Determining the freeze-thaw performance of mortar samples using length change measurements during freezing

Abstract

The Freeze-thaw (FT) performance of cementitious materials is dependent on the degree of saturation (DOS). It has been proposed that FT damage can occur during freezing when the DOS is greater than a critical DOS (DOSCR). In a previous study, a systematic methodology has been developed to determine the DOSCR of cement paste samples using high precision length change measurements during freezing and thawing in a thermomechanical analyzer (TMA). This paper explores the extension of the established methodology to mortar samples to determine their DOSCR. The influence of the drying temperature and the characteristics of FT cycle (temperature range, heating and cooling rate) were investigated to determine their impact on the FT performance of the mortar samples. The mortar samples tested in this study were obtained by making concrete and then wet sieving the concrete to obtain mortar. Mixtures with different air void content and air void quality were prepared in this study in order to determine the impact of air void content and air void quality on the FT performance of the samples using TMA testing. The results confirm that length change measurements can be used to determine DOSCR of mortar. A correlation considering the probability of failure was found to exist between the air void quality and the FT performance of mortar samples. The approach presented in this paper provides an alternative method that can complement other existing tests to determine the DOSCR for use in the sorption-based model.