In summer, when the temperature is high and the drying is fast, the setting speed and strength of newly poured concrete may be accelerated, so special attention should be paid when pouring, trimming and curing concrete.

1, concrete mixing and transportation:

When mixing concrete, measures should be taken to control the temperature rise of concrete and control the additional water at one time to reduce slump loss and plastic shrinkage cracking. The following measures can be taken during concrete mixing and transportation.

(1) Use water reducing agent or fly ash to replace part of cement, reduce cement consumption, and increase aggregate particle size when concrete pouring conditions permit.

⑵ Sprinkle water on the aggregate pile to reduce the temperature of concrete aggregate; If possible, it is best to spray groundwater or well water to cool down.

(3) In hot season or mass concrete construction, some mixing water can be replaced by cold water or ice cubes.

(4) Abroad, it is advocated to paint the outside of the drum of the mixer white in summer, so that the absorption of solar radiation heat energy by the drum is obviously reduced. In summer, taking the transportation distance of 1h as an example, the concrete temperature in the white mixing drum is at least 1℃ lower than that in the general red mixing drum.

5] If possible, a plan should be made to avoid pouring concrete at the highest daily temperature. Under dry conditions, the influence of wind and temperature on pouring concrete at night is relatively small. At the same time, concrete can be finally set near sunrise, when the relative humidity is the highest, so the possibility of early drying and cracking is the least.

[6] Except adding mixing water according to the design quantity to adjust the specified slump, try not to add mixing water to the construction site.

2, concrete pouring and finishing

When pouring concrete in hot climate, it is required to equip enough manpower, equipment and machinery to deal with emergencies in time.

(1) Detect the temperature of concrete transported to the construction site, and ask the mixing station to adjust it if necessary.

⑵ During concrete construction in summer, vibrating equipment is easily damaged by heat, so standby vibrators should be prepared.

(3) All kinds of tools, equipment and materials in contact with concrete, such as pouring chutes, conveyors, pump pipes, concrete pouring conduits, steel bars, trolleys, etc., should not be directly exposed to the sun, and water should be sprinkled to cool down when necessary.

(4) Concrete pouring in summer should be carefully planned, and concrete pouring should be continuous and rapid. If there is bleeding on the concrete surface, it should be repaired in time.

5] According to the specific climatic conditions, when it is found that concrete has the possibility of plastic shrinkage and cracking, measures should be taken (such as spraying curing agent, etc. ) to reduce the evaporation rate of concrete surface.

3. Maintenance of concrete

If the concrete poured in summer is not properly maintained, it will reduce the strength of concrete or cause plastic shrinkage cracks on the surface, so it is necessary to strengthen the maintenance of concrete.

(1) curing shall be carried out immediately after the completion of operation or initial setting of concrete.

⑵ Sprinkler curing method should be adopted for continuous curing. Within 1 ~ 2 days after concrete pouring, the concrete shall be kept fully wet and the curing age specified by national standards shall be strictly observed.

(3) When the formwork is dismantled after the specified curing time is completed, it is best to provide a wet covering layer for its surface.

(4) After the secondary lining concrete is demoulded, it must be watered and cured, and the watering and curing time shall not be less than 14 days. Strengthen the maintenance of hole section, and the maintenance shall be subject to concrete wetting.

Eight, other safety precautions

1, widely carry out publicity and education work, and it is strictly forbidden to bathe in the river without permission.

2, canteen food must have a health certificate, cooking personnel should have a health certificate, it is forbidden to buy corrosive food, to prevent food poisoning.

3, arrange specialized personnel to clean, keep the construction site and office, living place clean.

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