Determining the Optimal Percentage of Rice Husk Ash for Compressed Earth Blocks: To Enhance the Compressive Strength and Thermal Insulation Properties

Abstract

This study investigates the potential of using Rice Husk Ash (RHA) in the production of Compressed Stabilized Earth Blocks (CSEBs) as a sustainable alternative to traditional building materials. RHA, a waste product from rice production offers both environmental and economic benefits when used as a stabilizer in compressed earth blocks. The performance of CSEBs was assessed in terms of compressive strength at various percentages of RHA by weight of dry soil. The results showed significant improvements in compressive strength compared to unstabilized samples due to the addition of RHA and the optimal RHA content was found to be 7.5% at which the compressive strength was found as 2.51 N/mm2. Furthermore, the effect of RHA on dimensional characteristics, shrinkage analysis, and thermal conductivity of CSEBs was studied. CSEBs had a non-linear effect on dimensional characteristics as initially the block volume decreased upto the inclusion of 3.5% of RHA content but then it gradually increased and for RHA of 11.5 % the volume of CSEBs was similar to the block volume observed before the curing period. The shrinkage analysis showed that CSEBs with 0% RHA experienced the highest shrinkage of 8.15 % of its original volume. By increasing the percentage of RHA, shrinkage was reduced and for RHA content of 11.5%, shrinkage was almost zero. Thermal conductivity of CSEB samples was also measured and the results showed that the values ranged from 0.68 – 0.84 W/m.K. The minimum thermal conductivity was observed for 9.5 % RHA enhanced CSEBs, with a value of 0.68 W/m.K. Also the manually compacted CSEB samples outperformed the blocks where no compaction load was applied in terms of compressive strength and thermal conductivity. Therefore, an optimum RHA percentage of 7.5 % was found to offer a favourable balance between compressive strength and thermal insulation, with a thermal conductivity of 0.71 W/m.K.