Understanding the Role of Steel Fiber-Reinforced Concrete

Understanding of steel fiber reinforced concrete

Steel fiber reinforced concrete is a new type of high-strength composite material composed of a certain amount of short and fine steel fibers mixed in normal concrete. Because the steel fibers can block the formation of cracks in the matrix concrete, it not only has the excellent properties of ordinary concrete, but also has good characteristics such as resistance to bending, impact, fatigue, low shrinkage, good toughness, and strong wear resistance. It can not only thin the surface layer, expand the joint spacing, improve the performance of the road, and prolong the service life of the road, but also can save engineering cost and shorten the construction period.

Steel fiber reinforced concrete is a concrete with a relatively uniform and multi-directional reinforcement formed by adding a small amount of low-carbon steel, stainless steel, and glass fiber to normal concrete. The amount of steel fibers added is generally 1-2% by volume, and 70-100 kg of steel fibers are added per cubic meter of concrete calculated by weight. The length of steel fibers should be 25-60 mm, and the diameter should be 0.25-1.25 mm. The optimal ratio of length to diameter is 50-100. Compared with ordinary concrete, it can not only improve the tensile, shear, bending, wear, and crack resistance properties, but also greatly enhance the fracture toughness and impact resistance of the concrete, significantly improving the fatigue performance and durability of structures.

Effectiveness of steel fiber reinforced concrete

With the rapid development of the national economy and transportation, the load and density of vehicles on urban roads and national highways are increasing, and the driving speed is getting faster, resulting in increasingly serious damage to the road surface. In particular, for some damaged cement concrete road surfaces under the tunnel, repairing them not only requires a large investment, but also a long construction cycle, seriously affecting traffic flow and driving safety. Although ordinary cement concrete has the characteristics of high strength, good plate property, certain wear resistance, and good durability under the action of weather, its biggest disadvantage is that it is brittle, easy to crack, and has poor resistance to temperature. The road surface plates are prone to bending and fracturing, so it is required that the road surface plates should have sufficient bending and tensile strength and thickness.

Constructing a road surface using steel fiber reinforced concrete means evenly dispersing the steel fibers in the matrix concrete (mixed with the concrete), and reducing the stress concentration at the end of fine cracks caused by the load on the matrix concrete through the dispersed steel fibers, thereby improving the crack resistance of the entire composite material. At the same time, because there is a large interface bonding force between the concrete and the steel fiber, the external force can be transmitted to the fibers with high tensile strength and high elongation, making the steel fiber reinforced concrete resist external forces as a homogeneous unit, significantly improving the tensile, bending strength and fracture elongation of the concrete. In particular, it increases the toughness and impact resistance of the concrete.