Utilization of water treatment plant sludge in concrete mix

This article presents the results of research on the processing of sludge generated at the Main Treatment Facilities (MTF) of Almaty, Kazakhstan, for use in concrete mixes. A nominal concrete mix composition was selected for sample production, consisting of Portland cement, crushed stone, sand, water, Interplast AT superplasticizer, and sludge from the horizontal settling tanks of the MTF. Samples were tested for compressive and flexural strength, water absorption, permeability, and density, revealing that replacing 5% sand with MTF sludge decreases compressive and flexural strengths at 28 days by 13.3% and 3.7%, respectively. In terms of water absorption, the best performance was observed in the sample containing 10% sludge from the MTF replacing part of the sand.