Cold weather does not stop concrete work. It changes how you do it.
Concrete cures through hydration, a chemical reaction that slows as temperatures fall and effectively stops near freezing. Pour into frozen ground and the water in the mix freezes before the cement has bonded, leaving a slab that looks fine and fails within a few years.
So we thaw the subgrade first, use accelerating admixtures and a higher cement content, and cover every pour with insulated blankets to hold the heat the reaction generates.
We log the slab temperature for the first 72 hours and only strike the forms once the cylinder breaks confirm strength. Winter pours cost a little more per cubic yard, but they keep a project on programme through an Illinois January — and a properly cured winter slab is every bit as strong as a summer one.
