CompositesWorld
Issue link: https://cw.epubxp.com/i/919214
NEWS CompositesWorld.com 35 other residential structures, as well as commer- cial and public municipal buildings. In 2004, Altus Group (Greenville, SC, US) introduced CarbonCast technology into North America, enabling even further weight and cost benefits, thanks to the use of carbon fiber reinforcement. An alliance of precast concrete manufacturers that brings innovative tech- nologies to the construction market, Altus Group worked with Chomarat North America (Williamston, SC, US) to use its carbon fiber/ epoxy C-GRID as a shear truss in precast concrete panels, creating a precast wall system that is lighter, thinner and stronger than most cast-in-place concrete, solid precast concrete and conventional steel-reinforced precast concrete wall systems. Because carbon fiber is much stronger than steel, panel size can be increased, meaning fewer pieces are produced and transported, so installation is faster and the overall carbon footprint during construction is smaller vs. conventional precast. With more than 1,400 CarbonCast projects completed to date, totaling 40 million ft 2 (3.7 million m 2 ), Altus Group members see continued growth for C-GRID panels and struc- tures as a solution to increasing demands for efficiency and performance in construction. CW explores why and how through a recent project with serious cost and schedule challenges: the Georgia State University (GSU) Piedmont Central student housing in downtown Atlanta. Preparing the winning bid "e student housing market is very large and increasing its use of precast concrete," says John Carson, managing director for Altus Group. He explains that this type of project typically begins with an owner (e.g., college or university), an architect that has design responsibility for the project and/or a general contractor. e latter will help to define construction of the building envelope as part of the design process. Quite often, the owner/architect/contractor team will proceed through a design-assist model of devel- opment, where the precast manufacturer also is included, to help optimize the number of precast elements, which affects cost. e precaster also plays a large role in scheduling and determining how the finished elements are erected. e GSU Piedmont Central project was one of seven campuses receiving housing through a CFRP in Construction C-GRID, the key to CarbonCast economy The CarbonCast insulated wall system sandwiches EPS foam between two concrete wall sections, or wythes, held together using C-GRID shear trusses. Made from carbon fiber and epoxy resin by Chomarat North America (Williamston, SC, US), C-GRID can enable reductions in precast concrete panel weight of 40-50%. In the GSU Piedmont Central student housing project, CarbonCast wall panels featured a 2.5-inch/63.5-mm-thick exterior concrete wythe with molded-in facing brick, a 4-inch/102-mm-thick EPS foam core and a 3-inch/76.2-mm-thick interior concrete wythe finished with paint. Source | CW public/private partnership (P3) between e University System of Georgia and the private developer Corvias Group (East Greenwich, RI, US). After a competitive bid process, the Piedmont Central project was awarded to the team of Choate Construc- tion (Atlanta, GA, US), architecture firm Cooper Carry & Associates Inc. (Atlanta, GA) and precast manufacturer Metromont (Greenville, SC, US). "GSU is interesting because it is an urban campus," explains Tim Fish, architect and principal at Cooper Carry. "It actually had very little housing, but now has the largest student body in the state. is project was part of that growth." e urban setting meant space was at a premium. "e building would occupy 1 acre on the 1.4-acre site, so there was no room for staging materials," notes George Spence, business development manager at Metromont. e team decided early on to transfer labor to the Metromont plant. "In that way," he adds, "only one contractor would be on site to erect the walls and no space would be required for storage and staging. Trucks would simply pull up to the site and the precast panels would be installed directly." Another issue was cost. "e university was determined to maintain its afford- ability for students," says Fish. is meant the new dorm building had to be econom- ical and stay on budget. And then there was the schedule. "We had one year from pouring of the foundation to student move-in," says Spence.