Effect of Bentonite on the Coefficient of Consolidation of Soil

Bentonite is a fine clay, usually occurring as a byproduct of atmospheric weathering of volcanic ash. It is widely known for its capabilities of high absorption of moisture, and swelling, as a result of moisture contact. Bentonite has a crystalline structure with the main constituent as montmorillonite which has a dual-layered structure. It is the main ingredient responsible for imparting valuable properties to bentonite. In this study, several samples were tested from different regions of district Mardan, Pakistan, to analyze the collective effect of bentonite on the region's soil. An analysis was conducted based on the performed tests on the samples, to predict the consolidation behavior when samples were replaced with 0%, 5%, 10%, and 15% of bentonite by mass. Thecoefficient of consolidation gives the rate of increase of settlement or consolidation when the sample is subjected to externally applied pressure. This study observed a decrease in the coefficient of consolidation of soil with the percentage increase of bentonite reaching a minimum value of 0.005 in2/min showing about four times decrease in the coefficient of consolidation with 15% replacement of soil with bentonite. This behavior of bentonite is attributed to the fact that; being a fine clay, its addition to the soil reduces its pores and fills the open spaces, hence reducing the chances of fluid to penetrate or flow through the soil, resulting in the reduction ofthe coefficient of consolidation Cv.