Member Company: Ash Grove Cement Company
Selected Categories: High Performance
This bridge replacement project consisted of almost 2,000 feet of concrete pavement, widened lanes, sidewalks, and two bike lanes. Slag cement was used at 50% replacement of portland cement in the mass concrete to lower heat of hydration and had an average strength of over 6,700 psi in 56 days. The bridge deck contained 40% slag to meet Oregon DOT’s high-performance concrete specification. To keep traffic going while the new bridge was constructed, a shoofly (temporary) bridge was built utilizing the existing bridge trusses. Once the temporary structure was complete, the existing bridge was literally slid over in a weekend with the used of dish soap to reduce friction.
The new Sellwood bridge replaced the existing bridge built in 1925. The old bridge was built in an unstable geological area, that caused girders to crack. In addition, the existing bridge was not designed to withstand a significant earthquake. The new bridge was designed to address both 500 and 1,000-year recurrence period earthquakes. The 64-foot-wide cross section included two 12 foot travel lanes, two 12 foot shared use sidewalks, and two 6.5 foot bike lane/emergency shoulders.
The use of slag cement helped the mass concrete to meet maximum concrete temperature specifications. Slag cement in the bridge deck mix design passed the performance specification of a maximum 1,000 coulumbs at 90 days.
Project Team: (Owner: Multanomah County, OR) (Architect: Safdie Rabine Architects) (Engineer: T. Y. Lin International Group) (Contractor: Slayden/Sundt JV) (Concrete: Ross Island Sand & Gravel, Ken Gambill, Ready Mix Manager) (Slag Cement: Ash Grove Cement Company, Jeff Mendes, Sales Manager)