Breaking the Freeze Barrier

ASTM International has just released a new standard, Standard Specification for Cold-Weather Admixture Systems, that provides specifications for chemical admixtures that help protect concrete and maintain productivity, even when the temperature of concrete is expected to fall as low as 23 deg F shortly after mixing. This article reviews the work leading up to the adoption of this specification, and discusses the main features of the specification and their impacts on concrete and the concrete industry. A synopsis of a recent project that used a cold weather admixture system (CWAS) comprising a combination of commercially-available chemical admixtures is presented. The new standard, based in part on critical setting and strength performance criteria at 23 deg F, provides assurance that qualified chemical admixture systems are effective in producing workable and durable concrete mixtures. This standard should allow greater flexibility for placing and curing concrete in below-freezing conditions and boost the popularity of CWAS.