1, nature conservation
During the curing period of formwork concrete, measures such as formwork wrapping, watering and sprinkling should be taken to keep moisture and moisture, so as to ensure that formwork joints are not dehydrated and dry. In order to ensure the smooth form removal, the formwork can be loosened slightly after 24 ~ 48h of concrete pouring, and water conservation can be continued until the form removal, and then the moisture can be kept to the specified age.
After the concrete surface protective layer is removed or the formwork is removed, measures such as storing water, watering or covering with water should be taken to wet cure the concrete. When the concrete surface is wet, bare concrete can be quickly covered or wrapped with linen, straw curtains and other materials, and then wrapped with plastic sheets or canvas with linen, straw curtains and other moisturizing materials.
When painting, the coatings should be intact and completely overlapped with each other, and there should be condensed water droplets on the inner surface. Conditional areas should try to extend the concrete coating and moisture curing time.
2, health liquid method
Spray film curing liquid is suitable for special-shaped or large-area concrete structures that are not easy to spray curing. In this method, the solution of perchloroethylene resin is sprayed on the concrete surface with a spray gun, and a plastic film is formed on the concrete surface after the solution volatilizes, so that the concrete is isolated from the air, the water in it is prevented from evaporating, and the normal hydration is ensured.
Some films will age and fall off after curing, otherwise they are not suitable for spraying on the concrete surface to be painted in the future. In summer, the film should be protected from the sun after forming, otherwise it will crack easily. When curing concrete with spraying curing liquid, no leakage shall be ensured.
Gray curing agent or transparent material is usually used to cure the long-term exposed concrete surface. The color of gray curing agent is close to the color of concrete, and it can also paint and add color to the surface. By the end of weathering, its appearance is much better than that of white curing agent. Transparent curing agent is a kind of transparent material, which can't paint concrete, but can only keep its original appearance.
3. Cure the film
The water-saving and moisture-retaining curing film of concrete is made of a new controllable polymer material as the core and a plastic film as the carrier. Polymer materials can absorb 200 times their own weight of water, become transparent lenses after water absorption and expansion, turn liquid water into solid water, and then continuously penetrate the solidified surface through capillary action.
At the same time, the evaporation water of the curing body is continuously absorbed during the hydration heat of concrete. Therefore, in a curing period, the cured film can keep the cured surface moist, and the relative humidity is greater than or equal to 90%, which can effectively inhibit micro-cracks and ensure the engineering quality.
4, full water method
In the process of cast-in-place concrete slab, nine splint strips with thickness greater than 12mm (width 100mm) are spread along the periphery of cast-in-place concrete slab, and fixed with two nails with a length of 35mm per meter; Stair treads and cast-in-place slabs are also planking, which requires the stair treads to be flat and the step height difference is less than 3 mm; When the concrete slab is large, it should be cured in blocks according to the pouring time and plane size.
The boundary is also paved with 9 plywood strips with a width of100 mm; Slate laying should be smooth and close to the edge; After concrete is cast, it should be leveled with coarse wooden crabs in time and maintained in time, especially in summer. Before high-temperature initial setting, spray curing should be adopted. Coarse wooden crabs should be leveled for the second time, and before final setting, they should be filled with water (that is, three plywood and other plates should be laid on the board first).
Then water flows through the surface of the board to the concrete surface until the slats overflow. ) curing for 3 days to 7 days, and the curing time should be extended if conditions permit; Avoid moving concrete during curing; Stair treads shall be cancelled after the concrete strength reaches 100%.
Extended data
The quality of concrete curing directly determines the microscopic characteristics of concrete materials. Proper early curing will lead to high concrete density, low total void ratio and reduced capillary content, so reasonable curing will obviously improve the early performance of concrete.
Such as strength and impermeability. Temperature, humidity and curing time are the main control parameters in the curing process of concrete materials, and sufficient moisture, suitable temperature and necessary curing time are important guarantees to realize the durability of concrete.
Cracks in concrete structures are mostly caused by deformation, which is mainly caused by humidity, temperature and uneven settlement, among which cracks caused by humidity and temperature changes account for the main part.
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