Enhancement in pozzolanic reaction and properties of mixed mortar by recycling waste expanded perlite

This study examines the effects of mechanically ground waste expanded perlite (GEP) on the pozzolanic activity and overall performance of cement mortars. Waste expanded perlite was ground for 2 and 20 min using a ring mill to reduce particle size and enhance reactivity. The resulting GEP was incorporated into both conventional mortar and lightweight mortar in which 50% of natural sand was replaced with expanded perlite. The influence of grinding duration was evaluated in terms of particle characteristics, hydration behavior, pore structure, mechanical properties, and thermal conductivity. The results indicate that mechanical grinding effectively decreased particle size and increased the reactivity of expanded perlite. Thermogravimetric analysis revealed a reduction in calcium hydroxide content of up to 24%, confirming enhanced pozzolanic reactions. Incorporation of GEP refined the pore structure and improved compressive strength, with a maximum value of 39.26 MPa. For lightweight mortar containing 50% expanded perlite, GEP increased compressive strength by approximately 25% while preserving the material’s thermal insulation performance. Overall, mechanically activated waste expanded perlite can serve as a reactive supplementary cementitious material rather than solely as a lightweight filler. This approach offers an effective pathway for valorizing waste expanded perlite and producing lightweight mortars with improved mechanical performance and thermal efficiency.