Strong, lightweight and flexible composites are opening up new design possibilities.
Composite materials, sometimes referred to as fiber-reinforced polymers (FRP), combine the properties of a polymer (resin) and natural or man-made fibers to produce strong yet lightweight materials. Although the aerospace and the automotive industries have been using composites in their products for many years, the construction industry has been slower to adopt them. But now the interest in these materials is increasing as architects, engineers and builders explore their unique capabilities.
Here are three recent examples of innovative uses.
Composite molds for poured concrete
Completed last year, BHP Biliton Pavilion, the centerpiece of Confluence Park in San Antonio, Texas, consists of graceful concrete arches or “petals” that extend 30 feet into the air. The construction of the pavilion, designed by Andrew Kudless of Matsys, would not have been possible if the builder, Spawglass Contractors of Texas, hadn’t been willing to try something new — using composite materials to make the molds for the poured concrete arches.
Kudless had designed the structure with the idea of using composite molds. The builder was initially reluctant. But when it priced conventional wooden molds, it found that expense would devour almost the entire project budget. So, working with architectural composite company Kreysler and Associates, the project team constructed fiberglass (GFRP) molds for the poured concrete.
Using fiberglass instead of wood made it easier to shape the molds into the required curved. Plus, unlike wooden molds, fiberglass molds don’t shrink or warp, so they could be reused several times. The composite solution worked well, and visitors to Confluence Park are today enjoying the venue’s eye-catching pavilion.
The Museum of Modern Art in San Francisco chose a composite material for the eastern façade of its renovated and expanded building. It was the largest use of FRP cladding on a multi-story building in North America.
The composite exterior, which serves as a rain screen, features an undulating texture reminiscent of the water in the San Francisco Bay. Plans originally called for the 700-plus unique FRP panels to be installed at the building site. Because the composite materials were so lightweight, however, contractors were able to save time and money by mounting the panels on a unitized wall frame off site. The completed frames were then delivered to the site.
The composite FRP panels for this building had another important distinction: They were the first to pass the National Fire Protection Association’s rigorous tests for fire resistance. This opens up a whole new range of possibilities for the use of composites as a building cladding.
Carbon fiber composite roofs
Apple Inc. chose high-tech carbon fiber composite materials for the roofs of its theater building at Apple Park in Cupertino, California, and its Apple Michigan Avenue store in Chicago.
The theater roof is circular, approximately 140 feet in diameter, and weighs 80 tons. It is the largest freestanding carbon fiber roof ever made. Manufactured in Dubai, United Arab Emirates, it consists of 44 identical panels, each 70 feet wide and 11 feet long. The roof panels were shipped to the United States and then assembled next to the theater structure. The entire roof was then lifted into place.
The roof over the Apple store in Chicago measures 111 by 98 feet and was also manufactured in Dubai. Designed to resemble a giant MacBook, it is silver and very thin, ranging in thickness from 4 feet to 4 inches. It also carries a giant Apple logo.
Although the use of composites is still somewhat out of the ordinary, builders may become more accustomed to working with them, especially for infrastructure projects. In a March 2018 report to Congress, a representative of the National Institute of Standards and Technology noted, “Advanced composites can help us renew and repair the nation’s infrastructure with lighter, more durable materials that require less maintenance.”
Mary Lou Jay is a freelance writer who has been covering business and technical developments in the residential and commercial construction industries for more than 25 years.
Image Credit: Andrew Kudless at Matsys.