Some Studies on Desiccation Cracking of Fiber-Reinforced Expansive Clay Subjected to Drying and Wetting Cycles

A locally available expansive clay was reinforced with polypropylene fibers of cut-lengths 6, 12, and 18 mm and a fiber content of 0.5% by dry weight of the clay. The unreinforced and fiber-reinforced clay specimens mixed at a state close to liquid limit were subjected to five subsequent drying and wetting cycles. The desiccation tests were performed at a constant temperature and relative humidity. Crack propagation, moisture loss due to evaporation, and crack feature measurements were monitored. Digital image analysis (DIA) was used to measure the surfacial crack feature measurements. The results indicate that the desiccation cracking behavior was considerably affected by the subsequent drying and wetting cycles. The severity of cracks in unreinforced specimens increased with an increase in the number drying-wetting cycles and reached a stable value after three cycles. However, in the case of polypropylene fiber-reinforced clay specimens, bridging effect was predominant, and in turn integrity of soil matrix was maintained. The smaller crack widths and reduced cracked areas indicate the significant influence of discrete and randomly distributed fiber reinforcement in expansive clay layers.