Effect of Polypropylene Fiber (PP Fiber) on cement/concrete

Polypropylene fiber can improve the crack resistance, micro-cracks caused by temperature, leakage resistance, impact resistance, and seismic resistance of cement or concrete. It has high toughness and strength. It is cost-saving, simple to operate, and safe. It can be used in highly corrosive environments. Compared with ordinary fibers, the anti-permeability performance of micro-monofilament fibers with a dosage of 0.9kg/m3 is 60% - 70% better than that of ordinary fibers. Mixing cement and concrete can effectively control micro-cracks in cement or concrete caused by temperature changes.

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During the coagulation and hardening process of concrete, surface water loss will cause plastic shrinkage and cracks. Concrete mixed with PP Fiber can prevent such cracks. Since the elastic modulus of PP Fiber is lower than that of hardened concrete, the improvement of the crack resistance of hardened concrete (cracks caused by temperature stress or mechanical load, etc.) is limited, and the improvement of tensile and flexural strength is not large, but the toughness of concrete is improved to a certain extent.

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Under high temperature, PP Fiber will soften and burn first, forming many channels in the concrete. The water vaporized by high temperature in the concrete can be discharged along these channels, preventing the water vaporization from forming internal high pressure and causing the concrete to burst, thereby greatly improving the fire resistance time and fire resistance level of the concrete.

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After adding PP Fiber, it can effectively prevent the segregation of cement concrete and improve the overall uniformity of the cast body; significantly reduce the number, length and width of cracks, reduce the possibility of generating through cracks, play a role in blocking capillary cracks in concrete, and significantly improve the impermeability of concrete. At the same time, it reduces the transfer rate of moisture, chloride ions and air in concrete, thereby delaying the corrosion of steel bars.

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Adding PP Fiber to the cement matrix can reduce the brittleness of cement concrete and improve the toughness of the base material. Cement concrete mixed with PP Fiber can withstand tens of thousands or even millions of times of static strength stress repetition and still maintain a good state. This property is beneficial to some cement concrete structures that are often subjected to impact fatigue (such as roads, sidewalks, pavement overlays, warehouse pavements, etc.).