CEE April-June 2012

0 0 NanoTechnology in Cement and Concrete Industry by Yilmaz ERDOGAN R&D Institute Turkish Cement Manufacturers' Association Introduction Human beings have been trying to understand the things that they share togetherness in their common living environment since they started to use their minds. By making use of their sense organs which are excellent analysis mechanisms they collected data about the matter and interpreted these data and finally shaped and used them. After making observations at macro scale, human beings started to force their mind limits and had been in search for more details since then. Why then we limit ourselves at nano scale? Why then we have the border line of 1 o· 9 m? The reason lies in the size of the atom and its nucleus. When the atom is split down, the matter turns into energy. That is why our limit is the wall of the atom. Currently, we have the capability of investigating the matter at nano scale without breaking it down. The nanotechnological methods that are being used in cement and concrete research and industry are reviewed in this paper. Why Nanotechnology? The word nano comes from Greek, meaning "dwarf". As a length unit nanometer is one billionth of a meter. Considering the current methods of material s manufacturing, the sizes of matter involved goes as small as nanometers. The concept of nanotechnology was first pronounced by the famous Nobel Physics Laureate Richard Feynman in his speech entitled 'There is Plenty of Room at the Bottom", in 1959(2,3] . Upon reducing the size of a matter to Carbon, titanium, silver, silicon/silica and zinc are the most common elements that are used in the nano-technologically manufactured substances. Each year, a few Mega tonnes of white titanium pigment, aerosol silica and carbon black are being manufactured by a method know as "Flame Spray Synthesis". Nano view capability We should see the matter in order to deal with it. In other words we should be able to define it and know it properties. To change its properties at nano scale we should be using nano techniques. That is, we have to play the game with "nano rules". Nano things and events can be changed by nano techniques and nano devices. It is now known that the atomi c size is about 10· 10 m; the size of an atomic nucleus is about 10" 14 m; the size of a neutron or a proton within the nucleus is about 1 0" 15 m; the sizes of ~uarks forming the neutrons or protons are about 1 o· 8 m. Mega results of Nano effects The solubility and reactivity of a material can be optimized by adjusting its particle size. Particles reduced to nano sizes will possess novel characteri stics from optical, electrical, and magnetic points of view. We can get plenty of flowers and fruits by pruning the boughes of plants, but when we want to change the colour and smell of flower and to change the taste and size of fruit we must treat the genetic structure, in other words, DNA and chromosome structures at micro and nano levels. Thus, only the modifications we make at molecular level results in great changes. Table-1 nano, its surface area available for processing will increase. The number of surface atoms depends solely on the size of the particle. The surface atoms of a 10 - 20 nm sized particle represent the properties of that particle completely and they have a very high energy. For instance, gold is known as being not reactive with other elements however at nanoscale it was observed that it readily reacts with CO and H2. This is a striking example of how reduction in particle size may lead to significant changes in the properties [2,4]. Distance measurement units and some examples I micron = I x 10· 6 m -t The size of a living cell 80 microns -t Thickness of a human hair I nanometer = I x 10" 9 m -t The size of a chromosome of DNA inside a living cell 10-lo m -t The size of a carbon atom I Picometers = I x 10" 12 m -t The size of the orbits of electrons in atom 10 Picometers -t The huge space inside atom I Fermi= I x 10- 15 m -t The size of a neutron 100 Fermi -t The size of the nuclei of atom 100 Atom Meters = I x 10" 16 m -t Sub-atomic particles 10 .. I