The truth about the geopolymers

The basis for the geopolymers production was drawn up by prof. Kuhl, well known to present day from the introduction of the modulus of clinker lime saturation: M-NLP =100 CaO/2.8SiO(2) + 1.65Al(2)O(3) + 0.70Fe(2)O(3) This Kuhl's formula was lined on the assumption that the best clinker should be composed of C3S, C(3)A and C2F and the mass ratio of CaO in respect to other components is equal adequately: 2.8, 1.65 and 0.70. The analyses of the equilibrium condition in the four components system led Kuhl to the so-called lime criterion, equal to the permissible maximal lime content in clinker, in the conditions far from the equilibrium: M-NLP = 100 CaO/2.8SiO(2) + 1.1Al(2)O(3) + 0.7Fe(2)O(3) However, very little is known about Kuhl's hypothesis, which establishes that the good activators for blast furnace slag are sulphates and the slag activation was applied with lime and anhydrite, for which he obtained German patent: DRP 237777, in the year 1907. This sulphate-slag cement contained 80 - 85% of granulated slag, 10 - 15% of anhydrite and 5% of clinker. It was standardized in France, Great Britain and Germany. Also, Kuhl already in the year 1907, establish the possibility of cement production from slag, activated with sodium hydroxide. Thus Kuhl was the precursor of the geopolymers production. There are many studies of slag activated with the compounds of sodium and potassium. Usually, these compounds are both applicate and from some time the content of potassium silicate became higher. Gluhovsky obtained in 1958 the patent for cement obtained from slag activated with sodium hydroxide. However, the only industrial application of this binder and concrete obtained from, was the construction in 1965 of some houses in Kyiv by Gluhovsky. Gluhovsky introduced also the term geopolymer, which caused the storm of the critic in the former Soviet Union. In these years was in Russia many outstanding experts of the cement chemistry -alumni of Budnikov, for example, Butt and Timachev, and besides also Mchedlov-Petrosian, the organizer of 6th Congress of Cement Chemistry in Moscow, in 1974. Industrial application of geopolymers in Poland is limited to the activity of professor Malolepszy, which used this binder of blast furnace slag activated with NaOH addition to the construction of the students' hotel, in Cracow. It should be also added that there are very few articles about the application of geopolymers for concrete production and, what is the most important, is the shortage of the papers of these binders and concretes, in the construction applications. However, there are many papers about the laboratory studies of geopolymers, activated principally by two compounds NaOH and K2SiO3. Particularly the potassium silicate is in the last time the principal activator because it accelerates the C-S-H phase formation and simultaneously increases the strength of geopolymer.

Automated summary

Professor Kuhl established the foundation for the production of geopolymers, introducing the modulus of clinker lime saturation and lime criterion. His patents in 1907 regarding cement and concrete activation laid the groundwork for the development of geopolymers.