Accelerated Laboratory Test Suggests the Importance of Film Integrity of Sealers on the Protection of Concrete from Deicer Scaling

This work reports the laboratory performance of five film-forming sealers that protect concrete from deicer scaling (15 freeze-thaw and wet-dry cycles in diluted NaCl or ${\mathrm{MgCl}}_2$ solution). Regardless of the presence or type of sealer, no apparent scaling occurred on the concretes exposed to 2.54% by weight ${\mathrm{MgCl}}_2$ solution, but there was significant reduction in their splitting tensile strength (up to 55% for the nontreated concrete). The best-performing sealer in mitigating this risk of strength reduction was the methyl methacrylate (MMA) polymer. For the concrete exposed to 3% by weight NaCl solution, the scaling resistance and ability of strength preservation were significantly improved by the presence of a sealer. Regardless of the sealer type, the initial rate of water absorption of surface-treated concretes was greatly reduced by the sealer by at least 68%. The water absorption behavior of the sealer-treated concrete showed a strong correlation with mass loss caused by salt scaling. The concrete samples treated by the epoxy sealer featured the lowest initial gas permeability coefficient and the lowest water absorption rates, attributable to the formation of a highly impermeable and hydrophobic surface layer. The surface scanning electron microscope (SEM) micrographs of sealer-treated concrete reveal the importance of the integrity of hardened sealer film in upholding the concrete’s resistance to the transport of waterborne and gaseous phases and the attack by chloride deicers and freeze-thaw cycles.