Effects of rice husk ash and termite hill types on the physical and mechanical properties of burnt termite clay bricks for rural housing

Abstract

Clay bricks remain the most widely used materials in the building and construction industries, due to their good qualities, low cost and versatility compared to other materials for building purposes. More so, the large quantities of agricultural waste produced, such as rice husk resulting from high consumption of rice worldwide constitutes disposal problem and unhealthy environment. This waste can be recycled through inclusion as stabilizer in brick making, thereby eliminating the hazard posed to the environment. This paper examined the effects of rice husk ash (RHA) on the two termite clay soils in brick making. The two termite clay soils obtained from red and gray anthills were stabilized with rice husk ash at levels of 0 -10 % contents. The termite clay –rice husk bricks were fired at different temperature levels of 800^oC - 900^oC. The pasticity index varied upward with the addition of RHA contents. There was decreasing trend in the dry density values with increasing rice husk ash contents for both termite clay types. The inclusion of RHA in the two termite clay soils do not cause any change in optimum moisture content of the mixtures. Rice husk  ash cause increase in the compressive strength of both termite clay bricks attaining maximum value at 4% and 6% for gray and red type, respectively. Further increase in the RHA content did not cause corresponding increase in the strength values of both termite clay bricks. Bricks produced from both termite clay soils attained the highest compressive strength at 900^oC at all the RHA contents. The termite clay bricks burnt at the two temperature levels displayed increasing trend pattern in water absorption with increase in the RHA contents. There was decrease in the water absorption of both brick types burnt at higher temperature of 900^oC. The analysis of variance (ANOVA) study indicate no significance differences in the compressive strength of termite clay brick samples due to rice husk ash content, firing temperature levels and termite hill type.

Keywords: Clay bricks, termite hill, rice husk ash, stabilization, strength, building construction.