`Joseph DAVIDOVITS
Geopolymers
Wikipedia: Joseph Davidovits/Geopolymers
Biography
www.geopolymer.org: Introduction
www.geopolymer.org: Formula
Charles Bremner/The Times Online (December
01, 2006): Pyramids were built with concrete rather than
rocks, scientists claim
Davidovits' US Patents --- List
J. Davidovits: US Patent # 4,349,386 --
Mineral polymers and methods of making them
J. Davidovits: US Patent # 4,472,199
--- Synthetic mineral polymer compound of the
silicoaluminates family and preparation process
J. Davidovits: US Patent # 4,509,985 ---
Early high-strength mineral polymer
Joseph Davidovits
Joseph Davidovits (born 1935) is a French materials scientist who has posited that the blocks of the Great Pyramid are not carved stone, but mostly a form of limestone concrete. He holds the Ordre National du Mérite, is the author and co-author of more than 130 scientifical papers and conferences reports, and holds more than fifty patents.
Theory
Davidovits was not convinced that the ancient Egyptians possessed the tools or technology to carve and haul the huge (2.5 to 15 ton) limestone blocks that made up the Great Pyarmid. Davidovits suggested that the blocks were molded in place by using a form of limestone concrete. According to his theory, a soft limestone with a high kaolinite content was quarried in the wadi on the south of the Giza plateau. It was then dissolved in large, Nile-fed pools until it became a watery slurry. Lime (found in the ash of ancient cooking fires) and natron (also used by the Egyptians in mummification) was mixed in. The pools were then left to evaporate, leaving behind a moist, clay-like mixture. This wet "concrete" would be carried to the construction site where it would be packed into reusable wooden molds. In the next few days the mixture would undergo a chemical hydration reaction similar to the setting of cement.
Using Davidovits theory, no large gangs would be needed to haul blocks and no huge and unwieldy ramps would be needed to transport the blocks up the side of the pyramid. No chiseling or carving with soft bronze tools would be required to dress their surfaces and new blocks could be cast in place, on top of and pressed against the old blocks. This would account for the unerring precision of the joints of the casing stones (the blocks of the core show tools marks and were cut with much lower tolerances). Proof-of-concept experiments using similar compounds were carried out at Davidovit's geopolymer institute in northern France. It was found that a crew of ten, working with simple hand tools, could build a structure of fourteen, 1.3 to 4.5 ton blocks in a couple of days. According to Davidovits the architects possessed at least two concrete formulas: one for the large structural blocks and another for the white casing stones. He argues earlier pyramids, brick structures, and stone vases were built using similar techniques.
His ideas are not accepted by mainstream Egyptologists.
Summary of evidence
Davidovits cites primarily evidence related to his profession as a materials scientist, re-interpreting the observations of conventional Egyptology within this light. Briefly, his points include:
The thin layer of 'mortar' found at the top of casing blocks is actually the the result of settling and water percolating to the top of the block while drying; the layer found would be too weak to bind the massive blocks together
The humidity inside the pyramids is much higher than would be expected in a desert environment; this is caused by the moisture released into the halls and galleries while the blocks cure
The arrangement of fossils within the blocks is jumbled, rather than stratified, pointing to the blocks being crushed, then poured while casting rather deposited in layers as would conventional sedimentary rock
Certain blocks have elongated air pockets, caused by the cement
hardening while air bubbles were in the process of rising to the
top
Ancient descriptions of the pyramids being built featured the
use of short blocks of wood, conventionally seen as levers or
cranes; Davidovits suggests their use as frames to mold the
blocks
Books
Davidovits, Joseph, Margie Morris (1988). The Pyramids: An
Enigma Solved. New York: Dorset Press.
Davidovits, Joseph (1983). Alchemy and the Pyramids. Saint
Quentin, France: Geopolymer Institute.
Davidovits, Joseph (2002). Ils ont Bâti les Pyramides: Les
Prouesses Technologiques des Anciens Egyptiens. Paris: J.-C.
Godefroy.
Davidovits, Joseph (2005). La Bible avait raison, Tome 1:
L’archéologie révèle l’existence des Hébreux en Égypte. Paris:
J.-C. Godefroy.
Davidovits, Joseph (2006). La Bible avait raison, Tome 2: sur
les traces de Moïse et de l’Exode. Paris: J.-C. Godefroy.
Davidovits, Joseph (2006). La nouvelle histoire des pyramides.
Paris: J.-C. Godefroy.
http://www.davidovits.info/
Biography
Background of Joseph Davidovits
International renown French Scientist, born in 1935, working in
France, Europe, USA, Australia and China.
Honored with one of France’s two highest honors, the grade of ”
Chevalier de l’Ordre National du Mérite ” (Nov. 1998).
Discoverer and inventor of the geopolymer chemistry and its
technical applications.
Author and co-author of more than 130 scientifical papers and
conferences, and more than 50 patents.
Archaeology
Joseph Davidovits has also presented different papers and
studies in ceramics, ancient cement and roman concrete in
several congresses in archaeology and archaeometry.
He is mainly well-known by the general public for its theory on
the method of building the pyramids of Egypt with
re-agglomerated stones, say a natural limestone manufactured
like a concrete.
Member of the International Association of Egyptologists, he
presented several conferences on ceramics, blue faience,
cements, pigments, and the analysis of pyramids stones at
several International Congresses of Egyptology in 1979
(Grenoble, France), 1982 (Toronto, Canada), 1988 (Cairo, Egypt),
2004 (Grenoble, France).
Authors of several books:
1988, The Pyramids: An Enigma Solved.
2002, Ils ont bâti les pyramides édition Jean-Cyrille Godefroy,
Paris, ISBN 2-86553-157-0.
2004, La nouvelle histoire des pyramides d’Egypte édition
Jean-Cyrille Godefroy, Paris, ISBN 2-86553-175-9.
2005, La Bible avait raison t.1, l’archéologie révèle
l’existence des Hébreux en Égypte édition Jean-Cyrille Godefroy,
Paris, ISBN 2-86553-182-1.
2006, La Bible avait raison t.2, sur les traces de Moïse et de
l’Exode édition Jean-Cyrille Godefroy, Paris, ISBN
2-86553-190-2.
Education
French Degree in Chemical Engineering.
German Doctor Degree in Chemistry (PhD).
Professor and founder of the Institute for Applied
Archaeological Sciences, IAPAS, Barry University, Miami
,Florida, (1983-1989).
Visiting Professor, Penn State University, Pennsylvania
(1989-1991).
Honorary Professor, Xian Universtity of Architecture and
Technology, China (1999).
1979 to present: Professor and Director of the Geopolymer
Institute , Saint-Quentin, France.
2001 to present: Research Director at CORDI-Géopolymère .
Professional expertise
World expert in Modern and Ancient Cements.
World expert in Geosynthesis and man-made rocks.
Consultant (expert) to the European Union Commission.
Inventor of Geopolymers and the chemistry of Geopolymerization.
Polyglot: English, French, German, Spanish, Latin, Ancient
Greek, Hieroglyphs
Member of the following societies
International Association of Egyptologists
New York Academy of Sciences
American Concrete Institute (former member)
American Chemical Society (former member)
American Ceramic Society (former member)
International Scientific Awards
NASTS Gold Ribbon, awarded at the National Press Club,
Washington DC, Sept. 26, 1994, by the National Academy of
Engineering, The Federation of Materials Societies and the
National Association for Science, Technology and Society.
Honorary Membership awarded by the National Noise Observatory of
the Czech Republic (Narodni Hlukova Observator CR), Prague
(Czech Republic), 04 Nov. 2005
http://www.geopolymer.org/category/archaeology/pyramids/
What is a geopolymer? Introduction
The remarkable achievements made through geosynthesis and geopolymerisation include mineral polymers (geopolymers), flexible ceramics which transform like plastics at low temperatures, ceramic composite made at room temperature or thermoset in a simple autoclave, concrete which after 4 hours has higher strength and durability than the best currently-used concrete. Resulting from this are industrial applications which, while using ceramics as the basic material, no longer need heavy equipment and high temperatures. Geopolymers enable product designers to envisage the use of ceramic type materials with the same facility as some plastics and organic polymers.
The Geopolymer Institute not only coordinates the fundamental research in mineral polymer chemistry, but also promotes applied research made with industrial companies ( see the Proceedings of Géoplymère 2005 ). Because the range of applications is too vast, we only show the most interesting and innovative products. This insight will reveal how geopolymers can improve and change our daily life.
Joseph Davidovits , the inventor and developer of geopolymerization, coined the term “geopolymer” in 1978 to classify the newly discovered geosynthesis that produces inorganic polymeric materials now used for a number of industrial applications. If you want more information go to the Geopolymer Library and download the papers #12 J. Thermal Analysis and #3 NASTS award for scientific information, and #10 From ancient concretes to Geopolymers for general information.
You can also buy online samples of geopolymers to test these products in your laboratory.
http://www.geopolymer.org/category/archaeology/pyramids/
Pyramids (3) The formula, the invention of stone
Why do geologists see nothing?
This is due to the geological glue, which, though artificial,
is seen by the geologists either as an impurity, and therefore
useless to study, or as a natural binder. At best, the analysis
tools and the working methods of geologists consider the glue as
a perfectly natural “micritic binder”. A geologist not informed
of geopolymer chemistry will assert with good faith that the
stones are natural.
The chemical formula:
People think that because we use chemicals, it is very easy to find these ingredients in the final product. This is wrong. Thanks to the geopolymer chemistry, the chemical reaction generates natural elements, minerals that can be analysed as natural if scientists are not aware of their artificial nature.
During geosynthesis kaolinite clay (naturally included in the Giza limestone) first reacts with caustic soda (see chemical formula 2). To manufacture this caustic soda, one uses Egyptian natron (sodium carbonate) and lime (coming from plant ashes) (see chemical formula 1). The so obtained soda will react with clay.
The most interesting point is that this chemical reaction creates also pure limestone (calcite) as well as hydrosodalite (a mineral of the feldspathoids or zeolites family).
But, the mixture is still quite caustic. In order to neutralize it, one adds a special salt called carnallite (magnesium chloride) easily found in evaporites, in saline deposits like natron but not at the same place (see chemical formula 3 and 4).
The re-agglomerated stone binder is the result of this geosynthesis (a geopolymer) that creates several natural minerals: limestone (calcite), hydrated feldspars (feldspathoid, mica-chlorite), magnesite and halite. We understand why geologists can easily be misled.
http://www.timesonline.co.uk/article/0,,13509-2480751,00.html
The Times (December 01, 2006)
Pyramids were built with concrete rather than rocks, scientists claim
Charles Bremner
How the Egyptians really built a Pyramid
The Ancient Egyptians built their great Pyramids by pouring concrete into blocks high on the site rather than hauling up giant stones, according to a new Franco-American study.
The research, by materials scientists from national institutions, adds fuel to a theory that the pharaohs’ craftsmen had enough skill and materials at hand to cast the two-tonne limestone blocks that dress the Cheops and other Pyramids.
Despite mounting support from scientists, Egyptologists have rejected the concrete claim, first made in the late 1970s by Joseph Davidovits, a French chemist.
The stones, say the historians and archeologists, were all carved from nearby quarries, heaved up huge ramps and set in place by armies of workers. Some dissenters say that levers or pulleys were used, even though the wheel had not been invented at that time.
Until recently it was hard for geologists to distinguish between natural limestone and the kind that would have been made by reconstituting liquefied lime.
But according to Professor Gilles Hug, of the French National Aerospace Research Agency (Onera), and Professor Michel Barsoum, of Drexel University in Philadelphia, the covering of the great Pyramids at Giza consists of two types of stone: one from the quarries and one man-made.
“There’s no way around it. The chemistry is well and truly different,” Professor Hug told Science et Vie magazine. Their study is being published this month in the Journal of the American Ceramic Society.
The pair used X-rays, a plasma torch and electron microscopes to compare small fragments from pyramids with stone from the Toura and Maadi quarries.
They found “traces of a rapid chemical reaction which did not allow natural crystalisation . . . The reaction would be inexplicable if the stones were quarried, but perfectly comprehensible if one accepts that they were cast like concrete.”
The pair believe that the concrete method was used only for the stones on the higher levels of the Pyramids. There are some 2.5 million stone blocks on the Cheops Pyramid. The 10-tonne granite blocks at their heart were also natural, they say. The professors agree with the “Davidovits theory” that soft limestone was quarried on the damp south side of the Giza Plateau. This was then dissolved in large, Nile-fed pools until it became a watery slurry.
Lime from fireplace ash and salt were mixed in with it. The water evaporated, leaving a moist, clay-like mixture. This wet “concrete” would have been carried to the site and packed into wooden moulds where it would set hard in a few days. Mr Davidovits and his team at the Geopolymer Institute at Saint-Quentin tested the method recently, producing a large block of concrete limestone in ten days.
New support for their case came from Guy Demortier, a materials scientist at Namur University in Belgium. Originally a sceptic, he told the French magazine that a decade of study had made him a convert: “The three majestic Pyramids of Cheops, Khephren and Mykerinos are well and truly made from concrete stones.”
The concrete theorists also point out differences in density of the pyramid stones, which have a higher mass near the bottom and bubbles near the top, like old-style cement blocks.
Opponents of the theory dispute the scientific evidence. They also say that the diverse shapes of the stones show that moulds were not used. They add that a huge amount of limestone chalk and burnt wood would have been needed to make the concrete, while the Egyptians had the manpower to hoist all the natural stone they wanted.
The concrete theorists say that they will be unable to prove their theory conclusively until the Egyptian authorities give them access to substantial samples.
http://www.amazon.com/Pyramids-Enigma-Solved-Joseph-Davidovits/dp/0880295554
The Pyramids: An Enigma Solved
by
Joseph Davidovits, Margie Morris
Joseph DAVIDOVITS' US Patents
5,925,449 --- Method for bonding fiber
reinforcement on concrete and steel structures and resultant
products
5,798,307 --- Alkaline alumino-silicate geopolymeric
matrix for composite materials with fiber reinforcement and
method for obtaining same
5,539,140 --- Method for obtaining a geopolymeric
binder allowing to stabilize, solidify and consolidate toxic or
waste materials
5,352,427 --- Geopolymeric fluoro-alumino-silicate
binder and process for obtaining it
5,349,118 --- Method for obtaining a geopolymeric
binder allowing to stabilize, solidify and consolidate toxic or
waste materials
5,342,595 --- Process for obtaining a geopolymeric
alumino-silicate and products thus obtained
5,288,321 --- Method for eliminating the
alkali-aggregate reaction in concretes and cement thereby
obtained
4,888,311 --- Ceramic-ceramic composite material and
production method
4,859,367 --- Waste solidification and disposal
method
4,509,985 --- Early high-strength mineral polymer
4,472,199 --- Synthetic mineral polymer compound of
the silicoaluminates family and preparation process
4,349,386 --- Mineral polymers and methods of making
them
4,028,454 --- Process for agglomerating compressible
mineral substances under the form of powder, particles or fibres
4,000,027 --- Process of manufacturing panels
composed of units in, for example, ceramic, assembled by a
thermoplastic material
3,985,925 --- Composite floor coverings
3,950,470 --- Process for the fabrication of sintered
panels and panels resulting from the application of this process
Mineral polymers and methods of making them
September 14, 1982
Joseph Davidovits
Abstract --- New mineral polymers called polysialates have the empiral formula M.sub.n [--(Si--O.sub.2 --).sub.z --Al--O.sub.2 --].sub.n,wH.sub.2 O where z is 1, 2 or 3, M is sodium, or sodium plus potassium, n is the degree of polycondensation, and w has a value up to about 7. The method for making these polymers includes heating an aqueous alkali silico-aluminate mixture having an oxide-mole ratio within certain specific ranges for a time sufficient to form the polymer.
Current U.S. Class: 106/813 ; 106/286.2; 106/286.5;
106/626; 106/638; 264/319; 264/333; 423/328.2; 501/153
Current International Class: C04B 28/00 (20060101); B22C
1/18 (20060101); B22C 1/16 (20060101); C04B 35/63 (20060101)
Field of Search: 423/327-330,118 252/455Z
106/288B,39.5,4R,73.4,85,86,286.2,286.5,74,84 264/299,319,333
U.S. Patent Documents: 3030181 // 3054657
// 3248170 // 3374058 // 3594121
Other References
Barrer et al. "J. Chemical Society", 1959, pp. 195-208, 1956,
pp. 2882-2891. .
Barrer "Trans. Brit. Ceramic Soc." 56, 1957, pp. 155-173..
Description
This invention relates to a mineral polyconcondensation process for making cast or molded products at temperatures generally up to about 120.degree. C. This process is related to processes for making zeolites or molecular sieves. The products of this process, however, have characteristic three-dimensional frameworks which are successions of tetrahedrons TO.sub.4 where T is silicon, aluminum, gallium, phosphorous or the like. These products form channels or voids of regular dimensions when cast or molded. The voids are molecular in size. Accordingly, the polymers can be used to separate organic molecules of different molecular sizes. These structures also exhibit ion exchange properties. Moreover, the products catalyze several different organic polymerization systems.
Numerous patents and other references describe methods for making these synthetic minerals, zeolites and molecular sieves. D. W. Breck's book entitled "Zeolite Molecular Sieves," published by Interscience in 1974, is a good reference. Generally, these methods are hydrothermal synthesis of silico-aluminate gels in strong, highly concentrated aqueous alkali. The reactant mixture, containing a large excess of water, is sealed in a container at constant pressure and temperature. Preferably, the pressure is atmospheric, and the temperature is in the range of about 25.degree. C., to about 120.degree. C. The reaction continues until crystallization of the product occurs. The chemical formula for the resulting synthetic zeolites and molecular sieves may be written as follows:
wherein M is a cation with the valence "n." Many crystalline products have been made in such hydrothermal syntheses. However, these products are very porous, and have poor mechanical properties, even when agglomerated with a binder.
An object of this invention is to provide synthetic mineral products with such properties as hard surfaces (4-6 on the Mohs scale), thermal stability, and high surface smoothness and precision. Such products are useful for tooling, and for molding art objects, ceramics and the like.
Another object is to provide novel three-dimensional mineral polymers.
Another object is to provide a method of making such new three-dimensional polymers.
Other objects such as use of these polymers as binders are apparent from this specification and claims.
The names for these novel three-dimensional polymers are set forth in the following publications: IUPAC International Symposium on Macromolecules, Stockholm in 1976, Topic III; and PACTEC IV, 1979, Society of Plastic Engineers, U.S.A., preprint page 151. These mineral polymers are called polysialates, and have this empiracal formula:
wherein z is 1, 2 or 3; M is a monovalent cation such as potassium or sodium, and n is the degree of polycondensation. Where z is 2, the polysialate has the formula: ##STR1## and is called polysialatesiloxo or PSS for short.
Our new polymers are of the PSS type where M is sodium or a mixture of sodium and potassium. In the latter case, the polymer is called (sodium, potassium) polysialatesiloxo or NaKPSS. The chemical formula of NaKPSS may be written as: ##STR2##
A suitable method for distinguishing our new polymers from known polymers is through their x-ray powder diffraction patterns. NaKPSS has the characteristic x-ray powder diffraction pattern given in Table A below. To obtain this data, we used the Debye-Scherrer method. The radiation used was the K-alpha doublet of copper.
TABLE A ______________________________________ Diffraction Pattern for (Na,K)PSS Interplanar Spacing Relative Intensity (in Angstroms) of the Lines ______________________________________ 11.20 Broad amd blurred 4.30 Middle strong 3.43 Strong 3.29 Strong 3.08 Middle strong 2.97 Middle strong 2.71 Weak 2.46 Weak 2.30 Middle Strong 2.11 Weak 1.92 Very strong 1.81 Middle strong ______________________________________
The x-ray pattern of (Na,K)PSS is related to, but distinctly different from that of natural Gmellinite. Gmellinite is a zeolite with this chemical formula:
Gmellinite is called zeolite "S" in U.S. Pat. No. 3,054,657. The x-ray pattern of zeolite S shows middle strong lines at the interplanar spacings 7.16, 5.03, 4.50, and 4.12 Angstroms. Zeolite S plainly differs greatly from NaKPSS.
As Table B shows, the oxide-mole ratios of the reactant mixtures for these two polymers are completely different:
TABLE B ______________________________________ Oxide-Mole Ratios of the Reactant Mixtures Zeolite S (Na,K)PSS ______________________________________ Na.sub.2 O/SiO.sub.2 0.3 to 0.6 (Na.sub.2 O,K.sub.2 O)/SiO.sub.2 0.25 to 0.28 SiO.sub.2 /Al.sub.2 O.sub.3 6 to 25 SiO.sub.2 /Al.sub.2 O.sub.3 4.0 H.sub.2 O/Na.sub.2 O 18 to 100 H.sub.2 O/(Na.sub.2 O,K.sub.2 O) 16 to 17.5 Na.sub.2 O/Al.sub.2 O 1.80 to 15 (Na.sub.2 O/K.sub.2 O)/Al.sub.2 O.sub.3 1.0 to 1.14 ______________________________________
The method for making NaKPSS comprises preparing a sodium silico-aluminate/potassium silico-aluminate water mixture where the composition of the reactant mixture, in terms of oxide-mole ratios, falls within the ranges shown in table C below.
TABLE C ______________________________________ Oxide-Mole Ratios of the Reactant Mixture (Na.sub.2 O,K.sub.2 O)/SiO.sub.2 0.20 to 0.28 SiO.sub.2 /Al.sub.2 O.sub.3 3.5 to 4.5 H.sub.2 O/(Na.sub.2 O,K.sub.2 O) 15 to 17.5 (Na.sub.2 O,K.sub.2 O)/Al.sub.2 O.sub.3 0.8 to 1.20 ______________________________________
The usual method for preparing this mixture comprises dissolving in water an alumino-silicate oxide, alkali, and a colloidal silica sol or alkali polysilicate. The alumino-silicate oxide (Si.sub.2 O.sub.5,Al.sub.2 O.sub.2).sub.n may be prepared from a polyhydroxy-alumino-silicate having the formula (Si.sub.2 O.sub.5,Al.sub.2 (OH).sub.4).sub.n, where the aluminum cation is in the octahedral state and is in six-fold coordination. The polyhydroxy-alumino-silicate is calcined and dehydroxylated at, say, 550.degree. C. The resulting alumino-silicate oxide has the aluminum cation in four-fold coordination and in a tetrahedral position.
Various polyhydroxy-alumino-silicates may be used as the starting material for the preparation of alumino-silicate oxide, including minerals having basal spacings of about seven Angstroms and having at least one aluminum cation located in the octahedral layers. Examples are alushite, carnat, china clay, lithomarge, neokaolin, parakaolinite, pholenite, endellite, glossecolite, halloysite, milanite, berthierine, fraignotite, grovenite, amesite, and chamoisite.
The quantities of the reactants, namely colloidal silica sol and/or polysilicate, and strong alkalis such as sodium hydroxide and potassium hydroxide, fall in the ranges shown in Table C. Preferably, the ratio (Na.sub.2 O,K.sub.2 O)/Al.sub.2 O.sub.3 is about 1.0 and the ratio SiO.sub.2 /Al.sub.2 O.sub.3 is about 4.0. Higher ratios induce a free alkalinity in the solidified polymer and cause alkali silicate migration which can disturb the physical and mechanical properties of the resulting mineral products. However, if the ratio of sodium oxide and potassium oxide combined to aluminum trioxide is lower than 0.8, and the ratio of silicon oxide to aluminum trioxide is lower than 3.5, the alumino-silicate oxide in excess may not polycondense and will remain as a white powder within the hardened NaKPSS product. Preferably, the oxide-mole ratios should be close to stoichiometric values. The NaKPSS will have a composition expressed in terms of oxides as follows:
where, in the fully hydrated form, w is in the range of about 5 to about 7, x is a value in the range of about 3.5 to about 4.5, y and z have values up to 1, and the sum of y and z is 1.
By contrast, stoichoimetric conditions are not used to make synthetic crystalline zeolites and molecular sieves. The oxide-mole ratios of reactant mixtures for such products are always much higher than stoichoimetric values, as Table B shows.
In the reactant mixture, the quantity of water present equals the sum of solvent water plus the bound water in the reactants. The reactant mixture is viscous, but is not a gel. Rather, the mixture becomes a mineral resin with unique rheological properties after reacting for at least about one hour at ambient temperature, say 25.degree. C.
After aging, the mineral resin may be used alone, or may be mixed with inorganic or organic additives or fillers. The resin may be used as a binder or a mineral cement for organic or mineral particles or fibers. The resin is cast, poured or squeezed into a mold and heated to a temperature up to about 120.degree. C., but preferably to a temperature in the range of about 60.degree. C., to about 95.degree. C. When polycondensation is complete, the solids are separated from the mold and dried at a temperature in the range of about 60.degree. C., to about 100.degree. C.
Polycondensation and heating times are a function of the temperature and the heating process used. At an ambient temperature such as 25.degree. C., polycondensation requires more than 15 hours. At 50.degree. C., polycondensation requires about four hours; at 85.degree. C., about 1.5 hours, and at 95.degree. C., about 0.5 hours. These times may differ and are often shorter when other heating techniques are used. Such other techniques include high frequency, microwave, Joule effect, or electrical wires within the reactant mixture itself. Because the reactant mixtures are polyelectrolytes, these heating techniques effect polycondensation and drying very rapidly. For example, using a microwave heater, the polycondensation described in Example 1 is complete in only 30 seconds, instead of the 1.5 hours required there.
The shelf life of the mineral resin can be as long as two to four hours at ambient temperature depending on the sequence of mixing the reactants. Longer pot life is attained if the strong alkali is not mixed directly with the reactive alumino-silicate oxide. In fact, if the alkalis are added directly to the alumino-silicate oxide solution, the resulting product differs from the polymers of this invention. Direct addition gives a strongly exothermic reaction, and produces a product similar to zeolite A or hydroxysodalite.
Our method of preparing our new polymers comprises making either the alumino-silicate oxide or the sodium and potassium hydroxides. Making of the sodium and potassium hydroxides can be effected by mixing the alkalis in water with polysilicate, and then adding this solution to the alumino-silicate oxide. Preferably, we mix the alumino-silicate oxide with aqueous polysilicate, to the exclusion of alkali, and add this solution to a strong aqueous solution. These two reactant mixtures are stable and retain their reactivity even after long storage periods. Moreover, these mixtures are easy to handle and store.
Polycondensation is best effected in a closed mold under hydrothermal conditions and in the presence of water. Evaporation of water from the mixture during polycondensation is undesirable. To prevent water evaporation at the surface of a reactant mixture placed in an open mold, the surface can be covered with a thin plastic film or thin layer of a hydrophobic liquid. After heating the mixture in the mold, the polycondensed solid is separated from the mold and dried. The molded object has good physical and mechanical properties, including a surface hardness in the range of 3 to 6 Mohs, depending on the nature of the mineral fillers added to the resin. The precision of the molded product's surface compares favorably with the quality obtained with such organic resins as epoxies and polyurethanes.
The following examples illustrate the methods of making the new polymers, and some of the properties of these polymers as well.
EXAMPLE I
We prepared 317 grams of a reactant mixture containing 8.1 moles water, 0.47 moles sodium oxide, 1.65 moles of silicon dioxide, and 0.41 moles of aluminum trioxide. The source of aluminum trioxide is the alumino-silicate oxide prepared by dehydroxylating a natural polyhydoxy-alumino-silicate (Si.sub.2 O.sub.5,Al.sub.2 (OH).sub.4).sub.n. The source of silicon dioxide is this alumino-silicate oxide and an alkali silicate. The source of sodium oxide is sodium hydroxide. The oxide molar ratios in the reactant mixture are shown in Table D.
TABLE D ______________________________________ Na.sub.2 O/SiO.sub.2 0.28 SiO.sub.2 /Al.sub.2 O.sub.3 4.02 H.sub.2 O/Na.sub.2 O 17.20 Na.sub.2 O/Al.sub.2 O.sub.3 1.14 ______________________________________
The reactant mixture, which had the viscosity of a resin, was aged for a period of one hour at ambient temperature, then placed under vacuum to eliminate air and gas bubbles. The outgassed resin was poured into a urethane mold to reproduce the relief of a medal.
The surface of the resin in contact with the atmosphere was covered with a thin polyethylene film to prevent water evaporation during curing, which was effected at 85.degree. C., in an oven over a period of 1.5 hours.
The hardened mineral product was separated from the mold and dried at 85.degree. C. It reproduced the mold surface with all original details of the mold surface intact. The density of the product was 1.4 grams per milliliter, and its hardness was 3-4 (Mohs scale). The product was white and porous, and its external dimensions indicated that the polycondensation took place without any shrinkage or dilation of the material. Chemical analysis of the mineral product gave this molar composition:
which corresponds to the formula of (Na)PSS ##STR3## which has an x-ray diffraction pattern essentially that shown in Table A.
Materials from which the mold may be made include iron, paper, wood and plastics, indeed all materials except aluminum and copper. Even aluminum and copper molds can be used if they are covered with a thin layer of organic resin.
EXAMPLE II
Following the steps described in Example I, we prepared 296 grams of reactant mixture containing 7.5 moles of water, 0.33 moles of sodium oxide, 0.08 moles of potassium oxide, 1.65 moles silicon dioxide, and 0.41 moles of aluminum trioxide. The source of potassium oxide was anhydrous KOH. The oxide-mole ratios of the reactant mixture are set forth in Table E.
TABLE E ______________________________________ (Na.sub.2 O,K.sub.2 O)/SiO.sub.2 0.25 SiO.sub.2 Al.sub.2 O.sub.3 4.02 H.sub.2 O/(Na.sub.2 O,K.sub.2 O) 17.30 Na.sub.2 O/Al.sub.2 O.sub.3 0.8 (Na.sub.2 O,K.sub.2 O)/Al.sub.2 O.sub.3 = 1.0 K.sub.2 O/Al.sub.2 O.sub.3 0.2 ______________________________________
The reactant mixture, which had the viscosity of a resin, was aged for one hour at ambient temperature (25.degree. C.). To this aged mineral resin we added 280 grams of fine white mullite with a size range between 100 and 150 microns. We poured this mixture into the same mold used in Example I.
After polycondensation in the mold at 85.degree. C., for 1.5 hours, and following the drying conditions described in Example I, the cured mineral medal had a density of 1.8 grams per milliliter. The diameter of the product was 85.8 millimeters. (The mold's diameter at 25.degree. C. was just 85.4 millimeters. However, the mold had diameter of 85.08 millimeters at the 85.degree. C., molding temperature.) Apparently, the cured mineral polymer had the same diameter as the heated mold.
The molded product had a surface hardness of five on the Mohs scale, and the reproduction of the medal surface from the mold was very exact.
Chemical analysis of the mineral product gave a mixture of mullite and (Na,K)PSS with a molar composition as follows:
The x-ray powder diffraction pattern is a mixture of the lines characteristic of crystalline mullite and of NaKPSS as set forth in Table A.
Thermogravimetric analysis of NaKPSS gave two endothermic peaks, the first between 150.degree. C., and 200.degree. C., the second between 320.degree. C., and 370.degree. C. The first peak corresponds to the loss of "zeolitic water," amounting to about 9% by weight of the fully hydrated polymer. The second peak corresponds to the loss of hydroxyl groups constituting about 12% by weight of the fully hydrated polymer.
The pH of the fully hydrated NaKPSS is about 10 to 10.5, which means that the polymer was free from excess alkali. However, as with other zeolitic materials, the sodium and potassium cations may migrate in the presence of water. This effect vanishes if the NaKPSS is heated to a temperature higher than the second endothermic peak of the thermogravimetric analysis, or higher than 370.degree. C. After this postcuring at a temperature above 370.degree. C., the sodium and potassium cations do not migrate in the presence of water.
Full dehydration and dehydroxylation of NaKPSS transforms a mineral polymer into a product having properties like ceramic materials. Its formula ##STR4## corresponds to the molar composition
where x has a value in the range of about 3.5 to about 4.5, and y and z have values up to 1 such that the sum of y and z is 1.
EXAMPLE III
We mixed one kilogram of foundry sand with 50 grams containing 5% by weight of the mineral resin prepared according to Example II. The resulting sand/resin mixture was pressed into two molds. One mold was thermoset at 85.degree. C., for a period of 1.5 hours; the second mold was cured at ambient temperature for 15 hours. We obtained two cores suitable for foundry use in which the sand was bound with the mineral polymer having the following molar composition:
This molar composition corresponds to the molar composition of NaKPSS.
Synthetic mineral polymer compound of the silicoaluminates family and preparation process
Joseph Davidovits
September 18, 1984
Abstract --- A mineral polymer of the silicoaluminate family has a composition expressed in terms of oxides as follows: where, in the fully hydrated form, "w" is a value at the most equal to 4, "x" is a value in the range of about 4.0 to about 4.2, and "y" is a value in the range of about 1.3 to about 1.52. These mineral polymers are solid solutions which comprise one phase of a potassium polysilicate having the formula: and one phase of a potassium polysialate polymer having the following formula: ##STR1## where "n" is the degree of condensation of the polymer.
Current U.S. Class: 106/813 ; 106/286.2; 106/286.5;
106/600; 106/638; 264/319; 264/333; 423/328.2; 501/153
Current International Class: C04B 12/00 (20060101); C01B
33/00 (20060101); C04B 35/63 (20060101); C01B 33/26 (20060101)
Field of Search: 423/118,327-330 264/299,313,333
106/288B,85,86,286.2,286.5 252/455Z 501/1,80,153 502/60
U.S. Patent Documents: 2972516 // 3012853 // 3056654 //
4349386
Other References:
"IUPAC International Symposium on MacroMolecules", Stockholm
1976, Topic III. .
"PACTECIV", Society of Plastic Engineers, U.S.A. preprint pp.
151-154. .
Chemical Abstract 86:19049v, Synthetic Kaliophilite, Zhukova, R.
S.; Begletsov, V. V., (USSR), Khim Tekrol, (Kiev), 1976, (3),
63-4. .
Barrer, R. M. "Some Researches on Silicates: Mineral Syntheses
and Metamorphoses", Transactions of the British Ceramic Soc.,
vol. 56, No. 4, pp. 155-173, 1957..
Description
This invention relates to a mineral polycondensation process for making cast or molded products at temperatures generally up to about 120.degree. C. This process is related to processes for making zeolites or molecular sieves.
The products of such processes, however, have characteristic three-dimensional frameworks which are successions of tetrahedrons TO.sub.4, where T is silicon, aluminum, gallium, phosphorous or the like. Those products form channels or voids of regular dimensions. The voids are molecular in size. Accordingly, the mineral frameworks can be used to separate organic molecules of different molecular sizes. Those structures also exhibit ion exchange properties. Moreover, those products catalyze several different organic polymerization systems.
Numerous patents and other references describe methods for making those synthetic minerals, zeolitics and molecular sieves. D. W. Breck's book entitled, "Zeolite Molecular Sieves," published by Interscience in 1974, is a good reference. Generally, those methods are hydrothermal syntheses of silico-aluminate gels in strong, highly concentrated aqueous alkali. The reactant mixture, containing a large excess of water, is sealed in a container at constant pressure and temperature. Preferably, the pressure is atmospheric, and the temperature is in the range of about 25 C. to about 125.degree. C. The reaction continues over more than ten hours until crystallization of the products occurs. The chemical formula for the resulting synthetic zeolites and molecular sieves may be written as follows:
wherein M is a cation with a valence "n." Many crystalline products have been made in such hydrothermal syntheses. However, these products are very porous and have poor mechanical properties, even when agglomerated with a binder. I have discovered that when reaction conditions do not favor crystallization or crystal formation, I obtain novel products.
An object of this invention is to provide synthetic mineral products with such properties as hard surfaces (5-7 on the Mohs scale), thermal stability and high surface smoothness and precision. Such products are useful for tooling, and for molding art objects, ceramics and the like, and building materials.
The main object is to provide a novel mineral polymer, more precisely a novel mineral polymer compound, and to provide a method of making a new mineral polymer compound.
Other objects such as use of this mineral polymer compound as a binder are apparent from this specification and claims.
The names for these novel three-dimensional polymers are set forth in the following publications: "IUPAC International Symposium on Macromolecules," Stockholm, 1976, Topic III; and "PACTEC IV,", Society of Plastic Engineers, U.S.A., preprint page 151. These mineral polymers are called polysialates and have this empirical formula:
wherein "z" is 1, 2 or 3; M is a monovalent cation such as potassium or sodium, and "n" is the degree of polycondensation. Where "z" is 1, the mineral polymer has this formula: ##STR2## and is called polysialate or PS for short.
Our new polymer is of the K--PS polymer compound type where "M" is potassium.
A suitable method for distinguishing our new polymers from known polymers is through their X-ray powder diffraction pattern. K--PS polymer compound has the characteristic x-ray powder diffraction pattern given in Table A below. To obtain this data, we used the Debye-Scherrer method. The radiation used was the K-Alpha doublet of copper.
The X-ray pattern of K--PS is related to that of natural kaliophilite (KAlSiO.sub.4), which corresponds to the general formula of polysialate. This natural mineral is not a zeolite, but an anhydrous feldspathoid with the formula: ##STR3## where "w" is a value in the range of 0 to 1.
This distinction is very important. Mineral polymers containing zeolitic water must be dehydroxylated at a temperature up to about 400.degree. C. if they are to be used without damage at higher temperature. On the contrary, mineral polymers of the kaliophilite type will resist thermal shock. Thermal shock resistance is a fast test for distinguishing a zeolitic framework from a feldspathoidic one.
Mineral polymer polysialates K--PS have this chemical formula:
The method of making K--PS comprises preparing a reactant mixture in which the oxide-mole ratios are higher than stoichiometric values. For example, the ratio SiO.sub.2 /Al.sub.2 O.sub.3 is in the range of 3.3 to 4.5, instead of 2. These conditions differ from those used in a process of making synthetic (Na, K) Poly(Sialate-Siloxo) or (Na, K)--PSS mineral polymers which are described in French patent application No. 79.22041, and have this empirical formula: ##STR4##
In French application No. 79.22041 and corresponding U.S. patent application Ser. No. 182,571, filed Aug. 29, 1980, now U.S. Pat. No. 4,349,386 the oxide-mole ratios used for making (Na, K)--PSS fall in the range of:
______________________________________ (Na.sub.2 O, K.sub.2 O)/SiO.sub.2 0.20 to 0.28 SiO.sub.2 /Al.sub.2 O.sub.3 3.5 to 4.5 H.sub.2 O/(Na.sub.2 O, K.sub.2 O) 15 to 17.5 (Na.sub.2 O, K.sub.2 O)/Al.sub.2 O.sub.3 0.8 to 1.20 ______________________________________
TABLE A __________________________________________________________________________ Zeolite Z Zeolite G Zeolite W Kaliophilite (K)-PS __________________________________________________________________________ KAlSiO.sub.4,3H.sub.2 O KAlSi.sub.2 O.sub.6,5H.sub.2 O K.sub.5 Al.sub.5 Si.sub.9 O.sub.28,25H.sub.2 O KAlSiO.sub.4 ##STR5## d(A) I d(A) I d(A) I d(A) I d(A) I -- 9.47 mS 9.99 20 10 halo 10-11.5 halo -- -- 8.17 49 -- -- 7.45 VVS -- 7.09 54 -- -- -- 6.90 m -- -- -- -- 5.22 m 5.34 28 -- -- 4.78 vw -- 5.01 56 -- -- -- -- 4.45 21 4.49 35 4.49 m -- 4.32 S 4.28 35 4.28 40 4.27 w -- 3.97 mS -- -- -- -- 3.70 w 3.64 20 -- 3.47 m 3.46 S -- 3.52 35 3.52 m 3.29 m -- 3.25 100 3.32 35 3.33 S 3.09 VS 3.11 mw 3.17 75 broad band 3.23 halo 2.97 S 2.93 VVS 2.95 71 3.10 100 to 2.82 VS 2.80 w 2.72 53 broad band 2.79 -- 2.59 S 2.54 26 2.61 45 2.56 w 2.35 s 2.29 S 2.40 8 2.24 20 2.25 vw 2.20 w 2.19 mS 2.18 10 2.13 37 2.17 vw __________________________________________________________________________
However, if the reactant mixture is exclusively composed of a potassium polysilicate, potassium hydroxide (KOH) and alumino-silicate oxide (Si.sub.2 O.sub.5, Al.sub.2 O.sub.2).sub.n, then the mineral polymer produced is not (Na, K)--PSS. The X-ray powder diffraction pattern and the thermogravimetric analysis are different. The X-ray patterns of (Na, K)--PSS are related to those of natural analcime, gismondine, gmelinite and phillipsite, whereas the polymer obtained here is amorphous. Thermogravimetric analysis of this polymer gave a loss of water amounting to 5% by weight up to 325.degree. C., the weight remaining constant for higher temperature. By contrast, thermogravimetric analysis of (Na, K)--PSS gave a loss of water in the range of 21% to 29% by weight between 100.degree. C. and 500.degree. C. This polymer does not exhibit zeolitic properties. It is brittle, but hard: 5 on the Mohs scale.
A synthetic kaliophilite KAlSiO.sub.4.0.1H.sub.2 O has been prepared by H. Besson, S. Caillere and S. Henin (Comptes Rendue Academie des Sciences de Paris, Vol. 272, Series D, pp. 2749-2752 (1971)), using silico-aluminate gels and potassium carbonate (K.sub.2 CO.sub.3). The X-ray pattern of this anhydrous synthetic kaliophilite is given in Table A. Its pattern is related to that of K--PS, but shows a strong line at 3.10 Angstroms, accompanying the broad line at 2.79 to 3.23 Angstroms. Table A also gives X-ray patterns of synthetic zeolites related to the polymer K--PS, such as zeolite Z (or zeolite KF), zeolite G (or zeolite K--G), and zeolite W (or zeolite K--M, K--H). These patterns are given in D. W. Breck's book cited above.
Table B shows the oxide-mole ratios of the reactant mixture used for the synthetic zeolites from Table A.
TABLE B ______________________________________ Zeolite Kalio- Zeolite Z Zeolite G W philite K-PS ______________________________________ K.sub.2 O/SiO.sub.2 0.425 0.50 0.6 Excess 0.26 to 0.36 SiO.sub.2 /Al.sub.2 O.sub.3 4 5 6 2 to 4 4 to 4.2 H.sub.2 O/Al.sub.2 O.sub.3 Excess Excess 75 Excess 12.5 to 23 K.sub.2 O/Al.sub.2 O.sub.3 1.7 2.5 3 Excess 1.12 to 1.6 ______________________________________
The method for making K--PS polymeric compound comprises preparing a potassium silico-aluminate/water mixture where the composition of the reactant mixture, in terms of oxide-mole ratios, falls within the ranges shown in Table C below.
TABLE C ______________________________________ Oxide-Mole Ratios of the Reactant Mixture ______________________________________ K.sub.2 O/SiO.sub.2 0.25 to 0.48 SiO.sub.2 /Al.sub.2 O.sub.3 3.3 to 4.5 H.sub.2 O/Al.sub.2 O.sub.3 10 to 25 K.sub.2 O/Al.sub.2 O.sub.3 0.9 to 1.6 ______________________________________
The usual method for preparing this mixture comprises dissolving in water an alumino-silicate oxide, KOH, and a potassium polysilicate. The alumino-silicate oxide (Si.sub.2 O.sub.5, Al.sub.2 O.sub.2).sub.n may be prepared from a polyhydroxy-alumino-silicate having the formula (Si.sub.2 O.sub.5, Al.sub.2 (OH).sub.4).sub.n, where the aluminum cation is in the octahedral state and is in six-fold coordination. The polyhydroxy-alumino-silicate is calcined and dehydroxylated at, say, between 550.degree. C. and 800.degree. C. The resulting alumino-silicate oxide has the aluminum cation in four-fold coordination and in a tetrahedral position.
Various polyhydroxy-alumino-silicates may be used as the starting material for the preparation of alumino-silicate oxide, including minerals having basal spacings of about seven Angstroms and having at least one aluminum cation located in the octahedral layers. Examples are alushite, carnat, china clay, lithomarge, neokaolin, parakaolinite, pholenite, endellite, glossecolite, halloysite, milanite, berthierine, fraignotite, grovenite, amesite and chamoisite.
The silico-aluminate mineral polymer compound obtained by polycondensation of a reactant mixture as given in Table C, will have a composition expressed in terms of oxides as follows:
where, in the fully hydrated form, "w" is a value at the most equal to 4, "x" is a value in the range of about 3.3 to about 4.5, and "y" is a value in the range of about 0.9 to 1.6.
The mineral polymer compound is a solid solution which comprises 35 to 90 parts by weight of a potassium polysilicate (y-1)K.sub.2 O:(x-2)SiO.sub.2 :(w-1)H.sub.2 O and 10 to 65 parts by weight of the mineral polymer K--PS, which has the formula: ##STR6## and an X-ray pattern related to that of the natural mineral kaliophilite as shown in Table A.
The quantities of the reactants, namely potassium polysilicate, alumino-silicate oxide and potassium hydroxide, fall in the ranges shown in Table C. Preferably, the ratio (K.sub.2 O)/Al.sub.2 O.sub.3 is in the range of about 1.3 to 1.52, and the ratio SiO.sub.2 /Al.sub.2 O.sub.3 is in the range of about 4.0 to 4.2. Higher ratios induce a free potassium silicate phase in the solidified polymer compound, and cause potassium silicate migration which can disturb the physical and mechanical properties of the resulting mineral products. If the ratio of potassium oxide to aluminum trioxide is lower than 1.1, and the ratio of silicon dioxide to aluminum trioxide is lower than 3.7, the solidified polymer compound will have numerous cracks, and cannot be used in the fabrication of molded objects.
By contrast, the oxide-mole ratios of reactant mixtures for synthetic crystalline zeolites Z, G and W are always much higher than the values for the K--PS polymer compound, as Table B shows. In particular, water is employed in large excess, and the K.sub.2 O quantities are much higher.
In the reactant mixture, according to Table C, the quantity of water present equals the sum of solvent water plus the bound water in the reactants. The reactant mixture is viscous, but is not a gel. Rather, the mixture becomes a mineral resin with unique rheological properties after reacting for at least about one hour at ambient temperature, say 25.degree. C.
After aging, the mineral resin may be used alone, or may be mixed with organic or inorganic additives or fillers. The resin may be used as a binder or a mineral cement for organic or mineral particles or fibers. The resin is cast, poured, squeezed or vibrated into a mold and heated to a temperature up to about 120.degree. C., but preferably to a temperature in the range of about 60.degree. C. to about 95.degree. C. When polycondensation is complete, the solids are separated from the mold and dried at a temperature up to about 100.degree. C.
Polycondensation and heating times are a function of the temperature and the heating process used. At an ambient temperature, such as 25.degree. C., polycondensation requires more than 15 hours. At 50.degree. C., polycondensation requires about four hours; at 85.degree. C., about 1.5 hours; and at 95.degree. C., about 0.5 hours. These times may differ, and are often shorter when other heating techniques are used. Such other techniques include high frequency, microwave, Joule effect or electrical wires within the reactant mixture itself. Because the reactant mixtures are polyelectrolytes, these heating techniques effect rapid polycondensation and drying.
The pot life of the mineral resin can be as long as two to four hours at ambient temperature depending on the sequence of mixing the reactants. Longer pot life is attained if the potassium hydroxide is not mixed directly with the reactive alumino-silicate oxide solution. In fact, if the alkali is added directly to the alumino-silicate oxide solution, the resulting product differs from the polymers of this invention.
The method of preparing our new mineral polymer compound comprises masking either the alumino-silicate oxide or the potassium hydroxide. Masking of the potassium hydroxide can be effected by mixing the alkali in water with polysilicate, and then adding this solution to the alumino-silicate oxide. Preferably, we mix the alumino-silicate oxide with aqueous polysilicate, to the exclusion of alkali, and add this solution to a strong aqueous potassium hydroxide solution. These two reactant mixtures are stable and retain their reactivity even after long storage periods. Moreover, these mixtures are easy to handle and store.
Polycondensation is best effected in a closed mold under hydrothermal conditions and in the presence of water. Evaporation of water from the mixture during polycondensation is undesirable. To prevent water evaporation at the surface of a reactant mixture placed in an open mold, the surface can be covered with a thin plastic film or thin layer of a hydrophobic liquid. After heating the mixture in the mold, the polycondensed solid is separated from the mold and dried. The molded object has good physical and mechanical properties, including a surface hardness in the range of 5 to 7 Mohs, depending on the nature of the mineral fillers added to the resin. The precision of the molded product's surface compares favorably with the quality obtained with such organic resins as epoxies and polyurethanes.
The following examples illustrate the methods of making the new K--PS polymer compound and some of its properties.
EXAMPLE 1
We prepared 860 grams of a reactant mixture containing 11.33 moles water, 1.630 moles potassium oxide, 4.46 moles of silicon dioxide and 1.081 moles of aluminum trioxide. The source of aluminum trioxide is the alumino-silicate oxide prepared by dehydroxylating a natural polyhydroxy-alumino-silicate (Si.sub.2 O.sub.5, Al.sub.2 (OH).sub.4).sub.n. The source of silicon dioxide is this alumino-silicate oxide and a potassium silicate. The source of potassium oxide is this potassium silicate and potassium hydroxide. The oxide-mole ratios in the reactant mixture are shown in Table D.
TABLE D ______________________________________ K.sub.2 O/SiO.sub.2 0.36 SiO.sub.2 /Al.sub.2 O.sub.3 4.12 H.sub.2 O/Al.sub.2 O.sub.3 16.03 K.sub.2 O/Al.sub.2 O.sub.3 1.51 ______________________________________
The reactant mixture, which had the viscosity of a resin, was aged for a period of one hour at ambient temperature (25.degree. C.), then placed under vacuum to eliminate air and gas bubbles. The outgassed resin was poured into a mold.
The surface of the resin in contact with the atmosphere was covered with a thin polyethylene film to prevent water evaporation during curing, which was effected at 85.degree. C. in an oven over a period of 1.5 hours.
The hardened mineral product was separated from the mold and dried at 85.degree. C.
The density of the product was 1.7 grams per milliliter, and its hardness was 4.5 on the Mohs scale. The product was white and low in porosity. Physico-chemical analysis of the mineral product gave this molar composition:
which corresponds to the formula of a polymer compound. This polymer compound contains, in a solid solution, one phase of a potassium polysilicate which corresponds to the formula:
and one K--PS which corresponds to the formula: ##STR7## The X-ray powder diffraction pattern is essentially that shown for K--PS in Table A. To obtain this data, we used the Debye-Scherrer method, K-Alpha of doublet copper, in a 57.3 mm chamber.
The product obtained had many cracks in it. If at least one mineral filler is added to the reactant mixture after, during or even before aging, these cracks disappear. The mechanical and physical properties of the molded objects obtained following this process are excellent. Tensile strength is about 180 kg/cm.sup.2, hardness may reach 7 on the Mohs scale, and linear dilatation coefficient, as a function of temperature, is in the range of 2 to 5.times.10.sup.-6 m/m/.degree.C.
EXAMPLE 2
Following the steps described in Example 1, we prepared 960 grams of a reactant mixture containing 22.88 moles of water, the other components being unchanged. The oxide-mole ratios of the reactant mixture are set forth in Table D, except H.sub.2 O/Al.sub.2 O.sub.3 which was 21.
The fluid reactant mixture was aged for one hour at ambient temperature. Then we added 640 grams of synthetic cordierite (with mullite), with a size range lower than 120 microns. The viscous mixture was poured into a mold and hardened at 85.degree. C. The product had a density of 2.3 grams per milliliter and a surface hardness of 5 on the Mohs scale. Its external dimensions indicated that polycondensation took place without any shrinkage.
X-ray diffraction was determined by a different technique, plotting the theta/2 curve under cobalt emission at 1.79 Angstroms. The pattern showed the very strong lines of cordierite and the middle strong lines of mullite, weak lines at 4.49/4.28/3.53/2.59/2.28/2.16 Angstroms and a broad line between 3.38 and 2.80 Angstroms, which is covered with the strong lines of cordierite. This X-ray diffraction pattern is identical to that of K--PS shown in Table A.
EXAMPLE 3
Following the steps described in Example 1, we prepared 792 grams of a reactant mixture containing 13.5 moles of water, the other components being unchanged. The oxide-mole ratios of the reactant mixture are set forth in Table D, except H.sub.2 O/Al.sub.2 O.sub.3 which was 12.5.
The fluid reactant mixture was aged for one hour at ambient temperature. Then we added 540 grams of synthetic cordierite (with mullite), with a size range lower than 120 microns, and we followed the steps described in Example 2.
We determined the X-ray diffraction pattern by the same technique as in Example 2 and obtained the same lines for K--PS, plus weak lines at 3.24/2.95/2.88/2.82 Angstroms. These are in the broad amorphous band for K--PS, namely between 2.79 and 3.23, cited in Table A.
The ratios H.sub.2 O/Al.sub.2 O.sub.3 may vary from 10 to 25. Preferably, the ratio is in the range of 14 to 20. Higher ratios increase the porosity of the solidified product. Lower ratios induce a free alkalinity and cause migrations which can disturb the potassium silicate phase in the solid solution of the polymer compound. Preferably, the oxide-mole ratios of the reactant mixture fall within the range in Table E below.
TABLE E ______________________________________ K.sub.2 O/SiO.sub.2 0.30 to 0.38 SiO.sub.2 /Al.sub.2 O.sub.3 4.0 to 4.20 H.sub.2 O/Al.sub.2 O.sub.3 14 to 20 K.sub.2 O/Al.sub.2 O.sub.3 1.3 to 1.52 ______________________________________
EXAMPLE 4
Following the steps described in Example 1, we prepared 860 grams of a reactant mixture and added 220 grams of muscovite with a size range lower than 120 microns and 90 grams of calcium fluoride (CaF.sub.2) in fine powder form. We obtained a viscous resin which we mixed with 1,150 grams of zircon sand. The resulting zircon sand/resin mixture was cast and vibrated in a mold, then heated at 85.degree. C. for a period of 1.5 hours. The dried product had a density of 3.0 grams per milliliter. It was shiny and had a surface hardness of 6 on the Mohs scale.
Interpretation of the X-ray diffraction pattern is not easy. The strong lines of zircon and calcium fluoride and the numerous lines of muscovite cover practically all the lines of K--PS.
EXAMPLE 5
Following the steps described in Example 1, we prepared a reactant mixture. After aging, the resin was painted on a mold which was the negative of a sculpture. During the same period, we mixed five kilograms of flint with a size range from 0.5 to 5 mm, with 0.5 kilograms, or 10% by weight of the resin. This mixture was cast and vibrated in the painted mold. The mold was covered with a polyethylene film and cured at ambient temperature (25.degree. C.). Next day, we obtained a sculpture which was separated from the mold and had a very fine, hard and shiny surface.
We have used the potassium silico-aluminate reactant mixtures described above in order to make molded objects obtained by the agglomeration of 5 to 95 parts by weight of mineral and/or organic fillers, with 5 to 95 parts by weight of a binder which is a mineral polymer compound. This mineral polymer compound has a formula with a molar composition as follows:
where, in the fully hydrated form, "w" is a value at the most equal to 4, "x" is a value in the range of about 3.3 to about 4.5, and "y" is a value in the range of about 0.9 to about 1.6.
This mineral polymer compound is a solid solution which comprises 35 to 90 parts by weight of a potassium polysilicate with the formula:
and 10 to 65 parts by weight of a potassium polysialate with the formula: ##STR8## and having an X-ray powder diffraction pattern related to the natural mineral kaliophilite, as shown in Table A for K--PS.
Molded objects with high thermal shock resistance were obtained by addition of fillers such as muscovite, synthetic or natural alumino-silicate, zircon, chamotte and other ceramics or refractory products.
The molded objects resist the direct action of a flame and may be used at temperatures in the range of 300.degree. C. to 1,200.degree. C. Preferably, they are first dried and dehydrated at a temperature below 350.degree. C. Dehydration and dehydroxylation of the mineral polymer compound transforms the molded object into a product having excellent thermal stability properties equivalent to or better than ceramic materials. Its composition expressed in terms of oxides is as follows:
where "x" has a value in the range of about 3.3 to about 4.5, and "y" has a value in the range of about 0.9 to about 1.6. These polymer compounds are solid solutions comprising one phase of a potassium polysilicate with the formula:
and one phase of a K--PS polysialate with the formula: ##STR9##
The potassium silico-aluminate reactant mixture described above becomes a mineral resin which can be mixed with at least one mineral and/or organic filler, and used as a binder or cement. These mixtures may also include such additives and fillers as dyestuffs, pigments, reinforcement fibers and water-repelling agents. Polycondensation and setting occur in the range of room temperature up to 120.degree. C.
Molded objects of this invention have many uses, depending on the physical, mechanical or chemical properties required. They can be used in industries such as the building industry and may also be used as decoration, taking the form of objects, molds, tools, blocks and panels.
These molded objects may support several physicochemical, physical or mechanical post-treatments, as well as finishing or coating operations. If necessary, the molded objects can be heated to a temperature of at least 325.degree. C. One obtains ceramic-like products having excellent thermal and dimensional stability.
Early high-strength mineral polymer
Davidovits , et al.
April 9, 1985
Abstract --- An early high-strength mineral polymer composition is formed of a polysialatesiloxo material obtained by adding a reactant mixture consisting of alumino-silicate oxide (Si.sub.2 O.sub.5,Al.sub.2 O.sub.2) with the aluminum cation in a four-fold coordination, strong alkalis such as sodium hydroxide and/or potassium hydroxide, water, and a sodium/potassium polysilicate solution; and from 15 to 26 parts, by weight, based upon the reactive mixture of the polysialatesiloxo polymer of ground blast furnace slag. Sufficient hardening for demolding is obtained in about 1 hour with this composition.
Assignee: Pyrament Inc. (Houston, TX)
Current U.S. Class: 106/624
Current International Class: C04B 14/02 (20060101); C04B
14/04 (20060101); C04B 28/00 (20060101); C04B 28/26 (20060101)
BACKGROUND OF THE INVENTION
The present invention is directed to a mineral polymer composition which is employed for the making of cast or molded products at room temperatures, or temperatures generally up to 248.degree. F., where the composition has attained sufficient strength to be demolded within 90 minutes of casting or molding. These high early-strength compositions are obtained by the blending of a mineral geopolymer, referred to as a polysialate, blast furnace slag, obtained from the making of iron in a blast furnace and possibly, an inert filler.
The mineral geopolymers are called polysialates, and have the following empirical formula:
wherein "z" is 1, 2 or 3; "M" is a monovalent cation such as potassium or sodium, and "n" is the degree of polycondensation. Where "z" is 1, the mineral geopolymer has the formula: ##STR1## and is called polysialate or PS for short, and is of the K-PS polymer compound type when "M" is potassium. Where "z" is 2, the mineral geopolymer has the formula: ##STR2## and is called polysialatesiloxo or PSS for short. When "M" is sodium or a mixture of sodium and potassium, the geopolymer is called (sodium, potassium)polysialatesiloxo or NaKPSS. The chemical formula of NaKPSS may be written as: ##STR3##
The method for making NaKPSS or KPS is described in U.S. Pat. No. 4,349,386 and U.S. application Ser. No. 377,204. It comprises preparing a sodium silico-aluminate/potassium silico-aluminate water mixture where the composition of the reactant mixture, in terms of oxide-mole ratios, falls within the ranges shown in Table A below.
TABLE A ______________________________________ Oxide-Mole Ratios of the Reactant Mixture ______________________________________ M.sub.2 O/SiO.sub.2 0.20 to 0.48 SiO.sub.2 /Al.sub.2 O.sub.3 3.3 to 4.5 H.sub.2 O/M.sub.2 O 10.0 to 25.0 M.sub.2 O/Al.sub.2 O.sub.3 0.8 to 1.6 ______________________________________
where M.sub.2 O represents either Na.sub.2 O, or K.sub.2 O or the mixture (Na.sub.2 O,K.sub.2 O).
The usual method for preparing this mixture comprises dissolving in water an alumino-silicate oxide, alkali, and a colloidal silica sol or alkali polysilicate. The alumino-silicate oxide (Si.sub.2 O.sub.5,Al.sub.2 O.sub.2).sub.n may be prepared from a polyhydroxy-alumino-silicate having the formula (Si.sub.2 O.sub.5,Al.sub.2 (OH).sub.4).sub.n, where the aluminum cation is in the octahedral state and is in six-fold coordination. The polyhydroxy-alumino-silicate is calcined and dehydroxylated at, say 1112.degree. F. to 1472.degree. F. The resulting alumino-silicate oxide has the aluminum cation in four-fold coordination and in a tetrahedral position.
Various polyhydroxy-alumino-silicates may be used as the starting material for the preparation of alumino-silicate oxide, including minerals having basal spacings of about seven Angstroms and having at least one aluminum cation located in the octahedral layers. Examples are alushite, carnat, china clay, lithomarge, neokaolin, parakaolinite, pholenite, endellite, glossecolite, halloysite, milanite, berthiernine, fraignotite, grovenite, amesite, and chamoisite.
The quantities of the reactants, namely colloidal silica sol and/or polysilicate, and strong alkalis such as sodium hydroxide and potassium hydroxide, fall in the ranges shown in Table A.
After aging, the mineral mixture may be used alone, or may be mixed with inorganic or organic additives or fillers. The mixture may be used as a binder or a mineral cement for organic or mineral particles or fibers. The mixture is cast, poured or squeezed into a mold and heated to a temperature up to about 467.degree. F. but preferably to a temperature in the range of about 140.degree. F. to about 203.degree. F. When polycondensation is complete, the solids are separated from the mold and dried at a temperature in the range of about 140.degree. F. to about 212.degree. F.
Polycondensation and heating times are a function of the temperature and the heating process used. At an ambient temperature such as 77.degree. F., polycondensation requires more than 15 hours. At 122.degree. F., polycondensation requires about four hours; at 185.degree. F., about 1.5 hours; and at 203.degree. F., about 0.5 hours. These times may differ and are often shorter when other heating techniques are used. Such other techniques include high frequency, microwave, Joule effect, or electrical wires within the reactant mixture itself. Because the reactant mixtures are polyelectrolytes, these heating techniques effect polycondensation and drying very rapidly.
There is a need for a cement which has the high setting and very low volume change characteristics normal for polysialate geopolymers, but which has very early high compressive strengths. This need is particularly acute in the prestress and precast concrete industry. Considerable savings result from the required strength being obtained at early ages so that construction can continue and there is a more rapid reuse of molds. There is also a need for such a very early high-strength cement having the high setting characteristics of polysialate geopolymers in patching or resurfacing highways and airport runways or in any operation where early form removal is desired.
While there have been proposals in the past for a cement having early high compressive strength, none of them have had the early compressive strengths required; that is, cement having a compressive strength better than 1,000 psi by 1 hour at 150.degree. F. and 6,000 psi by 4 hours at 150.degree. F. when tested in a standard 1 to 2.75 by weight cement-sand mortar, and having the high setting and very low volume change characteristics that are normal for, and are typical of, polysialate geopolymers.
The best early high-strength Portland Cement described in U.S. Pat. No. 4,160,674 is made from a Portland Cement having substantially all of its particles of about 20 microns and smaller. This fine and expensive cement type "Incor" had a compressive strength of 3,000 psi in 4 hours at a temperature of 150.degree. F.
The second required component of the high early-strength composition of the present invention is a ground blast furnace slag. Part of the steel-making process is in the reduction of iron ore to pig iron in a blast furnace. A by-product of the iron-making operation is blast furnace slag, the material resulting from the purification of iron ore into pig iron. Blast furnace slags contain, in addition to the lime and magnesia added to the blast furnace as fluxing material, the impurities previously contained in the iron ore, usually silica, alumina, and minor amounts of other compounds.
The ground blast furnace slag employed is a latent hydraulic product which can be activated by suitable activators. Without an activation, the development of the strength of the slag is extremely slow. It is also known that the development of the slag necessitates a pH higher than or equal to 12. The best activators are then Portland Cement, clinker, Ca(OH).sub.2, NaOH, KOH, and waterglass. The 7 day compressive strengths of activated slags with different alkali activators are given in the paper presented by J. Metso and E. Kapans, "Activation of Blast Furnace Slag by Some Inorganic Materials", at the CANMET/ACI First International Conference on the Use of Fly Ash, Silica Fume, Slag and Other Mineral By-products in Concrete", July 31-August, 1983, Montebello, Quebec, Canada. An addition of 4% by weight of NaOH gave a compressive 7 day strength of 12 to 20 MPa (1740 to 2900 psi), and a compressive 28 day strength of 22 MPa (3190) psi.
The addition of ground blast furnace slag to the polysialate geopolymers accelerates the setting time, and improves compressive strength.
BRIEF DESCRIPTION OF THE INVENTION
The present invention is directed to a high early-strength mineral polymer composition, useful as a cement, which has very early high compressive strength; that is, compressive strength better than 1,000 psi by 1 hour at 150.degree. F. and 6,000 psi by 4 hours at 150.degree. F. when tested in a standard 1 to 2.75 by weight cement-sand mortar, and which has the high setting and very low volume change characteristics that are normal and typical of polysialate geopolymers.
This early high-strength cement composition is obtained by adding to a reactant mixture consisting of alumino-silicate oxide (Si.sub.2 O.sub.5,Al.sub.2 O.sub.2) with the aluminum cation in four-fold coordination, strong alkalis such as sodium hydroxide and/or potassium hydroxide, water and a sodium/potassium polisilicate solution, a certain amount of ground blast furnace slag. To 100 g of a reactant mixture having the following oxide-mole ratio:
M.sub.2 O/SiO.sub.2 : 0.21 to 0.36
SiO.sub.2 /Al.sub.2 O.sub.3 : 3.0 to 4.12
H.sub.2 O/M.sub.2 O: 12 to 20
M.sub.2 O/Al.sub.2 O.sub.3 : 0.6 to 1.36
where M.sub.2 O represents either Na.sub.2 O, or K.sub.2 O, or the mixture (Na.sub.2 O, K.sub.2 O), one adds 15 g to 26 g of a fine ground blast furnace slag.
Additional details of both the mineral geopolymers and its use as a cement for making cast or molded products are set forth in the description of the preferred embodiments.
Accordingly, it is an object of the present invention to provide a mineral binder of the polysialate type used as a cement, having a very early high compressive strength and having very low volume change characteristics that are normal for, and typical of, polysialate geopolymers. A further object of the present invention is the provision of such a very early high compressive strength with the use of fine ground blast furnace slag. A further object of the present invention is the provision of a mineral binder of the polysialate type M.sub.n [(Si--O.sub.2).sub.z --AlO.sub.2 ].sub.n,wH.sub.2 O, wherein "z" is 1 or 2, where M.sub.2 O represents either Na.sub.2 O, or K.sub.2 O or the mixture (Na.sub.2 O,K.sub.2 O).
Employing the compositions of the present invention, cast or molded bodies achieve sufficient strength to be demolded in approximately 1 hour.
Other and further objects, features and advantages of these mineral geopolymers, such as their uses as binders are apparent from this specification and claims.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The method for making NaKPSS or KPS geopolymers is described in U.S. Pat. No. 4,249,386 and U.S. application Ser. No. 377,204, filed Apr. 29, 1982. It comprises preparing a sodium silico-aluminate/potassium silico-aluminate water mixture where the composition of the reactant mixture, in terms of oxide-mole ratios, falls within the ranges shown in Table A below.
TABLE A ______________________________________ Oxide-Mole Ratios of the Reactant Mixture ______________________________________ M.sub.2 O/SiO.sub.2 0.20 to 0.48 SiO.sub.2 /Al.sub.2 O.sub.3 3.3 to 4.5 H.sub.2 O/M.sub.2 O 10.0 to 25.0 M.sub.2 O/Al.sub.2 O.sub.3 0.8 to 1.6 ______________________________________
where M.sub.2 O represents either Na.sub.2 O, or K.sub.2 O or the mixture (Na.sub.2 O,K.sub.2 O). The mixture may be used as a binder or a mineral cement for organic particles or fibers. The mixture is cast, poured or squeezed into a mold and heated to a temperature up to about 467.degree. F., but preferably to a temperature in the range of about 140.degree. F. to about 203.degree. F. When polycondensation is complete, the solids are separated from the mold and dried at a temperature in the range of about 140.degree. F. to about 212.degree. F.
Polycondensation and heating times are a function of the temperature and the heating process used. At an ambient temperature such as 77.degree. F., polycondensation requires more than 15 hours. At 122.degree. F., polycondensation requires about 4 hours; at 185.degree. F., about 1.5 hours; and at 204.degree. F., about 0.5 hours.
The following examples illustrate the methods of making the new early high-strength polysialate geopolymers of the NaKPSS or KPS types, and some of the properties of these cements as well.
EXAMPLE I (CONTROL)
We prepared 840 g of a reactant mixture containing 17.3 moles of water, 1.438 moles potassium oxide, 4.45 moles of silicon dioxide and 1.08 moles of aluminum trioxide. The source of aluminum trioxide is the alumino-silicate oxide (Si.sub.2 O.sub.5,Al.sub.2 O.sub.2).sub.n with Al in four-fold coordination prepared by dehydroxylating a natural polyhydroxy-alumino-silicate (Si.sub.2 O.sub.5,Al.sub.2 (OH).sub.4).sub.n with Al in six-fold coordination. The source of silicon dioxide is this alumino-silicate oxide and a potassium silicate. The source of potassium oxide is this potassium silicate and potassium hydroxide. The oxide mole ratios in the reactant mixture are shown in Table B.
TABLE B ______________________________________ K.sub.2 O/SiO.sub.2 0.32 SiO.sub.2 /Al.sub.2 O.sub.3 4.12 H.sub.2 O/Al.sub.2 O.sub.3 17.0 K.sub.2 O/Al.sub.2 O.sub.3 1.33 H.sub.2 O/K.sub.2 O 12.03 ______________________________________
We call this reactant mixture standard mixture. To the 840 g of this standard mixture was added 20 g of fine mica, 110 g of fine calcium flouride and 220 g of fine clay kiln dust. This slurry, weighing 1190 g, was added to 2210 g of graded Ottawa sand, and the obtained mixture was cast into standard 2" cube molds, cured 4 hours at 150.degree. F. The compressive strength after 4 hours at 150.degree. F. is 6730 psi; other data are given in Table I. Table II gives all volume changes in water and in air. The low volume change in air of the standard mixture (+0.009) compared with current cement (Type I, Lone Star New Orleans) (-0.074), illustrates the great advantage of a geopolymer. However, the standard mixture begins to harden at 150.degree. F. only after 2 hours, and may only be demolded after 4 hours. At ambient temperature (say 73.degree. F.), hardening begins after 15 hours and demolding may occur only after 24 hours or better at 48 hours. At 185.degree. F. hardening begins after 40 minutes and demolding occurs after 1 hour and 30 minutes. These hardening times are too long for numerous applications, especially when no heat may be applied, or when the molds and tooling costs are so high that an increase in productivity becomes a necessity.
EXAMPLE II
To the 840 g of the standard mixture of Example I, are added 20 g of fine mica, 110 g of calcium flouride and 220 g of Lone Star Miami ground sidmar slag which has the following characteristics:
______________________________________ MIAMI PLANT GROUND SIDMAR SLAG ______________________________________ Glass, % Microscope 70 SiO.sub.2 32.83 Al.sub.2 O.sub.3 11.59 Fe.sub.2 O.sub.3 1.58 CaO 41.43 MgO 8.03 TiO.sub.2 0.55 Na.sub.2 O 0.28 K.sub.2 O 0.41 SrO 0.06 SO.sub.3 0.42 S 0.99 Gain on Ignition 0.86 Corrected Loss 1.12 Hydraulic Index I 1.86 I.sub.H 1.80 ______________________________________
This slurry of Example II, weighing 1190 g, was added to 2200 g of graded Ottawa sand, and the obtained mixture cast into standard 2" cube molds. This mixture begins to harden after 21 minutes at 73.degree. F. The compressive strength after 24 hours at 73.degree. F. is 5575 psi. Cured 4 hours at 150.degree. F., the compressive strength is 7140 psi (see Table I), and reaches 8220 psi after 1 day at 73.degree. F., the shrinkage in air (Table II) remains low--0.021.
EXAMPLE III
To the 840 g of the standard mixture of Example I, are added 220 g of a fine ground, light weight expanded clay aggregate (used as an inert filler), and 130 g of the Miami ground sidmar slag as in Example II. This slurry of Example III, weighing 1190 g, is added to 220 g of graded Ottawa sand. The mixture begins to harden after 45 minutes at 73.degree. F. Compressive strength on 2" cubes cured 4 hours at 150.degree. F. (Table I), is 8350 psi and reaches 8770 psi after 1 day at 73.degree. F. The shrinkage in air (Table II), remains low at 0.015 compared with 0.074 for regular Portland Cement. It is also of interest to note that with this geopolymer mixture of Example III, the compressive strength on 2" cubes, cured 24 hours at 150.degree. F. reaches 10,000 psi.
Table I gives the compressive strength comparison on 2" cubes for the geopolymer standard mixture of Example I, the geopolymer mixture of Example III, cements of Lone Star Industries Type I, Type III, Super Incor and Reg. Set II Cement, cured 4 hours at 150.degree. F. or at room temperature.
Table II gives the volume change in water or in air after 2 months. Geopolymer mixture shows higher expansion in water than Portland Cement, but the very low shrinkage in air is a very important property.
TABLE I __________________________________________________________________________ COMPRESSIVE STRENGTH COMPARISON, 2" CUBES, PSI __________________________________________________________________________ 150.degree. F. for 4 hours Geopolymer Geopolymer Type I (N.O.) Super Reg. Set II Example I Example III Portland Cement Incor Cement Cement __________________________________________________________________________ 4 hours 6730 8350 260 3000 2200 1 day 6400 8770 2130 8150 3600 7 days 7050 8500 4500 8620 4400 28 days 6900 9000 7200 9720 5200 __________________________________________________________________________ No Heat Curing Geopolymer Standard Mixture Geopolymer Type I Cement Type III Cement Super Reg. Set II Example I Example II (Miami) (Greencastle) Incor Cement Cement __________________________________________________________________________ 4 hours -- 3500 -- -- 2000 1800 1 day 2000 7920 2000 4500 6600 3800 7 days 4500 8200 5000 6500 8600 4700 28 days 7000 9000 7100 7100 9000 6200 __________________________________________________________________________
TABLE II ______________________________________ VOLUME CHANGE IN WATER IN 50% R.H. AIR MIX 2 MONTHS 2 MONTHS ______________________________________ Geopolymer Standard +.062 +.009 Example I Geopolymer +.049 -.021 Example II Geopolymer +.053 -.015 Example III Type I +.006 -.074 Portland Cement ______________________________________
EXAMPLE IV
We prepared 800 g of a reactant mixture containing 16.7 moles of water, 1.294 moles potassium oxide, 4.22 moles of silicon dioxide and 1.08 moles of aluminum trioxide. The source of the reactants is the same as in Example I. The oxide mole ratios in the reactant mixture are shown in Table C.
TABLE C ______________________________________ K.sub.2 O/SiO.sub.2 0.36 SiO.sub.2 /Al.sub.2 O.sub.3 3.90 H.sub.2 O/Al.sub.2 O.sub.3 15.48 K.sub.2 O/Al.sub.2 O.sub.3 1.198 H.sub.2 O/K.sub.2 O 12.90 ______________________________________
To the 800 g of this reactant mixture, one adds 220 g of a fine ground, light weight, expanded clay aggregate (used as an inert filler), and 130 g of the Miami ground sidmar slag. This slurry of Example IV, weighing 1150 g, is added to 2200 g of graded Ottawa sand. Compressive strength on 2" cubes cured 4 hours at 150.degree. F. is 7250 psi, and after storage 7 days at 73.degree. F., 8470 psi. Compressive strength of 2" cubes cured 2 days at room temperature (73.degree. F.) is 6500 psi. The composition of this example began to harden, and could be demolded, after 60 minutes, at 73.degree. F.
EXAMPLE V
We prepared 732 g of a reactant mixture containing 15.6 moles of water, 1.043 moles of potassium oxide, 3.88 moles of silicon dioxide and 1.08 moles of aluminum trioxide. The sources of the reactants are the same as in Example I. The oxide mole ratios in the reactant mixture are shown in Table D.
TABLE D ______________________________________ K.sub.2 O/SiO.sub.2 0.268 SiO.sub.2 /Al.sub.2 O.sub.3 3.592 H.sub.2 O/Al.sub.2 O.sub.3 14.44 K.sub.2 O/Al.sub.2 O.sub.3 0.96 H.sub.2 O/K.sub.2 O 14.90 ______________________________________
To the 782 g of this reactant mixture are added 220 g of a fine ground, light weight, expanded clay aggregate (used as an inert filler), and 130 g of the Miami ground sidmar slag. This slurry of Example V, weighing 1082 g, is added to 2200 g of graded Ottawa sand. Compressive strength on 2" cubes, cured 4 hours at 150.degree. F. is 7935 psi, and after storage for 7 days at 73.degree. F., 8220 psi. Compressive strength of 2" cubes cured 2 days at room temperature (73.degree. F.), is 6650 psi. This composition began to harden, and could be demolded after about 45 minutes, at 73.degree. F.
In the above Examples III, IV, and V, 130 g of the Miami ground sidmar slag was added to different geopolymer reactant mixtures. The reduction of the ratios SiO.sub.2 /Al.sub.2 O.sub.3 and K.sub.2 O/Al.sub.2 O.sub.3 has a slight influence on the compressive strength, as shown in Table III.
TABLE III ______________________________________ Compressive strength on 2" cubes cured 4 hours at 150.degree. F. SiO.sub.2 /Al.sub.2 O.sub.3 K.sub.2 O/Al.sub.2 O.sub.3 PSI ______________________________________ 4.12 1.33 8350 3.90 1.198 7250 3.592 0.96 7035 ______________________________________
In Example II, 26% per weight of Miami slag was added to the geopolymer reactant mixture; in Example III, 15% of Miami slag; in Example IV, 16.2%; and in Example V, 17.7% by weight was added to the geopolymer reactant mixture.
In fact, another ratio seems to influence the compressive strength. In all above Examples III, IV, V, the H.sub.2 O/K.sub.2 O increases, whereas the compressive strength is decreasing.
EXAMPLE VI
In order to study the influence of water on the compressive strength, we prepared 686 g of a geopolymer reactant containing 13.0 moles of water, 1.043 moles of potassium oxide, 3.88 moles of silicon dioxide and 1.08 moles of aluminum trioxide. The sources of the reactants are the same as in Example I. To the 686 g of this geopolymer reactant mixture are added 220 g of a fine ground, light weight expanded clay aggregate (used as an inert filler), and 130 g of the Miami ground sidmar slag. To this slurry of Example VI are added increasing amounts of water, and the obtained mixture is added to 2200 g of graded Ottawa sand. In Table IV is given the relationship between the ratio H.sub.2 O/K.sub.2 O and the compressive strength for the reaction mixture according to this Example VI, which has the following oxide mole ratio:
K.sub.2 O/SiO.sub.2 : 0.268
SiO.sub.2 /Al.sub.2 O.sub.3 : 3.592
K.sub.2 O/Al.sub.2 O.sub.3 : 0.96
TABLE IV ______________________________________ Compressive strength on 2" cubes cured 4 hours at 150.degree. F. Variation of water content. ______________________________________ H.sub.2 O/K.sub.2 O 12.46 14.90 16.45 17.52 18.85 20.80 psi 4 days 7235 7035 6000 4900 4220 3670 psi 7 days 8420 8220 6280 5480 4850 4100 at 73.degree. F. ______________________________________
The compositions of this example began to harden, and could be demolded at times varying from about 30 to about 70 minutes, at 73.degree. F.
EXAMPLE VII
In order to demonstrate the major influence of this ratio H.sub.2 O/K.sub.2 O (that is to say, the starting pH of the reactant mixture), we prepared 500 g of a geopolymer reactant mixture containing 8.69 moles of water, 0.719 moles of potassium oxide, 3.308 moles of silicon dioxide, and 1.08 moles of aluminum trioxide. The sources of the reactants are the same as in Example I. To the 500 g of this geopolymer reactant mixture are added 220 g of a fine ground, light weight, expanded clay aggregate (used as an inert filler), 130 g of the Miami ground sidmar slag, and 113 g of water. To this slurry of Example VII is added 2200 g of graded Ottawa sand. The oxide mole ratios of the geopolymer reactant mixture, with water, are shown in Table E:
TABLE E ______________________________________ K.sub.2 O/SiO.sub.2 0.217 SiO.sub.2 /Al.sub.2 O.sub.3 3.062 H.sub.2 O/Al.sub.2 O.sub.3 13.18 K.sub.2 O/Al.sub.2 O.sub.3 0.665 H.sub.2 O/K.sub.2 O 20.80 ______________________________________
Compressive strength of 2" cubes cured 4 hours at 150.degree. F. is 3600 psi and when placed 7 days at room temperature (73.degree. F.), 4000 psi. One obtains the same value with H.sub.2 O/K.sub.2 O equal to 20.80, as in Table III; but in this Example VII, the ratio K.sub.2 O/Al.sub.2 O.sub.3 is 0.665, instead of 0.96 as in Example VI. The most important element is then obviously the H.sub.2 O/K.sub.2 O ratio, which determines the pH value of the reacting geopolymer mixture. A low ratio, in the range between 12 and 16 yields to high early compressive strength, whereas a big H.sub.2 O/K.sub.2 O ratio, higher than 16, reduced substantially the mechanical properties of the geopolymer reactant mixture. Hardening of the composition of this example began in about 70 minutes, at 73.degree. F.
EXAMPLE VIII
We prepared 870 g of a reactant mixture containing 20.0 moles of water, 0.724 moles of potassium oxide, 0.75 moles of sodium oxide, 4.45 moles of silicon dioxide and 1.08 moles of aluminum trioxide. The source of sodium oxide is sodium hydroxide. The sources of the other reactants are the same as in Example I. The oxide mole ratios in the reactant mixture are shown in Table F.
TABLE F ______________________________________ (K.sub.2 O,Na.sub.2 O)/SiO.sub.2 0.33 SiO.sub.2 /Al.sub.2 O.sub.3 3.592 H.sub.2 O/Al.sub.2 O.sub.3 18.6 [K.sub.2 O,Na.sub.2 O]/Al.sub.2 O.sub.3 1.36 H.sub.2 O/(K.sub.2 O,Na.sub.2 O) 13.56 ______________________________________
To the 870 g of this reactant mixture are added 220 g of a fine ground, light weight expanded clay aggregate (used as an inert filler), and 130 g of the Miami ground sidmar slag. This slurry of Example VII, weighing 1220 g, is added to 2200 g of graded Ottawa sand. Compressive strength on 2" cubes cured 4 hours at 150.degree. F. is 6670 psi, and after storage for 7 days at 73.degree. F., 7870 psi. Curing of the composition of this example began in about 70 minutes, at 73.degree. F.
Compared with the results obtained in Example III, there is a slight reduction in strength from 8350 to 6670 psi (curing 4 hours at 150.degree. F.), due to the replacement of 50% of the K.sub.2 O by Na.sub.2 O. Sodium hydroxide is relatively cheaper than potassium hydroxide, and results in compressive strengths which are lower, but still interesting for various applications.
EXAMPLE IX
We prepared 781 g of a reactant mixture containing 18.2 moles of water, 1.043 moles of potassium oxide, 3.88 moles of silicon dioxide and 1.08 moles of aluminum trioxide. The sources of the reactants are the same as in Example I. The oxide mole ratios in the reactant mixture are shown in Table G.
TABLE G ______________________________________ K.sub.2 O/SiO.sub.2 0.268 SiO.sub.2 /Al.sub.2 O.sub.3 3.592 H.sub.2 O/Al.sub.2 O.sub.3 16.85 K.sub.2 O/Al.sub.2 O.sub.3 0.96 H.sub.2 O/K.sub.2 O 17.25 ______________________________________
To the 781 g of this reactant mixture are added 220 g of fine ground, light weight expanded clay aggregate (used as an inert filler), and 130 g of the Miami ground sidmar slag. This slurry of Example IV, weighing 1131 g, is added to 2200 g of graded Ottawa sand. The compressive strengths of 2" cubes cured at different temperatures and during different times are given in Table V.
TABLE V ______________________________________ Effect of Time and Temperature, Reactant Mixture Example IX, Compressive Strength on 2" Cubes Temperature Curing Time PSI Stored 7 days at 73.degree. F. ______________________________________ (PSI) 100.degree. F. 1 hour.sup. 450 4780 100.degree. F. 4 hours 2630 4620 150.degree. F. 1 hour.sup. 1280 5500 150.degree. F. 2 hours 3680 5480 150.degree. F. 4 hours 4900 5480 200.degree. F. 1 hour.sup. 4230 4780 ______________________________________
Because of the relatively high H.sub.2 O/K.sub.2 O ratio, the compressive strengths are lower than 6000 psi (cured 4 hours at 150.degree. F.), but the 1 hour curing at 150.degree. F. gives a compressive strength higher than 1000 psi, which is high enough for demolding. Hardening of this composition began in about 60 minutes, at 73.degree. F.
The amount of slag added to the geopolymer reactant mixture varied in Examples III to VIII from 15.4% to 21% by weight. At the same time, the amount of water increases. Surprisingly, the increasing of water results in a reduction of the compressive strength, whereas, theoretically it is the opposite which might be expected. Indeed, increasing the water amount improves the dissolution of the slag. Table VI gives the variation of the compressive strength with the slag/water weight ratio of the reactant mixtures of Example VI.
TABLE VI ______________________________________ Compressive strength on 2" cubes, cured 4 hours at 150.degree. F. Variation of the slag/water weight ratio, according to Example VI. Slag/Water PSI ______________________________________ 0.55 7235 0.46 7035 0.42 6000 0.39 4900 0.36 4200 0.33 3670 ______________________________________
The minimum of 6000 psi early high-strength is obtained with a slag/water weight ratio at least equal to 0.42; at room temperature the slag/water weight ratio determines the setting time.
Table VII gives the setting time at room temperature (73.degree. F.) with the slag/water weight ratio.
TABLE VII ______________________________________ Slag/water weight ratio 0.70 0.55 0.46 0.42 Setting time (73.degree. F.) 12 min. 30 min. 45 min. 60 min. ______________________________________
From the above described Examples, the present invention consists in the production of an early high-strength concrete composition, which is obtained by adding to a reactant mixture consisting of alumino-silicate oxide (Si.sub.2 O.sub.5,Al.sub.2 O.sub.2).sub.n with the aluminum cation in four-fold coordination, strong alkalis such as sodium hydroxide and/or potassium hydroxide, water and a sodium/potassium polisilicate solution, a certain amount of ground blast furnace slag. To 100 g of a reactant mixture following oxide-mole ratio
M.sub.2 O/SiO.sub.2 : 0.21 to 0.36
SiO.sub.2 /Al.sub.2 O.sub.3 : 3.0 to 4.12
H.sub.2 O/M.sub.2 O: 12.0 to 20
M.sub.2 O/Al.sub.2 O.sub.3 : 0.6 to 1.36
where M.sub.2 O represents either Na.sub.2 O, or K.sub.2 O, or the mixture (Na.sub.2 O,K.sub.2 O), one adds 15 g to 26 g of a fine ground blast furnace slag. If more than 26 g of ground blast furnace slag is employed, the composition tends to "flash set". While it is more difficult to use, it can still be employed with higher amounts of slag. The 15 g to 26 g amounts of slag are based upon the reactive polysialate siloxo mixture, including water.
Tested in standard 1 to 2.75 by weight cement-sand mortar, the polysialate geopolymer/slag mixture used as a cement, yields to early high compressive strength; that is, compressive strength better than 1000 psi by 1 hour at 150.degree. F. and 6000 psi by 4 hours at 150.degree. F. Depending on the slag/water weight ratio, the setting time at room temperature varies from 12 minutes to 60 minutes with a slag/water weight ratio in the range of 0.70 to 0.42.
As plotted in Table II, the polysialate geopolymer/slag mixture yields to very low volume change characteristics that are normal and typical of polysialate geopolymers, such as a shrinkage in air after 2 months, as low as 0.015 compared with the value for regular Portland Cement (0.074).
The foregoing embodiments have been given for the purpose of disclosure and changes can be made therein which are within the spirit of the invention as defined by the scope of the appended claim.