CALCULATION MODEL OF EARLY CARBONATION DEPTH OF MINERAL ADMIXTURE CONCRETE

Based on the carbonation test of concrete with various admixtures (fly ash, mineral powder and gangue) in natural exposure environment, the influence of carbonation time and curing time on the early carbonation depth of concrete with admixtures was analyzed. Results showed that the carbonation depth of concrete with admixtures developed very fast within 90 days after pouring, while tended to slowly from 90 days to 180 days due to the phenomenon of alkali return, and the carbonation depth of concrete with admixtures continued to develop and tended to be stable after 180 days. The carbonation depth of concrete with admixtures had a linear relationship with the square root of carbonation time. The early carbonation speed of concrete slowed down with the extension of curing time, and the slowing down degree of concrete with single, double and triple admixtures weakened in turn. Combined with the previous research results, considering the type and amount of admixtures, curing time, carbonation time, carbonation position, water-binder ratio and other factors, the calculation model of early carbonation depth of concrete with admixtures was established, and the applicability of the model was verified by comparing with test results from others.