Study on the Brittleness Characteristics of Sand Reinforced with Polypropylene Fiber and Polyurethane Organic Polymer

The brittleness characteristics of sand reinforced with polypropylene fiber (PF) and polyurethane organic polymer (POP) was investigated in detail using direct tensile and unconfined compression tests. The effects of POP/PF content, curing time and sand density on the brittleness of reinforced sand were studied. The reinforcement mechanism was analyzed with images of scanning electron microscope (SEM) and sample failure mode. The test results indicated that the brittleness of sand increases with curing time, and it has no obvious change after 48 h. The brittleness was decreased obviously with the increase in POP and PF contents. The brittleness of reinforced sand reaches a relative stable state when the POP and fiber contents reach 3 % and 0.6 % respectively. The brittleness also increased with sand density and it reaches a plateau at 1.55 g/cm3. The POP forms a large number of polymer films with water volatilizing in the sand, and the sand particles were wrapped. Fibers improved the compressive strength of reinforced sand and changed it to a more ductile one. Polypropylene fiber plays the role of reinforcing the sand, effectively improving the strength of the sand and reducing the brittleness of the reinforced sand.