He adds, “We’re looking to help the building and construction markets understand their opportunities in advanced materials.” In particular, Advantic and its parent company, Cornerstone Research Group, have invested a decade researching and developing a family of proprietary cast polymer products. To meet flame, smoke and toxicity requirements, the subway panel incorporates glass microspheres, an epoxy resin, proprietary processing aids and additives for filler. The result is a material that has the strength of concrete at a significant weight savings.
For example, to cover a 7 x 3-foot opening the conventional precast concrete panel with a 4,000 psi compressive strength weighs 850 pounds. An Advantic cast polymer panel solution of the same strength tips the scales at 66 pounds. When the steel mounting structure is included, the weight of the concrete solution tops 1,200 pounds. The polymer solution, in contrast, weighs only 67 pounds.
During the first weekend of installation in March, workers mounted 225 cast polymer panels extending along approximately 2,000 linear feet of track.
The last point of comparison is critical. When cast polymer was first contemplated as a replacement, the impulse was to simply swap out the concrete for the new material. But the concrete mounting hardware ran to hundreds of pounds per panel, which meant that a large crew and special lifting devices were needed. Advantic redesigned the connection detail so the panels could be bolted directly to the subway wall. The difference in stiffness between the wall and the cast polymer meant that there would be movement of one relative to the other. This had to be handled without causing undue stress in the panel.
“We designed a connection detail, which we ended up patenting, which involves an incorporated rubber bushing to permit deflections to occur,” Doudican says. “We took out all the steel, thereby eliminating all the steel crews needed to do the installation.” The resulting panel assembly could be installed in 30 minutes, versus many hours for the concrete solution. The savings in labor costs can be substantial. Thus, while the polymer material may cost more than concrete, the total cost of the project is much lower with the new material.
