Concrete Foundation Walls - Structural Deterioration And Damage

Problem: Cracks and spalling from poor construction practices - 5.

Cause: Inadequate hot weather precautions - above 85°F (30°C).

Excessively rapid drying of concrete in hot weather will reduce the strength of the concrete. Concrete, in hot weather, may flash-set during placement.

Solutions: Minimize moisture loss from the concrete.

• Dampen the sub-grade and formwork. before you pour the concrete.
• Have the supplier provide a suitable mix for hot weather placement. Reducing concrete temperatures and using set retarders may prove advantageous. Avoid delays in transportation to, and placement on, the site (discharge within an hour of mixing in hot weather). Place concrete early in the morning or in the evening. Protect concrete from rapid drying caused by direct sun and winds. Apply fog spray immediately after placement and before finishing. Cover with opaque polyethylene between finishing stages.
• Suppliers can calculate the correct amount of water to be added to the mix, based on the rate of water loss as influenced by temperature, relative humidity, wind speed and concrete temperature.