It’s a Small, Smart World

Nanotech era draws closer

By Tom Kuennen, Contributing Editor

Nanotechnology offers long-term promise to boost performance of our highway, road and bridge infrastructure. New research is expanding and new applications are materializing. More recently, the long-term environmental impacts of nanomaterials are being studied. But implementation is going to take a long time.

The impact of nanotechnology on highway, road and bridge transportation infrastructure is just beginning. Nanotechnology involves the characterization, engineering and fabrication of matter at the molecular nanoscale, to improve existing products and to make feasible new materials and processes.

Nanoscale crystal seeds speed up concrete hardening. BASF’s X-Seed hardening accelerator makes additional heat superfluous and the concrete is particularly strong and durable. Magnification 960:1 (by 12 cm in width).

Nanotechnology embraces the nanoscale; that is, the range of dimensions from approximately 1 nanometer to 100 nanometers (1 to 100 billionths of a meter). One nanometer is 100,000 times smaller than the width of a human hair. That’s a molecular domain in which devices and systems exhibit properties that aren’t seen at larger scales. In that domain of quantum physics, clusters of atoms and molecules exhibit properties quite different from those found at larger scales. These properties have applications for pavement and bridge infrastructure.

“Nanotechnology should not be implemented in the pavement engineering arena merely because it is a new technology,” states Wynand Jacobus van der Merwe Steyn, Department of Civil Engineering, Tshwane University of Technology, Pretoria, in his paper, Development of Auto-Luminsecent Surfacings for Concrete Pavements. “[T]he application of nanotechnology should allow the engineer to deliver a better product to the client. This may, for instance, be a more cost-effective product, a more technologically suitable product or a safer product.”

Nanotechnology can focus on improving the general properties (e.g., strength, durability) of current materials, the ability to use marginal materials, or the novel application of nanotechnology to enable a safer transportation environment, Steyn says.

Nanomaterials and Construction

Nanomaterials offer significant advantages for the construction industry at large, from making more durable concrete to self-cleaning signs or windows. “The advantages of using nanomaterials in construction are enormous,” says Pedro Alvarez, chair of the Department of Civil and Environmental Engineering at Houston’s Rice University. “When you consider that 41 percent of all energy use in the U.S. is consumed by commercial and residential buildings, the potential benefits of energy-saving materials alone are vast.”

But widespread use in building materials comes with potential environmental and health risks when those materials are thrown away. Those are the conclusions of a study published by Rice University engineering researchers in the July 2010 issue of ACS Nano.

“[T]here are reasonable concerns about unintended consequences,” Alvarez says. “The time for responsible lifecycle engineering of man-made nanomaterials in the construction industry is now, before they are introduced in environmentally relevant concentrations.”

In fact, in a 2010 report, Nanomaterials in the Construction Industry: A Review of Their Applications and Environmental Health and Safety Considerations, Alvarez and co-authors Jaesang Lee, a postdoctoral researcher at Rice, and Shaily Mahendra, an assistant professor at UCLA, find that nanomaterials will likely have a greater impact on the construction industry than any other sector of the economy, following biomedical and electronics applications.

Nanomaterials, they find, can strengthen both steel and concrete, keep dirt from sticking to windows, kill bacteria on hospital walls, make materials fire-resistant, drastically improve the efficiency of solar panels, boost the efficiency of indoor lighting and even allow bridges and buildings to “feel“ the cracks, corrosion and stress that will eventually cause structural failures.