Nanotechnology in construction

What is Nanotechnology?

Nanotechnology is the use of very small particles of material either by themselves or by their manipulation to create new large scale materials. The size of the particles, though, is very important because at the length scale of the nanometer, 10-9m, the properties of the material actually become affected.

“Nanotechnology is an enabling technology that allows us to develop Materials with improved or totally new properties”

What is a Nanoparticle

A nano particle is a microscopic particle whose size is measured in nanometers (nm).

It is defined as a particle with at least one dimension less than 200nm. Nano particles made of semiconducting material (material that is between a conductor and insulator e.g. silicon).

Carbon Nanotubes are a sub set of nano particles.

  

Nano materials for ConstructionBecause the size of the particles is a critical factor,

the material Properties significant differ at the nanoscale from that at larger scales.

All these nano-properties actually affect the materials behavior at macro-scale and, from this point, the power of nanotechnology is emphasized: if the elements are proper manipulated at the nanoscale, the macro-properties are affected and new materials and processes can be developed

The Carbon NanotubesCarbon nano tubes are a form of carbon having a

cylindrical shape, the name coming from their nanometer diameter.

Nanotubes are members of the fullerene structural family and exhibit extraordinary strength and unique electrical properties, being efficient thermal conductors.

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).

Titanium Dioxide Nanoparticles (TiO2)

The titanium dioxide nano particles are added to concrete to improve its properties. This white pigment is used as an excellent reflective coating. Or added to paints, cements and windows for its sterilizing properties.

Being hydrophilic gives self cleaning properties to surfaces to which it is applied, because the rain water is attracted to the surface and forms sheets which collect the pollutants and dirt particles previously broken down and washes them off. The resulting concrete surface has a white color that retains its whiteness very effectively. Expected benefits are reinforcement in mechanical strength (in concrete); coolant, light transmission, and fire resistance (in ceramics); flame-proofing and anti-reflection (in windows).

Silicon Dioxide Nanoparticles (SiO2)

Nano-SiO2 could significantly increase the compressive strength of concretes containing large fly ash volume at early age, by filling the pores between large fly ash and cement particles.

Nano-silica decreases the setting time of mortar when compared with silica fume (micro silica) and reduces bleeding water and segregation by the improvement of the cohesiveness. Expected benefits are reinforcement in mechanical strength (in concrete); coolant, light transmission, and fire resistance (in ceramics); flame-proofing and anti-reflection( in window)

Nano Silica mixed in Concrete can improve:

Mechanical Properties Can Control the degradation of theFundamental C-S-H(Calcium-Silicate-Hydrate) reaction of concrete. Can block water penetration and therefore lead to improvements in durability. They also increase strength as well as offering the benefit of monitoring stress levels through the measurement of section electrical resistance.

Zinc Oxide Nanoparticles (ZnO)

Zinc oxide is a unique material that exhibits semiconducting and Piezoelectric dual properties.

It is added into various materials and products, including plastics, ceramics, glass, cement, rubber, paints, adhesive, sealants, pigments, fire retardants.

Used for concrete manufacturing, ZnO improves the processing time and the resistance of concrete against water.

Silver Nanoparticles (Ag)

The core technology of Nanosilver is the ability to produce particles as small as possible and to distribute these particles very uniformly.

When the Silver Nanoparticles are coated on the surface of any material, the surface area is increasing several million times than the normal silver foil.

Wolfram (Tungsten) Oxide Nanoparticles (WO3)

In recent years, tungsten trioxide has been employed in the production of electro chromic windows, or smart windows.

These windows are electrically switchable glass that change light transmission properties with an applied voltage.

This allows the user to tint their windows, changing the amount of heat or light passing through.

Application of Nanotechnolagy in construction

• Lighter and stronger structural composites

• Low maintenance coating

• Improving pipe joining materials and techniques.

• Better properties of cementations materials

• Reducing the thermal transfer rate of fire retardant and

insulation

• Increasing the sound absorption of acoustic absorber

• Increasing the reflectivity of glass

Nanotechnologies for Concrete

Silica (SiO2) is present in conventional concrete as part of the normal mix..

The addition of nano-silica (SiO2) to cement based materials can control the degradation of the calcium-silicate hydrate reaction caused by calcium leaching in water, blocking water penetration and leading to improvements in durability.

Carbon nanotubes increase the compressive strength of cement mortar specimens. The addition of small amounts (1%) of carbon nanotubes can improve the mechanical properties of mixture samples of Portland cement and water.

Synthesized cementations nanoparticles, and Carbon nano tubes bridging cracks in cement composite, Nanolayered calcium aluminates particles

Nanotechnologies for Steel

Fatigue is a significant issue that can lead to the structural failure of steel subject to cyclic loading, such as in bridges or towers.

The addition of copper nano particles reduces the surface unevenness of steel which leading to increased safety, less need for monitoring and more efficient materials use in construction subjected to fatigue issues.

Vanadium and molybdenum nano particles improve the delayed fracture problems associated with high strength bolts, reducing the effects of hydrogen embrittlement and improving the steel micro-structure.

Surface of the stainless steel after electro deposition of palladium nanoparticles at low and high magnifications are shown.

The use of TiO2 nanoparticles to glasses leads to so-called self cleaning technology. Due to the nanoparticles photo catalytic reactions, the organic pollutants, volatile organic compounds and bacterial membranes are decomposed. As well, TiO2 being hydrophilic, his attraction to water forms drops which then wash off the dirt particles decomposed in the previous process.

Fire-protective glass is obtained using fumed silica (SiO2) nanoparticles as a clear interlayer sandwiched between two glass panels which turns into a rigid and opaque fire shield when is heated.

Nanotechnologies for Glass

Nanotechnologies for Coatings and Paintings

Nanotechnology is applied to paints in order to assure the corrosion protection under insulation since it is hydrophobic and repels water from the metal pipe and can also protect metal from salt water attack.

Nanotechnologies for Fire Protection

Fire resistance of steel structures is often provided by a coating produced by a spray-on cementations process. Nano-cement (made of nanosized particles) has the potential to create tough, durable, high temperature coatings.

This is achieved by the mixing of carbon nanotubes with the cementious material to fabricate fiber composites that can inherit some of the outstanding properties of the nanotubes.

Nano technology in waterproofing building materials

Latest nano technology to produce eco-friendly Organo-Silicon products to waterproof practically all the different kinds of building materials.

The nano technology has ensured that service life of this approach will lead to life cycles beyond 20 to 30 years at very economical cost.

Building materials are known to have water seepage, water leakages due to inherent porosity and microcracks.

Future challenges

While nanotechnology based construction products provide many advantages to the design and construction process, the production of these products, however, require a lot of energy. Also, the nanotubes might cause a lung problem to construction workers. In other words, it creates an environmental challenge to the construction industry as well. Sustainability and environmental issues caused by growing economic development has gained intensive statewide and worldwide attention.

More research and practice efforts are needed with smart design and planning, construction projects can be made sustainable and therefore save energy, reduce resource usage, and avoid damages to environment. It is necessary to establish a system to identify the environmentally friendly and sustainable of construction nanomaterials and to avoid the use of harmful materials in the future.