1. In order to ensure the quality of the project, reduce the cost of the project, and reduce the difficulty of construction, winter construction can only be carried out as a last resort. Cold concrete construction should only be used as a last resort, because the exact amount of antifreeze in cold concrete is difficult to determine. In order to ensure that the concrete is not damaged by freezing, the amount added is often more than what should be added. Even if the amount is exceeded, if the temperature changes suddenly, you will still suffer from freezing damage.
Adding a large amount of antifreeze to cold concrete will not only slow the early strength development, but also affect the durability of the concrete to a certain extent no matter what measures are taken. Due to the low strength development speed, it is impossible to remove the formwork early and the construction progress cannot be accelerated, which is equivalent to increasing the cost in vain.
2. The scope of the project that should be carried out in winter can be reduced to a very small size. For example, underground projects (tunnels, underground factories, etc.), ground foundation projects, large-volume concrete and projects that easily store heat on the ground do not need to take winter construction measures at any temperature, as long as water reduction and slump reduction are adopted. This can ensure the quality of winter construction. If necessary, the heat storage method can fully meet the requirements.
For the slabs and columns on the first floor of ground factories, civil buildings and projects that are easy to insulate, when the temperature is below -10℃, measures should be taken to reduce water and reduce slump After the temperature is reached, the heat storage method is adopted. If necessary, heating the water and sand can ensure the quality and avoid freezing damage. When the temperature is -15~-10℃, in addition to the above measures, add a small amount of early strength agent appropriately.
In the concrete construction of the Hetao irrigation area in Inner Mongolia, the author prepares materials every winter and pours concrete in early spring. Although the temperature was as low as -15°C during the concrete pouring period, it was still in the warming season. Seizing this favorable opportunity, the above-mentioned heat storage construction methods were successfully adopted, which greatly saved project costs.
For structures that are higher than the ground and above the second floor, the temperature is above -10℃. Taking the above measures and adding early strength agent can also ensure the quality. When the temperature is as low as -10℃, construction should be avoided as much as possible.
In short, winter construction should be avoided as much as possible. In winter construction, the heat storage method should first be used, followed by material heating combined with heat storage method, and then a small amount of early strength should be added. agent. This not only reduces the cost, but also improves the quality and eliminates future worries. At the same time, it does not affect the construction progress.
Steam curing is suitable for factory-style precast concrete. The electric heating method consumes a lot of power and is not suitable for on-site use. The thermal storage method is not only simple and widely adaptable, but also fully meets the requirements of energy conservation and emission reduction in today's era.
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