08-05-2012, 04:06 PM
APPLICATION OF NANOTECHNOLOGY IN CONCRETE TECHNOLPGY
20697169-Paper-Nanotech-in-CONCRETE.pdf (Size: 365.85 KB / Downloads: 321)
ABSTRACT:
Albert Einstein first proved that each molecule measures about a nanometer (a
billion of a meter) in diameter. And in 1959, it was Richard P. Feynman who predicted a
technological world composed of self-replicating molecules whose purpose would be the
production of nano-sized objects. Nanotechnology is one of the most active research areas
that encompass a number of disciplines including civil engineering and construction
materials. Interest in nanotechnology concept for Portland cement composites is steadily
growing. Currently, the most active research areas dealing with cement and concrete are:
understanding of the hydration of cement particles and the use of nano-size ingredients such
as alumina and silica particles.
WHY NANOTECHNOLOGY FOR CONCRETE?
The mechanical behavior of concrete materials depends on structural elements and
phenomena that occur on a micro and a nano scale. As a result, nanotechnology can: modify
the molecular structure of concrete material to improve the material's bulk properties;
improve significantly the mechanical performance, volume stability, durability, and
sustainability of concrete; and have revolutionary effects, allowing the development of costeffective,
high-performance, and long- lasting products and processes for cement and
concrete, within the ideals of sustainable development. In addition, nano-engineering and the
modification of concrete materials can lead to unprecedented uses of concrete materials, as
well as new classifications of concrete, with extensive applications for the concrete
infrastructure of transportation.
DEFINITION OF NANO-CONCRETE
For discussions presented in this paper, nano-concrete is defined as “A concrete made
with Portland cement particles that are less than 500 nano-meters as the cementing agent”.
Currently cement particle sizes range from a few nano-meters to a maximum of about100
micro meters. In the case of micro-cement the average particle size is reduced to 5 micro
meters. An order of magnitude reduction is needed to produce nano-cement.
CONCRETE AND NANOTECHNOLOGY
One can claim that concrete utilizes nanotechnology because it contains nanoparticles
as ingredients including nano-water particles and nano-air voids. However, 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. The scales of various constituent materials of
concrete are shown in Fig c. If we can create chemical or mechanical tools to control nanoscale
pores and the placement of calcium-silicate hydration products then concrete becomes a
product of nanotechnology.