11-04-2014, 12:41 PM
30 Years of Successes and Failures in Geopolymer Applications. Market Trends and Potential Breakthroughs.
Successes and Failures in Geopolymer Applications.pdf (Size: 703.49 KB / Downloads: 114)
INTRODUCTION
When, 38 years ago, I received the 1964 annual award from the French Textile Chemical Society
(ACIT) for works performed on linear organic polymers, I did not imagine that the major part of
my scientific career would be conducted outside of the field of organic chemistry. Until 1972, I
had been involved in researches dealing with organic binders for foundries, synthetic textile
fibers, natural and synthetic leather, collagen, and organic membranes.
The quest for low-temperature reactive minerals
In 1972, the ceramicist team J.P. Latapie and M. Davidovics confirmed that water-resistant
ceramic tiles could be fabricated at temperatures lower than 450°C, i.e. without firing. One
component of clay, kaolinite, reacted with caustic soda at 150°C. I learned that the industrial
applications of this kaolinite reaction with alkali began in the ceramic industry with Olsen in
1934 and was, later on, reinvented in 1970 by the Russian team Berg & al., but without any
successful industrial implementation.
Low Temperature Geopolymeric Setting of ceramic, L.T.G.S. (1977-1982)
Low Temperature Geopolymeric Setting (L.T.G.S.) takes place at drying temperatures (50°C to
250°C), in alkaline conditions, through an oligosialate precursor (-Si-O-Al-O-) (Na) in
concentrations from 2 to 6% by weight of the ceramic paste. The kaolinite in clays is
transformed by LTGS into a three dimensional compound of the poly(sialate) Na-PS sodalite
type, stable to water and possessing high mechanical strength (French Patents 2,490,626;
2,528,822) (Fig.5).
MAM-MADE ROCK GEOSYNTHESIS
The Geopolymer Terminology
We showed that naturally occurring alumino-silicates, such as kaolinite, are transformed at low-
temperature, in an astonishingly short time, into tridimensional tecto-aluminosilicates. The
thermosetting method is very similar that used for the polycondensation of organic resins. The
process yields nanocomposites that are actually man-made rocks. This geosynthesis is manifest
in nature itself in great abundance. At least 55% of the volume of the Earth's crust is composed
of siloxo-sialates and sialates, with pure silica or quartz at only 12%. The geosynthesis is based
on the ability of the aluminum ion (6-fold or 4-fold coordination) to induce crystallographical
and chemical changes in a silica backbone.