The Effects of pore structure on freezing and thawing deterioration

Manufacturing of concrete resistant to freezing and thawing requires an in de understanding of the mechanisms triggering deterioration. Despite numerous attempts, a definitive and fully explanatory model has yet to be formulated. This paper presents part of study which analyzes influence of pore structure of cement-based matrix on the frost durability of Ordinary Portland Cement mortar is analysed. An empirical investigation was carried out on five air-entrained and one non-air- entrained mortar (with water-to-binder (W/B) ratio 0.4) subjected up to 732 freezing/thawing (Frr) cycles. Various concentrations of air-entraining admixture were used to differentiate the pore-structure of mortar. The examination of the microstructure and composition of the cement paste was performed by means of Scanning Electron Microscope (SEM) and Mercury Intrusion Porosimetry (MIP). Presented results demonstrate the magnitude of alterations to pore configuration due to pure freezing/thawing and its effect on the mechanical characteristics (compressive/flexural strength). Finally, on the grounds of apparent transformation. a generic pore size distribution of frost resistant cement-matrix is proposed.