1, thermal storage maintenance: when the temperature is not too low, the thermal storage method should be preferred. The heat storage curing method is to heat the components of concrete that still have a certain temperature after transportation and vibration, and then stir them. The poured concrete is closely covered with thermal insulation materials. In the construction of heat storage method, portland cement, ordinary portland cement or quick-hardening portland cement with high strength and high hydration heat should be selected. At the same time, choose thermal insulation materials with low thermal conductivity, low price and durability. After the insulation layer is laid, attention should be paid to moistureproof and ventilation prevention. For the edges, ends and convex corners of members, special insulation should be strengthened. In order to avoid heat conduction loss, local heating measures should be taken when necessary.
2. Comprehensive thermal storage maintenance: it is suitable for construction under the condition that the daily average temperature is not lower than-16℃ or the extreme minimum temperature is not lower than-16℃. Comprehensive thermal storage curing method is based on thermal storage technology, adding antifreeze to concrete to prolong hardening time and improve frost resistance. A small amount of antifreeze is added to the concrete mixture, the raw materials are preheated, and the mixing station and transportation tools should be well insulated. Generally, the temperature of the mixture after pouring should be above 10℃, and it must be above 13℃ when the section size of the component is less than 300mm. Thermal calculation should be carried out when the thermal storage method is used for maintenance.
3. Covering and curing: After the concrete is molded and leveled, cover it with transparent or black plastic film (0. 12 ~ 0. 14 mm thick), and then cover it with air cushion film (with bubbles facing downwards). The plastic film should be anti-aging and the joint should be thermally bonded. When covering, it should be close to the surrounding area and covered tightly with sandbags or other heavy objects to prevent it from being blown away by the wind. When the plastic film is overlapped, the overlapping length should be greater than 300 mm
4. Warm shed method maintenance: For underground engineering with a large amount of concrete, when the average temperature of the day is greater than-10℃, the warm shed method can be used for maintenance. Greenhouse method maintenance is to set up a greenhouse around the building or component, keep the air in the greenhouse at a positive temperature through artificial heating, and concrete pouring and maintenance are carried out in the greenhouse. Greenhouse is usually made of scaffolding materials (steel pipes or wooden poles) and is surrounded by plastic film or canvas. The plastic film can be a polyethylene film with a thickness greater than 0.65438 0 mm, or a composite cloth of polypropylene woven fabric and polypropylene film. Plastic film is not only light in weight, but also transparent, and it does not need artificial lighting during the day. After absorbing solar energy, it can also increase the temperature in the shed. The energy used for heating is generally coal or coke, and you can also use a hot fan or radiator with electricity, gas, kerosene or steam as energy.
5. Maintenance method of electric blanket: When the average temperature of the day is lower than-10℃, electric blanket can be used for maintenance. The electric blanket is made of four layers of glass fiber cloth with resistance wires sandwiched between them. When making, the 0.6mm Fe-Cr-Al alloy resistance wire is wound into a spiral shape on an asbestos rope with an appropriate diameter, and laid on the glass fiber cloth according to a serpentine line, and the resistance wires are evenly spaced to avoid being bent at the corner, and then fixed by sewing. The size of the electric blanket depends on the need. The electric blanket should be covered with rock wool as insulation material.