EFFECT OF BAGASSE ASH AND CALCIUM CHLORIDE ON CBR AND SWELLING INDEX OF EXPANSIVE SOIL by Amir Suhail
Abstract
Expansive soils are present throughout the world. The construction on expansive soil has always a big challenge to geotechnical engineer. Construction of buildings and other structures such as highways, dams etc on expansive soil is a very risky task due to high expansive behavior of such soils. Every year they cause damage of billions of dollars because of presence of montmorillonite mineral, that is highly unstable thus leading to shrinking and swelling of this type of soil that are able for captivating the water. They enlarge in volume when they come in contact with water. Behaviour of these types of soil causes the failure of structure in the form of fissures, settlements etc. To improve the stabilization of the expansive soils several types of additives have been evolved and are successfully being used for this purpose. One such additive that can be used for this purpose is calcium chloride(CaCl2) and baggase ash(B.A). Bagasse fibre is an agricultural waste remaining after the crushing of sugar cane for juice extraction. When bagasse fibre is burnt the ash produced is called bagasse ash(B.A). Bagasse ash(BA), contain a high percentage of silica (SiO2), which is investigated as a reasonable pozzolanic material having unreactive behaviour and has the ability to be used in the stabilization of road subgrade. The different percentages of bagasse ash used were 4%, 8% & 12%, whereas Calcium chloride was used at 0.5%, 1%, 1.5% & 2% resp. The available local soil was not expansive in nature and 20% bentonite powder was added in the soil to make it expansive. However, according to the observation, chemical additives (calcium chloride) exhibit superior performance over cementitious and non-cementitious (bagasse) additives in reducing the swelling characteristics (Gangadhara Reddy.N et al 2015). The laboratory tests performed were standard proctor test, CBR and Swelling index test. The results shows that the OMC increases but MDD decreases and CBR value increases upto 8% when bagasse ash used in the soil. The results also shows that when optimum value of bagasse ash and varying percentages of Calcium chloride, the OMC decreases but MDD increases and CBR value gradually increases. The maximum strength was obtained at 2% CaCl2 mixed with soil. However, the swelling index decreases with increase in the concentration of bagasse ash and calcium chloride
