Maximizing Strength of CKD — Stabilized Expansive Clayey Soil Using Natural Zeolite

The influence of pozzolanic materials on calcium-based soil stabilization technique has recently attracted researchers’ attention as such materials may catalyze the occurrence of pozzolanic reactions due to their high SiO 2 and AL 2 O 3 content. In this study, the effect of adding natural zeolite, which is a common pozzolanic material, on soil stabilized with cement kiln dust (CKD) is investigated. The optimal CKD content was determined by conducting tests on soil treated with percentages of CKD (0%, 2%, 4%, 6%, 8%, 10%, and 12%), and then, the optimal CKD treatment was applied on soil replaced by different zeolite percentages (1%, 3%, 5%, 10%, and 15%). Atterberg limits, swelling, California bearing ratio and unconfined compression tests were performed on all samples to evaluate the performance of additives in stabilization. Unconfined compression test samples were cured for 0, 7, 14 and 28 days to study the effect of time. Addition of CKD resulted in reduction of soil swelling and a significant increase in the long-term strength to an optimum of 10% that resulted in 3-folds of strength value higher than the based soil. Addition of 15% natural zeolite to the optimized CKD stabilized soil, caused 21% increase of strength higher than that with CKD optimized soil, however the swelling is only slightly reduced.