Textile sludge ash in mortar: Toward cleaner cement alternatives

This study explores the sustainable use of textile sludge ash, a by-product of textile effluent treatment plants, as a partial replacement for ordinary Portland cement in mortar production. Mortar mixes with 0–20 % TSA (5 % increments) and a constant water-to-binder ratio of 0.48 were evaluated. Increasing TSA reduced slump flow and setting time but enhanced consistency and soundness. Mechanical properties, including compressive strength, bulk density, and ultrasonic pulse velocity, improved up to 10 % replacement, surpassing the control mix. Durability tests revealed reduced porosity, water absorption, and sulfate attack susceptibility at optimal TSA levels. Microstructural analyses (scanning electron microscopy-, X-ray diffraction-, thermogravimetric analysis, differential thermal analysis-, and Fourier transform infrared spectroscopy) confirmed denser matrices, lower mass loss, and improved hydration products in TSA-modified mortars. Overall, TSA exhibited strong potential as a sustainable cement substitute, with 10 % replacement delivering superior performance. This approach provides an eco-friendly solution for cement reduction and textile sludge disposal, advancing circular economy and sustainable construction. • TSA classified as Class N pozzolan with high reactivity in cementitious systems. • Up to 10 % TSA improved strength, UPV, bulk density, and matrix densification. • TSA mortars showed reduced porosity, water absorption, and higher sulfate resistance. • Microstructural tests confirmed denser matrices and enhanced hydration products. • TSA use reduces cement demand and supports sustainable waste valorization.