Development of sustainable mortar using waste rice husk ash from rice mill plant: Physical and thermal properties

The rice processing industry generates a significant amount of rice husk ash (RHA) waste, which is considered as cost-efficient and environmentally friendly pozzolanic material. This study used RHA as a replacement for filler material/fine aggregate in the mortar. The mechanical, thermal, and environmental performance of mortar comprising RHA waste as a replacement of river sand in different contents (0, 10, 20, 30 and 50% by weight of river sand) were investigated through experimental tests and environmental impact assessment. The RHAs were obtained from both controlled burnt (CBRHA) and opened burnt (OBRHA) processes and used to produce the mortar mixtures. Results show that OBRHA can be used as a partial replacement for river sand for up to 30% of weight to improve the thermal performance by reducing thermal conductivity up to 62% while keeping the adequate compressive strength. Further, the replacement of 30% weight of sand with OBRHA in conventional mortar production significantly reduces greenhouse gas emissions (i.e. 13% reduction per kg) and cost (4% reduction per kg).