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Nanotechnology in Civil Engineering

Nanotechnology in Civil Engineering, Nanotechnology is an enabling technology that allows us to develop materials with improved or totally new properties”

It is rather an extension of the sciences and technologies already developed for many years ,to examine the nature of our world at an ever smaller scale. Nanotechnology is the use of very small particles of material. A nanometer is a billionth of a meter.

The size of the particles is very important because, at the length scale of the nanometer, 10-9m, the properties of the material actually become affected.

This paper report aims to discuss various concepts behind nanotechnology, implementation of nanotechnology in Civil Engineering field and to other fields also.

Civil Engineering is always restricted to cement, sand and stones. But it is something beyond that. It deals with innovations in each and every step of constructing a structure. This paper deals with “NONATECHNOLOGICAL TREATMENTS” IN Civil Engineering.

Nanotechnology in Construction

The construction business will inevitably be a beneficiary of this nanotechnology. In fact, it already is in the fields of concrete, steel and glass, and more. Concrete is stronger, more durable and more easily placed; steel is made tougher; glass is self-cleaning. Paints are made more insulating and water repelling.

Introduction to Nano Materials:

Nano particle,  It is defined as a particle with at least one dimension less than 200nm.It is quantum dots if they are small enough (typically sub 10nm) such that jumps in energy levels occur.

Nano composite, It is produced by adding nano particle to a Bulk material in order to improve the bulk material properties.

Carbon Nano Tubes(CNT):

  • They are cylindrical with nanometer diameter.
  • They can be several millimetres in length.
  • They have 5 times Young’s modulus and 8 times (theoretically 100 times) the strength of steel whilst being 1/6th the density.
  • Thermal conduction is also very high along the tube axis

impression of a carbon nanotube

Artist’s impression of a carbon nanotube. Image: Digital Art/Corbis

Titanium oxide:

  • Titanium dioxide is a widely used white pigment.
  • It can oxidize oxygen or organic materials, and so added to paints, cements, windows, tiles, or other products for sterilising, deodorising & anti-fouling properties
  • When incorporated into outdoor building materials can substantially reduce concentrations of airborne pollutants.

Additionally, as TiO2 is exposed to UV light, it becomes increasingly hydrophilic, thus it can be used for anti-fogging coatings or self-cleaning windows.

Nanotechnology in Concrete:

Concrete is a mixture of cement, sand (fine aggregate), coarse aggregate & water. As concrete is most usable material in the construction industry it’s been required to improve its quality.

The mechanical behaviour of concrete materials depends on phenomena that occur on a micro and a nano scale.

Nano-concrete is defined as “A concrete made with Portland cement particles that are less than 500 Nano-meters as the cementing agent”.

  • Concrete is, after all, a macro-material strongly influenced by its nano-properties.
  • NANO-SILICA: particle packing in concrete can be improved by using nano-silica which leads to a densifying of the micro & nanostructure resulting in improved mechanical properties
  • Nano-silica addition to cement based materials can also control the degradation of the fundamental C-S-H (calcium-silicate hydrate) reaction of concrete caused by calcium leaching in water as well as block water penetration and therefore lead to improvements in durability.
  • Related to improved particle packing, high energy milling of ordinary Portland cement (OPC) clinker and standard sand, produces a greater particle size diminution with respect to conventional OPC and, as a result, the compressive strength of the refined material is also 3 to 6 times higher.

TiO2 in Concrete:

  • TiO2 is a white pigment and can be used as an excellent reflective coating.
  • It is hydrophilic and therefore gives self cleaning properties to surfaces to which it is applied.
  • The process by which this occurs is that 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, already used in projects around the world, has a white colour that retains its whiteness very effectively unlike the stained buildings of the material’s pioneering past.

CNTs in Concrete:

  • The addition of small amounts (1% wt) of CNT’s can improve the mechanical properties of samples consisting of the main Portland cement phase and water.
  • Oxidized multi-walled Nano tubes (MWNT’s) show the best improvements both in compressive strength (+ 25 N/mm2) and flexural strength (+ 8 N/mm2) compared to the samples without the reinforcement.
  • A number of investigations have been carried out for developing smart concrete using carbon fibres.

 

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