Nanomaterials are particularly suited to protecting the surface of various construction materials such as glass, concrete, sand limestone or marble from environmental influences like water staining, moss, algae as well as soot and oil stains; and can also function as corrosion inhibitors for reinforced steel. Nano additive paints and surface coatings are commercially available that create a low energy facing thus rendering a building surface highly hydro- and oleophobic, thereby helping to prolong maintenance cycles and reduce cleaning.
Dirt repellent protective paints and photocatalytic coatings are the most prominent applications in the construction and exterior protection industry. Dirt collection (accumulation) in building exteriors poses considerable problems for building maintenance. Cleaning such building surfaces is generally done by using detergents accompanied with scrubbing, wiping and high-pressure water jets. These processes have several shortcomings such as use of chemical detergents, high consumption of energy and labour cost. These naturally lead to high maintenance cost; therefore, an effective self-cleaning coating is desirable.
Nanoparticle TiO2 self-cleaning coating technology is applicable for use on surfaces. Such coatings greatly benefit building maintenance, especially for skyscrapers, as they reduce the need for costly surface cleaning. Photocatalyst coatings are also used to improve indoor air quality by reducing the amount of volatile organic compound and other toxic chemicals people are exposed to. Other applications utilising nanomaterials in the construction industry include nanoporous aerogel insulation, nanocomposite additives to steel, fire retardant materials, and environmentally sustainable materials.
Insulation
Nanotechnology can facilitate developing high performance insulation materials / systems. Different forms of insulation solutions, like coatings, vacuum insulation glazing, and nanofoams can be realized. Nanoporous aerogels are used in construction materials as insulators. The percentage of open space within an aerogel structure is about 94%, giving a tortuous path for heat, and this leads to it having the lowest thermal conductivity value of any solid.
Protection
Nanopowders have been added to construction ceramics, which include floor and wall tiles, countertop ceramics and sanitary ware products. They have found a place on the market with self-cleaning, anti-bacterialism hygienic and scratch resistant features. Nanoparticles exhibit properties of water/dirt repellency, UV protection, antibacterial, anti-corrosion for application on glass. The coatings contain functionalized nanoparticles such as nano silver that impart a bacteria-free surface which is anti-fouling & anti-algae.
Cement
Nanomaterials affect cement and concrete in different ways including their processing conditions, released CO2 emissions, service life and functionalities. 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 are being used are nano silica (silica fume), nanostructured metals, carbon nanotubes and carbon nanofibers.
Glass
Self-cleaning coatings incorporating photocatalytic Titanium Dioxide (TiO2) use UV light for strong oxidation power and super-hydrophilicity on windows. Strong oxidation power can be used to kill bacteria attached on the wall, or oxide/remove foul smell from stains in toilets (TiO2-coated tile and TiO2-coated glass are commercially available). Super-hydrophilic properties allow dirt and stains to be easily washed away with water or by rainfall when the coating is applied to exterior surfaces.
Questions & Answers
Q
Who are the companies with activities in nanotechnology for building materials?
A
A number of global companies are involved in the market such as Akzo Nobel, BASF, Clou, DAW Caporol and most multi-nationals with products related to surfaces (especially household care, paint, varnish and lacquer companies) are heavily involved in R&D on nanomaterials; however the main thrust for innovative applications is provided by SMEs such as Nanopool, Green Millenium and Sarastro.
Q
What are the prospects for nanotechnology in the construction industry?
A
Nanostructured materials are allowing companies to develop the next generation of protective coatings for buildings. Costs are prohibiting widespread adoption but TiO2 nanoparticles have been widely applied in self-cleaning coatings and carbon nanotubes are being used in concrete to improve strength. Modification or impregnation of resins with nanomaterials could improve hardness, wear and decay resistance in wood products.
