Quality of concrete

Although the concrete formulation study phase in the laboratory must result in a material that satisfies all the specifications, this verification must also take into account the concrete constraints of the production plant (mixing efficiency, production time for each batch...) and those induced by delivery times, unavoidable waiting times on site and ambient conditions during casting.

The "robust" compositions, defined in the laboratory, are then tested in situ as part of initial trials, which in fact turn out to be feasibility tests:

• precisely match the composition to the actual means of manufacture and transport;

• take account of scale effects;

• correct the volume yield if necessary.

Once these operations have been carried out, the physical (consistency, air content, actual density, maturity, etc.) and mechanical (breaking strengths at sensitive times) characteristics can be specified. It may also be advisable to estimate the influence of dosage variations (within the tolerances defined above) on the development of mechanical characteristics, as these variations may disrupt the setting of the material and therefore its final characteristics.

In the current production phase, the control plan provides the necessary guarantees for the proper behavior of hardened concrete, based on a whole series of control operations covering the entire manufacturing and implementation chain:

• production control in ready-mix concrete plants or prefabrication plants ;

• manufacturing and transport process control ;

• checks before, during and after concreting;

• control of hardened concrete ;

• checking the appearance of facings.