Concrete sets much slower when it’s cold, especially when the temperature dips below 50 degrees. There are many times when a concrete project can’t wait for milder temperatures and, for those working with concrete during the cold weather months, proper execution of cold weather concreting is essential. Cold weather concreting takes place when the concrete is placed somewhere that the temperature may fall below 40 degrees F. Specific steps need to be taken to protect against early freezing and thermal cracking. If executed properly, low temperature concrete that has been protected from cold weather exposure and correctly cured will result in a much durable concrete with a higher ultimate strength. Accelerating admixture and hot water are the recommended combination to allow concrete to set up in a reasonable time, while keeping internal temperatures on track.
Accelerating chemicals reduce the initial set time of concrete and will greatly reduce the time required for finishing activities. With the proper use of accelerators, concrete can be put into service within hours of placement if needed.
We can recommend a dosage rate based on your project needs and set time requirements. Contact us with more information about your project.
The benefits of using hot water:
In cold weather, concrete mixing temperature can be controlled using hot water when necessary so that when the concrete is placed, its temperature is not too low for the conditions and the application. Hot water can be added at the plant during batching. According to the American Concrete Institute (ACI), the more massive the concrete section being poured, the slower it loses heat; therefore, lower minimum placement temperatures are recommended as concrete sections become larger. In a section of 12” or less the minimum recommended concrete temperature is 55 F (13C). For air temperatures above 30 F (-1 C), it is recommended that the concrete temperature be a minimum of 60 F (16 C).
At Silver Strike Concrete, we utilize industrial water heaters that can bring batch water temperatures up to 160 degrees F to warm all of the ingredients in the concrete mix. Concrete at a temperature of 70 degrees F has an approximate set time of 5 hours, half the set time of concrete at 50 degrees F.
Hot water allows for increased concrete temperature, which equals reduced initial set times. This also maintains concrete temperature at or above the recommended placement temperature while reducing the risk of early age freezing.
The benefits of using accelerating admixture:
“Accelerator is added to concrete to speed up hydration (the process by which cement and water react to harden). Depending on temperature, set times can be reduced by several hours, or even cut in half. There are two main points to remember when deciding to work with accelerator: 1) it is the concrete temperature, and not the ambient temperature that dictates the effectiveness of accelerator and 2) accelerator tends to rapidly lose effectiveness under a concrete temp of 50 degrees F. Thus, adding hot water in tandem to accelerator admixture really produces a winning combination that protects concrete […]”
We use AC 534 as liquid additive for ready mix concrete to reduce concrete set times and increase early age strengths. It can be used in a variety of dosages for different temperatures and set times allowing contractors to predict the optimal time of surface finishing and form removal which reduces initial set time and reduces labor costs. It also reduces or eliminates the need for heating and protecting time in cold weather while increasing early strength.
Combining hot water and accelerating admixture:
Concrete needs to gain strength of 500 psi in order to be able to handle the cold on its own. Using hot water and accelerator, we are able to change the mix to set more quickly while protecting the concrete from the cold until it can reach that 500 psi strength.
The combination of the two allows workers to place concrete in freezing temperatures and have it reach the required strength for the safe removal of forms in a timely manner. Because we limit rapid temperature changes, the concrete has an opportunity to develop sufficient strength to withstand thermal stresses and avoids diminished strength, durability and cracking.
Silver Strike Concrete believes in providing the highest quality concrete to our customer and we do this by coupling the best quality products available with our 20+ years of expertise in the business.
Are you planning a project that includes a cold weather concrete pour? Do you need a manufacturer you can trust with the process? We can help. Contact us today: (775) 900-2939