Emergent Materials for Aging Infrastructure
Zaragoza Bridge by Zaha Hadid depicting use of rebar-free FibreC concrete. Photo by Helene Binet.
As we know too well, the current state of US infrastructure is considered to be in dire straits. A large percentage of transportation infrastructure including bridges, roads, and tunnels has reached capacity in its utilization and requires important repairs. The American Society of Civil Engineers gave a “D” grade for US infrastructure in 2009, estimating some $2.2 trillion would be required to achieve a good condition in the next five years. The Federal Highway Administration claims that a quarter of bridges in the US require repair, and cautions that the average age of US bridges is over 40 years old despite the fact they have a 50-year design lifespan. US roadways are also in trouble, and nearly 15% of the nation’s roads have been deemed “not acceptable” by the National Surface Transportation Policy and Revenue Study Commission. Moreover, the Economic Policy Institute warns that existing road materials are between 35 and 40 years old, and roadway utilization only continues to accelerate—one estimate points to an increase of 25 million drivers in the next ten years.
Degradation thus represents a threat to the security of infrastructural systems that must be seriously considered, in addition to threats originating from terrorist activity and natural disasters. Due to the sheer magnitude of economic investment required to improve US infrastructure, it goes without saying that new technologies and processes that may be employed economically will gain approval. In addition, there are many new material offerings that demand our scrutiny with regard to potential long-term benefits. After all, new materials and products that utilize sustainable strategies will produce healthier environments and encourage innovation within green industries.
This summer I gave a lecture at a symposium sponsored by Columbia University and the Department of Homeland Security focused on aging infrastructure. The emergent materials, systems, and processes I presented for further study included high-performance materials that establish new performance benchmarks and accomplish more with less; smart conservation strategies that facilitate construction, repair, and energy savings; power harvesting materials that employ renewable energy for secure, localized power; remediating materials that clean up local environments; biomimetic materials that emulate natural systems to achieve new levels of performance; and responsive materials that monitor, diagnose, and respond to local changes.
Although expensive, these materials can be strategically applied to aging infrastructure in a targeted fashion appropriate to the required function. As a result, this kind of surgical approach may only necessitate small (or at least manageable) quantities of materials used to repair, reinforce, or otherwise protect existing structures.