Concrete—that gray, monolithic building material—is getting a face-lift. Inventors are reshaping it to do more, last longer and show off. A new kind of “translucent” concrete uses fiber optics to carry light and shadow. New light-sensitive terrazzo flooring can reflect a rainbow of colors. And high-strength concrete placed inside buildings and bridges can flex like hard rubber to dampen earthquake shocks. The possibilities seem endless.
Innovation is infusing other traditional building blocks, such as steel, glass and wood, with renewal, while nanotechnology and “green” building has brought a host of hybrid materials. A heightened interest in building smart, clean and fast is driving this rapid research across the material world.
Finding thousands of examples is easy, thanks to new resources. Bringing these products to market is another story, inventors say.
The ongoing quest for innovation has put some wild, new products on the designer’s palette. Reflect for a moment on glass: It protects people from the elements, provides modest insulation and offers a nice view. But now it can do so much more. One type can clean itself using a catalytic film that uses sunlight and rain to break down and wash away dirt particles and smudges. Suppliers are starting to experiment with similar substrates that help concrete buildings, bridges, and highway barriers take pollutants out of the air. Even paint can clean itself.
You might say that designers wishing to use radically new concretes are waiting for the critical mass. New materials are a tough sell. Some offer a long-term cost benefit at a short-term price premium; others simply have architectural appeal controlled by the whimsy of consumers.
Fast computers, aeronautic inventions and environmental sensibilities have contributed to these recent material developments. The playing field is broad. If these innovative products have one thing in common, it is their ability to transcend expectations, often confusing the mind and engaging the eye.
One of the most striking examples is a new type of translucent concrete called “Litracon,” developed by Åron Losonczi, a Hungarian architect. Inside Litracon’s precast blocks and panels are glass fibers, arranged in parallel like millions of tiny windows. They transmit light from one side of the concrete to the other. Tight manufacturing tolerances make production of this material a challenge, not to mention complicating on-site casting.
The end result, however, is illuminating. On his website, the inventor says he has inked agreements with “leading manufacturers” and hopes to offer it soon worldwide. Designers are fascinated because the addition of the glass fibers completely changes the whole way architects think about concrete.
Kinetic and Mimetic
Innovative materials are finding new ways to interact within the natural world and reflect its beauty, both architecturally and structurally. A promising new technology is ultra-high-performance concrete, such as Lafarge’s “Ductal” product. Introduced several years ago, it casts like concrete and feels like concrete. Once cured, it behaves more like a metal, using carbon fibers, polyvinyl-alcohol fibers and other embedded materials that bring compressive capacities up to 30,000 psi and flexural strengths to 6,000 psi. Available in custom precast shapes, it costs somewhere “between” traditional concrete and steel, says the French producer. It is the featured material on a highway bridge completed this past spring in Wapello County, Iowa.
“Bendable” concrete is another material emerging in the fast-growing UHPC segment. It is similar to Ductal, resisting cracking 500 times more than traditional concrete, weighing 40% less and reducing the need for reinforcements and joints, especially in seismic zones. Under development at the University of Michigan, the combination of high strength and elasticity comes from synthetic fibers placed in the mix using traditional construction equipment and techniques.
Engineers are also experimenting with fiber-reinforced-polymer composites, such as glass-epoxy wraps, that can be applied to existing buildings and infrastructure to extend their life. Structural engineers say that the greatest aspect of this material is the high strength-to-weight ratio.
The construction industry prides itself in innovation, yet inventors cite major problems in bringing new building materials and systems to market. Building codes that do not yet address new technology and risk-averse owners are partly to blame.
The conservation movement also has helped bring along some “green” materials, such as a new product called “Kirei Board.” Made from sorghum and starting at $7 per sq ft, it behaves like plywood but is friendlier to the environment, the manufacturer claims.
Inventor Bob Simmons is doing for steel what others are doing for concrete. The design-build contractor invented a moment-resisting space frame, called “ConXtech,” that arrives on site and within minutes snaps together like a model airplane. But the building system is no toy, having solid roots in a seismic region and capable of rising to heights of up to 100 ft in about half the time of traditional frames. His patented “boltless” connectors, which robotic welding machines affix to the ends of 12-in.-deep beams, mate with dovetails welded on faces of hollow columns. The beams lock into the tubular columns, measuring between 4 in. and 8 in. square, using gravity. With the help of a mobile crane, the contractor can stand the frame without bolts. “We erect it from the top down,” explains Simmons, “then we deck from the bottom up.” Crews install bolts at each floor before pouring concrete slabs.
Amid the innovation, traditional materials still have their place, and can look just as cool. In Chicago, an 82-story rectangular, mixed-use tower called “Aqua,” which begins construction this month, will have concrete balconies that cantilever as far out as 12 ft. Each slab has a unique shape in plan, with random undulation that will make the building appear to “ripple” from bottom to top. Underneath, the 10-in.-thick slabs and the core-and-outrigger structure couldn’t be more typical.
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