Properties of Clay Soil and Soil Cement Reinforced with Polypropylene Fibers

Randomly reinforced cohesive soils can be used as construction material in many civil engineering projects. These materials may be subjected to compressive, tensile, or flexural stresses in their life. The presence of stabilizing agents or fibers may affect their resistance against various loads. In this work, a clay soil was reinforced randomly at four different lengths of fiber (10, 15, 20 and 25 mm [0.394, 0.591, 0.788, and 0.985 in.]) with fiber inclusions of 0.5 and 1%. Reinforced soil cement samples were also prepared with 8 and 10% cement and reinforced similar to the soil. Unconfined compressive and tensile strength tests were carried out on the prepared samples. The results show that the compressive strength is increased with fiber length up to approximately 10 mm (0.394 in.). When length of fiber is longer than 10 mm (0.394 in.), the compressive strength is still increased, but with a slow rate. The results for the reinforced soil cement samples indicate that, for a given fiber and cement content, increasing the length of fiber has no significant effect on the strength of the sample. The tensile strength of reinforced soil is increased by increasing the fiber inclusion and length of fiber. For the reinforced soil cement samples, the tensile strength is increased with increasing fiber content, length of fiber, percent of cement, and curing time.