Abstract: steel mesh, also known as welded steel mesh, steel welded mesh, steel welded mesh, steel welded mesh, steel mesh, etc., is widely used in the fields of beam column floor slab, roof, wall, concrete pavement, bridge deck pavement, airport runway, tunnel lining, box culvert, wharf floor, prefabricated components and so on.
Steel mesh can be divided into cold-rolled ribbed steel mesh, cold-drawn smooth round steel mesh, hot-rolled ribbed steel mesh and so on.
The welded mesh has carried out industrialized production of all the original on-site production processes, which not only protects the quality of reinforcement production and binding but also greatly shortens the construction cycle of the project, solves the problems of narrow construction site and noise pollution caused by straightening reinforcement, and promotes on-site civilized construction.
Steel fabric can be divided into cold-rolled ribbed steel fabric, cold-drawn smooth round steel fabric and hot-rolled ribbed steel fabric according to raw materials, among which cold-rolled ribbed steel fabric is most widely used.
Reinforcement mesh is divided into fixed reinforcement mesh and customized steel welded mesh according to the brand, diameter, length and spacing of reinforcement.
The minimum diameter and maximum spacing of steel welded mesh for reinforced concrete pavement shall comply with the provisions of the current industry standard code for design of highway cement concrete pavement jtgd40.
When cold-rolled ribbed reinforcement is used, the diameter of reinforcement shall not be less than 8mm, the spacing of longitudinal reinforcement shall not be greater than 200mm, and the spacing of transverse reinforcement shall not be greater than 300mm.
The longitudinal and transverse reinforcement of welded mesh should adopt the same diameter, and the thickness of protective layer of reinforcement should not be less than 50mm The welded mesh for reinforcement of reinforced concrete pavement can be implemented in accordance with the relevant provisions of welded mesh for reinforced concrete pavement.
When the expansion joint between the concrete pavement and the fixed structure cannot be provided with a dowel bar, a double-layer reinforcement mesh can be configured in the plate end adjacent to the structure;
Or gradually increase the plate thickness by 20% in the range of about 6 to 10 times the plate thickness.
When the concrete pavement is connected with the bridge and the bridge head is provided with approach slab, a 6-10mm long reinforced concrete surface transition slab shall be set between the approach slab and the concrete surface slab.
When the bridge is skew, the acute corner of the reinforced concrete slab shall be reinforced with reinforcement mesh.
Under the concrete surface, there are box structures crossing horizontally.
When the distance from the top surface to the bottom surface of the surface layer is less than 400mm or embedded in the base layer, double-layer steel welded mesh shall be arranged in the concrete surface layer at the top width and both sides of the structure, and the upper and lower steel welded mesh shall be 1 / 4 to 1 / 3 of the thickness from the top surface and bottom surface of the surface layer.
There is a circular tubular structure crossing under the concrete surface.
When the distance from the top surface to the bottom surface of the surface is less than 1200mm, a single-layer steel welded mesh shall be arranged in the concrete surface on both sides of the structure, and the steel welded mesh shall be set at the thickness of 1 / 4 to 1 / 3 from the top surface of the surface.
It is mainly used in bridge deck pavement of municipal bridges and highway bridges, old bridge deck reconstruction, pier crack prevention, etc.
The quality acceptance of thousands of bridge application projects in China shows that the use of welded mesh can significantly improve the quality of bridge deck pavement, the qualified rate of protective layer thickness is more than 97%, the flatness of bridge deck is improved, the bridge deck is almost free of cracks, the pavement speed is increased by more than 50%, and the cost of bridge deck pavement is reduced by about 10%.
Welded mesh or prefabricated cold-rolled ribbed mesh shall be used for the steel welded mesh of bridge deck pavement, and binding mesh shall not be used. The diameter and spacing of steel welded mesh for bridge deck pavement shall be determined according to the bridge structure and load grade.
The spacing of steel welded mesh can be 100 to 200mm, and its diameter should be 6 to l00mm. The longitudinal and transverse spacing of steel welded mesh should be equal, and the thickness of protective layer between welding mesh and top surface should not be less than 20mm.
According to the national standard code for design of highway tunnel jtgd70-2004.
Ribbed steel welded mesh shall be set in the shotcrete, which is conducive to improving the shear and bending strength of shotcrete, improving the punching shear capacity and bending capacity of concrete, improving the integrity of shotcrete, reducing the shrinkage crack of shotcrete and preventing local block falling.
The steel welded mesh shall be arranged in a rectangle, and the reinforcement spacing of the steel welded mesh shall be 150 ~ 300mm. 150mm may be used × 150mm，200mm × 200mm，200mm × 250mm，250mm × 300mm，300mm × 300mm combination. The overlapping length of reinforcement mesh shall not be less than 30d (D is the diameter of reinforcement).
The thickness of shotcrete protective layer of steel welded mesh shall not be less than 20mm. When double-layer steel welded mesh is adopted, the spacing between two layers of steel welded mesh shall not be less than 60mm.