Effect of Rice Husk Ash (RHA) on structural properties of fired clay bricks

Abstract

In Sri Lanka, some amount of rice husk has been used as a fuel to fire bricks. However, rice husk ash (RHA) produced from the brick firing process has not yet been utilized effectively. Objective of this study is to utilize the rice husk ash wasted from the brick kiln to enhance structural properties of fired clay bricks. Rice husk ash was collected from the brick kiln, located in Embilipitiya area, while the clay was collected from Dankotuwa area, where a brick manufacturing has been well established. Sieve analysis was performed for the collected RHA to identify the particle size distribution. The clay was mixed manually with different percentage of RHA: 0%, 2%, 4%, 6%, 8% and 10%. Atterberg limit of the mixture was investigated in order to identify suitability of the mixture for brick production. Bricks having a size of 195mm x 95mm x 50mm were cast manually and kept for drying. All the bricks were fired in a brick kiln. The burning temperature was within the range of 600 oC to 850 oC. Compressive strength and water absorption of fired bricks were investigated. All percentages of addition of RHA improve the mixture for brick manufacturing. The optimum compressive strength of 3.55 N/mm2 was found at 4% of addition of RHA. It was found that 32.7% improvement in the compressive strength of the bricks with 4% RHA addition compared to the control bricks (i.e., fired clay bricks with 0% of RHA), implying that RHA wasted from the brick kiln can be effectively used to improve the structural properties of the fired clay bricks.