Fiber-reinforced concrete is a new type of composite material that has developed rapidly at home and abroad in recent years. Among them, polypropylene fiber-reinforced concrete has developed the fastest. It is widely used on highways due to its excellent impermeability, frost resistance, impact resistance, and impact resistance, in airports, bridges, hydraulic engineering, construction, and other fields. The external admixture of fibers added to the concrete is fiber-reinforced concrete, and the fibers include steel, polyester, and composite fibers.
Adding long fibers alters the properties of fresh concrete based on the kind of fibrous material used. There are four categories of fibers generally used in producing fiber-reinforced concrete: Steel fibers, Glass fibers, Synthetic fibers, and Natural fibers.
Here we focus on Tenabrix® synthetic fibers or polypropylene fibers. It is a type of thermoplastic. Polypropylene shares many characteristics with polythene, with improved hardened properties, flexural strength, and higher heat resistance. Additionally, Tenabrix® polypropylene fiber has a high resistance against chemicals like acids and organic solvents and imparts similar properties to concrete.
The volume fraction of fibers used in concrete is usually 0.1% to 5%. The size of this volume ratio is mainly determined by the ease of mixing the mixture and the application scenario of the project. For example, secondary stresses caused by concrete shrinkage and temperature changes are usually controlled with low doses of fibers (0.1% to 0.3% by volume). When the fiber dosage exceeds 0.3%, compared with ordinary concrete without fibers, the mechanical response of fiber-reinforced concrete will be significantly different, which is mainly manifested in its bearing capacity after cracking. The ability of fiber-reinforced concrete to absorb energy after it has cracked is called “toughness”. When higher doses of fibers were added to concrete, in addition to its post-cracking toughness, fiber-reinforced concrete exhibited strain-strengthening properties. That is to say, the composite material can withstand more tensile stress than ordinary concrete itself should have.