Nanotechnology in the Construction Industry
The question of where nanotechnology will take us in the construction industry should be considered not only for enhancing material properties and functions but also in the context of energy conservation. This is a particularly important prospect since a high percentage of all energy used (e.g., 41% in the United States) is consumed by commercial buildings and residential houses by applications such as heating, lighting, and air conditioning.
So, where is nanotechnology used today in the construction industry? According to an economic assessment (pdf), nanotechnology has a significant impact in the construction sector. Several applications have been developed for this specific sector to improve the durability and enhanced performance of construction components, energy efficiency and safety of the buildings, facilitating the ease of maintenance and to provide increased living comfort.
Though self-cleaning features have been possible to attain using micron sized coatings and surface treatments e.g. Teflon, polysilazane based coatings, etc. now this feature has become a marketing tool / motto for nanotechnology applications, especially for consumer markets like construction, textile, etc.
"Nanoparticles of TiO2, Al2O3 or ZnO are applied as a final coating on construction ceramics to bring this characteristic to the surfaces. TiO2 is being used for its ability to break down dirt or pollution when exposed to UV light and then allow it to be washed off by rainwater on surfaces like tiles, glass and sanitaryware. ZnO is used to have UV resistance in both coatings and paints. Nanosized Al2O3 particles are used to make surfaces scratch resistant. These surfaces also prevent / decelerate formation of bad smells, fungus and mould.
"Basic construction materials cement, concrete and steel will also benefit from nanotechnology. Addition of nanoparticles will lead to stronger, more durable, self-healing, air purifying, fire resistant, easy to clean and quick compacting concrete. Some of the nanoparticles that could be used for these features are nano silica (silica fume), nanostructured metals, carbon nanotubes (CNTs) and carbon nanofibers (CNFs).
Current pressure to reduce CO2 emissions from the manufacture of cement is guiding research to use nanotechnology to alter the processing conditions of cement, therefore reducing these emissions. Concrete structures also make profit from nano-enhanced coatings that prevent graffiti and other unwanted stains to adhere on to it.
In addition to these materials, new lightweight, flame-retardant, self-healing and resilient construction materials, e.g. new nanocomposites, are expected to be helped in their development by nanotechnology.
"Nanotechnology will also have a considerable impact on glass and therefore on windows. For marketing purposes, these windows are commonly called smart windows which implies that they are multifunctional through their energy saving, easy cleaning, UV controlling and photovoltaic features.
"Nanotechnology could allow the development of materials with better insulation properties, intelligent structures capable of optimizing the use of energy. New insulating materials have been developed with the help of advances in nanotechnologies. These insulating materials are: nanofoams, nanostructured aerogels and vacuum insulated panels.
"In the future, smart living spaces will be made possible via embedded sensing systems that would enable buildings sense and act according to environment and also to the users' needs."
A review by scientists at Rice University has looked at the benefits of using nanomaterials in construction materials but also highlights the potentially harmful aspects of releasing nanomaterials into the environment. The team compiled a list of current use of nanomaterials in various building applications and also highlighted potential and promising future uses.
Which nanomaterials are used in construction
Carbon nanotubes – Expected benefits are mechanical durability and crack prevention (in cement); enhanced mechanical and thermal properties (in ceramics); real-time structural health monitoring (NEMS/MEMS); and effective electron mediation (in solar cells).
Silicon dioxide nanoparticles Expected benefits are reinforcement in mechanical strength (in concrete); coolant, light transmission, and fire resistance (in ceramics); flame-proofing and anti-reflection (in windows).
Titanium dioxide nanoparticles – Expected benefits are rapid hydration, increased degree of hydration, and self-cleaning (in concrete); superhydrophilicity, anti-fogging, and fouling-resistance (in windows); non-utility electricity generation (in solar cells).
Iron oxide nanoparticles – Expected benefits are increased compressive strength and abrasion-resistant in concrete.
Copper nanoparticles – Expected benefits are weldability, corrosion resistance, and formability in steel.
Silver nanoparticles – Expected benefits are biocidal activity in coatings and paints.
Quantum dots – Expected benefits are effective electron mediation in solar cells.
One particular area for nanotechnology in the construction industry is concrete, specifically research on how to reinforce concrete to improve its mechanical performance. The video below shows how researchers are using nanosilica to strengthen concrete:
Another research focus is on how to reduce the time cement takes to harden by increasing its reactivity (see: "Nanotechnology in cement mixers").