Enhancing the Durability of Concrete with Agricultural Bagasse Ash

Concrete, a prime material used in civil construction because of its high compressive strength, suffers a disadvantage as it is attacked by chloride, sulphate, etc. In this paper, an attempt is made to overcome these problems as well as to reduce the environmental damage in the production of cement by replacing cement to the extent possible with agricultural waste bagasse ash. Detailed experimental studies are conducted with various levels of replacement of cement in concrete with sugarcane bagasse ash designed for M25 grade. While the strength of concrete has been maximum with 5% of bagasse ash, up to 15% of bagasse can be used to meet the targeted strength. Conventional concrete is attacked in aggressive environment mainly due to presence of excess lime liberated in the hydration of cementitious phases of Portland cement. Bagasse ash which contains reactive silica can very well advantageously use this lime to produce more cementitious compounds as well as to reduce excess lime to enhance durability of these compounds. The results have shown that not only the compressive strength increases but also the tensile strength and in fact the per cent increase in tensile strength is more than the increase in compressive strength. Concrete with bagasse ash has lower water permeability than concrete without bagasse ash which helped to penetrate of harmful effects of chloride, sulphate, and alkali leading to much lesser effects of concrete in their presence. However, the effects of sulphate and alkali are not completely eliminated with cement replacement with 15% bagasse ash but the adverse effects are lower than in conventional concrete. Differences are seen during drying shrinkage in presence of these chemicals compared to concrete with normal water which are explained by microstructural changes. Thus, from the durability point of view, 15% cement can be replaced with bagasse ash used.