EFFECT OF BRICK KILN DUST AND CALCIUM CHLORIDE ON STRENGTH AND SWELLING INDEX OF EXPANSIVE SOIL by Zark K. Khan
This research is carried on the expansive soil, which has weak strength, swelling and shrinkage problems. Available soil is clayey soil, which is converted into expansive soil by the addition of 20% Bentonite. After adding 20%bentonite in the clayey soil, liquid limit increases from 41% to 74% and plasticity index increases from 19.3% to 49.5%. Results show that clayey soil converts into an expansive soil. Research aims in increasing its strength and also improving its swelling characteristics. For this purpose, additives are added in the soil to enhance its properties. Brick kiln dust and calcium chloride are the additives used in different proportions for the study. Brick kiln dust is used indifferent proportions as a replacement of soil at 10%, 20%, and 30% by dry weight. Compaction test and CBR test are carried out on virgin expansive soil and also on the soil treated with different proportions of brick kiln dust. Results obtained shows that MDD increases while OMC decreases with the increase in brick kiln dust content. CBR test result shows that CBR value increases with the increase in brick kiln dust content. The highest value of CBR is achieved at 20% BKD by weight. The 20% BKD is the optimized value which is added in the expansive soil in combination with the different proportions of calcium chloride. The proportions of calcium chloride added as a replacement of 20%BKD treated soil are 1%, 3% and 5%. Compaction test, CBR test, UCS tests and free swell index test are performed on the calcium chloride treated soil. Compaction test shows that with increase in calcium chloride content, there is increase in MDD and decrease in OMC of treated soil. CBR test result shows that CBR increases by adding 1% and 3% calcium chloride content while with the addition of 5% calcium chloride by weight, CBR decreases. UCS test shows that by the addition of 1% and 3% calcium chloride content UCS value improves while with the addition of 5% calcium chloride by weight UCS value decreases. Free swell index test shows a significant improvement by adding calcium chloride in the treated soil. Maximum decrease in the swell is achieved at 5% calcium chloride content. These results show that strength and swell characteristics of expansive soil improve with the addition of brick kiln dust and calcium chloride in the expansive soil. Thus both brick kiln dust and calcium chloride can be used as a good stabilizer for expansive soil.