<p class="MDPI12title"><span lang="EN-US">Sustainable Use of Gypsum Waste for Applications in Soil-Cement Bricks: Mechanical, Environmental, and Durability Performance

This study explores the use of gypsum waste from civil construction as a partial replacement for cement in soil-cement formulations, aiming to produce eco-friendly bricks aligned with circular economy principles. Formulations were prepared using a 1:8 cement-to-soil ratio, with gypsum replacing cement in proportions ranging from 5% to 40%. The raw materials were characterized in terms of their chemical composition, crystalline phases, plasticity, and thermal profile. The formulations, molded by uniaxial pressing into cilindrical bodies and cured for 7 or 28 days, were tested for crystalline phases, compressive strength, water absorption, durability, and microstructure. Water absorption remained below 20% for all samples, with an average value of 16.20%. Compressive strength after 7 days decreased slightly with increasing gypsum content, from 16.36 MPa (0% gypsum) to 13.74 MPa (40% gypsum), still meeting the quality standard. After 28 days of curing, the formulation containing 10% gypsum achieved the highest strength (26.7 MPa), surpassing the reference sample without gypsum (25.2 MPa). Mass loss due to water immersion remained within acceptable limits for formulations containing up to 20% gypsum. Notably, samples with 5% and 10% gypsum exhibited superior mechanical performance, while samples with 20% gypsum showed comparable results to the reference. These findings suggest that replacing up to 20% of cement with gypsum waste is a viable and sustainable alternative, promoting circular economy practices and reducing the environmental impact of construction waste.