1. First use a polisher to polish the width of the crack at 5 cm on both sides, and then clean the crack with acetone. There should be no oil, dust, etc. on the interface.
2. For shallow cracks with a depth of less than 5 mm, use epoxy resin thin liquid to soak and dry, and then scrape epoxy resin cement. The proportion of epoxy resin thin liquid is epoxy resin: thinner: curing agent 1:0.4:0.25, which can penetrate deep into the crack roots. Its structure is strong and can fill cracks.
3. For cracks with a depth greater than 5 ㎜, bury the squeeze nozzles at a distance of 30 to 50 ㎝, and then seal the cracks with epoxy resin cement, with a sealing width not less than 5 ㎝. Epoxy mortar seals the cracks, one is to close the superficial cracks, and the other is to prepare for grouting. The selection of the position of the grouting nozzle hole is particularly important. This should be determined according to 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 hollow part to ensure that the grout can reach each gap. The parts play a role of reinforcement and crack prevention.
4. After the epoxy resin mortar is completely dried, a gas test should be carried out to check the integrity of the slurry inlet, liquid outlet and crack closure. Use 4 ㎏/㎝ 2 compressed air to input from the grouting hole. If the gas is output from the liquid outlet and the cement seal and other crack outlets do not leak, it means that the crack grouting port and liquid outlet are set correctly and the cement is sealed reliably. , 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 glue leaks after ventilation and pressure increase, it should be closed again. If more than 2 liquid outlets are vented after ventilation and pressure increase, it means that the crack and more than 2 cracks are through. At this time, the leaking and liquid outlets should be closed until there is no leakage and the pressure can be maintained, and records and marks should be made . After ventilating and boosting pressure, there is no gas output from the liquid outlet. It may be that the crack channel 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. , There is a flow, can maintain pressure, no leakage.
5. After the gas test is qualified, pressure grouting is carried out with epoxy resin slurry. The air pressure of the grouting should not be less than 4㎏/㎝2.
6. When grouting, pay attention to observe the liquid state of the squeeze nozzle. After confirming that it is full, close the squeeze nozzle outlet and increase the pressure to 4 ㎏/㎝ 2, keep the pressure for no less than 5 minutes, and then let it dry naturally , The natural drying time should be 72 hours. 7. Check whether there are any omissions in crack repair. 8. Remove the squeeze nozzle and smooth the epoxy mortar that protrudes from the concrete surface. 4. Conclusion After 20 days of construction, the crack repair project of Zhentou Bridge was successfully completed. After actual inspection, the crack repaired with epoxy resin grout has achieved the effect of increasing the strength of the arch ring.