NASTS award 1994
Presentation at the national “Real Advances in Materials” Symposium, Washington DC, Sept. 26,1994
GEOPOLYMERS: Inorganic polymeric new materials
by Joseph Davidovits
published in Journal of Materials Education, Vol. 16 (2,3), pp. 91-138 (1994)
In the aftermath of various catastrophic fires in France between 1970-73, which involved common organic plastic, research on non-flammable and non-combustible plastic materials became my objective. I founded a private research company in 1972, which is today called CORDI-GÉOPOLYMÈRE. In my pursuit to develop new inorganic polymer materials, I was struck by the fact that simple hydrothermal conditions govern the synthesis of some organic plastics and also heat-resistant mineral feldspathoids and zeolites. The scientific and patent literature indicate that, before 1978, the geochemistry that yields the synthesis of zeolites and molecular sieves had not been investigated for producing mineral binders and mineral polymers. I proceeded to develop amorphous to semi-crystalline three-dimension alsilico-aluminate materials, which I call «geopolymers» (mineral polymers resulting from geochemistry). These reactions are of the poly(sialate), poly(sialate-siloxo/ disiloxo) types. Geopolymerization involves a chemical reaction between various alumino-silicate oxides Al3+ in IV-V fold coordination) with silicates, yielding polymeric Si-O-Al-O sialate bonds like the following:
2(Si2O5,Al2O2)+K2(H3SiO4)2+Ca(H3SiO4)2—> (K2O,CaO)(8SiO2,2Al2O3,nH2O)
Geopolymers involved in materials developed for industrial applications, are non-crystalline. Nuclear Magnetic Resonance 27Al and 29Si(MAS-NMR) spectroscopy provide some insight into their molecular frameworks.Other than my archaeological research on ancient cements, my research has been purely industrial. Thus, almost all of the scientific literature concerning geopolymerization is found in the patent literature.
The Industrialization of Geopolymeric Products
Our subsidiary company, GEOPOLYMERE sarl (France), was founded in 1984 in association with my brothers Michel Davidovics and Nicolas Davidovits. Our products include advanced mineral binders that withstand harsh environmental conditions, high temperature stable GEOPOLYMITE® binders and GEOPOLYCERAM® compounds, fireproof carbon/geopolymer composites. Some US Patents are: J. Davidovits US 3,950,470 (1976); 4,349,386 (1982); 4, 472,199 (1984); 4,859,367 (1989); 5,288,321(1994); J. Davidovits and J.J. Legrand US 4,028,045 (1977); N.Davidovits, M. Davidovics and J. Davidovits US 4,888,311 (1989); other patents granted in 1994 or pending. In the USA, LONE STAR INDUSTRIES Inc. began product development in 1983, and in 1988 this company introduced PYRAMENT®, a new class of special blended cements; US Patents: J. Davidovits and J.L. Sawyer US 4,509,985 (1985); R.F. Heitzmann, M. Fitzgerald and J.L. Sawyer US 4,642,137 (1987); R.F. Heitzmann, B.B. Gravitt and J.L. Sawyer US 4,842,649 (1989). In Germany, HÜLS TROISDORF AG began product development in 1982 (Dynamit-NobelAG).
Newly industrialized Geopolymeric Products
In Europe, the multidisciplinary BriteEuram industrial research project GEOCISTEM (see time chart), is preparing to introduce acid-resistant Poly(sialate-siloxo) cements for restoring sites highly contaminated with uranium mining waste (WISMUT sites in former East-Germany). This project also provides new geopolymeric cements that can help address the problem of global warming by reducing 80% of the CO2 emissions produced by the cement industries.
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