To cure or not to cure…

Fall time is the only time that we should ever ask the question “should we cure our concrete or not?”

Curing is the process of ensuring young concrete has sufficient water to fully hydrate. The most susceptible area is the surface of concrete because it is dehydrating far faster due to moisture evaporating off the surface. During curing, moisture is either added to the surface to raise the surface humidity or a curing membrane is applied to the surface of the concrete to minimize moisture loss.

Although it is always a best practice to cure concrete, impending freezing conditions create a new problem. By curing concrete just before freezing temperatures the concrete is saturated with water. Left to freeze that water expands some 9%. Young concrete hasn’t reached the potential strength required to resist this expansion and if the concrete is fully saturated the air void structure may not be adequate to relieve the internal pressures of the expanding water.

This creates the problem, if I cure my concrete it has too much moisture for freezing temperatures and if I don’t cure my concrete the surface may not fully hydrate reducing the surface strength of the concrete.

The correct answer is to plan for this scenario. Reduce water cement ratios even further as winter approaches. Use accelerators and early strength mix designs to reduce the time to potential strength. Hoard and heat if necessary to ensure concrete reaches sufficient strength before the internal water is allowed to freeze.

As always, work with your concrete provider to ensure they are giving you the ideal concrete design to set you up for success.