Desiccation and Cracking Behaviour of Clay Under Wetting and Drying

Cracks are formed when moisture loss in soil creates channels for water flow. This research investigates the cracking behavior of clayey soil subjected to wetting-drying cycles. Laboratory tests were performed on both natural (control soil) and bentonite added soils. Desiccation rates were observed and recorded for soil specimens using the air-dry and oven-dry approach at 60oC. Soil specimens containing different percentages of bentonite (5% and 10%) were subjected to four wetting and drying cycles. Double punch test was conducted to determine the tensile strength of natural soil. The swelling and shrinkage tests were carried out on natural soil specimens as well as examining the matric suction. Results of the desiccation method employed showed that cracks did not occur on the natural soil at any stage of the air-drying condition while in the oven-drying method, cracks were observed in the increasing drying stages. Crack dimension was quantified by using digital image processing known as ImageJ software. The results for the experimental cyclic wetting and drying indicated that the crack intensity factor, CIF increased with an increasing number of cycles. Soil water characteristic curve, SWCC of the control soil was constructed using filter paper method and the air-entry value, AEV was obtained at 31% water content. This water content obtained from the SWCC is in good harmony with the value obtained using the silica gel drying method.