concrete utilizes nanotechnology because it contains nano-particles as ingredients including nano-water particles and nano-air voids.
to claim the use of nanotechnology, we should be able to control the amount and the locations of these nano- ingredients inside the final products.
If we can create chemical or mechanical tools to control nano-scale pores then concrete becomes a product of nanotechnology.
Fig. 3: Scale of various Constituents of concrete. http://www.uwm.edu/~sobolev/ACI/2-Balguru-ACI-F.pdf .
sol-gel method was used to synthesize each component of Portland cement using nano-particles.
sol is a combination of monomers of solvent-soluble or water-soluble polymers along with a precipitator. Once formed, the sol can be transformed into a gel under similar controlled conditions for temperature, pressure, etc.
In this experiment, the hydration rate for each type of tricalcium silicate component are measured.
When the tri- or di- calcium silicates react with water a calcium-silicate-hydrate gel is formed.
This calcium-silicate hydrate (C-S-H) is the principal hydration product and primary binding phase in Portland cement.
4. component was synthesized by dissolving the solid particles in water and mixing the solution by hand with a metal spatula to form a homogenous sol.
heated on a heat plate at 100°C for approximately 30 to 40 minutes .
the samples were placed in crucibles and annealed at 1000°C for 30 min
Finally, the samples were ground to a fine powder using a mortar grinder then placed in glass tubes and sealed with Para Film for protection from moisture
Fig.6:Prepared Nano cement Samples.
15 mL of de-ionized water was placed in a vacuum flask.
1g of cement was added to the water and the flask was covered with a piece of Styrofoam board.
The water and cement were mixed by shaking the flask and the temperature as a function of time was recorded using data acquisition software.
The sampling rate was set at 10 points/second .
Fig.7: Hydration Test Experiment Setup
Cylindrical specimens were prepared using PVC pipe, 1.25 cm in diameter and 2.5 cm in length.
The samples were mixed with water, cast in the PVC pipe molds, and covered with thin glass plates.
cured for one day at room temperature and then for 6 days in a moist curing room.
Following the 7-day curing period, the samples were removed and allowed to dry.
Some specimens fractured during the curing process and therefore, could not be tested.
Load and strain data were recorded using data acquisition software.
The loading rate was set at 0.3 inches/minute
Fig.8:Specimen Prepared for Curing. Fig.9:Fractured Specimen .
Fig.10: Specimen Prepared for Testing .
. Hydration tests indicated that the nano-cement had a more rapid hydration rate than portland cement.
Compressive strength of the cement synthesized using nano-particles was found to be less than that of ordinary portland cement.
It is clear that nanotechnology has changed and will continue to change our vision, expectations and abilities to control the material world.
These developments will definitely affect construction materials.
Large amounts of funds and efforts are being utilized to develop nanotechnology.
Feynman.R “There’s Plenty Of Room” (reprint from speech given at Annual meeting of the West Coast section of the American physical society), Engineering and science , 23, 2008 pp. 22-36.
Drexler, K.E. Peterson.C and Pergamit. G , Unbounding the Future, William Morrow , New York 2007.