Engineers with the City of Winnipeg in Manitoba, Canada, took a bold step and used high-performance concrete (HPC) for the deck of the new Provencher Bridge. But when cracks started to appear on the surface, the city's maintenance engineer and consultant Wardrop Engineering contacted Specialty Construction Products Ltd. to inspect the span and recommend a procedure and repair material.
The inspection revealed the cracking appeared to be from shrinkage while the new HPC bridge deck was curing. The 10,000-square-foot deck had several small cracks, in addition to 1600 linear feet of larger-width cracks.
Specialty Construction Products recommended a high molecular weight methacrylate penetrating crack healer sealer for the surface. Specifically, Sealate by Transpo Industries Inc., has a very low viscocity of 25 cps to allow it to penetrate deep into cracks. When fully cured, it restores more than 50% of the original strength of the concrete across the crack. One gallon covers about 100 square feet.
Workers treated the larger cracks individually to make sure they were completely filled with the Sealate. After the material cured, the bridge's entire surface was treated with a flood coat. This not only filled the smaller cracks that are too expensive to seal individually, but also allowed the resin to penetrate into any open pores in the concrete.
The process increased the surface's strength and reduced the permeability of the deck. Before the flood coat cured, a crew broadcast coarse sand onto the surface to increase skid resistance until the excess sealer wore off. The result was a bridge deck that was good as new.
Visit www.transpo.com for more on the manufacturer of the product in this story.