The main properties of steel fiber

Steel fiber is a new, high-performance steel fiber varieties. With steel fiber and ordinary concrete road is substantially the same ratio design method, the points of difference: dual control standard strength (compressive strength and flexural strength); steel fiber content is determined in accordance with the requirements of the design bending strength; unit of water and sand rate and fiber content related to each mixed with 0.5** (volume ratio) of steel fiber, the unit water consumption increases 6kg, sand ratio increased 2**.

Steel fiber reinforced concrete and ordinary concrete has stirred the same, construction and operation performance fibers do not cabbage in concrete, distribution, commercial concrete mixing station in production and can be used for pumping construction. Early large slump loss milling steel fiber reinforced concrete, 30 minutes loss of 32**, 42** loss of two hours. The actual work of steel fiber reinforced concrete is better than the same general slump concrete. Steel fiber reinforced concrete with good material properties, compared with ordinary concrete, the compressive strength increased by 2** to 20**; flexural strength increased by 20** to 50**; splitting tensile strength increased by 20** to 40**; wear resistance increased by 40 ** or so, which can fully meet the physical force of rational urban road engineering and inspection covers and other supporting member needs technical indicators. Steel fiber rough and clean surface, can be firmly combined with concrete cement paste, which is milled steel fiber concrete to improve various properties of the root causes.

In addition, high-strength concrete drill rod dimension in the pre-railway sleepers, highway expansion joints, and other precast cement concrete pavement, cast, production of construction, etc. have been widely used, and its excellent performance can achieve good technical and economic and social environment benefit.

First, adhesion

Since the interfacial bonding steel fiber and concrete matrix is ​​primarily physical in nature, that is, to deliver friction shear, hence the steel fiber itself, it should be from the surface of the fiber and the fiber shape both to improve its bonding properties . There are four specific methods.

1. Steel fiber surface roughening, irregular cross-sectional shape. Using melt pump production will be able to achieve this goal. In the case of steel fiber because when air is rapidly cooled, the surface becomes rough and uneven shrinkage, but also shrink into a crescent-shaped cross section, increase the matrix

Contact area.

⒉ along the fiber axis direction by a certain distance on steel fiber plastic working. For example, Japanese company Kobe Steel, "the letter Ke" Steel Fiber American Leibang company "XOREX" steel fiber (Figure 2-1, c) and Qingan steel plant "S-2" and "S - 3" No. steel fibers. Since the surface is pressed into prismatic, or pressed into a wave, increasing the mechanical adhesion.

⒊ both ends of the profiled steel fibers. Austin of the United States Becker public "DRAMⅨ" steel fiber (Figure 2-1, e) and Qingan steel plant "S-4 and as-so steel fibers, are formed at both ends of the hook. There melt pumping method to extract the bulk of shaped steel fibers. Since the ends of the anchoring effect, increase the pull-out resistance.

⒋ steel fiber surface coated with epoxy resin and surface micro-rust treatment. This approach to improve the interfacial bond strength is not as before in several ways, but there are also some enhancement.

Kobayashi, one auxiliary, University of Liege, Belgium and Wen-face classes and other test proved hooked steel fiber reinforcing effect higher than straight steel fiber is about double the effect of a secondary test described Kobayashi pressure ridge near the steel fibers have curved hook steel fiber. These deformed steel fiber not only improves the strength of steel fiber and improved toughness. Although corrugated steel fiber to improve the strength of steel fiber reinforced concrete plays a minor role, but can exponentially increase the toughness.

II: Hardness

No matter what kind of processing methods of manufacturing steel fibers during processing are experiencing high fever and rapid cooling, quenching equivalent status. Therefore, the surface hardness of the steel fibers are high. For concrete reinforcement bending phenomenon rarely occurs when stirred. If the steel fiber excellent too brittle, easily broken while stirring also affect enhancement. When melt pumping steel fiber production, from the melt pump discharge centrifugal wheel steel fibers are still in a high temperature state, to be spread with a roller or a vibrating conveyor and cooling methods. Otherwise, steel fiber aggregate, difficult to distribute heat, but from the annealing effect.

Three: corrosion resistance

About steel fiber reinforced concrete corrosion test shows that steel fiber reinforced concrete member cracking in humid environments, concrete carbonation, steel fiber corrosion carbonation zone, carbonation depth and extent of corrosion cracks grow and evolve over time, steel fiber concrete, the main use of crack after post-rad and fracture toughness, although smaller than the crack width of reinforced concrete, but after all, there is a crack, so response in wet conditions, especially in adopting anti-corrosion protection of steel fiber reinforced concrete in the oceanfront measures. Face trial proved that, to ensure the steel fiber reinforced concrete member has the same carrying capacity of the premise, the use of relatively large diameter steel fiber, can improve the corrosion resistance, the use of epoxy coated or galvanized steel fibers, will be able to improve the corrosion resistance, If the construction permit process, it can only use this in the concrete surface 1-2cm steel fiber can also be used when necessary, not lure steel fibers.