Rebar is used to prevent cracking in highways. Typically epoxy-coated steel, welded into place in metal “baskets,” have been used to keep the 15-foot slabs of concrete from shifting every time a tire passes over the edge. However, Hershberger says, the 40-year-old corrosion-resistant solution can cause its own problems.
Over time, the epoxy coating develops fissures that actually lead to accelerated corrosion at the site of these micro-cracks. A typical lifespan for these bars is anywhere from 20 to 30 years, depending on the environment, while today’s roads are built to last 40 to 50 years, at a minimum. That can be a costly disconnect: As Hershberger puts it, “A typical dowel bar costs about $5, and it costs $150 to replace an in-service dowel.”
CRT’s steel GFRP-wrapped dowel bar, which the company says has an infinite service life, is designed to reduce concrete cracking by applying less bearing stress and corner pressure on the concrete as compared to today’s steel bars, says Hershberger.
“Our sleeve is not just a coating, it’s actually a structural component of the dowel, which serves to completely eliminate corrosion,” Hershberger explains. Because the steel is hermetically sealed within the composite material – a blend of corrosion-resistant vinyl ester resin and ECR glass – highways gain a truly corrosion-resistant product, with the same load transfer as a 1½-inch piece of steel for about the same price as those steel bars, he adds.
“We conservatively estimate that two-thirds of dowel bars are in corrosion areas. So not only will ours be cost competitive, but they will have better performance in terms of lower concrete cracking, and they will also never corrode,” Hershberger says.