1, reduce the hydration heat of cement?

Choose cement with low hydration heat, such as slag silicate cement, pozzolanic silicate cement or fly ash cement. ?

Try to choose well-graded aggregate, add a lot of additives such as fly ash, make full use of the late strength of concrete and reduce the amount of cement. If the cement dosage per cubic meter of concrete is reduced by 10kg, the hydration temperature of concrete will be reduced by 1℃. ?

Pre-embedded cooling water pipes in concrete can circulate cooling water to take away heat.

2, reduce the concrete into the mold temperature?

In summer, sand and gravel should avoid direct sunlight, and can be precooled by spraying cold water fog or cold air; Mixing concrete with low-temperature water or ice water; Sun exposure should also be avoided during transportation. ?

Ensure ventilation in the mold and accelerate heat dissipation in the mold. ?

Add retarding water reducer to avoid hydration heat concentration.

3. Strengthen temperature control during construction?

After concrete pouring, keep warm and moisturize for a long time, and slowly cool down to avoid excessive temperature and humidity gradient inside and outside the concrete. ?

Strengthen temperature measurement and control, timely adjust insulation and maintenance measures, and control the temperature difference between inside and outside of concrete below 25℃. ?

Arrange the construction sequence reasonably, so that the poured concrete will rise evenly and avoid excessive height difference.

Extended data:

Concrete curing methods are:

1. Natural curing: it is divided into sprinkler curing and plastic film spraying curing. The former covers concrete with straw curtains, etc. , and often sprinkle water to keep wet. The curing time depends on the type of cement, such as ordinary portland cement concrete not less than 7 days and nights.

The latter is suitable for high-rise structures and large-area concrete structures that are not easy to be cured by water spraying. The perchloroethylene resin plastic solution is sprayed on the concrete surface with a spray gun, and a film is formed on the concrete surface after the solution volatilizes, so that the concrete is isolated from the air, the water in the concrete is prevented from evaporating, and the normal hydration of cement is ensured. After maintenance, the film can age and fall off by itself.

Second, steam curing: put concrete members in a curing room filled with saturated steam or a mixture of steam and air to accelerate concrete hardening in a high temperature and high humidity environment.

The curing effect is related to the steam curing system, including: standing time before steam curing, heating and cooling speed, curing temperature, constant temperature curing time, relative humidity and so on. Steam curing room has pit type, vertical kiln type and tunnel kiln type.

Maintenance requirements

1. When concrete may come into contact with flowing water after form removal, effective heat preservation and moisture preservation measures should be taken before concrete comes into contact with flowing surface water or groundwater. The curing time should be extended (at least 14d) than the time specified in the above table, and the concrete strength should reach more than 75% of the design strength. After the maintenance, it shall be backfilled in time.

2. Concrete in direct contact with seawater or saline soil shall be guaranteed not to be eroded before its strength reaches the design strength grade. And as far as possible to postpone the age of direct contact between fresh concrete and seawater or saline soil, generally not less than 6 weeks.

3. When the day and night average temperature is lower than 5℃ or the minimum temperature is lower than -3℃, it shall be treated as winter construction. When the ambient temperature is lower than 5℃, it is forbidden to spray water on the concrete surface for curing. At this time, curing liquid can be sprayed on the concrete surface, and appropriate insulation measures can be taken.

4. For concrete structures or members mixed with a large amount of fly ash in severely corrosive environment, after the specified curing period, if conditions permit, the wet curing time should be further appropriately extended on the basis of the above-mentioned curing measures.

5. During the curing period of concrete, the temperature of representative structures should be monitored, the core temperature and surface temperature, environmental temperature, relative humidity, wind speed and other parameters of concrete should be measured regularly, and the curing system should be adjusted in time according to the changes of concrete temperature and environmental parameters, so as to strictly control the temperature difference inside and outside the concrete to meet the requirements.

6, during the period of concrete curing, concrete curing process should be recorded in detail, and establish a strict post responsibility system.

Reference: Baidu Encyclopedia-Concrete Maintenance