Plastic concrete with high fluidity is often encountered on construction sites. The amount of pouring is not large, the concrete strength grade and cement strength grade are low, the cement consumption is small, the early hydration degree is not high, the drying shrinkage is not high, and there is no autogenous shrinkage.
In this case, this plastic concrete may need to be watered and cured within 12 hours after pouring, but for modern concrete, too much watering and curing will cause concrete cracking, which will have a negative impact on the potential quality.
Extended data
When pouring concrete in winter, its freezing critical strength shall meet the following requirements:
1, ordinary concrete constructed by heat storage method, greenhouse method and heating method. When portland cement or ordinary portland cement is used for configuration, its freezing critical strength should not be less than 30% of the design concrete strength grade value; When slag portland cement, fly ash portland cement, pozzolanic portland cement and composite portland cement are used, they should not be less than 40% of the design concrete strength grade value;
2. When the lowest outdoor temperature is not lower than-15℃, the freezing critical strength of concrete constructed by comprehensive heat storage method and negative temperature curing method should not be less than 4.0MPa；; When the lowest outdoor temperature is not lower than -30℃, the critical strength of concrete constructed by negative temperature curing method should not be less than 5.0MPa；;
3. For concrete with strength grade equal to or higher than C50, it should not be less than 30% of the design concrete strength grade value;
4. For concrete with impermeability requirements, it should not be less than 50% of the design concrete strength grade value;
5. For concrete with frost resistance and durability requirements, it should not be less than 70% of the design concrete strength grade value;
6. When the early strength agent is mixed into the concrete constructed by greenhouse method, the critical strength can be obtained by comprehensive heat storage method.
7. When the construction needs to improve the strength grade of concrete, the critical strength of freezing should be determined according to the improved strength grade.