Any person who is a regular traveller would be able to notice that an airport comprising both the airside and landside is built using four main base materials – cement, metal, glass and plastic. Concrete including its variants, such as reinforced concrete, widely used to build runways, taxiways, aprons, terminals buildings and other key elements of airport infrastructure, is largely based on cement. These are the key base materials of today’s technosphere – part of the environment that is made or modified by humans for use in human activities, including habitats and transport infrastructure. This is what 95% of all human-built infrastructures surrounding us are made of.
The concrete-based infrastructure is extremely heavy. While there are no alternatives to this material, engineers recognize the main disadvantage of concrete: low strength with a large mass – the compressive strength of concrete is on average ten times less than the strength of steel. In large structures, reinforced concrete “carries” more of its own weight rather than the useful weight.
In the recent years significant research was undertaken in order to investigate the potential ways to make the base construction materials lighter and stronger. It is not only a question of science and engineering, it is a question of construction economics, as stronger materials would imply that the world would need less of them to build exactly same structures. Moreover, geometric progression comes into play: if the building becomes twice as strong, it does not mean that only the walls can be made two times thinner. In fact, less cement will need to be poured, less transport will be required, this transport will burn less fuel, it will be necessary to produce less, respectively, the effect will be enormous throughout the entire process chain.
As regards the technological solutions on the horizon capable of giving a tangible, visible breakthrough effect in base materials, there are two separate technology streams. The first one refers to as composite materials. The main composite materials of today are carbon fiber, fiberglass and basalt fiber. These are very important materials in several industries including aircraft manufacturing. The leading companies such as Boeing and Airbus have been increasing the amount of carbon fiber used per aircraft with every new model, in both primary (wings, fuselage, tail) and secondary structures (inspection panels, spoilers, air brakes).
The second technology stream, known to a lesser extent, refers to nanomodified materials. There are nanomaterials that have strength properties hundreds of thousands of times better than the basic materials existing on Earth. Adding them to the existing base materials fundamentally changes their properties. For example, aluminum becomes durable, like titanium, while remaining lightweight. Similarly, there are promising opportunities in the area of nanomodified concrete.
In 2012, the Transportation Research Board in the US issued a Transportation Research Circular E-C170: Nanotechnology in Concrete Materials. The synopsis explores promising new research and innovations using nanotechnology that has the potential in improved mechanical properties, volume change properties, durability, and sustainability in concrete materials.
Among other things, the document contains a discussion of the key breakthroughs in concrete technology that are most likely to result from the use of nanotechnology, such as development of high-performance cement and concrete materials as measured by their mechanical and durability properties, and development of sustainable concrete materials and structures through engineering for different adverse environments, reducing energy consumption during cement production, and enhancing safety. It is argued that if nanoparticles are integrated with traditional building materials, the new materials would possess outstanding properties for the construction of super high-rise, long-span or intelligent civil infrastructure systems.
Significant progress has been made in the field of polymer concrete, which is a type of concrete where polymer binder replaces cement, and which is characterized by high compressive and tensile strengths and superior durability as compared to conventional Portland cement concrete. However, the use of polymer concrete is limited due to its higher cost than conventional concrete. Incorporating a very limited amount of nanomaterials (below two percent of carbon nanotubes or alumina nanoparticles) can result in significant improvement in mechanical properties of polymer concrete including strength, ductility, and fracture toughness.
As discussed above, airports rely heavily on concrete for constructing the key elements of infrastructure on both airside and landside. With the steady traffic growth and positive outlook for the industry, the demand for the airport infrastructure is strong. Nevertheless, developing new airports and expanding and improving the existing ones comes at a cost. In addition to the cost of the construction materials, one needs to add the cost of transporting these materials to the construction site as well as other applicable costs in the construction process. Since concrete is by far the leading construction material for the airports as well, it is important to monitor the developments in the domain of nanomodified concrete and assess the potential economic impact on building airport infrastructure.
Since aviation at large is a technology-intensive industry, adopting newest cutting-edge technology by every player in the value chain is essential for realizing the full potential of the entire industry. Focusing on the base materials is especially important. Just like a wide adoption of carbon fiber resulted in lighter and stronger by design aircraft, which eventually translated into better fuel efficiency and consumer benefits in terms of lower airfares among others, it is equally important for the airport sector to investigate the best use of advanced construction materials including nanomodified concrete.