Toward Sustainable Lightweight Concrete: Reviewing the Role of Sewage Sludge Ash, Wood Ash, and Metakaolin in Performance Improvement

This review paper examines the novel and sustainable utilization of industrial and agricultural waste materials in the production of Lightweight Concrete (LWC), offering a transformational strategy to tackle environmental and resource efficiency issues in the construction industry. In particular, it looks into using Sewage Sludge Ash (SSA) as a partial replacement for fine aggregate, Wood Ash (WA) as a partial replacement for cement, and Metakaolin (MK) as an extra cementitious material. By incorporating these byproducts, the study emphasizes how they could improve LWC's durability, mechanical qualities, and environmental sustainability. A systematic assessment of existing research critically analyses key performance indicators, including compressive strength, flexural strength, density, water absorption, and resistance to environmental stresses. This thorough examination reveals growing trends, ongoing obstacles, and critical research deficiencies, highlighting the unexploited potential of waste material valorization in promoting sustainable construction practices. The results demonstrate the combined advantages of minimizing environmental impact and ensuring economic feasibility, establishing waste-derived LWC as a crucial solution for a resource-efficient and sustainable building sector. This assessment leads to the development of new, sustainable, and high-performance concrete technologies.