Degradation of concrete in cold weather conditions Introduction

Concrete and cement composites are forgiving materials and the expectation of a long service life at an extreme ambient temperature is not unreasonable. Extreme temperatures in hot and cold climates do not in themselves present a threat because dry concrete has an acceptably low coefficient of thermal expansion and moderate movements can be taken into consideration in design. A durability threat does, however, exist when moist concrete in cold climates is exposed to repeated temperature cycles that cause freezing and thawing of pore water. The number of cycles is more significant than the absolute lowest temperature. Expansion of wet concrete can be considerable and stresses induced within the concrete may be unacceptable.

This chapter explores the fundamental issues involved in producing freeze- thaw resistant concrete. The phenomenon is reviewed, factors of influence are examined and the particular effects of deicing agents are considered. Air entrainment has a role to play and this is considered in detail. Test methods and related specification issues, current and future, are examined. The prospect of moving to performance-based specifications and design for durability is also addressed.