Expected life of Silane water repellant treatments on bridge decks (FHWA-OK-12-08)

Abstract

This report covers techniques used to evaluate the presence of silane coatings on bridge decks in the lab and in the field. After these techniques are established they are then used to determine the effective service life of silane and the ability to reapply silane to the surface of the concrete. The following techniques are investigated in this study: surface resistivity, German water permeability, contact angle measurements, selective dyes, and a XRF Microscope. The most promising techniques were used to evaluate the field performance that had been in service between 5 and 28 years. The work showed that the silane coatings lasted at least 6 years and that after 9 years about 30% of the silane coatings were no longer effective. Lab based reapplication efforts suggest that it is possible to reapply silane; however, additional efforts are needed above what is typically done for concrete less than a year old.