What Is Polypropylene Fiber Concrete (PFRC)？

Polypropylene fiber concrete(PFRC) is a composite material that evenly distributes polypropylene fiber (PP fiber) in the base material of concrete to enhance its physical and mechanical properties. It has excellent properties such as light weight, high tensile strength, impact resistance, crack resistance, acid resistance and alkali resistance.

Polypropylene fiber concrete is the most studied and applied synthetic fiber concrete. The density of polypropylene fiber ranges from 0.90 to 0.92 g/cm3, and the melting point is low, generally between 165 and 173°C.

Research shows that polypropylene fiber concrete has the following superior properties:

1. Improve the crack resistance of concrete. During the concrete mixing process, Polypropylene Fibers are evenly distributed in the concrete, which restricts the sinking of concrete particles, reduces the number of capillary channels formed by water overflow in the concrete, reduces the change in concrete volume and water seepage, thereby inhibiting the generation of concrete microcracks and improving the crack resistance of concrete.

2. Improve the impermeability of concrete. The addition of polypropylene fibers can effectively inhibit the plastic shrinkage of concrete and prevent the development and extension of original cracks. The service life of buildings using polypropylene fiber concrete is extended.

3. Enhanced the strength and impact toughness of concrete. During the compression test, the polypropylene fiber concrete specimens did not break after fracturing. Since the added polypropylene fibers are evenly distributed in the concrete, the deformation performance of the polypropylene fiber concrete can be significantly improved, so that it will not break even after the load is increased to the maximum. The use of polypropylene fiber concrete in building structures can improve the safety of personnel when they are damaged by earthquakes.

4. Improve the freeze-thaw resistance of concrete. Some researchers conducted freeze-thaw tests on concrete specimens with low dosage of short-cut polypropylene fibers. After twenty-five repeated freeze-thaw cycles, no delamination or cracking was found. Polypropylene fibers are randomly and evenly distributed in all directions inside the concrete, similar to the role of micro-reinforcement inside the concrete, which slows down the development of temperature stress and temperature cracks inside the concrete.

5. Improve the wear resistance of concrete. Researchers used different test methods to conduct anti-abrasion tests on polypropylene fiber concrete, and all confirmed that the wear resistance of polypropylene fiber concrete was significantly improved.

6. Improve the bending fatigue performance of concrete. A certain test study shows that when the amount of polypropylene fiber added to polypropylene fiber concrete is 0.8kg/m3, its flexural strength is only increased by 7.6%, indicating that low amount of polypropylene fiber has little effect on improving the flexural strength of concrete.

In addition, polypropylene fiber basically does not change in acidic and alkaline environments, making the concrete mixed with polypropylene fiber have better corrosion resistance in seawater environment. Polypropylene fiber has a low melting point and can melt quickly under high temperature of fire, forming a gas channel in the concrete, which can effectively prevent the explosion of high-strength concrete.

At present, polypropylene fiber concrete is widely used in highway engineering and water conservancy projects. The application of polypropylene fiber concrete in highway pavement and airport runway can effectively control its plastic cracking, improve its fatigue resistance, impact crushing resistance and wear resistance, and extend the service life of the pavement. Now many countries have widely used polypropylene fiber concrete in the reinforcement measures of airport runways, underground transmission pipelines and other projects. The application of polypropylene fiber concrete in water conservancy projects can significantly improve its high performance requirements such as impermeability, crack resistance, wear resistance, impact toughness and durability.