Effect of waste rice husk ash from rice husk fuelled brick kilns on strength, durability and thermal performances of mortar

Abstract

Effect of waste RHA, residual ash generated from rice husk fuelled brick kilns, on strength, durability and thermal performances of mortar was investigated. Cement in the mortar was replaced by 0%, 5%, 10%, and 20% of waste RHA. Compressive strength, bulk density, water absorption, porosity, sorption rate, sulfate, acid and alkaline resistance, thermal performance, and microstructural analysis of specimens were examined.Bulk density of control (i.e. 0%) and 20% waste RHA mortar were 2033 kg/m 3 and 1821 kg/m 3, respectively, promising a lightweight mortar by blending waste RHA into the mixture. At 56 days, Strength activity index (SAI) was achieved to be 95% and 85% for 5% and 10% waste RHA mortar, respectively, indicating better compressive strength achievement with waste RHA added mortar. The expansion due to sulfate exposure was reduced by 54% and 70%, for 5% and 10% waste RHA mortar, respectively. Weight loss due to acid exposure was reduced by 45%, 40%, and 25% for 5%, 10%, and 20% waste RHA specimens, respectively. The weight loss due to alkaline exposures was reduced from 3.13% to 2.41% with rising waste RHA level from 0% to 5%. Mortar with 20% waste RHA had a higher temperature difference than the control mortar, indicating that RHA contributed to the reduced thermal conductivity. At 5% waste RHA sample, high counts of CSH was formed, micro-voids were filled, making it a dense structure, which is favorable to achieve improved strength and durability performances.