The modification methods of pozzolan slurry combined with sodium silicate and silicon-based additive were respectively adopted to treat recycled coarse brick-mixed aggregate(RCBA)in this study.The compressive strength...The modification methods of pozzolan slurry combined with sodium silicate and silicon-based additive were respectively adopted to treat recycled coarse brick-mixed aggregate(RCBA)in this study.The compressive strength and chloride permeability resistance of recycled aggregate concrete(RAC)before and after modification treatment were tested,and the microstructure of RAC was analyzed by mercury intrusion porosimetry(MIP)and scanning electron microscopy(SEM).The results show that the physical properties of RCBA strengthened by modification treatment are improved,and the compressive strength and chloride permeability resistance of treated RAC are also significantly improved.The modification treatment optimizes the pore size distribution of RAC,which increases the number of gel pores and transition pores,and decreases the number of capillary pores and macro pores.The surface fractal dimension shows a significant correlation with chloride diffusion coefficient,indicating that the variation of chloride permeability of treated RAC is consistent with the microstructure evolution.展开更多
In this study, two types of reinforcing steels(conventional low-carbon steel and a novel duplex alloy steel with Cr and Mo) were exposed to chloride-contaminated extract solutions(ordinary Portland cement(OPC) extract...In this study, two types of reinforcing steels(conventional low-carbon steel and a novel duplex alloy steel with Cr and Mo) were exposed to chloride-contaminated extract solutions(ordinary Portland cement(OPC) extract and alkali-activated slag(AAS) extract) to investigate their pitting corrosion resistance. The results confirm that the pitting corrosion resistance of the alloy steel is much higher than that of the low-carbon steel in both extract solutions with various Na Cl concentrations. Moreover, for each type of steel, the AAS extract contributes to a higher pitting corrosion resistance compared with the OPC extract in the presence of chloride ions, likely because of the formation of flocculent precipitates on the steel surface.展开更多
Through the rapid chloride ion penetration test,the influence of fly ash and slag on chloride ion permeability and microstructure of concrete was studied.The results indicate that the addition of fly ash increases con...Through the rapid chloride ion penetration test,the influence of fly ash and slag on chloride ion permeability and microstructure of concrete was studied.The results indicate that the addition of fly ash increases concrete permeability at 28 days.With the slag content of 20% and 30%,the permeability of concrete at 28 days is reduced.The positive effect of slag is due to its relatively stronger pozzolanic reactive ability resulted in the most probable pore size and total porosity decreased.When the slag content reaches 40%,the concrete permeability showes the tendency ofincrease.展开更多
基金Funded by the National Natural Science Foundation of China(No.52078050)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2020JZ-22)。
文摘The modification methods of pozzolan slurry combined with sodium silicate and silicon-based additive were respectively adopted to treat recycled coarse brick-mixed aggregate(RCBA)in this study.The compressive strength and chloride permeability resistance of recycled aggregate concrete(RAC)before and after modification treatment were tested,and the microstructure of RAC was analyzed by mercury intrusion porosimetry(MIP)and scanning electron microscopy(SEM).The results show that the physical properties of RCBA strengthened by modification treatment are improved,and the compressive strength and chloride permeability resistance of treated RAC are also significantly improved.The modification treatment optimizes the pore size distribution of RAC,which increases the number of gel pores and transition pores,and decreases the number of capillary pores and macro pores.The surface fractal dimension shows a significant correlation with chloride diffusion coefficient,indicating that the variation of chloride permeability of treated RAC is consistent with the microstructure evolution.
基金financially supported by the National Natural Science Foundation of China (Nos.51461135001 and 51678144)the Major State Basic Research Development Program of China (No.2015CB655100)+2 种基金the Natural Science Foundation of Jiangsu Province (No.BK20161420)the Industry-University Research Cooperative Innovation Fund of Jiangsu Province (No.BY2013091)the China-Japan Research Cooperative Program by Ministry of Science and Technology of China (No.2016YFE0118200)
文摘In this study, two types of reinforcing steels(conventional low-carbon steel and a novel duplex alloy steel with Cr and Mo) were exposed to chloride-contaminated extract solutions(ordinary Portland cement(OPC) extract and alkali-activated slag(AAS) extract) to investigate their pitting corrosion resistance. The results confirm that the pitting corrosion resistance of the alloy steel is much higher than that of the low-carbon steel in both extract solutions with various Na Cl concentrations. Moreover, for each type of steel, the AAS extract contributes to a higher pitting corrosion resistance compared with the OPC extract in the presence of chloride ions, likely because of the formation of flocculent precipitates on the steel surface.
基金Funded by the National Natural Science Foundation of China (No.50070819)
文摘Through the rapid chloride ion penetration test,the influence of fly ash and slag on chloride ion permeability and microstructure of concrete was studied.The results indicate that the addition of fly ash increases concrete permeability at 28 days.With the slag content of 20% and 30%,the permeability of concrete at 28 days is reduced.The positive effect of slag is due to its relatively stronger pozzolanic reactive ability resulted in the most probable pore size and total porosity decreased.When the slag content reaches 40%,the concrete permeability showes the tendency ofincrease.
