1. Use a polisher to polish the cracks 5 ㎝ on both sides, and then clean the cracks with acetone. There should be no oil or dust on the interface.
2. For the superficial cracks less than 5 mm in depth, use epoxy resin dilute and dry it, then scrape the epoxy resin cement in batches. The ratio of epoxy resin dilute solution is epoxy resin: diluent: curing agent 1: 0.4:0.25, the ratio of dilute material can penetrate deep into the root of the crack. Its structure is strong and can fill cracks.
3. For cracks with a depth greater than 5 mm, bury the grouting nozzle at a distance of 30-50 mm, and then close the crack with epoxy resin cement, and the sealing width is not less than 5 mm. Epoxy mortar seals the cracks. One is to seal the cracks of the superficial turtle, and the other is to prepare for the grouting. It is particularly important to choose the location of the hole for embedding the grout nozzle, which should be determined according to the length, depth, direction, shape and other factors of the concrete crack. It is generally required to select points at the two ends of the crack and the empty solid part to ensure that the slurry can reach each gap The part plays a role of strengthening and preventing cracking.
4. After the epoxy resin cement is completely dry, a gas test should be conducted to check the soundness of the slurry inlet, liquid outlet, and crack closure. Use 4 ㎏/㎝ 2 pressure air to input from the grouting hole, if the gas is output from the liquid outlet, and the leakage of the cement seal and other crack outlet is not leaking, it means that the crack grouting port and liquid outlet are set correctly, and the cement seal is reliable ，Close the liquid outlet, increase the pressure in the crack to 4㎏/㎝ 2, keep the pressure for 2 minutes, if there is no air leakage, it is normal. If the air leaks after the pressure rises, it should be closed again. If there are more than two liquid outlets after the pressure is increased, it means that the crack and more than two cracks have penetrated. At this time, the leaked liquid outlet should be closed until no leakage can maintain the pressure, and the record and mark should be made. . After aeration and pressure increase, there is no gas output from the liquid outlet. It may be that the crack passage is blocked by 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. , There are out, can keep pressure, no leakage.
5. After the gas test is qualified, the epoxy resin slurry is used for pressure grouting. The air pressure of the grouting is not less than 4 ㎏/㎝ 2.
6. Pay attention to observe the liquid state of the grouting nozzle during grouting. After confirming the filling, close the liquid outlet of the grouting nozzle and increase the pressure to 4㎏/㎝ 2. Keep the pressure for not less than 5 minutes, and then let it dry naturally , The natural drying time should be 72 hours
7. Check whether there is any omission in crack repair.
8. Remove the grouting nozzle and smooth out the epoxy resin cement that protrudes from the concrete surface. 4. Conclusion After 20 days of construction, the crack repair work of the Zhentou Bridge was successfully completed. After actual inspection, the cracks repaired with epoxy resin slurries achieved the effect of increasing the strength of the arch ring.