Durability Design of Concrete Structures

3Freeze–Thaw Damage

This chapter treats concrete damage caused by the freeze–thaw (FT) actions in natural environments. Normally, the hardened structural concretes are rather resistant to low temperature, so concretes can be used in most atmospheric temperature ranges, even in some cryo‐storage facilities, such as liquid gas storage tanks. However, this resistance can be compromised by the presence of water, especially as the concrete pores are saturated by water. The external freezing and the subsequent thawing can generate pore pressure associated with the water phase change in pores that high enough to cause damage in the solid matrix of concrete. The damage extent can be further enhanced by the presence of salts on the concrete surface, resulting in significant surface scaling of RC elements. This chapter introduces first the phenomena of FT damage of RC elements and then presents the mechanisms of concrete damage due to pore phase change under freezing, together with the influential factors for the damage process. Then, two models are presented on the basis of the state‐of‐the‐art knowledge for engineering use. Finally, the basis of design is brought forth for the RC elements exposed to FT actions.

3.1 Phenomena and Observations

Structural concrete exposed to natural environments is susceptible to frost action in cold regions.¹ Normally, structural concretes are rather resistant to natural low temperature as long as concrete hardening is properly achieved. That is why concrete ...