Main function of polyacrylonitrile (PAN)fiber in concrete
In cement concrete and asphalt concrete, we often use polyacrylonitrile fiber as the main reinforcement. Because PAN fiber can significantly improve the tensile strength, fatigue strength and flexural strength of concrete, polyacrylonitrile fiber can significantly improve the early crack resistance of concrete. Polyacrylonitrile fiber in asphalt can significantly improve the adhesion, high temperature stability, fatigue durability, and polyacrylonitrile fiber for concrete can effectively prevent low temperature cracking and reflection cracks, effectively improve the tensile, shear, compressive and impact strength.
Through the application of "nano beads", polypropylene fiber, three component superplasticizer and other high-tech, the mechanical and working properties of concrete have been greatly improved. At the same time, the localization of materials has greatly reduced the cost. Fiber reinforced concrete (FRC) is a new type of composite material developed rapidly at home and abroad in recent years, especially polyacrylonitrile fiber reinforced concrete (Pan FRC). It is widely used in highway, airport, bridge, hydraulic engineering, construction and other fields for its excellent performance of impermeability, frost resistance, abrasion resistance and impact resistance. At present, the use of synthetic fiber concrete in the United States accounts for 7% of the total output value of concrete. Since the mid-1990s, polypropylene fiber concrete has been used in thousands of projects in China, and remarkable results have been achieved.
Polyacrylonitrile (PAN) fiber is a new type of concrete reinforcing material. A series of indoor tests should be carried out and the best scheme should be selected. In order to avoid the economic loss in construction, it is better to use the first mixing method; Workers should pull the plate vibrator as slowly as possible, so that the vibration time of fiber reinforced concrete can be extended by about 25 s, which is more conducive to the three-dimensional random distribution of fiber. Segregation and bleeding often occur in ordinary concrete from mixing to hardening. Due to the incorporation of polypropylene fiber, the evenly distributed fiber presents a three-dimensional network structure in the concrete, which plays the role of supporting aggregate, preventing the sinking of coarse and fine aggregate, inhibiting the bleeding and segregation of fresh concrete, thus improving the workability of concrete mixture.
