Experimental study on chloride ion permeability of carbonated recycled aggregate concrete considering the effects of multiple factors

The chloride ion permeability is an important index of durability of carbonated recycled aggregate concrete (CRAC), but the resistance to chloride ion permeability of CRAC is affected by many factors and has yet been fully explored, which needs further systematic study. Considering the effects of the replacement ratio of carbonated recycled coarse aggregate (CRCA), the carbonation time of CRAC, the bending load level, the carbonation temperature of CRAC, and the replacement ratio of carbonated recycled fine aggregate (CRFA), the resistance to chloride ion permeability of CRAC was investigated by conducting tests in this paper. The results indicated that, compared with the non-carbonated recycled aggregate concrete (NCRAC), the electric flux of CRAC decreased by 9.14-37.34 %. An increase in the replacement ratio of CRCA could reduce the resistance to chloride ion permeability of CRAC, while an increase in CRAC carbonation time had a significant effect on improving the resistance to chloride ion permeability. When the replacement ratio of CRCA was 100 %, as the carbonation time increased from 0 to 14 days, the maximum reduction in electric flux of CRAC was 31.66 %. With the same replacement ratio of CRCA, as the bending load level increased, the decrease in electric flux of CRAC showed an increasing trend compared to that of NCRAC. The resistance to chloride ion permeability of CRAC could be improved with an increase in carbonation temperature. Compared with the CRAC with carbonation temperature of 20 degrees C, the electric flux of the CRAC with carbonation temperature of 40 degrees C decreased by 11.03 %. When the replacement ratio of CRFA was in the range of 0-20 %, the resistance to chloride ion permeability of CRAC could be improved by incorporating CRFA, but the improvement effect was not significant. Therefore, compared with the NCRAC, the resistance to chloride ion permeability of CRAC is enhanced, and the research results can provide data support for the engineering application of CRAC.