Examining the Influence of the Degree of Saturation on Length Change and Freeze-Thaw Damage

Concrete can be susceptible to damage when it is exposed to freezing and thawing (FT). It has been shown that the potential for damage depends on the degree of saturation (DOS). When concrete has a low DOS, it does not show damage during an FT cycle. However, when the DOS exceeds a specific value (critical DOS), the concrete shows damage resulting from the FT cycle. The objective of this article is to measure the length change for cementitious specimens with varying DOS. It is hypothesized that these length change measurements can be used to quantify the critical DOS (DOS_CR) for cementitious paste specimens exposed to FT. Specimens with a low DOS show a nearly linear length change response throughout the entire range of temperatures tested. Specimens with a high DOS (i.e., DOS > DOS_CR) show a notable change in length at temperatures associated with the freezing and thawing points of water. The strain reduction associated with the melting of ice is calculated by normalizing the length reduction during the melting of ice with the initial length of the specimen. A DOS_CR can be obtained by fitting a line between the strain reduction and the DOS. Another parameter known as residual strain can be used to quantify damage. Residual strain is defined as strain that exists in the specimen after an FT cycle. Only specimens with a high DOS (DOS > DOS_CR) show residual strain. The approach presented in this paper provides an alternative method that can complement other existing tests to determine the DOS_CR for use in the sorption-based model.