Gypsum powder recycled from waste drywalls as a partial cement replacement in concrete

Abstract

This experimental study was divided into three main phases using recycled gypsum powder in concrete aiming to introduce a more sustainable and ecological alternative to traditional concrete, while maintaining adequate strength and durability. Phase I and II included the fabrication and compressive strength testing of mortar and concrete, prepared using various proportions of gypsum and fly ash as partial cement replacement. Increasing gypsum content decreased strength at all ages, however, incorporating fly ash with gypsum as partial cement replacement greatly improved the compressive strength at later ages. Phase III was designed to test the durability of a selected concrete mix subject to multiple dry and wet conditions (seawater and fresh water) after various exposure durations. Strength development throughout all durations indicated that concrete was durable to the tested conditions. Presented research suggests that incorporating recycled gypsum in concrete is achievable from a structural perspective, and including fly ash is essential.