The main things to consider during hot weather concreting are:
a) minimising the early loss of water from concrete;
b) preventing early setting through too-rapid drying.
If these problems are not anticipated, there may be:
• Strength reduction
• Shrinkage cracks
• Crazing or cracking
• Finishing difficulties.
In very hot conditions the following steps should be undertaken:
• Thoroughly moisten the sub-grade, reinforcing steel and wooden forms before placing the concrete.
• Avoid delay in placing the concrete. Have sufficient labour and equipment on hand to perform the placing
• During placement in very hot weather, try to shade the concrete from direct sunlight.
• Use wet coverings until final finishing can be completed.
• If a float finish is required, uncover only a small section immediately ahead of the finishers.
Cover again at once after final finish.
• Keep covers wet.
• Start curing as soon as possible, using a method that will keep temperature of the covered concrete at or
about a constant 21ºC.
• Discharge concrete from waiting trucks as soon as possible. Heat builds up in mixer drums if this is not done.
• In very hot weather shade concrete from sunlight or use wet coverings until finishing can be completed.