The construction calendar is predictable: Rain or snow delays in the winter. Heat concerns in the summer.
We’re building a job outside Dallas right now that has dealt with both. We had what seemed like monsoons for weeks and have finally gotten 2-3 weeks of good (but hot) weather.
When the temperature of fresh-mixed concrete hits 77 degrees, quality is at risk, depending on the site conditions. When you get above 90 degrees in ambient temperature, you’ll have difficulty producing quality concrete without some serious adjustment to the mix. We’ve made it our practice to pour starting at midnight in the summer, which alleviates some of the temperature issues, and also makes it easier for trucks to get on and off the road.
We also use total station laser screeds loaded with 3D models of the grades which reduces labor and increases accuracy. Beyond this, we’ve recently started using a special spray-on crack suppression fog, which reduces the speed of moisture loss resulting from wind and high temperatures. A few other things that have helped:
- Moisten subgrade, steel reinforcement, and formwork before pouring concrete.
- Use cool aggregates with water added (sparingly and within tolerance) to the concrete mix to reduce initial temperature.
- Use wet cures on slabs, even with a curing compound.
This particular pour was sizable, and being adaptable was key.