(2) The duration of sprinkler maintenance is related to cement varieties. Concrete mixed with ordinary portland cement and slag portland cement shall not be less than 7d, and concrete mixed with pozzolanic portland cement and fly ash portland cement shall not be less than14d; ; Not less than 14d concrete mixed with retarding admixture or with impermeability requirements.
(3) The number of curing and watering should be able to keep the concrete surface in a wet state. At the initial stage of hydration, the chemical reaction of cement is sufficient, which can increase the watering times. When the temperature is around 15℃, water it 2 ~ 4 times a day, and increase the watering times when the temperature rises. The water used should be consistent with the concrete mixing water, and it is not suitable for water conservation when the average temperature is lower than 5℃.
When plastic film is used for curing, all exposed parts of concrete are covered tightly with plastic sheets to ensure that there is condensed water in the plastic sheets, so as to achieve the purpose of wet curing. Spraying plastic film curing solution can be used for the maintenance of water-deficient areas and high-rise buildings that are not easy to water. That is, the curing liquid 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 and the water in it is prevented from evaporating, thus ensuring normal hydration.
Generally, it is 2 ~ 4 hours after concrete pouring, and the bleeding has just separated and there is no floating water. When the finger has no fingerprints, you can spray the film curing liquid. People are not allowed to walk before the strength of concrete reaches 1.2MPa. Generally, it is advisable to steam at a temperature of about 65℃. Under the conditions of high temperature and high humidity, concrete can quickly reach the required strength. Due to the limited construction site conditions, cast-in-place prefabricated members can generally be covered by temporary ground or underground maintenance pits, with maintenance covers or with simple canvas and tarpaulin.