Modeling of Water Transport in Highly Saturated Concrete with Wet Surface During Freeze/thaw

Abstract

Wet frost exposure is a usual environmental condition for cement-based materials (CBM) during winter and the most common way of frost testing in the lab. In this study, the temperature gradient, pressure gradient, and the liquid flow under wet frost exposure are modeled for highly saturated CBM with different amount of entrained air. It is found that the water uptake happens at the melting stage, and for non-air-entrained CBM, the hydraulic pumping effect is dominant and will suck the water from wet surface. While for air-entrained CBM, the cryosuction pressure is the main driving force of the inward flow. The results are compared with experimental data from rapid freeze/thaw testing of various types of concrete in water, showing a satisfactory agreement. Sensitivity analysis also indicates that the hydraulic induced flow depends on the amount of entrained air, while the cryosuction induced flow mainly relies on the permeability and temperature gradient.