Function and Application of Steel Fibers

Function of steel fibers

Steel fibers used in the construction industry are usually made of low-carbon steel drawn and cut without rust-proof or anti-corrosion agents. They can improve casting performance by 2-6 times, replace or reduce the amount of steel used, shorten the time for steel making and manufacturing, and achieve a degree of mechanized construction progress that cannot normally be achieved by construction methods. They can also remedy problems like roof cracking and pipeline leakage in the construction of bay houses. Steel fibers can also reduce pressure on concrete prefabricated components used in highway bridges, concrete sleepers, explosion-proof warehouses, nuclear test sites, rocket launch sites, and more.

Stainless steel fiber concrete does not have a reinforced volume effect, and the volume rate varies slightly depending on the type and aspect ratio of the fiber. Typically, the minimum volume rate is 0.5%. When the fiber volume rate exceeds 2%, the workability of the mixture decreases, making construction more difficult and quality difficult to ensure. However, in special circumstances, by conducting experiments and taking necessary measures to ensure quality and enhance the effect, the fiber volume rate can be increased.

By adding appropriate fibers to concrete, the compressive strength can be improved by 10% to 80% (significant progress beyond C50 concrete), and the tensile and flexural strength can be improved by 50% to 100%. Experiments show that the strength of ultra-short fibers (5 to 15 mm in length, with an aspect ratio of 10 to 30) is higher than that of short fibers, but the tensile and flexural strength is much lower than that of short fibers.

When using steel fiber concrete, it is important to keep the surface moist for at least 7 days, and longer is better. Damp bags or curing materials can be used to cover the surface. Steel fiber conversion beams should be protected from wind, sun, rain, etc., and the construction beams should be enclosed to prevent wind and rain. For steel fiber conversion beams, the demoulding time should be strictly controlled to after the concrete reaches the strength specified in the regulations for 28 days. If construction is in winter, conventional anti-freezing measures can be taken.

Application of steel fibers in concrete

The application of steel fibers in concrete is also widely used, and we should see that steel fibers play a greater role in concrete. These two theories do not fully explain the strengthening of concrete by steel fibers. The composite material theory ignores the crack-arresting effect of steel fibers on the matrix, that is, it ignores the coupling effect of the composite. The fiber spacing theory's biggest disadvantage is that it ignores the fiber's coupling effect and focuses on the fiber's crack-arresting effect. Moreover, the determining fiber spacing should be the theoretical fiber spacing. Although the high-modulus steel fibers added to the concrete matrix primarily play a reinforcing and toughening role, the theoretical explanation for how steel fibers strengthen the matrix remains unsatisfactory, and both composite theory and fiber spacing theory coexist.