(1) winter pouring concrete, before

(1) winter pouring concrete, before freezing using slag Portland cement or ordinary Portland cement concrete.(2) the winter construction of concrete mixing, in order to shorten the curing time, choose ordinary Portland cement, cement strength grade should not be less than 32.5MPa, the dosage of cement per cubic meter of concrete should not be less than 300Kg.(3) In order to reduce freezing injury, reduce the water consumption in the mix proportion to the minimum. It is mainly to control slump, add air-entraining water reducer, and control air content by 3%~ 5%.(4) when plain concrete is mixed with hot materials, the chlorine salt content shall not be greater than 3% of the cement weight; when mixed with cold materials, the chlorine salt content shall not be greater than 5% of the mixing water weight.(5) the winter mixing concrete adopts the method of heating water. Water can be heated to 100C, but cement should not be in direct contact with water above 80C. In the feeding sequence, aggregate and heated water should be added first, and then cement should be added. Since cement cannot be directly heated, it should be transported into the greenhouse for storage before use.⑥ When mixing concrete, the aggregate shall not contain ice and snow or frozen lumps, and the mixing time shall be prolonged by 50% than that during normal temperature construction. The stone with excessive mud content shall be washed in advance for standby.⑦ According to the test grading, special personnel shall be assigned to prepare admixtures, and the dosage shall be strictly controlled.