Original post by Ted Cushman, Senior Editor. Published online in The Journal of Light Construction, January 2016
Slabs and basements in freezing weather? Let’s talk about it.
On a 9°F day in December 2014, Connecticut concrete contractor Dennis Purinton was pouring a slab on grade. It was the kind of work Purinton had done often enough before. But this time, he had a small audience of experts and supplier representatives from around the concrete industry—some of them, like Purinton himself, members of the consensus committee that creates ACI 306, the American Concrete Institute’s Guide to Cold Weather Concrete.
Purinton’s goal was to demonstrate for his audience—and, by extension, for the full ACI 306 committee—something that he already knew from decades of experience working in New England conditions: “Concrete performs very, very well in cold weather.”
ACI 306 isn’t a code, or even a standard. It’s an advisory document that helps professionals in the concrete industry understand how to accomplish their goals when the outside temperature drops toward freezing. Committee insiders say the 2010 edition of the document, which incorporates advances in concrete technology and practice that have evolved since the previous update, in 1988, was a significant upgrade. Recommendations from the 1988 version remain in the book to provide grounding in the basics. But current practice continues to advance, and even the 2010 document doesn’t incorporate all of the latest industry research. So the ACI 306 committee is working on yet another update. After a formal ACI review process, a new edition is likely to be released in 2016 or 2017.
COLD-WEATHER BASEMENT WALLS
Dennis Purinton’s work with cold-weather slab placement follows in the footsteps of an earlier program carried out by the Concrete Foundations Association (CFA), a trade group with headquarters in Mount Vernon, Iowa (cfawalls.org). From 2001 to 2004, CFA contractors studied the practical limits of concrete basement-wall placement in winter. The association developed dozens of concrete mixes using different cements and admixtures, and tested the concrete’s performance in cold conditions.