What problems can occur due to high temperature, high wind and low humidity?
The National Ready Mixed Concrete Association (NRMCA) defines hot weather concreting as anytime during high temperatures in which special precautions need to be taken to ensure proper handling, placing, finishing and curing concrete. During the summer months you will most generally experience problems that require precautions being taken for hot weather concreting, but the associated climatic factors of high winds and dry air can occur at any time. These conditions often produce a rapid rate of evaporation of moisture from the surface of the concrete and an accelerated set time among other problems.
Hot weather is a major factor to consider when planning a concrete project. Too often it is assumed that not much can be done to combat hot and dry conditions. Many times the addition of large amounts of water is used to fight off rapid set times or to ease the placing and finishing process. These assumptions and practices often times prove to be detrimental to the concrete.
Problems that can occur due to high temperature, high wind and low humidity are:
- Increase slump loss, making concrete more difficult to place and finish.
- Accelerated set time, decreasing the amount of finish time.
- Increasing the potential for plastic and drying shrinkage cracking.
- Decreased air content.
- Reduced strength if water is added to offset slump loss.
- Thermal cracking may result from a rapid drop in concrete temperature when placed on a hot day followed by a cool night.