Capillary suction model for characterizing salt scaling resistance of concrete containing GGBFS

This paper presents a rational method to characterize the freeze–thaw salt scaling performance of concrete based on capillary suction forces. The testing program included evaluating the concrete’s chemical chloride binding capacity, degree of hydration, total porosity, compressive strength, sorptivity and de-icer salt scaling resistance conducted at both, 28 days and 2 years. Mixtures consisted of paste and concrete containing 0–60% GGBFS as cement replacement, and a water-to-binder ratio of 0.31 or 0.38. The proposed capillary suction model was adapted to include the concrete’s chloride binding capacity, pore characteristics, and age. Results from the capillary suction model are found to correlate with experimentally measured ionic sorption coefficients. Results revealed that the capillary suction depth decreases with increasing percentages of GGBFS due to blocking of capillary pores as a result of the chemical interaction between the saline solution and the binder material. A freeze–thaw salt scaling resistance factor (F/T SSRF) is proposed which accounts for the concrete’s degree of hydration, sorptivity and tensile strength and is shown to correlate with the concrete’s cumulative mass loss tested in accordance with MTO LS-412. Accordingly, the salt scaling performance of concrete containing GGBFS is influenced by the combined effect of the concrete’s pore size distribution of the exposed surface, chloride binding capacity, degree of hydration, and tensile strength.