Quantifying the effects of wet carbonated recycled cement paste powder on the properties of cement paste

Abstract

The use of carbonated recycled cement paste powder (RCPP) as a mineral admixture affects the properties of the cement paste through multiple effects. This study proposes a model to decouple and quantify these effects based on their contribution to the compactness (1 − porosity) of the paste. Experimental results showed that the filler effect significantly contributed to the increase in compactness by 10.4 %–55.9 % at 1d-28d, while the contribution of the pozzolanic effect of silica gel was 2.7 %–7.3 % at 1d and then reduced remarkably at 3d. The nucleation effect contributed to the compactness of paste by 7.0 %–12.8 % within 3d. The contribution of the chemical effect varied largely among the different pastes at 1d and 28d. This explains the difference observed in the properties of the pastes. Increasing the carbonation time and temperature during wet carbonation of RCPP could improve the properties of paste by increasing the total contribution of chemical, nucleation, and pozzolanic effects.