Surface properties of ceramic waste powder and its effect on the rheology, hydration and strength development of cement paste

Abstract

To reduce carbon emissions and environmental impacts, ceramic waste powder (CWP) can be used to replace part of the cement in concrete. To understand the mechanisms of the influence of CWP on the properties (i.e. rheology, hydration and strength) of cement-based materials, a zeta potential test with different Ca2+ concentrations was conducted. It was found that CWP has a similar absorption for Ca2+ as cement and quartz particles, which is directly related to its surface chemical properties. The adsorption of Ca2+ on the particle surface affects the formation of C–S–H and the rheology of the cement paste. Based on the similarity in surface chemistry, it is elucidated that the effect of CWP on the rheology and early-age hydration of cement paste is attributed to its size or shape, not the surface chemical properties. In addition to strength measurement, the effect of CWP on the strength of cement paste was investigated by crack characterization and fracture surface observation. The results demonstrated that as hydration proceeded the interface strength between CWP and hydrates increased, and the chemical reaction of CWP became apparent. It also showed that CWP is an inert filler similar to quartz particles at early age. Nevertheless, at late age the pozzolanic reaction becomes obvious and improves the strength development of the cement paste.