The cracks and pores of concrete buildings are the main reasons for the damage of concrete buildings, and the leakage of cracks and pores is the most headache problem, because the cracks inside the concrete are completely irregular. In general, the traditional way to stop the leakage is to cut the crack or water leakage to stop the leakage on the surface, but the result is often to block here, where leakage begins. Because the water can move irregularly in the cracks inside the concrete and seep out from the relatively weak parts.
Chemical grouting method was used. The chemical grouting material is injected into the concrete cracks by mechanical high-pressure power (high-pressure grouting machine). When the slurry meets the water in the concrete crack, it will disperse, emulsify, expand and consolidate rapidly. The depth of water-soluble polyurethane grouting material entering the crack is related to the width of the crack: the wider the crack, the greater the slurry flow rate, the deeper it enters the crack, and the better the grouting effect. The initial expansion rate of water-soluble polyurethane can reach 100%. After the formation of the gel, the first expansion disappears, but it has good elasticity and becomes a stable elastomer similar to water stop rubber. In addition to the concrete, the concrete will be completely consolidated to block the leakage.
The cracks with width greater than 0.2mm shall be grouted with water-soluble polyurethane paste; cracks less than 0.2mm shall be sealed with epoxy resin adhesive (for dry joints, modified epoxy resin base solution shall be used; for wet joints, water-soluble polyurethane grouting shall be used as far as possible, and modified epoxy resin base liquid shall be used for sealing and reinforcement after water stop and drying. The cracks that are difficult to be grouted are sealed with "plugging agent" and sealed with modified epoxy resin base fluid after drying). Note: after water-borne polyurethane grouting, the modified epoxy resin grouting shall be determined according to the specific situation.
Advantages of chemical grouting waterproof and plugging construction
Water soluble polyurethane chemical grouting material is a kind of low viscosity, single component synthetic polymer polyurethane material, which is in the form of paste. It has the characteristics of crosslinking reaction when meeting water and foaming to form multi-component network closed elastomer. When it is injected into the concrete crack structure under high pressure until all the cracks are filled (including the 0.015mm micro crack which is hard to be detected by the naked eye), after encountering water (water injection), a large amount of carbon dioxide gas is released, resulting in secondary seepage pressure. The high-pressure thrust and secondary seepage pressure again press the elastomer into and fill all the cracks, so as to achieve the purpose of leakage prevention.
Construction technology of chemical grouting waterproof and plugging
High pressure chemical grouting plugging construction should be carried out by the construction team with professional training personnel and professional construction equipment.
1. Cleaning: check and analyze the leakage in detail to determine the position and spacing of grouting holes. Clean up the construction area and chisel out the precipitates on the concrete surface to ensure the surface is clean.
2. Drilling: use drilling tools to drill pressure relief holes around the hole. The diameter of the drill bit is 14mm, the drilling angle should be ≤ 45 ° and the drilling depth should be less than 2 / 3 of the structure thickness. The drilling must be inclined through the main leakage hole. However, it is not allowed to pierce the structure, because the moving water is large, the dust in the hole will be washed away by itself. For slow seepage on the wall surface, plum blossom holes are drilled on the seepage surface. Wash the grouting hole with the cleaning machine until the water out of the grouting hole is clear, then the next step can be carried out.
3. Burying nozzle: observe the pressure of the main leakage hole. When the water flow is not rapid and the pressure is not large, the quick drying plugging agent can be used to bury and inject the grouting water stop needle (according to the construction situation, the wood wedge can also be inserted and then the quick drying plugging agent can be used for plugging. After the structure is stable, the wood wedge can be re drilled and the expansion water stop needle can be installed). When the structure reaches a certain strength and there is no leakage, other drain holes are respectively installed with expansion water stop needles and tightened with a special hexagon wrench, so that there is no gap between the grouting nozzle and the drilling hole, and there is no water leakage. For slow seepage on the wall, the expansion water stop needle shall be installed in turn. The leakage points are installed with 25cm, 10cm and 8cm water stop needles according to the layers, so that the grouting can be completely dense from the deep layer to the surface layer. Plug all holes and gaps.
4. Grouting: high pressure grouting machine shall be used for pressure test, which shall not exceed the pressure range of concrete structure. The chemical grouting material is poured into the grouting hole. The single hole is continuous one by one. When the grouting of adjacent holes starts, the grouting of this hole can be stopped and the grouting of adjacent holes can be changed after maintaining the pressure for 3-5 minutes. After all holes have been filled, return to the previous first grouting hole and grout again to ensure maximum pressure. The wall grouting sequence is from bottom to top; after all the holes are grouted, it is also back to the previous first grouting hole for reinjection.
5. Nozzle removal: the exposed grouting nozzle can be removed or knocked out after 24 hours of grouting. Clean up the solidified spilled grouting fluid.
6. Reinforcement: use impermeable cement-based permeable crystalline compressive sealant for full sealing or rigid RG material plastering as protective layer reinforcement. Finally, polymer JS waterproof coating will be applied three times for surface waterproof treatment. (applicable to overall plugging, for reference only)
Scope of application: leakage stoppage with water and pressure, subway, tunnel, pump house, reservoir, sewage pool, underground civil air defense cavern, basement, cable trench, culvert, dam, power plant dam, acid (alkali) pool, cooling tower, mine, elevator shaft, tunnel rock foundation seepage prevention, leakage prevention, leakage stoppage of concrete engineering cracks, expansion joints, construction joints, structural joints Waterproof and plugging of external wall.
Grouting plugging technology: without slotting, it will not damage the structure, and it can be constructed with water and pressure, which is the best choice for plugging.