Durability study of polypropylene fibers on enzyme-induced carbonate precipitation cured sandy soil under dry-wet cycling

To study the durability of sand under the action of dry and wet cycling, the fiber reinforcement method to improve EICP was studied. Utilizing the waste mask as fiber reinforcement after crushing, the unconfined compressive strength, mass loss rate, soaking water absorption rate, and calcium carbonate content of sand under different fibers content and different dry-wet cycles were studied. Additionally, the method of EICP combined with polypropylene fiber solidification of sand soil was integrated with scanning electronic microscopy under the microscope. The results demonstrate that the improved sand soil's unconfined compressive strength gradually decreases as the number of dry-wet cycles increases. At the minimum sample strength loss rate at the fibers content of 0.2% set, too few fibers are unable to form the "bridge effect" and too many fibers are too prone to clustering. Additionally, the fibers reinforcement can significantly increase the production of calcium carbonate in EICP-solidified sand soil and can also play a role in fixing calcium carbide crystals. The number of wet-dry cycles causes the quality loss rate to first decline before increasing and the rate is lowest when the fibers content is 0.2%; following the addition of polypropylene fibers, more calcium carbide is generated to fill in gaps and lessen the erosion effect of water flow in the dry-wet circulation.