National Concrete Pavement Technology Center

Project description

The main objective of this research was to compare the performance of five bridge deck sealer products using a synthesis of two testing methods: National Cooperative Highway Research Program (NCHRP) Report 244 Series II tests and standards developed by the Alberta Ministry of Transportation (BT Series). This research also sought to develop an improved method for future evaluation of bridge deck sealer products for the Alabama Department of Transportation (ALDOT). The sealer products were evaluated for their resistance to moisture and chloride ingress, performance after simulated traffic wear, and depth of sealer penetration into the concrete. The products tested included four epoxy-based sealer products and one sodium silicate sealer product. The sealers were evaluated on three different concrete mix designs representing the range of bridge deck concrete in service with ALDOT. Concrete cube specimens were fabricated, sealed, conditioned, and subjected to different tests. One test evaluated the waterproofing performance of sealers before and after abrasive conditioning (representing traffic wear). Another test determined the products’ ability to resist chloride penetration and their waterproofing performance in a saltwater solution. The chloride content was measured by potentiometric titration with silver nitrate and X-ray fluorescence spectroscopy (XRF). Sealer penetration depth was determined by a dye method and scanning electron microscopy (SEM). Initial (pre-abrasion) waterproofing performance results generally showed a good correlation to chloride resistance. XRF and titration analyses provided nearly identical results for measuring chlorides in concrete; however, XRF is a preferred method for determination of chloride content because it is much faster than titration. Two epoxy sealers outperformed all products for all evaluation criteria. A third epoxy sealer had good overall performance, but many specimens sealed with this product developed cracks that warranted further investigation. The sodium silicate sealer performed poorly compared to all four epoxy-based sealers. The epoxy-based sealers did not exhibit any measurable sealer penetration into the concrete and the sodium silicate sealer penetrated less than 100 µm into the concrete.