Enhanced physical and mechanical properties of gypsum mortar incorporating recycled fine aggregate

Abstract

The resource utilization of recycled fine aggregates (RFA) in building materials presents a promising strategy to reduce environmental burdens associated with natural resource extraction and construction waste disposal. This study investigates the effects of incorporating high volumes of RFA on the physical and mechanical properties of gypsum mortar. First, the RFA was selected from Portugal and the physical properties were characterized. Then, five mortar mixtures were prepared by replacing natural sand with RFA at 0 %, 25 %, 50 %, 75 %, and 100 %. Finally, the fresh mortar workability was evaluated, and after 28 days of curing, properties such as density, capillary absorption, compressive strength, and flexural strength were assessed. Results indicated that increasing RFA content up to 75 % led to a 28.7 % reduction in the capillary absorption coefficient (from 1.341 to 0.956 kg/ (m2 ⋅min 0.5 )) and enhancements of 26.7 % and 30.8 % in compressive strength (from 8.6 to 10.9 MPa) and f lexural strength (from 1.3 to 1.7 MPa), respectively. These improvements are attributed to the fine particles in RFA contributing to pore filling and a denser microstructure. The findings demonstrate the feasibility of employing high contents of RFA in gypsum mortar.