Mechanical, physical, and morphological characteristics of concrete incorporating wastewater treatment plant sludge as a supplementary cementitious material

The production of wastewater treatment plant (WWTP) sludge is constantly increasing due to global population growth, posing significant environmental challenges related to its sustainable management. This study aims to present an innovative approach for reusing dried waste sludge (DSS) as a cementitious additive in concrete production, contributing to reducing waste generated by WWTPs and mitigating negative environmental impacts. DSS was incorporated into concrete mixtures by replacing cement at levels of 0%, 5%, 10%, and 15% by weight. The mechanical properties of the resulting concrete, including compressive, tensile, and flexural strengths, were evaluated after 7, 14, and 28 days of curing. Additionally, microstructural and compositional analyses were performed using XRD, XRF, and SEM techniques. The results showed that the incorporation of DSS affects the mechanical properties of concrete, with a strength reduction of up to 40% observed when 5% of cement was replaced by DSS. These results indicate the potential of DSS as a sustainable alternative to conventional cement, with further studies needed to improve mechanical performance and balance sustainability with structural efficiency.