NANOTECHNOLOGY IN CONSTRUCTION

• “  Nanotechnology  is an enabling technology that allows us to develop materials with   inproved 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 use of very small particles of materials. A nonometer is a billionth of a meter.
• Nanoparticle is defined as a particle with atleast one dimension lessthan 200nm.

NANOTECHNOLOGY IN CONSTRUCTION:

• The construction business will inevitably be a beneficiary of nanotechnology.
• Using nanotechnology……………..
• concrete is made much stronger,durable and easily placed.
• Steel is made tougher.                                                                                                             
• Glass is self cleaning ……
• Paint  are made more insulating and water repelling.
• Wireless  Nanosensors could  save bridges ,buildings.

NANOMATERIALS:

• Nanoparticles.
• Nanocomposites.
• Carbon nano tubes( CNT).
• Titanium oxide(TiO2)

NANOTECHNOLOGY IN CONCRETE:

• Concrete is  a mixture of cement , sand(fine aggregates), coarse aggregate and water.
• Generally  concrete is mostly used material in construction.
• NANOTECHNOLOGY can modify the molecular structure of concrete material to improve the materials properties like …….

                                                   

                                                        * Bulk properties.

                                                        * Mechanical performance.

                                  *Volume stability.

                                                         *  Durability .

                                                         *  Sustainability of concrete.

• Nano concrete is defined as “ A  concrete made with Portland cement particles that are < 500nm. As cementing agent.
• The role of nanotechnology in concrete is to determine the quality of the concrete during placement. Now the technology being used in concrete are temperature probes and maturity meters.However the probes are large in addition strain gauges are being placed on reinforcing to determine yielding. NANOTECHNOLOGY can be used to fill cracks in concrete.
• NANO-SILICA: particle packing in concrete can be improved by using nano-silica. Which leads to a densifying of the micro and nano structure 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 particles 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.
• Average size of Portland cement particles is bout 50 microns .
• In thinner final products and faster setting time , micro cement with a maximum particle size of about 5microns is used .
• Therefore is reduced to obtain nano-portland cement.
• HYDRATION TEST indicated that the nanocement has the more rapid hydration rate than Portland cement.

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 surface to which it is applied .

*  The resulting concrete , already used in projects around the world which has a white colour that retains its whiteness effectively unlike the stained building of the material’s  pioneering past.

* EXAMPLE:  In  California  TiO2 is used to make self cleaning ceramic tiles for use in hospitals, public restrooms etc…

CNTs  IN CONCRETE :

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

NANOTECHNOLOGY IN 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.
• This can happen at stress significantly lower thatn the yield stress of the material and  lead to a significant shortening of useful life of the structure .
• Stress risers are responsible for initiating  cracks from which fatigue failure results and research has shown that the addition of copper nanoparticles reduces surface unevenness of steel which then limits the number of stress risers and hence fatigue cracking.
• Advancements in the technology would lead to increased safety , less need for monitoring  and more efficient materials use in  construction prone to fatigue issues .

TEMPERATURE RESTRICTION :

      

• Above 750 F  regular steel starts to loose its structural integrity and  1100 F regular steel loses 50% of its strength.
• A new formula infuses steel with NANO SCALE COPPER  particles ,this formula could maintain structural integrity at temperatures up to 1000 F.

TWO PRODUCTS IN INTERNATIONAL MARKET:

• Sandvik nanoflex : produced by sandvik materials technology  (SWEDEN).
• MMFX2  Steel: produced by MMFX steel corp (America).

NANOTECHNOLOGY  AND GLASS:

 VITAL ROLE OF GLASS IN BUILDING:

• The current state of art in cladding is an active system which tracks sun,wind and rain inorder to control building environment and contribute to sustainability
• Consequently there is a lot of research being carried out on the application of nanotechnology to glass.
• Most of glass in construction is , on the exterior surface of  building and the control of light and heat entering to glazing is the major issue.

SELF CLEANING GLASS USING TiO2:

• Tio2 is used in nanoparticle form to coat glassing since it has sterilizing and anti-fouling  properties.
• The particles catalyze powerful reactions which breakdown organic pollunts, volatile organic compounds and bacterial membranes .
• Glass incorporating this  SELF CLEANING TECHNOLOGY is available on the market today.

FIRE AND HEAT PROTECTION:

• Fire protective glass is another application of nanotechnology /
• This is achieved by using a clear intumescent layer sandwitched between glass panels formed of FUMED SILICA(SiO2) NANOPARTICLE which turns into a rigid and opaque fire shield when heated .
• For heat protection thin films coatings are being developed which are spectrally sensitive surface application for window glass and filter out unwanted infrared frequencies of light and reduce heat gain in buildings,however these are effectively a PASSIVE SOLUTION.
• As an ACTIVE SOLUTION , thermo chromic technology are being  studied which react to temperature and provide insulation to give protection from heating whilst  maintaining adequate lighting .

NANOTECHNOLOGY AND WOOD:

• Wood is also composed of nanotubes or nanofibrils, lignocellulose are twice as strong as steel .
• Nanofibrils which lead to new paradigm in sustainable construction .
• Functionality on to lignocellulose surface at the nano scale could open new opportunities for such things as self-sterilizing surfaces internal self-repair,and electronic lignocellulose divices .
• Currently, however , researchers in these areas appear limited .
• Researchers have developed a  HIGHLY WATER REPELLENT  coating based on  actions of the lotus leaves as a result of the incorporation of silica and alumina ,nano particles and hydrophobic polymers .

NANOTECHNOLOGY AND COATINGS……

• Nanotechnology is being applied to paints and insulating properties ,produced by the addition of nano sized cells,probes and particles ,giving very limited paths for thermal conduction .
• This type of paint is used ,for corrosion protection under insulation since it is hydrophobic and repels water from the metal pipe and can also protect metal from salt water attack.

·        Engineers developed a spray or paint that coats bridges with carbon nanotubes,

             allowing inspectors to check for damages without depending on visual inspections.

·        The skin conducts electrical current. If the bridge corrodes or cracks, it breaks the current or increases electrical resistance, and the location of that damage can be pinpointed by a computer,

•  alerting inspectors to damage smaller than what human eyes can see.

ELIMINATION  OF  TOXIC GASES:

• The absoption of carbon monoxide (CO) is done byusing cuprous salts and adsorption of hydrocarbons is done by using a complex nanomaterial i.e., CARBON MONOLITHIC AERO GELS.
• Production of  aerogels is done by sol-gel process.
• Sol-gel is a chemical solution process used to make ceramic and glass materials in the form of thin films ,fibres,or powders.
• Adsorption capacity measurements show that modified hydrophobic carbon aerogels are excellent adsorbents for different  toxic organic compounds from water .

POLLUTANT	POLLUTION( tons/day)
Carbon monoxide	421.84
Hydrocarbons	184.37
Nitrogen oxides	110.45
Particulate matter	12.77
Total pollution load	729.43

  

ADVANTAGES OF NANOTECHNOLOGY:

• The use of nanomaterials allows product manufacturers to offer longer product warranties.building owners  are expected to enjoy lower maintainance costs while consumers can look forward to houses that maintain themselves.
• The use of nanotechnology in future through the development of  nano-electromechanical systems could see whole buildings become networked detectors; as such devices are embedded either into elements or surfaces.

        CONCLUSION:

• In conclusion , nanotechnology offers the possibility of  great advances where as conventional approaches ,at best ,offer only incremental improvements.
• “ At this moment the main limitation is the high cost of nanotechnology.Also concerns with the environmental effects “
• The waves of change being propagated by progress at the nanoscale will therefore be left far and wide and no where more so than in construction due its large economic and social presence.

BIBILOGRAPHY:

• SURINDER  MANN 2006 “  Nanotechnology and construction –nanoforum report”
• Nanocement , steel and construction industries conference.

By

s@meer :)