Innovative Building Materials that will Impact Future ArchitectureShawn Martin | August 22, 2017
Innovative materials are shaping the future of architecture. As reinforced concrete was innovative in the earlier 19th century, the latest building materials look to further capitalize on what is possible by incorporating shape-memory alloys, bendable concrete composites, self-healing materials and electrochromic glass.
Seattle’s Flexible Bridge
A flexible bridge built by the Washington State Department of Transportation (WSDOT) is engineered with shape-memory alloys and bendable concrete composites to withstand seismic activity in the Cascadia region's largest metropolitan area, Seattle, Washington. The new State Route 99 exit ramp in downtown Seattle could lead to the evolution of reinforced concrete if it can prove not only to withstand a major earthquake without collapsing but rather escape the event damage free.
Shape-memory alloys (SMA) are composed of a titanium and nickel alloy referred to as Nitinol. It exhibits shape memory properties due to two distinct solid phases. Normally the material is in a martensite phase which allows it to be bent into various shapes. Friction from deformation elevates the temperature past a transition point and the crystal structure enters an austenite phase that forces the material back to its parent shape, achieving the most compact and regular pattern possible.
The alloy has excellent damping characteristics at temperatures below the transition temperature. It is also corrosion resistant, non-magnetic, exhibits high fatigue strength and is a low-density alloy at 6.5 g/cm3.
Nitinol, however, is not all of what makes Seattle’s flexible bridge innovative. The alloy was discovered by William J. Buehler, a researcher at the Naval Ordnance Laboratory in White Oak, Maryland, in 1961, so that material is not exactly revolutionary. It has been used in eyeglasses, hydraulic couplers for military applications and several other medical and robotic applications. Its use as a reinforcement bar in the bridge is the innovation; this application is only made possible by incorporation of bendable concrete composites that are crack resistant and hold the SMA in position while it experiences strain.
Bendable concrete composites incorporate tiny synthetic particles. The fiber-reinforced cement-based composite counteracts some of the disadvantages of conventional concrete. Instead of experiencing brittle failure the material exhibits ductile failure as closely spaced micro cracks form that allow the structure to carry an increased load, similar to the way metals experience strain-hardening.
The melding of SMA and bendable concrete composites is an innovative civil engineering architecture that is now in its pilot phase. The materials are used at stress points and mixed with conventional materials to make Seattle’s ‘flexible-bridge’ an economical solution if it can prove to withstand the test of time.
Research at Cardiff University has been underway for the development of self-healing materials. The original project, Materials for Life (M4L), originated in 2013 and identified several methods that would allow a conglomerate material to continually monitor, regulate, adapt and repair itself without the need for external intervention.
The focus of self-healing materials is on conglomerate materials such as concrete, grouts, mortars, hydraulically-bound materials and grouted soil systems. Techniques include microencapsulation of biomimetic materials to address microscale deformation, use of conductive fibers to form shape-memory polymers, and flow networks containing mineral-based healing agents and calcite-forming bacteria.
The first self-healing asphalt road already exists in the Netherlands, built in 2010, where small steel fibers can be charged to heat and re-melt the bitumen binding the surface together. The adaptation of technologies developed by M4L looks to greatly improve the life expectancy of self-healing conglomerates. The outlook is promising as further research is being conducted through a newly-funded project, Resilient Materials 4 Life (RM4L).
The RM4L project was made possible by a sizeable investment — on the order of £4.7 million — from the United Kingdom's Engineering and Physical Sciences Research Council (EPSRC) in March of 2017. The vision of RM4L is to achieve a transformation in construction materials by 2022, using the biomimetic approach first adopted in M4L.
Electrochromic glass is yet another innovative building material that has already progressed into the early stages of implementation. This innovative material enabled manufacturers to develop smart windows that transition through multiple tint states due to an applied voltage and electrochromic technology. Manufacturers can control the transmission properties of the window or even develop privacy glass, where a frosted opaque tint blocks visibility when a voltage is applied.
San Francisco International Airport (SFO) has selected View®, a leader in electrochromic glass, to redevelop its Terminal 1, using their View Dynamic Glass. Sixty-six thousand square feet of View Dynamic Glass will be used to create a world-class travel experience showcasing its brilliance.
As electrochromic glass increases its market share, cost will be driven down. Ultimately the smart-window market could offer a viable, economical solution for architects who choose to forgo the added expenditure of blinds, shades and other window treatments by incorporating electrochromic glass.
Shape-memory alloys, bendable concrete composites, self-healing materials, and electrochromic glass are just a few of the latest innovative building materials that are redefining what is possible. Further advances in graphene, precise polymer nano-trusses for unbreakable materials and self-cleaning finishes that incorporate titanium dioxide nanoparticles to reject water, oil, and even red wine are other innovative building materials leading us towards next generation architecture.