Utilizing Wheel Washing Machine Sludge as a Cement Substitute in Repair Mortar: An Experimental Investigation into Material Characteristics.

The construction industry strives for sustainable solutions to tackle environmental challenges and optimize resource use. One such focus area is the management of industrial byproducts and waste materials, including fugitive dust control through wheel washers. While wheel washers play a pivotal role in dust management, they generate a challenging byproduct known as wheel washer sludge (WWS). The disposal of WWS is complicated due to its composition and potential hazards. Recent research explores reusing WWS in construction materials, particularly in repair mortar, aiming for sustainability and circular economy principles. This study investigates the incorporation of WWS into repair mortar formulations, evaluating mechanical properties, durability, and environmental implications. Results show that WWS enhances workability but prolongs setting time. Mechanical strength tests reveal improvements with WWS addition, especially when pretreated. Water absorption rates decrease with pretreated WWS, indicating enhanced durability. Chemical attack tests demonstrate resistance to carbonation and chloride penetration, especially with modified WWS. Freeze-thaw tests reveal improved resistance with WWS addition, particularly modified. Microstructure analysis confirms hydration products and denser matrices with WWS inclusion. Environmental hazard analysis shows WWS contains no harmful heavy metals, indicating its suitability for use in repairs. Overall, this study highlights the technical feasibility and environmental benefits of incorporating WWS into repair mortar, contributing to sustainable construction practices.