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4/30/15

Smart concrete using nano particles


Nano concrete
Addition of nano particles gives significant improvement to concrete than conventional concrete. Addition of nano particles improves the bulk properties of materials by controlling or manipulating at the atomic scale due to nanoscale attack by alkali silicate reaction. It is possible to obtain thinner final products and faster setting time besides lower levels of environmental contamination.
Nano concrete is a concrete made with Portland cement particles that are less than 500nm as a cementing agent as against normally used cement particle which range in size from a few nano-meters to a maximum of about100 micro meters. The benefits are cessation of contamination caused by micro silica solid particles, lower cost per building site, high initial and final compressive and tensile strengths, good workability, cessation of super plasticizing utilization and cessation of silicosis risk of concrete.
Nanomaterials used are nano-silica (nano-SiO2), nano-titanium oxide (nano-TiO2), nano-iron (nano-Fe2O3), nano-alumina (nano-Al2O3), nanoclay particles, and nanotubes/nanofibers (CNTs/CNFs) of nano-SiO2.
Nanosilica
Nanosilica is the first nano product that replaced the micro silica and is superior to silica used in conventional concrete. It makes high compressive strengths concretes (15 MPa and 75 MPa at 1 day; 40 MPa and 90 MPa at 28 days and 48 MPa and 120 MPa at 120 days). The advantages are high workability with reduced water/cement ratio with no need of super plasticizing additives. It fills up all the micro pores and micro spaces and saves cement up to 35-45%.
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 sterilizing, deodorizing and to give anti-fouling properties. When added to outdoor building materials, it can substantially reduce concentrations of airborne pollutants. When exposed to UV light, it becomes increasingly hydrophilic, and can be used for anti-fogging coatings or self cleaning glass panes.
Polycarboxylates
Polycarboxylates or polymer based concrete admixtures are high range water reducing admixture. Higher dosage-produces self compacting concrete and this admixture type is very suitable for concrete used in constructions made underwater. They produce high resistance even with low addition up to 1.5 % of the cement weight and gives self compacting characteristics. Resistance to compression is from 40 to 90MPa in 1 day and from 70 to 100 MPa or more in 28 days.
Carbon nanotubes
CNT are highly flexible, mechanically stronger, have stiffest and strongest fibers of cylinders with nanometer diameter, several millimeters in length, 5 times the Young’s modulus and 8 times (theoretically 100 times) the strength of steel whilst being 1/6th the density and  very high thermal conductivity along the axis.


1 Responses to “Smart concrete using nano particles”

Andrei said...
June 2, 2015 at 12:11 AM

Now that is something!!


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