GFRP grid CFRP grid use continues to grow in precast concrete By Throughout the last decade, carbon-fibre-reinforced polymer (CFRP) grid has earned widespread acceptance in the precast concrete industry, primarily as a shear connector in insulated wall panels and as a flange reinforcement in double tees for parking structures. Across the USA, nearly 3 million square metres of precast surface area have been erected on almost 600 projects under the CarbonCast brand name using the C-GRID CFRP grid enabling technology supplied by Chomarat North America LLC. John Carson Executive Director AltusGroup T here are several reasons CFRP grid in precast has been so successful. Most centre on the building industry's focus on energy efficiency and sustainability: - Thermal efficiency: CarbonCast high-performance insulated wall panels are composed of two concrete C-GRID CFRP grid is used as a shear truss to connect the inner and outer wythes of concrete in precast insulated wall panels. wythes (layers) separated by continuous insulation and connected by C-GRID shear trusses. The C-GRID connectors have relatively low thermal conductivity, virtually eliminating thermal transfer through the panel. The energy-saving performance is important given increasingly stringent energy codes such as ASHRAE 90.1, which favours mass walls with continuous insulation. - Load-bearing performance: extensive research has proven the outstanding load-bearing performance of CarbonCast high-performance insulated wall panels. C-GRID shear trusses render a panel with full structurally composite action. For example, a 200-mm CarbonCast high-performance insulated wall panel - 100 mm of insulation between two 50-mm concrete wythes - behaves structurally as if it were a 200-mm solid panel. (For primary flexural reinforcement, prestressing strand or steel rebar is used in each 36 jec composites magazine / No85 November - December 2013 Diagram showing how the grid is deployed as a connector in the panel. wythe and optional pilasters internal to the panel.) A load-bearing panel can eliminate the need for perimeter steel, which can lower cost, reduce the building's carbon footprint and lead to more usable floor space. - Lower weight: lowering the weight of a building component - whether it's a cladding panel or a double tee