Effect of wet carbonated recycled cement paste powder on the rheology of cement paste

This study investigated the effect of wet carbonated recycled cement paste powder (RCPP) on the rheological properties of cement pastes. The results showed that wet carbonated RCPP decreased the cement paste's setting time and flowability, increased its yield stress and plastic viscosity, and changed its thixotropy. The high absorption capacity of the silica gel in the carbonated RCPP was the most dominant factor influencing the rheological properties of the paste. The absorption capacity of silica gel was dependent on its pore structure, specific surface area, and the amount of hydroxyl groups on its surface. These properties varied with the carbonation method, time, temperature, and CO2 flow rate. The use of monoethanolamine as the aqueous solution for wet carbonation was found to be an effective approach to mitigate the adverse effect of carbonated RCPP on the rheological properties of cement paste.