Effect of Chloride Erosion on the Multiple Interface Microstructure of Recycled Concrete

Abstract

The range of the transition zone of different interfaces of different strength grades was determined by studying the microhardness of different interfaces of recycled concrete with chloride salt erosion, and the influence of chloride age on the microstructure of regenerated concrete was studied. These reveal the mechanism of deterioration of chloride salt erosion in multiple interfaces of recycled concrete. The results show that the microstructures of the old aggregate - the new slurry interface (LG-XJ interface), the old paste - the new slurry interface (LJ-XJ interface) and the old aggregate - the old slurry interface (LG-LJ interface) with the same strength decrease as the increase of the age of chloride salt, and the transition zone gradually increases. The LJ-XJ interface transition zone of C30 reclaimed concrete has almost no change when the erosion age is 30d. When the erosion age is 90d, the range of LJ-XJ interface transition zone of C60 recycled concrete is still not obvious. The strength of the interface with the same strength recycled concrete against chloride corrosion: LJ-XJ interface> LG-LJ interface> LG-XJ interface. The changes of the microhardness and the range of the transition between the LG-XJ interface and the LJ-XJ interface, and the LG-LJ interface are reduced to some extent with the increase of the strength grade, and the degree of change in the microhardness of the cement paste itself is also reduced to varying degrees.