3. Concreting in hot weather

3.1 Effects on workability of fresh concrete

Any rise in temperature encourages the evaporation of free water from fresh concrete, which naturally lowers its plasticity. This drop in plasticity is measured by consistency tests (slump or spread).

For concrete with a relatively low effective water content, evaporation may restrict the development of hydration reactions. In the latter case, the possibility of slightly increasing the water dosage or adding a water-reducing plasticizer to the mix can be tested beforehand,...