Experimental identification of ice formation in small concrete pores

Freezing of water or salt solution in the concrete pores may be the cause for severe damage and significant reduction of service life. Although being one of the main research subjects during the past decades, a complete understanding of the deterioration mechanisms is still missing. This is probably because of a lack of understanding in the freezing of a liquid solution in the very small (some 10 nm) pores. In a series of experiments, the freezing process, its initiation, continuation and the resulting damage, was studied. Calorimetric, expansion and acoustic (ultrasonic pulse transit time, acoustic emission) methods were applied to monitor heat release, mechanical deformation and damage during a series of frost cycles. The results give an insight into supercooling, salt segregation, ice front penetration and thawing characteristics. Based on these data, a qualitative sequential damage model is proposed.