Posted August 22, 2018

Cool Stories: Building with foam

Giant foam blocks are being used in major construction projects across Puget Sound.

Giant blocks of foam are being used in construction projects across the Puget Sound, and you might be driving over them everyday without even knowing it.

The large white blocks - known as expanded polystyrene, according to a spokesman for the Washington State Department of Transportation - look like pieces in a Jenga game. They will soon support the future Northbound 99 off-ramp near the stadiums.

About 700,000 pounds of the blocks are packed inside some walls in Renton for the new flyover ramp that will connect the Interstate 405 HOV lanes to the HOT lanes on state Route 167.

"At this edge here, you can see a little bit of the Geofoam, which is what was used for fill for the entire ramp," said Gil McNabb as he stood next to the new ramp that's still under construction. McNabb is the engineering manager for the I-405/SR167 Program.

The specialized foam has actually been around for years, according to WSDOT. It's found in projects from Seattle to Bellevue to Kirkland to Tacoma.

Click here to read more and see photos.