Curing Concrete Under Cold Conditions

There are many detrimental factors that can directly affect the curing concrete process of fresh concrete, but cold weather is one of the worse to deal with. This is because concrete that freezes when is fresh, or before it has cured to a strength that can resist the expansion associated with the freezing water, will suffer a permanent loss of strength. In other words, if fresh concrete is frozen during the first 24 hours, it can lose 50% or more of its strength and in some cases, that concrete is rendered nonconforming. This is a term used to describe concrete that does not meet the required strength specification based on a concrete mix design. And that is an undesirable outcome that not many General Contractors (GC) or Engineers would want to undergo because it basically means that the in-placed concrete must be removed and replaced, which could be resulting in massive delays in project completions and extra costs.

The American Concrete Institute under ACI 306 states that cold weather concreting is “a period when for more than three successive days the average daily air temperature drops below 40 degrees Fahrenheit and stays below 50 degrees Fahrenheit for more than one-half of any 24-hour period.”

This information is very useful because allows GCs & Engineers to reduce the margin of errors for concrete placement. Additionally, one of the most important factors in the ACI 306 guidance is the monitoring of the temperature factor. And because of this, many innovative solutions have emerged in the last decade to assist GCs, Engineers, and the concrete industry as a whole with the monitoring of temperature for fresh concrete.

Technology such as temperature meters, strain gauges, and nowadays IoT sensors are bringing peace of mind to GCs & Engineers today. This is because some of these technologies provide immediate access to actionable data, like IoT sensors, that can reduce uncertainty by accurately and continuously monitoring the in-place temperature of fresh concrete. Thus, IoT sensors allow GCs & Engineers to act proactively rather than reactively. This means that by having a better understanding of the in-place temperature of fresh concrete in rea-time, GCs 7 engineers can decide when and where to place cotton mats to protect the fresh concrete from freezing if needed.