Iron Oxide Powders Containing Arsenic from Water Treatment Processes Mixed with Cement as Environmental and Structural Solution

This study explores the stabilization and utilization of hazardous waste (HW) derived from iron oxide powders containing arsenic, a byproduct of a water purification process. Cement paste samples were prepared with varying waste content (0.0%, 2.5%, 10% and 20% by weight) through mechanical mixing of all the components. Utilizing this waste offers two key environmental benefits: first, it addresses the issue of large-scale waste production globally by providing a method for its stabilization; second, it reduces cement consumption in concrete by serving as an admixture and filler, thereby lowering the cement industry's significant CO₂ emissions. After 28 days, compressive strength and density tests were conducted, and the microstructure was examined using scanning electron microscopy and X-ray diffraction. The results demonstrated compressive strengths exceeding 20 MPa, with the presence of calcite, portlandite, and ettringite phases in the samples. Additionally, Weibull statistics were conducted over a wide number of samples per composition in order to account for the variability of the compression properties, which can be important for deciding the applications. The results showed that the prepared formulations can be used in structural applications such as walls, infrastructure, sidewalks, and soil stabilization.