Construction cycle. Stop and restart of concrete pouring

To study formwork rotation, start from a given point, such as the beginning of a wall formwork installation, and follow the steps below:

• installation of a bench and mannequins ;

• reinforcement placement ;

• closing the formwork by installing the second panel;

• concreting ;

• start of demoulding ;

• end of demoulding ;

This allows the formwork to be set up again in a new location, thus completing the entire operation.

This operation can last a day, which is the usual case, with the quantity of sail to be completed defined in relation to the schedule and the team set up to ensure that it is neither under- nor over-employed.

There is then one rotation per day. However, for other elements such as flights of stairs, for which steamed concrete is used, it is possible to produce two flights per day in the same mold. In contrast, for a prefabricated cable-stressed beam, formwork, reinforcement and concreting will take more than a day to set up, and the rotation will take several days, as the concrete must be allowed to reach a certain strength before the prestressing can be tensioned.

For concrete walls, a daily quantity has been determined. The cycle therefore comprises a single rotation per day. At the end of the formwork, it will be necessary to stop concreting so that it can be resumed at the next rotation. To do this, steel will protrude from the "recovery formwork", usually made of expanded metal. This concreting stop must be carefully considered, as it is essential to the quality of the work to be obtained: it can affect the stability of the wall. The consequences of the choice of concreting stop must therefore be carefully considered. This depends on the characteristics of the work to be obtained, the equipment used by the contractor, the technical constraints to be met by the concrete, and the obligations defined in the CCTP.