Warm to HOT weather concrete
Our climate is hard on concrete, especially in the spring and summer months. We have warm winds, high temperatures and low humidity. All of these things contribute to rapid loss of moisture to concrete.
That rapid loss of moisture causes rapid surface shrinking or plastic shrinkage, not to be confused with normal shrinkage cracking which can be controlled with “control” joints properly spaced. So, what can we do to keep that much needed water in the concrete to control plastic shrinkage cracking?
A few things to consider:
- Time of placement
- Watch the weather and schedule accordingly
- Pour in early cooler less windy hours
- Have a curing plan-Keep moisture in the concrete
- Cover with Plastic as soon as possible not to mar surface
- Use Curing Compound
- Wet the surface as soon as possible not to mar the surface, even flood if possible
- Cure for the first 4 to 7 days. This time is critical in controlling shrinkage issues
- Add Fiber to your concrete
- Dramatically reduces plastic shrinkage cracking ($7 per yard)
- Do not add extra water to the concrete
- It is very tempting to add water to the concrete, especially in hot weather. Our mixes are designed to give the cement particle the correct amount of water to meet required strengths at a 4 inch slump. Extra water will increase the shrinkage dramatically. We have admixtures that can give you a higher slump and better workability without increasing the water cement ratio. Ask our representative about adding a mid-range water reducer.
- Wetting the subgrade- A misnomer
- By wetting the subgrade the concrete will dry unevenly and cause the surface to crack even more, unless you are able to fog the surface. You want the concrete to set up as even top to bottom.
(An early morning pour time helps reduce temperatures across the board.)