: Compressive strength, setting time, hydration heat and hydration product were investigated to evaluate the effects of Zn₂+ ion concentrations and the anion of zinc salts on the hydration characteristics of Portland cement paste. The results show that the hydration characteristics of zinc-doped cement pastes depend on Zn₂+ ion concentrations and the anion of salts. With the incorporation of ZnCl₂, the hydration heat, exothermic rate and the early-age strength of cement pastes were reduced, the arrival time of the highest temperature was delayed, and little negative influences on the compressive strength at 28 days were observed. The total hydration did not decrease incorporating ZnSO₄; the hydration exothermic process was delayed. There were little negative influences on the compressive strength of the samples at 3 days and 28 days. Moreover, for the samples with the same Zn concentration, the retardation effect of ZnCl₂ samples was stronger than that of ZnSO₄ samples.

Abstract: Water content has important influences on the compression strength of mortar material. It is necessary to consider these influences when evaluate performances of mortar structures after flood soaking. This paper carried out experiments to explore the rule of water content’s effects on the compression strength of mortar. The results showed that 6 hours after the mortar in the soaking water content close to saturation, moisture content about 14%, after 6 hours the water content change little. Compression strength decreases rapidly after the mortar soaked. Finally, the mortar compression strength formula considering the effects of water content is regressed.

Abstract: This paper deals with the ultimate load capacity test on 14 short columns of separation concrete-filled steel tubes (CFST) which are subjected to the eccentric compression on separate side. The experimental parameters include the separation ratio and the eccentricity ratio. The result shows that the separation ratio and the eccentricity ratio will influence the load capacity of the components of the concrete-filled steel tubes which are subjected to the eccentric compression. The confinement of steel tubes to core concrete will be continuously weakened and the ultimate load capacity of the components will be decreased obviously with both the separation ratio and the eccentricity ratio increasing gradually.

Abstract: Through unconfined compressive strength tests and triaxial compression tests made by sea water wet fly ash, fly ash solidified by cement, and the analysis with water wet strength of the material solidified fly ash formation mechanism, getting their basic mechanical properties and index. The results showed that curing water wet fly ash cement has good stability and durability, mixing curing mixture strength with age of stable growth, increased strength by adding cement content. The pilot research on the retaining structure, embankment reinforcement and ground improvement has important engineering applications such as theory and practice of value.

Abstract: The application of Buckling Restrained Braces(BRBs) in the frame structure becomes mature, but relevant research hasn’t reported for application of steel arch structure with BRBs, so according to the large-span steel arch structure characteristics, puts forward BRBs to replace some braces of steel arch structure system, using finite element method, analyzes the damping performance for steel arch structure with BRBs and compares it with original under different excitation, results show that large-span steel arch structure with BRBs is provided with better damping performance.

Abstract: To understand the impacting law of lightweight aggregate moisture content on the cement paste pore structure and its relationship with humidity and deformation of the lightweight aggregate concrete, it is necessary to study the effect of water absorptivity and pre-wet moisture content of lightweight aggregate on the pore structure interfacial transition zone (ITZ) cement paste. The experimental results indicated that the species and moisture content of lightweight aggregate have a greater effect on the pore structure in interfacial transition zone of cement paste in low w/c concrete than that in high w/c concrete. With the saturation level of lightweight aggregate increased, the overall pore structure shows a refinement tendency. The porosity and the larger pore of ITZ in ordinary aggregate are notably higher than those in the basal body cement paste. Meanwhile, we find that the pore structure of ITZ in lightweight aggregate concrete is much different from that in ordinary aggregate concrete. Especially in the concrete using the lightweight aggregate with a high absorption–desorbtion water rate, the pore aperture in ITZ is significantly lower than that in the cement paste, the pore content below 50nm can reach as high as 80%.