Effect of ceramic polishing waste on the properties of alkali-activated slag pastes: Shrinkage, hydration and mechanical property

In order to reduce carbon emissions and realize the resource utilization of solid wastes, the ceramic polishing waste (CPW) was applied to replace part of slag to prepare alkali-activated slag/CPW (AASC) composite cementitious material. The influence of CPW contents on the fluidity, setting time, autogenous shrinkage, chemical shrinkage and compressive strength of AASC pastes was investigated. Moreover, the hydration products and microstructure of AASC pastes were also studied by means of XRD, TGA, and BET-BJH method. Experimental results showed that the fluidity and setting time of AASC pastes were continuously increased when CPW contents increased from 10% to 50%, but the autogenous shrinkage decreased from 6.2% to 51.8%. This is due to the dilution effect of CPW, which decreased the early-age chemical shrinkage. In addition, the compressive strength of AASC pastes containing 30% CPW (P30) at 7 d was basically equal to that of the reference sample, being attributed to more amount of C-A-S-H gels. Although the late-age strength of P30 was decreased due to the increase of pore volume, it could still reach over 90% of reference sample. This indicated that maximum proportion of CPW used to replace slag was 30%, which can not only reduce the risk of shrinkage cracking of AASC pastes, but also have less effect on the strength.