We are very familiar with the concept of getting raw materials, bringing them together in an organized way and then putting them together into a recognizable form. This is our role in society and we have performed it well for hundreds or thousands of years. So we can say construction is definitely not a new science or technology and yet it has undergone great changes over its history. In the same vein, nanotechnology is not a new science and it is not a new technology either. It is rather an extension of the sciences and technologies that have already been in development for many years.
What is Nanotechnology ? Nanotechnology is the use of very small pieces of material by themselves or their manipulation to create new large scale materials. At the Nano-scale material properties are altered from that of larger scales. The Nano-scale is the size range from approximately 1nm to 100nm. Nanotechnology is an enabling technology that allows us to develop materials with improved or totally new properties.
Nanotechnology in Construction… The Construction Business will inevitably be a Beneficiary of this Nanotechnology. In fact it already is in the field of Concrete, Steel & Glass, and many more… Concrete is more stronger, more durable & more easily placed; Steel is made Tougher; Glass is Self –Cleaning. Paints are made more Insulating and Water Repelling.
Introduction to Nano Material♦ Nano Particle: 1 • Nano ParticleIt is defined as a particle with atleastone Dimension less than 200 nm. It isquantum Dots if they are small enough 2 • Nano Composite(typically 10 nm) such that jump in energylevel occur. 3 • Carbon Nano Tube(CNT)♦ Nano Composite: 4 • Titanium Dioxide(TiO2)It is produced by adding Nano Particle to aBulk material in order to improve the Bulkmaterial’s Property.
Carbon Nano Tube(CNT)♦ They are cylindrical withNano-diameter.♦ They can be severalmilimeter in Length.♦ They have 5 times theYoung’s Modulus & 8 timesthe strength of steel.♦ Thermal conduction is alsovery high along the TubeAxis.
Titanium Dioxide♦ Titanium Dioxide is widely used whitePigment.♦ It can oxidised Oxygen and Organicmaterial, and so added to paints,cement, windows, Tiles, or otherproduct for sterilizing, Deodorizing andAnti-Fouling Properties.♦ When incoporated into outdoorbuilding material can substantiallyreduce concentration of airbornepollutants.♦ Additionally, as TiO2 is exposed to UV Light, it becomes increasinglyhydrophilic, thus it can be used for Anti-fogging coating & Self –cleaningWindows.
CONCRETE♦ Concrete is a mixture ofcement,sand,coarse aggregate andwater.♦ As concrete is a most usablematerial in construction industryit’s been require to improve itsquality.♦ The Mechanical behaviour ofconcrete materials depends onphenomena that occurs on a Microand Nano scale.
Nanotechnology in Concrete♦ Nanotechnology can: Bulk PropertiesModify the molecular structure ofconcrete material to improve the Mechanical PerformanceMaterial’s Properties as shown in theChart. Volume Stability♦ Nano Concrete is defined as“ A Concrete made with Portland DurabilityCement that are less than 500 Nano-meters as cementing Agent.” Sustainability of Concrete
♦ Concrete is, after all, a micro-material 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 macro and the nanostructure resulting inimproved mechanical properties.♦ Nano-silica addition to cement based materials can also control thedegradation of the fundamental C-S-H (calcium-silicate hydrate) reaction ofconcrete caused by calcium leaching in water as well as block water penetrationand therefore lead to improvements in durability.♦ Related to improve particle packing, high energy milling of ordinary Portlandcement (OPC) clinker and standard sand, produces a greater particle sizediminution with respect to conventional OPC and, as a result, thecompressive strength of the refined material is also 3 to 6 times higher .
♦ If these Nano Cement Partical are processed with Nano Tubes and NanoSillica Particles, conductive, strong, tough ceramics can be developed bothfor Electronic & Coatings Purpose.♦ Average size of Portland Cement Particles is about 50 microns.♦ In the thinner final product and faster setting time,micro Cement withmaximum particle size of about 5 micron is being used.♦ Therefore, It is used to obtain Nano-Portland Cement.♦ Hydration Test indicated that the Nano Cement had more rapidHydration rateThan Portland Cement.
TiO2 in Concrete♦ TiO2 is a white pigment and can be used as excellent reflectivecoating.♦ It is Hydrophilic and therefore it gives self cleaning properties to thesurface to which it is applied.♦ The process by which it occur is that Rain water is attracted to thesurface and forms which collect the pollutant and dirt particlespreviously broken down and wahses the out.♦ The resulting Concrete, already used in the project around theworld, has a white color which retains its whiteness very effectivelyunlike the stained buildings of the materials pioneering past.
CNTs in Concrete♦ The addition of small amount (1%)of CNT’s can improvethe Mechnical Property of the samples containing themain Portland Cement phase and water.♦ Oxidised multi –walled Nano Tubes shows the bestimprovements in both compressive strength and flexturalstrength as compared to the sanples withoutreinforcement.♦ A number of investigations have been carried out fordeveloping smart concrete using Carbon Fibres.
Need For Nanotechnology In Steel?♦ Fatigue is a significant issue that can lead to structural failure of steelsubject to cyclic loading , such as in Bridges and Towers.♦ This can happen at stresses significantly lower than the yeild stress of thematerial lead to significant shortening of useful life of structure.♦ Stress risers are responsible for initating cracks from which fatigue failureresults and research has shown that the addition of copper Nanoparticlereduces the surface unevenness of steel which then limits the number ofstress risers and hence fatigue cracking.♦ Advancement in this techonology would lead to increased safety, less needfor monitoring and more efficient material use in constructions prone tofatigue issues.
Temperature Restrictions♦ Above, 75000 F regular steel starts to loose its structural Integrity , and at11000 F ,steel loose 50% of its strength.♦ A new formula infuses steel with Nano scale copper particles, this formula canmaintain structureal integrity at temperature upto 10000 F.♦ The new steel allows Ulra-High strength to be combined with goodformability, corrosion resistance and a good surface finish.
High Strength Cables ♦ Current researches into Refinement of the cementite phase of a steel to a nano size has produced longer cables. ♦ A stronger cable material would reduce the cost and period of constructions, especially in suspension Bridges. ♦ Sustainability is also enhanced by the use of higher cable strength as this leads to more efficient use of the material. ♦ High rise structure needs high strength joints and this in turns leads to the needs for high strength Bolts.
High Strength Bolts ♦ The capacity of high strength bolt can be relised generally quenching & tempering and microstructures of such products consist of tempered Martensite. ♦ When the Tensile strength of tempered steel exceeds 1200 MPa even a very small amount hydrogen embrittle the grain boundaries and the steel material may fail during use. ♦ Vanadium And Molybdenum Nano particle has shown that they improve the delayed fractures problems associated with high strength Bolts, improving the steel Micro- structure.
Two Product in International MarketsSandvik Nanoflex♦ Produced by SandvikMaterials Technology(Sweden).♦ Desirable qualities of a highYoung’s Modulus & Highstrength.♦ Resistance to corrosion dueto the presence of very hardNano-meter sized particles.♦ The use of stainless steelreinforcement in concretestructures is limited as it iscost prohibitive.
MMFX2 Steel♦ Produced by MMFX steel CorpLTD. (America)♦ Has a Mechanical properties ofconvectional steel.♦ Has a modified Nano structurethat make it corrosion resistance.♦ It is an alternative to convectionalstainless steel,but at lower cost.
Vital role of Glass in Buildings♦ The current state of art in clading is an active system whichtracks sun,Wind and Rain inorder to control the building environmentand contribute to sustainability .♦ Consequently, there is a lot of research being carried out onthe application of Nanotechnology to Glass.♦ Most of Glass in construction is, on exterior surface of thebuilding and the control of Heat and Light entering throughglazing is a major issue.♦ Research into Nano technological solutions to this centersaround four different strategies to block Heat & Light comingthrough windows.
Self Cleaning Glass using TiO2♦ Titanium Dioxide is used in the form of Nano particle tocoat glazing since it has Sterilizing and Anti Foulingproperties.♦ The particles catalyze powerful reaction whichbreakdown organic pollutant, volatile organic compoundand Bacterial membranes.♦ TiO2 is hydrophilic and this attractions to form watersheets out of rain drops which then wash off the dirtparticles broken down into previous process.♦ Glass incorporating this “Self Cleaning Technology” isavailable in the Market Today.
Fire And Heat Protection♦ Fire Protective Glass: It is an another example ofNanotechnology.♦ This is achieved by by using a clear intumescent layersandwiched between glass panels formed by fumedSilica(SiO2) Nano particle which turns into rigid an opaquefire shield when Heated.♦ For Heat Protection thin film coating is being developedwhich are spectrally sensitive surface applications forwindow glass and filter out unwanted infrared frequenciesof light and and reduce the heat gain in buildings, however,these are effectively Passive solution.♦ As an Active solution, Thermo chromic Technologies arebeing studied which react to temperature and provideinsulations to give protection from heating whilemaintaining adequate Lighting.
Nanotechnology in Wood♦ Wood is also composed of nanotubes or“Nanofibrils” , lignocelluloses are twice as strongas steel.♦ Nanofibrils would lead to a new paradigm insustainable constructions.♦ Currently, research in these areas appers to belimited.But,♦ Researchers have developed a highly waterrepellent coating based on the actions of thelotus leaf as a result of the incorporation of sillicaand alumina Nanoparticle and hydrophobicpolymers.
Nanotechnology & Coatings♦ Nanotechnology is being applied to Paints &insulatings properties,produced by nano sized cells,pores and particles, giving verylimited paths forThermal Conductivity.♦ This type of Paints is used,for corrosion resistanceunder insulation since it is hydrophobic and repelswater from the metal pipe can also protect metalsfrom salt water attack.
CONCLUSION♦ In conclusion, Nanotechnology offers the possibility ofgreat advances whereas convectional approaches, atbest, offers only incremental improvements.♦ “ At this moment the main limitation is the high costsof Nanotehnology.Also concerns with theenvironmental effects ”♦ The wave of change being propagated by progress at thenanoscale will therefore be felt far & wide & nowhere moreso than in construction due its large economic and socialpresence.