Credit: Allen Engineering.
The specially designed slipform paver used hydraulic automatic grade control, a full-width stainless steel paving pan, and external hydraulic vibrators on 24-inch centers.
The landmark San Francisco - Oakland Bay Bridge spans the San Francisco Bay from the East Bay through Yerba Buena Island to downtown San Francisco. Built in 1936, it is one of the busiest transportation arteries in California, carrying more than 280,000 vehicles per day.
To complete the final phases of this project, in May 2006, Caltrans partnered with American Civil Constructors Inc. (ACC), Benicia, Calif., to resurface over 1.2 million square feet of both the upper and lower decks of the western span with 2138 cubic meters of polyester concrete, an engineered composite overlay system. The paving is expected to be completed by late 2006 at a cost of $13 million.
The polyester concrete, provided by Kwik Bond Polymers, Benicia, Calif., is an engineered composite system that has been in continuous use since 1981. It was mixed onsite using six mobile mixer trucks specially designed for this project. To spread and finish the material, ACC used a specialized slipform paver that was designed and built by Allen Engineering Corp. and sold by Allen Concrete Pavers, both of Paragould, Ark. Designed specifically for spreading and finishing polyester concrete, this slipform paver uses a hydraulic automatic grade control system to ensure a smooth final ride surface. Other unique features of the paver include a full-width stainless steel paving pan with external hydraulic vibrators mounted at 24-inch centers, for complete and uniform consolidation of the polyester concrete. A dual reversible auger mounted on the front of the machine feeds the material to the paving pan, and an adjustable tining system on the back of the machine grooves the surface for its final finish. Using these specialized materials and equipment also allows ACC to open the bridge to traffic in just two to three hours after placement of the polyester concrete.
Further project information is available from Caltrans (www.baybridgeinfo.org), American Civil Constructors, Inc. (www.acconstructors.com), Kwik Bond Polymers (www.kwikbondpolymers.com), and Allen Concrete Pavers (www.allenpavers.com).