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Construction process
Look for cracks: For wet bases, first clean the stagnation water; for dry bases, clean the surface dust and carefully look for cracks. Use a color pen or chalk to mark along the crack.
Drilling: According to the thickness of the concrete structure, about 50-150mm away from the crack, drill holes on both sides in the direction of the crack 14mm drill bit is required for the hole diameter. The cross section of the hole and the crack should form a 45 ° -70 ° intersection and cross in the 1/2 range of the middle of the structure.
Embed the grouting nozzle: embed and fasten with a tool to ensure that the rubber part of the nozzle and the wall of the hole are absolutely matched, otherwise it will easily cause slippage during fastening.
Matters needing attention before construction
· Firstly, the cracks should be analyzed, and the cores should be taken according to the different width and length of the cracks to determine the development law of crack depth. If the surface is not easy to dry, you can use a blowtorch to dry. If there is water seepage at the crack, it can be found immediately and improve efficiency.
Crack repair
· The pouring slurry should be poured from the vertical surface of the structure from bottom to top. When the slurry emerges from the crack, it should be stopped immediately, and then proceed forward. During the filling process, if the slurry has filled the position of the adjacent needle, it can be skipped without injection; if after the grouting, it is found that there are still crack extensions at both ends of the crack, or there are cracks crossing it, re-grouting.
· In order to completely fill the cracks with slurry, a second grouting should be performed before the slurry solidifies.
Notes on grouting
· When a needle is poured for a long time (about 5 minutes), the slurry has not yet emerged from the crack, the injection should be stopped, and it should be carried out after a period of time.
If it is still not filled, check whether the borehole crosses the buried pipeline, whether the structure has holes, etc.
· Please pay close attention to the working pressure gauge of the filling machine during pouring. If it exceeds the rated pressure (above 45Mpa), it should be shut down before proceeding. If the pressure remains high, it should be checked whether the borehole completely crosses the crack and whether the borehole depth is greater than half of the structure thickness.
Crack repair detection
For the cracks that have been repaired, use a drilling machine for core detection after 3 months. The test result should be that the surface of the concrete is smooth and dense, the slurry is completely filled with cracks, and the core sample is tested for concrete strength compression to reach the original design value.
