Improvement of Clayey Soil Using Fly Ash and Cement

Clayey soils are found in abundance in few regions of India. To improve its properties, local soil stabilization by addition of an admixture is important. Stabilizing the locally available weak soils is important practice in construction industry. The widespread availability of fly ash which is a by-product of coal combustion requiring effective disposal with bulk utilization on a continuous basis to avoid environmental pollution is widely used for such beneficial stabilization purpose. Many research on the performance assessment of soil–fly ash systems have been published in the literature. The primary goal of this research is to determine the optimal proportion of fly ash that may be added to soil with cement as a stabilizing agent, as well as to analyze the index characteristics, influence of compaction, and compressive strength using an unconfined compressive strength (UCS) test. These experimental investigations were carried out for 13 different combinations. The first combination is only virgin clayey soil, followed by 3 combinations of clayey soil + fly ash, and 9 combinations of clayey soil + fly ash + cement. A little addition of cement even at 1% to the soil–fly ash mixes significantly increases the unconfined compressive strength. The unconfined compressive strength increases linearly for 7, 14, and 28 days curing period by about 12–30%. The stabilization of clayey soil with fly ash using and cement is effective in order to enhance the compressive strength by about 6 times. The strength in compression is found to be higher in case of soil stabilized with 30% fly ash and 3% cement, i.e., soaked and unsoaked conditions, indicating the optimum performance of the mix with 30% fly ash at 3% cement content.