innovations in building construction material

8/3/2019 Innovations in Building Construction Material

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BY: SHIVAKUMAR V. BHAT

USN NO: 1DA06CV050

CIVIL ENGINEERING DEPT


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Nanotechnology is not a new science and it is not a newtechnology.

Nanotechnology is an enabling technology that allows us todevelop materials with improved or totally new properties

It is rather an extension of the sciences and technologies alreadydeveloped for many years, to examine the nature of our world atan ever smaller scale.

Nanotechnology is the use of very small particles of material. Ananometre is a billionth of a meter.

The size of the particles, is very important because at the lengthscale of the nanometre, 10-9m, the properties of the materialactually become affected


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The construction business will inevitably be a beneficiaryof this nanotechnology.

In fact it already is in the fields of concrete, steel andglass, and many more.

Concrete is stronger, more durable andmore easily placed;

steel is made tougher ;

glass is self-cleaning.

Paints are made more insulating andwater repelling.


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Nano particle: It isdefined as a particle withat least one dimensionless than 200nm.It isquantum dots if they aresmall enough (typically

sub 10nm) such thatjumps in energy levelsoccur.

Nano composite : It isproduced by addingNano particle to a bulkmaterial in order toimprove the bulkmaterials properties.


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They are cylindricalwith nanometresdiameter.

They can be severalmillimetres in length

They have 5 times theYoungs modulus and 8times (theoretically 100times) the strength ofsteel whilst being

1/6th the density. Thermal conduction is

also very high alongthe tube axis


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Titanium dioxide is a widely used white pigment.

It can oxidize oxygen or organic materials, and soadded to paints, cements, windows, tiles, or otherproducts for sterilizing, deodorizing and anti-fouling

properties When incorporated into outdoor building materials

can substantially reduce concentrations of airbornepollutants.

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


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The ceramic tile used on the exterior contains

titanium dioxide, a material that reduces the

need for heavy maintenance, withstands moldin a tropical environment and is believed to

reduce smog and pollutants in the air of

urban environments.


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Concrete is a mixture ofcement, sand(fineaggregate), coarseaggregate and water.

As concrete is most usablematerial in constructionindustry its been require toimprove its quality.

The mechanical behaviourof concrete materialsdepends on phenomenathat occur on a micro and anano scale.


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Nanotechnology can:modify the molecularstructure of concretematerial to improve the

materials properties asshown in the chart.

Nano-concrete is definedas A concrete made with

Portland cement particlesthat are less than 500Nano-meters as thecementing agent.


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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 and nanostructureresulting in improved mechanical properties.

Nano-silica addition to cement based materials can also control thedegradation of the fundamental C-S-H (calcium-silicate hydrate)reaction of concrete caused by calcium leaching in water as well asblock water penetration and therefore lead to improvements indurability.

Related to improved particle packing, high energy milling of ordinaryPortland cement (OPC) clinker and standard sand, produces a greaterparticle size diminution with respect to conventional OPC and, as aresult, the compressive strength of the refined material is also 3 to 6times higher.


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If these Nano-cement particles can be processed with

Nano tubes and reactive Nano-size silica particles,conductive, strong, tough and room temperatureprocessed ceramics can be developed both forelectronic applications and coatings.

Average size of Portland cement particle is about 50microns. But for thinner products and faster setting,micro cement with a maximum particle size of about 5microns is being used.

Hydration tests indicated that the Nano-cement had amore rapid hydration rate than Portland cement


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TiO2 is a white pigment and can be used as anexcellent reflective coating.

It is hydrophilic and therefore gives self cleaningproperties to surfaces to which it is applied.

The process by which this occurs is that rain water isattracted to the surface and forms sheets whichcollect the pollutants and dirt particles and laterbroken down and wash themselves off.

The resulting concrete, already used in projectsaround the world, has a white colour that retains itswhiteness very effectively unlike the stained buildingsof the materials pioneering past.


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The addition of small amounts (1% wt) of CNTscan improve the mechanical properties ofsamples consisting of the main Portland cementphase and water.

Oxidized multi-walled Nano tubes (MWNTs)show the best improvements both in compressivestrength (+ 25 N/mm2) and flexural strength (+8 N/mm2) compared to the samples without thereinforcement.

A number of investigations have been carried outfor developing smart concrete using carbonfibres.


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Designed By Gret Wingardh


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Constructed by Swedish construction

giant Skanska


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Fatigue is a significant issue that can lead to the structuralfailure of steel subject to cyclic loading, such as in bridgesor towers. This can happen at stresses significantly lowerthan the yield stress of the material and lead to asignificant shortening of useful life of the structure.

Stress risers are responsible for initiating cracks fromwhich fatigue failure results and research has shown thatthe addition of copper Nano-particle reduces the surfaceunevenness of steel which then limits the number of stressrisers and hence fatigue cracking.

Advancements in this technology would lead to increasedsafety, less need for monitoring and more efficientmaterials use in construction prone to fatigue issues.


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Above 750 F, regular steel starts to lose itsstructural integrity, and at 1100 F, steel loses50 percent of its strength.

A new formula infuses steel with nanoscalecopper particles, this formula could maintainstructural integrity at temperatures up to1000 F.

The new steel allows ultra-high strength tobe combined with good formability, corrosionresistance and a good surface finish.


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U.S. Navy - Hybrid Modular Piers- San Diego, California High-rise Condominiums inAventura, Florida


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U.S. Army Corps of Engineers . Oklahoma Spillway .Phase II - Channel bridge

Sacramento Regional Transit Authority . Sacramento

County . New bridge structure

New Haven, Connecticut - Church St Extension - Bridgedeck

New Castle County - Delaware-State Route 82 over

Dupont . Louisville, Kentucky, plant reconstruction

City of Chicago - Millennium Park renovation Airport Control Tower east central coast of

Florida


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Current research into therefinement of the cementitephase of steel to a Nano-sizehas produced stronger cables.

A stronger cable material would

reduce the costs and period ofconstruction, especially insuspension bridges .

Sustainability is also enhancedby the use of higher cable

strength as this leads to a moreefficient use of materials.

High rise structures requirehigh strength joints and this inturn leads to the need for highstrength bolts


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The capacity of high strength bolts is realizedgenerally through quenching and tempering andthe microstructures of such products consist oftempered martensite.

When the tensile strength of temperedmartensite steel exceeds 1,200 MPa even a verysmall amount of hydrogen embrittles the grainboundaries and the steel material may failduring use.

vanadium and molybdenum Nanoparticle hasshown that they improve the delayed fractureproblems associated with high strength bolts,improving the steel micro-structure.


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Sandvik Nanoflex Produced by Sandvik Materials

Technology(Sweden)

Desirable qualities of a highYoungs Modulus and high

strength

Resistant to corrosion due tothe presence of very hardnanometre-sized particles

The use of stainless steel

reinforcement in concretestructures is limited as it iscost prohibitive

MMFX2 steel Produced by MMFX Steel

Corp(America)

has the mechanical

properties of conventionalsteel

Has a modified nano-structure that makes itcorrosion resistant

It is an alternative toconventional stainless steel,but at a lower cost.


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The current state of the art in cladding is an active systemwhich tracks sun, wind and rain in order to control thebuilding environment and 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 the exterior surface ofbuildings and the control of light and heat

entering through glazing is a major issue.

Research into nano technological solutionsto this centres around four different strategiesto block light& heat coming through windows.


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Titanium dioxide (TiO2) is usedin Nano-particle form to coat glazing since it hassterilizing and anti-fouling properties.

The particles catalyze powerful reactions whichbreakdown organic pollutants, volatile organiccompounds and bacterial membranes.

TiO2 is hydrophilic and this attraction to water formssheets out of rain drops which then wash off the dirtparticles broken down in the previous process.

Glass incorporating this self cleaning technology isavailable on the market today


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Macquarie Bank buildingIn Sydney


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Fire-protective glass is another application ofnanotechnology.

This is achieved by using a clear in tumescent layersandwiched between glass panels (an interlayer) formed offumed silica (SiO2) Nanoparticle which turns into a rigid andopaque fire shield when heated.

For heat protection thin film coatings are being developedwhich are spectrally sensitive surface applications for windowglass and filter out unwanted infrared frequencies of light(which heat up a room) and reduce the heat gain in buildings,however, these are effectively a passive solution.

As an active solution, thermo chromic technologies are beingstudied which react to temperature and provide insulation togive protection from heating whilst maintaining adequate

lighting.


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A third strategy, that produces a similar outcomeby a different process, involves photo chromictechnologies which react to changes in lightintensity.

Electro chromic coatings are beingdeveloped that react to changes inapplied voltage by using tungsten oxidelayer; thereby becoming more opaque atthe touch of a button.

All these applications are intended toreduce energy use in cooling buildings.


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Wood is also composed of nanotubes or nanofibrils,lignocelluloses are twice as strong as steel.

Nano-fibrils would lead to a new paradigm in sustainableconstruction

Functionality onto lignocelluloses surfaces at the nanoscale couldopen new opportunities for such things as self-sterilizingsurfaces, internal self-repair, and electronic lignocellulosesdevices.

Currently, however, research in these areas appears limited.

Researchers have developed a highly water repellent coatingbased on the actions of the lotus leaf as a result of theincorporation ofsilica and alumina Nano-particle andhydrophobic polymers.


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Nanotechnology is being applied to paints andinsulating properties, produced by the additionof nano-sized cells, pores and particles, givingvery limited paths for thermal conduction (Rvalues are double those for insulating foam), arecurrently available.

This type of paint is used, for corrosionprotection under insulation since it is

hydrophobic and repels water from the metalpipe and can also protect metal from salt waterattack.


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Lotus effect on external wall by Nanoparticles


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The absorption of carbonmonoxide is done by usingcuprous salt and adsorption ofhydrocarbons is done by usinga complex nanomaterial. i.e.,Carbon Monolithic Aero gels.

Production of Aero gels is doneby sol-gel process.

Adsorption capacitymeasurements show thatmodified hydrophobic Carbon

aero gels are excellentadsorbents for different toxicorganic compounds from water.


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In conclusion, nanotechnology offers thepossibility of great advances whereasconventional approaches, at best, offer onlyincremental improvements.

At this moment the main limitation is the highcosts of nanotechnology. Also concerns with theenvironmental effects

The waves of change being propagated by

progress at the nanoscale will therefore be feltfar and wide and nowhere more so than inconstruction due its large economic and socialpresence.


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