Performance of thin bonded epoxy overlays on asphalt and concrete bridge deck surfaces.
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2014-06-01
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Abstract:This study is the evaluation of two thin bonded epoxy overlays: SafeLane (marketed by Cargill), and Flexogrid
(developed by PolyCarb). SafeLane is advertised as an anti-skid/anti-icing overlay that stores deicing chemicals for
release during winter events. Flexogrid is an anti-skid overlay. These two products were compared on the basis of
physical properties, including mean texture depth, surface friction, bond strength, ability to stop chloride intrusion,
and anti-icing properties, as well as traffic safety and cost. Both overlays worked as intended when they were initially
applied on the bridge decks. Mean texture depth and friction testing have shown that they both provide a durable
wearing surface with good traction. All the SafeLane bond tests exceeded 250 psi (1.72 MPa). Flexogrid had initial
high bond strengths, but had varied failure modes. However, the delamination of the Flexogrid overlay was identified
on the bridge deck even after this product was reapplied. Permeability and chloride testing of the underlying concrete
decks indicated that both overlays work well to protect bridge decks from chloride ingress. Permeability was high, but
the chloride counts did not increase with age. The anti-icing property of SafeLane is effective when pre-charged with
deicing chemicals. The three sites evaluated in this study indicate a reduction in crashes, but further study is needed to
monitor the long-term performance in crash reduction.
Implementation
CDOT should use the information contained within this report to develop construction specifications for thin bonded
overlays. SafeLane can be considered for use on high crash rate bridges, where its high cost can be offset by an
increase in traffic safety. If SafeLane is to be used as an anti-icing overlay, it should have deicing chemicals applied
more often, and in smaller amounts. Pre-charging should be used when possible. Installation of Flexogrid should not
be considered on bridges before the reasons causing the delamination are investigated. Studies of both overlays should
continue so their long-term impacts on traffic safety can be analyzed.
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