Investigation of the potential use of waste from ornamental stone processing after heat treatment for the production of cement-based paste

This paper aims at investigating the potential pozzolanic use of ornamental stone processing waste after heat treatment (OSWHT) as an admixture in Portland cement paste. Heat treatment at 1200 °C was carried out to potentialize the possible pozzolanic characteristics of the waste. The chemical composition of OSWHT was analyzed, together with its mineralogy, the visual characteristics of its grains, its specific surface area and fineness, and its pozzolanic capacity. The OSWHT was used as admixture at the rates of 5% and 10% by mass of Portland cement in preparation of the cement paste. The microstructural characteristics of these pastes were evaluated at the ages of 3, 7, 28 and 90 days. The results indicate that OSWHT has low pozzolanic activity when used in the production of cement-based pastes, being able to provide the final product with a denser microstructure due to the filler effect and possibly due to a small pozzolanic reaction.