Strength Characteristics of Concrete Produced by Replacing Sawdust as Fine Aggregate and Domestic Wastewater as Admixture

Abstract

This study investigated the strength characterization of concrete produced with sawdust as a partial replacement for fine aggregate and utilizing domestic kitchen wastewater. The materials used are Sawdust, fine aggregates, coarse aggregates, ordinary Portland cement, potable water and kitchen wastewater.  The sawdust was used to replace 5-30% of fine aggregates by volume, while kitchen wastewater was compared to potable water for mixing. Tests were conducted on fresh and hardened concrete properties including workability, water absorption, compressive strength, and tensile strength.  The experimental results demonstrate that replacing up to 30% of fine aggregate with sawdust is feasible without significantly compromising the workability of concrete, as indicated by consistent slump test results. However, water absorption increased with higher sawdust content and curing time, attributed to the porous nature of sawdust. Concrete made with potable water exhibited slightly higher water absorption compared to that made with kitchen wastewater. Compressive strength tests revealed that strength decreased as the sawdust content increased, with the most significant strength gains occurring within the first 7 to 14 days, and continued development up to 28 days. The 30% sawdust replacement achieved approximately 60% of the control mix strength at 28 days. The optimal sawdust replacement percentage was identified as 5-10%, balancing environmental benefits with structural performance. The study also highlights the necessity of treating kitchen wastewater before use in concrete production, due to its high organic content, acidity, and elevated levels of potentially harmful ions.