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Specification: 0.55*30, 0.55*35,0.6*30,0.6*30,0.75*35
L/D Ratio: 50-35
The addition of steel fiber to shotcrete can improve the ability of concrete to absorb energy and resist impact, provide resistance to cracking, control cracking, and obviously improve ductility. For example, after cracking of concrete matrix, it still has bearing capacity. Compared with plain concrete and reinforced concrete, the performance of concrete with steel fiber is improved and improved.
The main purpose of adding steel fiber to shotcrete is to improve the toughness of shotcrete which is brittle material. Toughness refers to the ability of steel fiber sprayed concrete to absorb deformation in the bearing process, which is an important flexibility of steel fiber sprayed concrete. After adding steel fiber into the shotcrete, the deformation ability and residual bending strength of the shotcrete are improved significantly.
2. Fracture and Fracture Toughness
The common shotcrete is easy to shrink and crack because of the surface tension, and the fracture joint becomes the tunnel groundwater seepage channel. The concrete after fracture is stripped and shed under the long-term erosion of groundwater, and the supporting structure loses its supporting function, and the serious one collapses. Therefore, it is particularly important to emphasize the fracture performance of shotcrete in tensile condition. after adding steel fiber to the shotcrete. The deformation property is improved effectively and the steel fiber is more obvious when cracks appear in steel fiber concrete. Therefore, steel fiber shotcrete is very suitable for harsh environment. Tunnel engineering structure that needs crack resistance and impact resistance.
In tunnel engineering, the toughness of steel fiber shotcrete not only makes the shotcrete layer close to the rock surface flexible, but also provides the supporting resistance effectively and continuously during the joint deformation with the surrounding rock, which is helpful for the surrounding rock to form a large enough plastic zone through stress adjustment. Give full play to the "unloading" effect of rock mass in plastic zone, so that the pressure on the supporting body is greatly reduced.
3. Other major mechanical properties
The main function of the disordered distribution of short fibers in steel fiber shotcrete is to hinder the expansion of micro-cracks inside concrete and block the occurrence and development of macroscopic cracks. therefore, the addition of steel fibers has a significant improvement on the tensile strength of shotcrete and the shear, bending and torsional strength, which are mainly controlled by the main tensile stress, see figure 2.
4. Application prospects
Steel fiber shotcrete has been widely used in many countries in the world because of the unique advantages of new composite materials from the spraying process to the comprehensive economic benefits.