Nanotechnology In

civil engineering

CREATED AND EDITED BY

AHMED NADIM JILANI

07J61A0103

10

Nanotechnology in constructionThe construction business will inevitably be a beneficiary

of this nanotechnology.In fact its already in this field of concrete ,steel, glass and

many more.Concrete is stronger, more durable and more easily

placed.Glass is self cleaning.Paints are made more insulating and water repelling.

Introduction to nano materialsNanotechnology :- 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 ion ) such that jump in energy levels occurs.

Nano composite:-it is produced by adding nano particle to a bulk material in order to improve the bulk materials properties.

Carbon Nano Tubes (CNT)They are cylindrical with nanometer diameter.They can be several millimeters in length.They have 5 times the Young’s modulus and8times

the strength of steel whilst being 1/6 density.Thermal conductivity is also very high along the tube

axis

Titanium oxide Titanium dioxide is a widely used pigment.It can oxidize oxygen or organic materials, and so

added to paints, cements, windows tiles. or other products for sterilizing, deodorizing and anti-fouling properties.

When incorporated in outdoor building materials can substantially reduce concentration of airborne pollutants.

Additnally, as tiO2 is exposed to UV light,it becomes increasing hydrophilic, thus it can be used for anti fogging coating or self-cleaning windows.

Nanotechnology in concreteNanotechnology can modify the molecular structure

of concrete material to improve the materials properties as shown.

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

Concrete is, after all a macro- material strongly influenced by its nano-properties.

Nano-silica particles packing in concrete can be improved by using nano silica which leads to a dandifying of the micro and nanostructure resulting in improved mechanical properties.

Nano-silica addition to cement based materials can the degradation of the fundamental C-S-H(calcium-silicate hydrate)reaction of the 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 redefined of the refine materials also 3 to 6 time higher.

if these nano-cement particles can be processed with Nano tubes and reactive nano size silica particles, conductive, strong, tough and room temperature processed ceramics can be developed both for electronic application and coatings .

Average size of Portland cement particles is about 50 microns.

In thinner final products and faster setting time, micro cement with a maximum particle size go about 5 microns is being used.

Therefore is reduced to obtain nano Portland cement.Hydration test indicates that the nano-cement had a more

rapid hydration rate than Portland cement.

TiO2 in concreteTiO2 is a white pigment can be used as an excellent

reflecting coating.Its hydrophilic and therefore gives self cleaning properties

to surface to which it is applied.The proceed 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 color that retains its whiteness very effective unlike the stained buildings of the material's pioneering past.

CNT in concreteThe addition of small amounts (1%wt) of cnt 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(+8n/mm2)compared to the sample without reinforcement.

A number of investigation has been carried out developing smart concrete using carbons fibers.

Nanotechnology in steelFatigue 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 stresses significantly lower than the yield stress of the material and lead to a significant shortening of useful life of the structure.

Stress rise are responsible for initiating cracks from which fatigue failure result and research has shown that the addition of copper then limits the number of number of stress rises and hence fatigue cracking.

Advancements in this technology would lead to increased safety ,less need for monitoring and more efficient materials use in construction prone to fatigue issues.

Temperature restriction

Above 750F, regular steel starts to lose its structural integrity, and at 1100 Fahrenheit, steel loses50% of its strength.

A new formula infuses steel with nanoscale copper particles, this formula could maintain structural integrity at temperature up to 1000 F.

The new steel allow ultra high strength to be combined with good formability, corrosion resistance and a good surface finish.

High strength steel cables

Current research into the refinement of the cementite phase of steel to a nano size has produce stronger cables.

A stronger cable material would reduce the cost and period of construction , especially in suspended bridges.

Sustainability is also enhanced by the use of higher cable strength as this leads to more efficient use of materials.

High rise structures requires high strength joints and this in turn leads to the need for high strength bolts.

Products In MarketSandvik nanoflex Mmfx2 steel Produced by sandvik materials

technology Sweden.Desirable qualities of high

young's modulus and high strength.

Resistant to corrosion due to the presence of very hard nanometer sized particles .

The use of stainless steel reinforcement in concrete structures is limited as it is cost prohibitive.

Produced by mmfx2 steel corp. America

Has the mechanical properties of conventional steel.

Has a modified nano structure that makes it corrosion resistant.

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

Vital role of glass in buildings The current state of the art in cladding is an active system

which tracks sun, wind and rain in order to order to control the 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 buildings and the control of light and heat entering through glazing is major issue.

Research into nanotechnological solutions to this centers around four different strategies to block light & heat coming thorough windows .

Self cleaning glass using TiO2Titanium dioxide is used in nanoparticle form to coat

to coat glazing since it has sterilizing and anti fouling properties.

The particles catalyze powerful reactions which breakdown organic pollutants, volatile organic compounds and bacterial membranes.

Tio2 is hydrophilic and this attraction to water forms sheet out of rain drops which then wash off the dirt particles broken down in the previous process.

Glass incorporating this self cleaning technology is available on the market today.

Self cleaning glass

Fire heat protectionFire- protective glass in another in application of nanotechnology.This is achieved by using a clear intumescing layer sandwiched

between glass panels (an interlayer formed ) of fumed silica(sio2). Nanoparticles which turns into rigid and opaque fire shield when heated.

For heat protection this film coating are bearing developed which are spectrally sensitive surface application for window glass 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 being studied which react to temperature and provide insulation to give protection from heating whilst maintain adequate lighting .

Nanotechnology and coatingsNanotechnology is being applied to paints and

insulating properties, produced by the addition of nano-sized cells, pores and particles, giving a very limited paths for thermal conduction, are currently available.

This types of paints are use 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.

conclusionIn 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 felt far and wide and nowhere more so than in construction its large economic and social presence.

Thank you

NANOTECHNOLOGY AND CIVIL EGINEERING

DEFINITELY THE FUTURE