Cold joint refers to that during the construction process, for some reason, after the initial setting of the pre poured concrete, the post poured concrete continues to be poured, resulting in a weak joint surface at the link between the front and rear concrete, which belongs to improper construction.

1. Surface repair method

Surface repair method is a simple and universal repair method. It is mainly applicable to the solution of surface cracks and deep cracks that are stable and do not harm the bearing capacity of the structure. The general solution is to wipe cement mortar, Epoxy Mastic on the surface of the crack or brush paint, asphalt and other anti-corrosion materials on the concrete surface. At the same time, in order to avoid the continuous cracking of the concrete by various effects, it is usually possible to paste glass fiber cloth on the surface of the crack.

2. Grouting and inlay plugging method

The grouting method is mainly applicable to the repair of concrete cracks that have an impact on the structural integrity or have anti-seepage requirements. It uses pressure equipment to press the cementitious material into the cracks of concrete. After hardening, the cementitious material forms an overall with the concrete, so as to achieve the purpose of plugging and reinforcement. Common cementitious materials include cement slurry, epoxy resin, methacrylate, polyurethane and other chemical materials. Caulking method is the most common method in crack sealing. It generally chisels along the crack and fills the groove with plastic or rigid water stop materials to seal the crack.

3. Structural reinforcement method

When the cracks affect the concrete structure, it is necessary to consider the reinforcement method to deal with the concrete structure. The common key methods in structural reinforcement are as follows: increasing the cross-sectional area of concrete structure, outsourcing section steel at the corners of components, selecting prestressed reinforcement, pasting thick steel plate reinforcement, adding fulcrum reinforcement and shotcrete reinforcement.

4.Concrete replacement method

Concrete replacement method is a reasonable method to solve the serious damage of concrete. This method is to remove the damaged concrete first, and then replace it with new concrete or other materials. Common replacement materials are: ordinary concrete or cement mortar, polymer or modified polymer concrete or mortar.

5. Electrochemical protection method