How to carry out necessary maintenance after concrete pouring?

The concrete shall be cured in time after pouring to avoid quality problems such as dry crack and insufficient strength of the concrete. What basic requirements should be met to do a good job of concrete maintenance?

 

1. The curing time of concrete shall comply with the following provisions:

1) The concrete prepared with Portland cement, ordinary portland cement or slag Portland cement shall not be less than 7d; When other types of cement are used, the curing time shall be determined according to the cement performance;

2) The concrete prepared with retarding admixture and large amount of mineral admixture shall not be less than 14d;

3) Impermeable concrete and concrete with strength grade C60 and above shall not be less than 14d;

4) The curing time of post cast strip concrete shall not be less than 14d;

5) The curing time of basement bottom wall and column and superstructure first floor wall and column should be appropriately increased;

6) The curing time of foundation mass concrete shall be determined according to the construction scheme.

 

2. Watering and curing shall meet the following requirements:

1) Watering maintenance should be carried out after the exposed surface of concrete is covered with gunny bags or straw curtains, or direct watering, water storage and other maintenance methods can be adopted; Watering curing shall ensure that the commercial concrete is wet;

2) When the low temperature of the day is lower than 5 ℃, watering shall not be used for curing.

 

3. Covering and curing shall meet the following requirements:

1) Covering and curing should be carried out by covering the exposed surface of concrete with plastic film, plastic film plus gunny bag and plastic film plus straw curtain;

2) The plastic film shall be close to the exposed surface of the concrete, and there shall be condensate in the plastic film;

3) The covering shall be tight, and the number of layers of the covering shall be determined according to the construction scheme.

 

4. Spraying curing agent shall meet the following requirements:

1) The exposed surface of concrete shall be sprayed with dense curing agent for curing;

2) The curing agent shall be evenly sprayed on the surface of structural members without missing spraying; The curing agent shall have reliable moisturizing effect, and the moisturizing effect can be tested;

3) The use method of curing agent shall comply with the relevant requirements of the product manual.

5. The exposed surface of foundation mass concrete shall be covered for curing

When the difference between the temperature within 40mm ~ 80mm of the concrete surface and the ambient temperature is less than 25 ℃, the covering curing can be ended. When the covering curing is completed but the curing time requirements have not been met, the watering curing method can be adopted until the curing is completed.

 

6. The curing method of column and wall concrete shall comply with the following provisions:

1) The curing time of concrete with formwork for the column and wall on the first floor of basement and superstructure shall not be less than 3D; After the completion of formwork curing, watering curing can be used to continue the curing. If necessary, covering curing or spraying curing agent can also be used to continue the curing;

2) The column and wall concrete in other parts can be cured by watering; If necessary, it can also be cured by covering or spraying curing agent.

 

7. Before the concrete strength reaches 1.2n/mm2, it is not allowed to step on it, stack load, install formwork and support.

 

8. The curing conditions of specimens cured under the same conditions shall be the same as those of solid structure parts, and measures shall be taken to keep them properly.

 

9. The construction site shall have the conditions for making concrete standard specimens, and a standard specimen curing room or curing box shall be set. The curing of standard specimens shall comply with the provisions of relevant current national standards.