Transforming agricultural waste into cement additives for durable and eco-friendly construction materials: rheological and mechanical properties

Abstract The management of agricultural waste, such as rice husk ash (RHA), is a major environmental issue, particularly because it is often burned in the open air, leading to smog and air pollution, besides greenhouse gas emissions. This article discusses the potential of RHA as a sustainable supplementary cementitious material with added value in agricultural waste reutilization and enhanced properties for construction applications. The rheological and mechanical properties of cement mortar are systematically evaluated by partially replacing ordinary Portland cement (OPC) with RHA (5–25 % by weight). Mortar cubes (50 mm cubes) incorporating RHA demonstrate significant improvements in durability and sustainability metrics. The results reveal that RHA incorporation increases setting time and reduces water absorption and chloride penetration, with up to a 70 % decrease in chloride ingress at just 10 % RHA replacement. Compressive strength exceeds standard cement mortar after 28 days, especially at 5–10 % RHA substitution, indicating better mechanical performance. Although workability is slightly degraded with greater RHA content, this issue is compensated by enhanced durability and environmental benefits. The use of RHA for sustainable production of durable and environment-friendly cement mortar promotes greener construction practices and substantial reductions in greenhouse gas emissions. This study reveals a scalable, sustainable approach to agricultural waste management and construction innovation.