look what we did!

Category: Architecture

Anyone Order A Polyurethane Sandwich?

In 2007, durable polyurethane saved a 104-year old bridge. Amazingly, polyurethane saved the bridge by making a sandwich! The design team working to repair the historic Dawson Bridge in Edmonton, Alberta recommended using the Sandwich Plate System (SPS) from Intelligent Engineering Ltd. to serve as a lightweight solution to rehabilitate the bridge.

Built in 1912, the bridge was due for a new deck. Engineers feared that traditional decking materials would be too heavy, but polyurethane offered a solution. Not only did SPS present a lighter alternative, but use of SPS would enable the bridge to be refurbished in less time and reduce the amount of stress imposed on the structure.

So how is a polyurethane sandwich made? SPS is comprised of two steel face plates sandwiching a core of polyurethane. This PU elastomer core allows SPS to absorb vibration, creating a high tolerance for impact, and to weigh up to 70% less than reinforced concrete while still being as strong and more durable.

Spanning 776 feet long and 26.8 feet wide, the Dawson Bridge is the first major bridge project to utilize SPS technology, remarkably without welding. Turns out, a sandwich can help save infrastructure, as long as the sandwich is made out of flexible, durable and incredible polyurethane!