Construction joint retention position

The location of the construction joints should be set at the parts where the structure is less sheared and easy to construct. The construction joints in different spaces have different positions, and the following requirements should be met: horizontal joints should be left for columns, and vertical beams, slabs and walls should be left vertical Sew.
1. Construction joints should be left on the top surface of the foundation, under the corbel of the beam or crane beam, above the crane beam, and under the column cap of the beamless floor.
2. For large-section beams that are connected to the floor as a whole, the construction joints should be left 20mm-30mm below the bottom of the slab. When there is a corbel under the slab, it is left under the corbel.
3. For one-way boards with a length-to-width ratio greater than two to one, the construction joints should be left at any position parallel to the short side of the board, and the construction joints should be left vertically, and cannot be made into a diagonal chamfer.
4. Floor slabs with primary and secondary beams should be poured along the direction of the secondary beams, and the construction joints should be left in the middle 1/3 of the span of the secondary beams.
5. The construction joints on the wall should be left within 1/3 of the middle span of the door opening, or at the junction of the vertical and horizontal walls.
6. The construction joints on the stairs should be left at 1/3 of the treads. The concrete of the stairs should be poured continuously. If it is a multi-storey staircase, and the upper floor is cast-in-place slab but not poured, the construction joint can be left; it should be left in the middle 1/3 of the stair section, but it should be noted that the joint surface should be diagonally perpendicular to the axis of the staircase direction.
7. The construction joints of the pool wall should be left on the vertical wall 200mm~500mm higher than the bottom surface.
Construction joints: the joints left between the construction units due to the needs of the construction organization. The construction joint is not a real “joint”, it is just because the post-pouring concrete exceeds the initial setting time, and there is a joint surface with the first-poured concrete, which is called a construction joint. Because the joint surface formed by successive pouring of concrete is prone to various hidden dangers and quality problems, different structural projects need to be cautious in handling construction joints.
Treatment method of construction joint
Before pouring concrete on the hardened concrete surface (the concrete strength is required to reach 1.2MPa), rubbish, loose sand and gravel and weak concrete layer on the surface of the cement film should be cleaned up. At the same time, the surface should be chipped. Rinse with water and fully moisten it. Generally, the moistening time should not be less than 24h. Remains in coagulation.
The role of construction joints
Construction joints: the joints left between the construction units due to the needs of the construction organization. The construction joint is not a real “joint”, it is just because the post-pouring concrete exceeds the initial setting time, and there is a joint surface with the first-poured concrete, which is called a construction joint. Because the joint surface formed by successive pouring of concrete is prone to various hidden dangers and quality problems, different structural projects need to be cautious in handling construction joints.