When Mother Nature blows in her absolute blizzard best, and the mercury goes flirting with the depths, precast concrete producers—especially those operating in Northern Latitudes—have only one thing to worry about:
Not to let the cold weather affect their precasting process.
For concrete to attain the required levels of compressive strength, it’s important that its curing is done the right way, under the right conditions. Cold temperatures can disrupt the “normal” procession of curing, causing the concrete to cure prematurely without allowing it to accomplish the standard levels of compressive strength.
In simpler words, cold weather may produce premature precast concrete products that is simply not strong enough to bear high tensile stresses. It is not ready for deployment.
Such situations are unwanted. Precast concrete producers cannot afford that to happen.
A concrete having low compressive strength than what is required (5000 psi is the minimum requirement), then needs to be discarded. It can cost businesses money and time. Not to mention their reputation.
Obviously, no one wants to work with a company that can’t deliver project on time.
So what can precast concrete producers do to make sure their cold weather precasting does not get affected by falling temperatures?
There are few precautions anyone in the business would be well advised to take…
- To start with, use heated water for precasting. But make sure the water is not heated to a temperature above 180 degrees Fahrenheit.
- Avoid using frozen aggregates for curing as these aggregates are likely to compromise the integrity of the process.
- If possible, add air-entraining admixture to your concrete mix. You can use air-entraining cement for the purpose.
- When hydrating your cement, cover it with polyethylene sheets. It would protect the heat, produced during hydration, from escaping. This retained heat can make a big difference by preventing concrete to freeze.
- Use windbreaks to protect concrete against cold winds.
- Constantly monitor concrete temperatures during curing and take steps to maintain it. Ideally, the curing temperature should be kept at above 55 degrees F. The lowest you can allow it to drop to is 35 degrees F, but then make sure you extend the curing time.
- Heat the forms before and after casting to protect the final product from cold weather effects.
Have you ever performed cold weather precasting? What steps did you take to keep it from getting cold feet?
Let us know in the comments section below, we would love to hear from you.
A BONUS read: Understanding Precast and Its Use