The manufacturing process of cement steel fiber mainly includes the following methods:
Wire cutting method: Use cold-drawn steel wire with small diameter (0.4-0.8mm) as raw material, cut it according to the specified length, and the tensile strength can reach 1000-2000MPa, but the cost is high and the bonding strength with the matrix is low. Special-shaped steel fibers can be made by pressing edge method, corrugation method, hook method, etc. to improve bonding.
Thin plate shearing method: Use cold-rolled thin steel plate to cut into steel fibers. The raw material is generally annealed cold-rolled steel plate, and unannealed steel plate can also be used to improve strength. The steel fiber produced by this method has a smoother surface and lower bonding strength, which can be improved by changing the shape.
Ingot milling method: Use thick steel plate or ingot, and cut it by rotating flat-blade iron knife. This method can increase the bonding force with the matrix such as concrete, and the strength is high after work hardening.
Melt steel wire drawing method: melt scrap steel into molten steel, scrape out the molten steel through a high-speed rotating melting wheel and cool it into shape. This method has a wide source of raw materials, low cost, simple process and high efficiency, and is currently the most promising production method.
The construction process of cement steel fiber includes the following steps:
Mixing: In order to ensure the uniform distribution of steel fiber in concrete, a dry-first and wet-later mixing process should be adopted. First, dry-mix the steel fiber and coarse and fine aggregates, and then add other materials for wet mixing. The mixing amount each time should not exceed 1/3 of the nominal capacity of the mixer, and the mixing time should be appropriately extended.
Transportation: Choose different transportation methods according to the consistency of steel fiber concrete. Plastic concrete should be transported by concrete mixer trucks, and semi-fluid and semi-dry concrete can be transported by dump trucks.
Pouring and vibrating: The mixture should be poured within 30 minutes. If there is stratification or overdrying, it should be stirred twice before pouring. When vibrating, try to avoid arranging the steel fibers in the direction of insertion of the vibrating rod.
Curing and demolding: Special attention should be paid to early wet curing and maintaining a certain curing temperature. The demolding time can be slightly shorter than that of ordinary concrete. If there are exposed steel fibers or vibration leakage after demolding, they should be handled.