Figuring out the best way to construct an architect’s design can be challenging for contractors, who may be limited by traditional building materials like concrete, steel and wood. In recent years, however, some architects and builders have turned to composite materials to remove constraints. The light weight and flexibility of composites can make FRP the material of choice for stand-out design features.
These four projects showcase the benefits and possibilities that composites can offer the building industry.
Project: The Latitude office building
Composite Component: GFRP façade
Tasked with renovating and adding space to a 1970s-era office building, Studio Architecture designed a striking façade of curved ribbons that connect the original, newly glazed section and a new wing of the Latitude building in Paris. Construction was challenging for general contractor Bouygues Bâtiment Ile-de-France.
“Originally, the ribbon shapes were going to be made using thermal forming of thermoplastic plates with a steel structure inside,” says Samuel Durand, senior structural engineer and manager at the engineering/design firm Meca. However, the steel/thermoplastic ribbons would be too heavy, and Bouygues could not find a subcontractor capable of meeting the architect’s visual standards.
So, Bouygues worked with Meca and specialty chemical supplier Sika on a composite solution. Sika suggested blocks of freestanding polyurethane foam for the triangular ribbon shapes, using a heavier density of the material for longer spans. It joined the blocks with a fast-curing polyurethane resin, then had a subcontractor machine the lengths into individual ribbon shapes.
Next, subcontractors Le Prince Borel and SMM Technologies covered the tops and sides of the blocks with fiberglass fabric impregnated with an epoxy resin, SikaBiresin® CR82. It cured the ribbons at room temperature and then post-cured them at 50 to 55 C.
For the ribbon undercovers, Armacell supplied PET foam boards, which Sika sandwiched between two layers of fiberglass fabric and infused with SikaBiresin CR80 epoxy resin.
Finding a material that was easy to work with, durable and color-consistent to withstand long-term weather exposure was a challenge, says Patrick Noirclerc, composite products engineer at Sika. Since manufacturing consistency was another concern, Sika performed Meca-developed testing on a mock-up ribbon section, measuring properties such as tensile strength, thermal expansion, fatigue and mechanical junction strength.
Composites provided a cost-effective solution that gave the architects freedom of design.
“Glass reinforced concrete, or any other type of more conventional building material, would not allow this type of curves,” says Henri Chapelle, sales and marketing manager, PET foams, Armacell.