Impact of sample saturation on the detected porosity of hardened concrete using low temperature calorimetry

Abstract

The present work studied the impact of sample saturation on the analysis of pore volume and pore size distribution by low temperature (micro-)calorimetry. The theoretical background was examined, which emphasizes that the freezing/melting temperature of water/ice confined in non-fully saturated pores is further depressed compared with that when the pores are fully saturated. The study of the experimental data on hardened concrete samples showed that for a same concrete mix, the total pore volume detected from the capillary saturated samples was always lower than that of the vacuum saturated samples and a higher proportion of pores with small radii were found in the capillary saturated samples. In addition, the observed hysteresis between the freezing and melting curves of ice content of the capillary saturated samples was more pronounced than that of the vacuum saturated samples. The major reason for the observed phenomena could be related to that capillary saturation cannot fully saturate the pores under study.