1. Antifreeze dosage: add 4~5% of the cement weight.
2. Before mixing, rinse the mixer with hot water or steam. First add sand, gravel and hot water and stir for about 1 minute, then add cement and antifreeze and stir for 3 minutes. The temperature of the mixing water is determined by ensuring that the concrete entering mold temperature is ≥10°C.
3. Sand and stones should be covered with canvas or plastic sheeting to prevent the sand and stones from freezing. The cement must not be heated directly and should be transported to a greenhouse for storage one day before use to keep it at a positive temperature.
4. Before pouring concrete, remove ice, snow and dirt from the formwork and steel bars. Do not use steam to melt ice and snow directly to avoid refreezing. The exposed surface of the newly poured concrete should be covered with plastic film and insulation materials in a timely manner, and the operation should be continued according to the principle of pouring, vibrating and covering.
5. The cement should be Portland cement or ordinary Portland cement with a strength grade of 32.5 or above. Sand and stones must be clean and sieved, and must not contain ice, snow and other frozen substances and substances that are easy to freeze and crack.
6. Mixing of concrete mixed with antifreeze agent should comply with the following regulations:
① Strict control The amount of antifreeze and water-cement ratio, the moisture brought by the aggregate and the water in the antifreeze solution should be deducted from the mixing water.
②The exit temperature of the concrete mixture mixed with antifreeze shall not be lower than 15℃ in severe cold areas; and shall not be lower than 10℃ in cold areas. The mold entry temperature shall not be lower than 10°C in severely cold areas and shall not be lower than 5°C in cold areas.
7. The maintenance of concrete mixed with antifreeze should comply with the following regulations:
① Under load Watering is not allowed during maintenance under warm conditions. Concrete should be covered with plastic film and insulation materials immediately after pouring. Insulation measures should be strengthened in severely cold areas.
②The initial curing temperature shall not be lower than the specified temperature. When the temperature of the concrete drops to the specified temperature, the strength of the concrete must reach the critical strength of freezing; when the lowest temperature is not lower than -10°C, the compressive strength of concrete shall not be less than 3.5Mpa; when the lowest temperature is not lower than -15°C, the concrete compressive strength The compressive strength shall not be less than 4.0Mpa; when the lowest temperature is not lower than -20°C, the compressive strength of concrete shall not be less than 5.0Mpa.
③After the formwork is removed, when the difference between the concrete surface temperature and the ambient temperature is greater than 20℃, insulation materials should be used for covering and curing.
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