Summer is definitely upon us. During the last few weeks, we have seen unseasonably high temperatures across the United States. This combination of conditions (high temperature and low humidity) can make placing concrete a challenge. When temperatures rise above 80 degrees, fast setting, lower strengths and cracking are all more likely. Concrete can be placed as long as precautions are taken to keep it from drying while still fresh. Following general precautions will help in performing a successful concreting project in hot weather conditions and mitigate the negative impacts of hot weather.
The following are best practices for hot-weather concreting:
- High temperatures and low humidity increase the frequency of cracking. To eliminate this problem, keep the surface wet to prevent drying, shrinking and cracking. Fog spray the area during placing and finishing to cool contact surfaces and the surrounding air, while also increasing relative humidity. This slows the concrete’s temperature rise and reduces the evaporation rate of mix water after placement.
- Concrete hardens faster in hot weather. Reduce concrete temperatures by using cool water or substituting ice for some of the mixing water to achieve cooler concrete.
- Plan ahead. Have all forms, equipment and workers ready to handle concrete, especially during the first delivery of the day to avoid delays.
- Use materials and mix proportions that have a good record in hot weather conditions. Use a concrete consistency that allows rapid placement and consolidation.
- Reduce the time of transport, placing and finishing as much as possible.
- When the weather is extremely hot, restrict placement to early morning, evening, or nighttime hours.
Let us know how we can use our experience to help you ensure a successful project during hot-weather conditions.