1. First, use a polisher to polish the cracks with a width of 5 cm on both sides, and then clean the cracks with acetone. There should be no oil, dust, etc. on the interface.
2. For superficial cracks with a depth of less than 5 mm, saturate with epoxy resin thin liquid, dry and solidify, and then scrape the epoxy resin cement. The ratio of epoxy resin to thin liquid is epoxy resin: diluent: curing agent 1:0.4:0.25. This ratio of thin material can penetrate deep into the root of cracks. Its structure is strong and can fill cracks.
3. For cracks with a depth greater than 5 cm, bury grouting nozzles at intervals of 30 to 50 cm, and then use epoxy resin cement to seal the cracks with a sealing width of not less than 5 cm. Epoxy resin cement seals cracks, firstly to seal superficial cracks, and secondly to prepare for grouting. The selection of the hole position for the embedded grouting nozzle is particularly important. This should be determined based on the length, depth, direction, shape, and other factors of the concrete crack. Generally, it is required to select points at both ends of the crack and the empty and solid parts to ensure that the grout can reach every gap to play the role of reinforcement and crack prevention.
4. After the epoxy resin cement is completely dry, a gas measurement test should be conducted to check the integrity of the slurry inlet, liquid outlet, and crack sealing. Use 4 ㎏/㎝ 2 pressure air to input from the grouting hole. If the gas is output from the liquid outlet and there is no air leakage in the cement sealing area and other crack outlet openings, it means that the crack grouting opening and liquid outlet are set correctly, and the cement sealing is reliable. Close the liquid outlet to increase the pressure in the crack to 4 ㎏/㎝ 2 and maintain the pressure for 2 minutes. If there is no air leakage, it is normal. If air leaks from the cement after ventilation and pressure increase, it should be resealed. If air is released from more than 2 liquid outlets after ventilation and pressure increase, it means that the crack is connected with more than 2 cracks. At this time, the leaking liquid outlets should be closed until there is no air leakage and the pressure can be maintained, and records and marks should be made. After ventilation and pressure increase, there is no gas output from the liquid outlet. It may be that the crack channel is blocked during the cement sealing process. At this time, the liquid outlet and grouting port should be added at the appropriate position of the crack in this section. In principle, it is ensured that the entire section of the crack has an inlet and an outlet, can maintain pressure, and does not leak.
5. After passing the gas test, use epoxy resin slurry for pressure grouting. The air pressure for grouting shall not be less than 4㎏/㎝2.
6. When grouting, pay attention to the liquid output from the grouting nozzle. After confirming that the grouting nozzle is full, close the liquid outlet of the grouting nozzle, increase the pressure to 4 kg/cm2, maintain the pressure for no less than 5 minutes, and then wait for it to dry naturally. The natural drying time should be 72 hours.
7. Check whether there are any omissions in crack repair.
8. Clean the grouting nozzle and smooth the epoxy resin glue protruding from the concrete surface.
