Limestone replacements by fine crushed concrete and ceramic wastes during the production of Portland cement

This study assesses the feasibility of limestone (LS) replacement by recycled fine aggregates (RFAs) on grindability and Portland cement properties. Two RFA types generated from the fine fraction of crushed concrete and ceramic wastes are ground in 22-liters grinding mill at 310 and 400 +/- 20m(2)/kg Blaine fineness, and then incorporated at 20% and 35% rates in clinker cement mixtures. Because of their porous nature, RFAs required about 22% to 30% less communition energy than LS, which could be advantageous to reduce grinding costs for given Blaine fineness. Mortars prepared with RFA-based cements yielded better strength recovery over time and lower water sorptivity than LS-based cement, either due to promoted hydraulic activity or pozzolanic reactions. The comminution of RFA fillers to 400 +/- 20m(2)/kg fineness is a viable alternative to mitigate the dilution effect while maintaining similar grinding energy and mechanical strengths as the control 95% clinker cement.