Combinations of chemical admixtures allow portland cement concrete to cure when its internal temperature is below freezing. Therefore, one can extend the concrete construction and repair season by adding off-the-shelf chemical admixture “suites” that, in combination, lower the initial freezing-point temperature of the concrete mixture. This allows a lower temperature range at which concrete can be placed without the need for artificial heating, thus saving time, money and energy. Admixture suites lower the initial freezing-point temperature and promote early strength gain as the concrete cures. In place, strength is estimated using the maturity method. Laboratory and field tests show improved freeze-thaw durability with antifreeze concrete mixtures. Cold Weather Admixture Systems (CWAS or “antifreeze concrete”) concrete, which allows users to mix, place, finish and cure concrete exposed to near- and sub-freezing air temperatures, was developed by engineers at the US Army Engineer Research and Development Center’s (ERDC) Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, NH.
Antifreeze concrete is
- structurally comparable to conventional concrete,
- resistant to freezing and thawing,
- predictable to formulate and test for quality,
- cost-competitive with conventional concrete and
- capable of preventing frost damage during cure.
Two Decades of Experience
CWAS technology has been used in a dozen full-scale field demonstrations from New Hampshire to Alaska. In Concord, New Hampshire, a 6 in. (152 mm) thick slab using antifreeze concrete was placed when the air temperature was −4°F (−20°C) and rose to a high to +14°F (−10°C). No external heating was used as the slab was covered only with a vapor retarder. The concrete continued to cure even as the overnight temperature dropped to −4°F (−20°C).
CRREL has developed the tools and methods to design, mix, place and cure antifreeze concrete in conditions where normal concrete suffers irreparable damage.
Antifreeze concrete mixtures:
- Use admixture dosages within manufacturer-published guidelines
- Use commercially available chemical admixtures that either meet ASTM standards or are widely accepted within the industry
- Have an initial set time at 25°F (−4°C) that is not longer than regular concrete at 40°F (+5°C)
- Ensure “workable” concrete, allowing up to a 45-minute transit time to a job site and at least 20 to 30 minutes of working time for emplacement and finishing; additions, adjustments and compliance testing may also be done at the job site prior to placement
- Protect fresh concrete from freezing down to an internal concrete temperature of at least 23°F (−5°C)
- Develop early-age compressive strength when cured at 25°F (−4°C) as well as, or better, than regular concrete cured at 40°F (+5°C)
- Provide additional protection below the design temperature of 23°F (−5°C)
- Do not adversely affect long-term durability of concrete
- Are compatible with steel reinforcement (i.e., non-corrosive)
- Do not promote alkali-silica reactions
- Produce concrete able to accept air entrainment
- Do not adversely affect finishability
- Do not present significant problems with equipment and cleanup in cold weather
The Latest Research
The latest CRREL research provides guidance to optimize the admixture dosage rates in antifreeze concrete formulations based on job-site-specific forecasted weather conditions. Research has presented recommendations on the minimum exposure conditions for antifreeze concrete based on varying the admixture dosage. A one-dimensional thermal model is in development to right-size the admixture dosage to design the concrete mixture to the job site conditions.
CRREL offers guidance, research, and consulting services on the development of suitable admixtures based on the specific requirements of each project, including temperature ranges, structural design criteria and the concrete mixture design. More information may be found via the links to publications below.
Documentation, Training, and Support
- ERDC/CRREL TR-10-6 Cold Weather Admixture Systems Demonstration at Fort Wainwright, Alaska, Barna, Korhonen, Seman, 2010.
- ERDC/CRREL TR-06-8 Extending the Season for Concrete Construction and Repair—Phase II, Defining Engineering Parameters, Korhonen, 2006.
- ERDC/CRREL TR-05-9 Placing Antifreeze Concrete at Grand Forks Air Force Base, Korhonen, Seman, 2005.
- ERDC/CRREL TR-04-2 Extending the Season for Concrete Construction and Repair—Phase I, Establishing the Technology, Korhonen, Seman, Barna 2004.
- ERDC/CRREL TR-02-7 Off-the-Shelf Antifreeze Admixtures, Korhonen, 2002.
- ERDC-CRREL TR-01-2 Off-the-Shelf Antifreeze Admixture for Concrete, Korhonen, Orchino, 2001.
- CRREL SR-90-32 Antifreeze Admixtures for Cold Regions Concreting, Korhonen, 1990.
Force Projection and Sustainment Branch (CEERD-RRH)
US Army Engineer Research and Development Center, Cold Regions Research and Engineering Laboratory