Infrastructure and construction — credit where due
The composites universe is broad, but it’s easy to develop “tunnel vision.” Composites in aerospace and automotive applications dominate industry headlines, and I’ll admit to spending much of my time in those markets and the wind energy sector. But one needs to back out and take a wider look sometimes. It’s been a while since I opined on the infrastructure and construction market, so I looked around and found a lot worth writing about.
Although some consider infrastructure and construction distinct markets (certainly there are subsets within each), I lump them together because they compete for similar materials, processes and building technologies, such as poured concrete, lumber and plywood, and welded or bolted steel structures. So, for my purposes, this one market includes housing, other buildings, roads, bridges, parking structures, column wrapping, stationary marine, offshore oil, chemical plants and power distribution. A broad category, for certain. Composites have many advantages in these applications — notably, reduced weight and much greater corrosion resistance and weatherability than this market’s conventional materials. Composites also offer tailorable properties, due to anisotropy, so a process like pultrusion is a natural fit, especially for profiles, such as beams and window lineals. Because the aforementioned competing materials are economically produced in very, very high volumes, the vast majority of existing and new applications in this market rely on fiberglass reinforcement. Carbon fiber gets the nod only in niche situations. Although a few applications for thermoplastics exist, this market is dominated by thermosets — polyester, vinyl ester, epoxy and polyurethane.
Some applications are decades old, such as fiberglass bathtubs and shower surrounds. More recently in housing, a handful of companies are fabricating modular fiberglass panels for inexpensive and fast assembly of residential housing, offices, schools and shelters. The panels look a bit like shower surrounds — just with a lot more engineering in them.
When I ran a compounding plant in France in the mid-1990s, we produced many tons of UV-resistant polyester BMC for compression molded wall claddings to rehabilitate old apartment buildings in Eastern Europe. These not only added aesthetic appeal but also greatly improved building energy effciency thanks to their insulative properties. As 2017 dawns, Apple Inc. (Cupertino, CA, US), for one, is taking advantage of composites in the construction of a 1,000-seat theater at its new corporate headquarters. The circular venue will feature a roof that at a diameter exceeding 40m, Apple claims, will be the largest freestanding carbon fiber structure in the world. Its 44 wedge-shaped panels are being produced by Premium Composite Technologies (Dubai, UAE).
Insituform Technologies (St. Louis, MO, US) relined the first underground pipe with a cured-in-place (CIPP) composite liner in 1976. Today, CIPP and other “trenchless technologies” continue strong, but barely register news coverage. Unless someone can show me otherwise, I believe the largest single composite structure cured at one time lies underground in an out-of-sight relined sewer system that stretches for miles.
And when one mentions composites in infrastructure, the subject inevitably turns to replacing deteriorating vehicle bridges, accompanied by discussion of the frustration of trying to convince government customers to pay a bit more for a composite bridge that will last several times longer. But why only chase unhealthy bridges? Composite Advantage (Dayton, OH, US), a supplier of vehicle bridge decks, has developed parallel opportunities for “healthy” bridges as well, adding cantilevered sidewalks to steel-and-concrete bridges to improve their utility with minimal added weight. Lightweight, long-lasting pedestrian-only bridges also are a growing market: Composite Advantage provided the FiberSPAN decking for the beautiful Columbia River Skywalk, a 295m over-water pedestrian bridge that opened in December 2016.
In the marine market, where saltwater corrosion is the issue, composites are used extensively in offshore oil platforms. Fiberglass gratings, for example, have been around for 50 years. Closer to shore, composite docks, sheet piles and fenders are increasingly common. And the Port of Valencia (Spain) has a new, all-composite, 35m-tall lighthouse, designed and installed by Acciona Infrastructures SA (Madrid, Spain). It features carbon fiber columns and joints, and glass fiber stairs and floors, made variously by pultrusion, vacuum infusion and RTM. The 20-ton structure was assembled off site and erected in only six hours.
In electrical transmission, composite utility poles are finally gaining traction after demonstrating the ability to remain upright in hurricane-force winds. Utilities in US and Mexico coastal areas are now selectively installing composite poles to “harden the grid.” I could go on, but it’s clear that a lot of innovation is happening in all these sectors. They bear watching more closely.
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