Lightweight bricks manufactured from ground soil, textile sludge, and coal ash

Reuse of textile sludge as construction materials has been proved to an economic and environmental friendly strategy to mitigate its disposal problems. Previous studies have illustrated the successful fabrication of common fired bricks using textile sludge as a partial replacement of clay, but no such a specific work was focused on the feasibility of manufacturing lightweight bricks from textile sludge. In this study, a strategy involving the mixing of ground soil, textile sludge, and coal ash as the raw materials for the successful production of lightweight bricks is presented. Coal ash and ground soil have different combustible contents but similar main chemical composition, which facilitates the separable adjustment of these two factors of the raw material mixture to achieve their suitable values at the same time, and thus results in the successful manufacture of lightweight bricks. To meet the requirement for compressive strength and consume textile sludge as more as possible, an optimal ratio of the raw materials was obtained as textile sludge:coal ash:ground soil = 20:20:60. The brick products manufactured from this ratio show a compressive strength of 13.7 MPa, bulk density of 1.47 g cm^-3, water absorption of 14.6%, and volumetric shrinkage of 13.61% after sintering. The results of toxicity characteristic leaching procedure test show that the heavy metal concentrations in the leachates of the brick products are very low, which also satisfy the regulations. This study provides a feasible and economical technology for the treatment of textile sludge.