Reusing Alum Sludge as Cement Replacement to Develop Eco-Friendly Concrete Products

Abstract Alum sludge is a typical by-product of the water industry. The traditional management method, disposing in landfill sites, poses critical environmental and economic concern due to significant increase amount disposal cost. In this paper, feasibility reusing as cement replacement investigated, physical performance microstructure modification concrete products made with discussed. obtained results indicated that satisfying pozzolanic reactivity after calcination at high temperatures grinding appropriate size was identified. When 10% replaced sludge, reaction degree up 39%, blocks exhibited superior mechanical performance. Based on microstructural analysis, e.g., x-ray diffraction, thermogravimetric advanced nanoindentation aluminum content incorporated into C–(A)–S–H gel; original “Al-minor” gel pure paste converted ‘Al-rich’ gel. Also, promoted formation aluminum-bearing hydrates, such ettringite calcium aluminate hydrates (C–A–H). Although Al incorporation had no effect hardness modulus gel, homogeneous properties (hardness measured nanoindentation) binder degraded increasing ash above 10%, attributing lower unreacted than clinker relatively degree. Using offers an economical environmentally friendly way dispose preserve diminishing natural resources. reduction usage may contribute achieving carbon neutrality.