Natural conservation can be divided into covering water conservation and plastic film conservation. (1) Covering and water conservation. Covering and watering maintenance refers to the maintenance method of covering the surface of newly poured concrete with grass curtain, sand and soil. Within 12h after pouring, and sprinkle water to keep it moist. The duration of sprinkler maintenance depends on the functional requirements of cement varieties and structures. Concrete mixed with ordinary portland cement and slag portland cement shall be no less than 7d. Not less than 14d concrete mixed with retarding admixture or with impermeability requirements. Sprinkling times shall be subject to ensuring the wet state of concrete. Large-area structures such as floors, floors and roofs can be maintained by storing water. For reservoir engineering, the internal formwork can be removed, and the concrete can be cured by water injection after reaching a certain strength; For underground structures or foundations, asphalt emulsion can be painted on their surfaces or backfill soil can be used instead of sprinkling water for maintenance. Concrete must be cured until its strength reaches 1.2 MPa or above, before other construction can be carried out. (2) the plastic film is cured. Plastic film curing is to cover the surface of concrete with plastic film, which can prevent the water in concrete from evaporating, and the cement is hardened by hydration and condensation of water in concrete, thus achieving the purpose of curing. Plastic film curing can be divided into direct covering curing with plastic cloth and spraying plastic film curing liquid. Natural conservation has low cost and good effect, but the maintenance period is long. In order to shorten the curing period, improve the turnover rate of formwork and the utilization rate of site, heating curing is generally used when producing prefabricated components. Heating curing is to accelerate the strength growth of concrete by heating. Common methods include steam room maintenance and hot mold maintenance. Steam curing is to put concrete components in a curing room filled with steam, so that concrete can quickly reach the required strength under high temperature and high humidity conditions. The steam curing process is divided into four stages: static stop, temperature increase, constant temperature and temperature decrease. Hot film curing belongs to steam curing. Steam does not contact with concrete, but is sprayed on the formwork for heating, and heat is exchanged with newly formed concrete through the formwork. This method uses less steam for curing and even heating, and can be used for both prefabricated components and cast-in-place walls.