LAUSR

Abstract Prior work to characterize the hydration products in a cement paste prepared with a sodium nitrite-based antifreeze admixture that effectively promoted hydration at subfreezing temperatures did not reveal anything unusual in the chemical composition, suggesting that the nature of the antifreeze action was physical (i.e., preventing the freezing of water) rather than chemical. To confirm this, the time domain reflectometry (TDR) technique was used to track the evolution of the volumetric water content together with hydrated and unhydrated cement in control and antifreeze-added cement pastes that were cured at −10 °C for three weeks. The results show clear evidence of the existence of liquid water in the antifreeze treated samples, and that the amount of water and unreacted cement decrease with time, confirming the presence of ongoing hydration. Modelling results also suggest that the liquid water available for the hydration reactions is in the form of adsorbed water at subfreezing temperatures and as free water above freezing.