The Performance of Crystalline Hydrophobic in Wet Concrete Protection

Reflecting the need to protect concrete structures from deicing salt and freeze-thaw loading, the study introduced in this paper springs from the uncertainty that exists in the benefit of in situ performance of isobutyl silane as a protection material. It is likely that environmental loading and internal moisture at the time of application are the main contributory factors for underperformance. This paper deals with alternative materials—a high-solids silane and an aqueous crystallization solution—operating by a moisture-driven crystallization mechanism rather than demanding a dry application regime. The results demonstrated similar substantial performance reduction of both materials at 0–5% moisture on medium-strength (C25: 25  N/mm2) and high-strength (C40: 40  N/mm2) concrete. There is greater take-up of protection materials by C25 concrete than by C40 concrete, together with greater chloride reduction, indicating that the level of achieved dosing is a significant factor. The similarity between the absorption of water and of the two protection materials relative to initial water content points to a possible basis for predicting achievable dosing of surface-applied protection materials. The crystallization material achieved greater application volume and chloride reduction than the silane material.