Paddy husk ash stabilized soil bricks

Abstract

Recent trend of using stabilized soil as a construction material necessitates the need to search for alternative binders other than cement, bitumen and chemicals due to their higher costs. Rice husk is produced in millions of tons per year as a waste material in agricultural countries as Sri Lanka. Previous researches have been conducted to identify chemical and physical properties of RHA. Therefore, the use of rice husk ash, which contains pozzolanic amorphous silica component, will considerably reduce the cost of construction. The objective of this research is to investigate the performance of soil bricks stabilized using rice husk ash (RHA) and lime. It will also determine the optimal percentage of lime that can be mixed with rice husk ash in order to gain maximum strength and durability. Totally twenty six number of brick samples were cast to find the compressive strength, density and water absorption. One brick sample was cast without binder (0% RHA, 0% Lime). Other twenty five brick samples were cast by varying binder/ soil mix percentage as well as rice husk ash/ lime mix percentage up to a maximum binder percentage of 25% by weight of dry soil. Five brick samples were tested for water absorption and all the twenty six brick samples were tested for compressive strength and density. Results depicted a considerable increment in compressive strength in bricks stabilized with RHA and lime compared to unstabilized sample. Density and water absorption is lower compared to currently available local bricks. Maximum compressive strength was 4 N/mm2 at 12.5% lime and 12.5% RHA combination. Economical dosage to stabilize the soil bricks was found to be 10 % lime and 2.5% of RHA combination by which compressive strength of 3.9 N/mm2 can be achieved. Optimum lime content to stabilize soil blocks was observed to be 10% for most of the RHA combinations.