As the weather gets hotter and hotter, we all know that concrete is a material that is very vulnerable to temperature, so how should concrete be constructed in summer?
1. The construction time
shall be selected in the morning or afternoon as far as possible, and the construction shall be avoided when the sun shines directly at noon, so as to prevent the premature dehydration of concrete leading to insufficient strength.
II. Sunshade or temporary sunshade shall be set up at the construction site for environmental protection
to keep the concrete pouring area cool and avoid adverse effects such as direct sunlight and rain.
3. Adjustment
of concrete mix proportion In summer, when the temperature is high, the setting time of concrete will be shortened, so it is necessary to reduce the cement content in the mix proportion and increase the use of mineral admixtures to improve the crack resistance of concrete.
4. Reduce the temperature
of concrete. In the process of concrete mixing, appropriate amount of borneol or ice water can be added to reduce the temperature of concrete, so as to control the hydration rate of cement, delay the hardening time of concrete and avoid cracks.
5. To ensure the hydration reaction
of concrete, the temperature is high in summer, and the hydration reaction speed of concrete is fast, so it is necessary to keep the concrete moist to avoid premature dehydration leading to insufficient strength. Immediately after placement, the concrete may be covered with moisture retaining paper or wet mortar, or may be moistened with water jets until the concrete reaches the expected strength.
6. Prevent the temperature of concrete from rising
. Set up water spraying and cooling equipment on the construction site to water the concrete in time to prevent the temperature of concrete from rising due to direct sunlight, which will affect the strength.
7. To prevent rainwater from intruding into
rainy summer, it is necessary to cover the construction area in advance before pouring concrete to ensure that the construction area is not eroded by rainwater, which will affect the strength of concrete.
VIII. Preparation
before construction Before construction, the formwork shall be watered to reduce the surface temperature, but there shall be no water storage in the formwork. At the same time, ensure that there is no debris and dirt in the formwork, the formwork is assembled tightly and seamless, and the position of embedded parts is correct.
IX. Pouring sequence and vertical structures with large height such as vibrating
walls and columns shall be poured in layers, and the pouring height of each layer shall not exceed 500 mm, subject to no segregation when the concrete mixture falls. After pouring in layers, insert the vibrator into the next layer of concrete for about 5cm to fully vibrate. During
concrete pouring, the material shall be distributed evenly and dispersedly, and it is strictly prohibited to use a vibrating spear to drive the material. The vibrating method of "inserting quickly and pulling out slowly" shall be adopted for full vibration. The sign of dense vibration is that the concrete mixture will not sink significantly, the surface is bleeding, there is no bubble overflow, and the coarse aggregate is evenly distributed in the concrete mixture.
10. Covering curing
In summer, the temperature is high and the water evaporates quickly, so moisturizing curing is an effective measure to control plastic shrinkage cracks caused by water loss of concrete mixture. Curing compound or film covering shall be sprayed on the concrete surface to ensure that the concrete surface is wet.
11. Strengthen management and monitoring
. In summer, the temperature is high. Concrete construction needs to strengthen site management and monitoring to ensure construction quality. The construction personnel shall continuously pay attention to the temperature and humidity changes of the concrete, make records and adjust the construction scheme according to the situation.
12. Safety protection
In summer, high temperature can easily cause personal safety problems such as heatstroke. Construction personnel need to do a good job of heatstroke prevention and cooling, such as wearing breathable, heatstroke prevention and cooling work clothes and hats, and replenishing water regularly.
Following the above precautions can ensure the quality and safety of concrete construction in summer.
