Nanotechnology is the creation of materials and devices by controlling matter at the level of atoms, molecules, and supramolecular (nanoscale) structures.
Nanotechnology has provided a new path for material innovation. These new materials are not only lighter but also stronger, more flexible, and the material has the characteristics of high sensibility, multifunction’s, and intelligence.
Nanotechnology is a recently developed, major enabling tool, already well-established in several sectors of science, which is expanding rapidly into applied sciences, technology and engineering.
Nanotechnology enhances our understanding of the “origins” of key properties of everyday materials and structures; of manufacturing processes and interactions between materials, structures, external elements and internal components. It leads to development of advanced characterization and eventual prediction and inevitably control of properties of materials at a sub-micron level.
Nanotechnology is the creation of materials and devices by controlling matter at the level of atoms, molecules, and supramolecular (nanoscale) structures. In other words, it is the use of very small particles of materials to create new large scale materials (Mann, 2006). Although more thorough definitions were used by some researchers as well, the key factor is the size of particles because properties of materials are dramatically affected under a scale of the nanometer (nm), 10-9 meter (m).
Nanotechnology is the technology of controlling matter under nanoscale to create and utilize a material, structure, device or system. Nanostructure is manipulated through the control at atom, molecular and supermolecular level to produce a bigger structure of a new molecular structure.
The materials possess original physical, chemical and biological characteristics, and the main change is primarily caused by the nano-quantum dimensional effect and surface effect, which can lead to the change in melting point, magnetism, heat resistance, electrical potential energy, optical properties, chemical activity, surface energy and catalysticities of the matter. Consequently these materials can therefore be used for a host of previously unconsidered applications.
Nanotechnology has provided a new path for material innovation. These new materials are not only lighter but also stronger, more flexible, and the material has the characteristics of high sensibility, multifunction’s, and intelligence. Therefore, the nanotechnology industry is likely to be the prime mover for industry development in the 21st century. Apart from the quantum effect and surface effect, the bottom up assembly concept has overthrown conventional top down material manufacturing methods. The development of nanotechnology and its applications will give the industry a cheap and mass producible method of creating new materials and products.
Below about 1 nm, the properties of materials become familiar and predictable, as this is the established domain of chemistry and atomic physics. It should be noted that nanotechnology is not just one, but encompasses a wide range of technologies in many technical disciplines including chemistry, biology, physics, material science, electronics, MEMS and self-assembly.
Nano-structures have the ability to generate new features and perform new functions that are more efficient than or cannot be performed by larger structures and machines. Due to the small dimensions of nano-materials, their physical/chemical properties (e.g. stability, hardness, conductivity, reactivity, optical sensitivity, melting point, etc.) can be manipulated to improve the overall properties of conventional materials.
At a level of nanometers, the surface properties start becoming more dominant than the bulk material properties, generating unique material attributes and chemical reactions. More fundamentally, the electronic structure of materials becomes size-dependent as the dimensions enter the nanoscale.
Nanotechnology can be used in many different areas of design and construction processes since, nanotechnology generated products have many unique characteristics. These characteristics can, again, significantly fix current construction problems, and may change the requirement and organization of the construction process.
These include products with the following applications:
- Lighter and stronger structural composites
- Low maintenance coating
- Improving pipe joining materials and techniques.
- Better properties of cementitious materials
- Reducing the thermal transfer rate of fire retardant and insulation materials
- Increasing the sound absorption of acoustic absorbers
- Increasing the reflectivity of glass
Concrete is one of the most common and widely used construction materials. Its properties have been well studied at macro or structural level without fully understanding the properties of the cementitious materials at a micro level. The rapid development of new experimental techniques makes it possible to study the properties of cementitious materials at to a micro/nano-scale. Research has been conducted to study the hydration process, alkali-silicate reaction (ASR), and fly ash reactivity using nanotechnology. Better understanding of the structure and behavior of concrete at a micro/nano-scale could help to improve concrete properties and prevent known detrimental reactions , such as ASR.
Addition of nanoscale materials into cement could improve its performance. Li (2004) found that nano- SiO2 could significantly increase the compressive for concrete, containing large volume fly ash, at early age and improving pore size distribution by filling the pores between large fly ash and cement particles at a nanoscale. The dispersion/slurry of amorphous nanosilica is used to improve segregation resistance for self-compacting concrete. It has also been reported that adding a small amount of carbon nanotube (1%) by weight could increase both compressive and flexural strength.
Coatings’ incorporating certain nanoparticles or nanolalyers have been developed for a specific purpose and is one of the major applications of nanotechnology in construction. For example, TiO2 is used to coat glazing because of its sterilizing and anti-fouling properties. The TiO2 will break down and disintegrate organic dirt through powerful catalytic reaction. Furthermore, it is hydrophilic, which allows water to spread evenly over the surface and wash away dirt previously broken down. Other special coatings also have been developed, such as anti-graffiti, thermal control, energy saving, and anti-reflection coatings.
Nano and microelectrical mechanical system (MEMS) sensors have been developed and used in construction to monitor and/or control the environmental conditions and the material/structure performance. One advantage of these sensors are their dimensions. A Nanosensor typically ranges from 10-9 m to 10-5m. The micro sensor ranges from 10-4 to 10-2 m. These sensors are utilized by embedding them into the structure during the construction process.
Smart aggregate, a low cost piezoceramic-based multi-functional device, has been applied to monitor early age concrete properties such as moisture, temperature, relative humidity and early age strength development. The sensors can also be used to monitor concrete corrosion and cracking. The smart aggregate can also be used for structure health monitoring. The enclosed system can monitor internal stresses, cracks and other physical forces in the structures during the structures' life. It is capable of providing an early indication of the health of the structure before a failure of the structure can occur.