World Journal of Science and Engineering (WJSE) 4 2019, 11-17 INFLUENCE OF RICE HUSK ASH AS ADMIXTURE IN CONCRETE TO SEAL MOISTURE Md. Abul Hasanath * , Md. Tanvir Ahmed, Iftekhar Alam Dipta, Rokhshana Parvin Lecturer, Department of Civil Engineering, World University of Bangladesh Abstract The key rationale of this study is to find the opportunity for application of rice husk ash in concrete as admixture to close up the permeable gaps. Concrete is a naturally porous or absorbent material with interconnected capillaries, which confesses deleterious liquids and gases into the hardened concrete and reduce the durability of concrete. The possibility of using rice husk ash (RHA) to undertake this problem was investigated by studying the water sealing effect of rice husk ash (RHA) into hardened concrete through a water absorption trial. RHA was added to six separate batches of the concrete mix in varying percentages of 0%, 2%, 4%, 7%, 10% and 12% by weight of cement content and concrete mix ratio was1:2:4. Two concrete cubes were cast from each mixing proportion and the slump tests were done to get the workability. These twelve concrete cubes were tested for water absorption by immersion after 28 days curing. The results showed that the slump values were reduced from80mm (for 0% rice husk ash content) to 20mm (for 12% rice husk ash content). Water absorption capacity reduced from 750 cm 3 for 0% RHA (normal concrete) to 100 cm 3 for 12% RHA. It was then concluded that RHA can be used to seal off deleterious liquids and gases from concrete. Keywords: absorption capacity, admixture, deleterious fluids, durability of concrete, rice husk ash, slump. 1. Introduction: Concrete is physically an absorbent and porous material, filled with pores and capillaries. These pores and capillaries permit the absorption of deleterious liquids and gases into the concrete, which reduces the durability of the concrete. These deleterious substances may be in the form of acidic effluents from factory, weak acid from rainwater, sulphates in lakes, sea water and organic soil and also chloride salts in contact with structures near the sea (Schuster, 1957). The key factor that determines the extent of deteriorative action of these harmful liquids and gases in concrete is the absorptive power of the concrete. This problem of concrete has always been tackled through the use of admixtures (Dabai, Muhammad, Bagudo, & Musa, 2009), which are defined as materials added in small quantities to the concrete during mixing to improve one property of the concrete (Adinna, *Corresponding Author: Md. Abul Hasanath, Lecturer, Department of Civil, World University of Bangladesh.