WO2001019751A1 - Ciment portland riche en gypse - Google Patents

Ciment portland riche en gypse Download PDF

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Publication number
WO2001019751A1
WO2001019751A1 PCT/US2000/024621 US0024621W WO0119751A1 WO 2001019751 A1 WO2001019751 A1 WO 2001019751A1 US 0024621 W US0024621 W US 0024621W WO 0119751 A1 WO0119751 A1 WO 0119751A1
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WO
WIPO (PCT)
Prior art keywords
opc
amoφhous
calcium sulfate
alumina
cementitious
Prior art date
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PCT/US2000/024621
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English (en)
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WO2001019751A9 (fr
Inventor
Elisha Stav
Meir Gamliel Goldgraber
Original Assignee
M. Gold Investments (1999) Ltd.
Friedman, Mark, M.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority claimed from US09/538,217 external-priority patent/US6197107B1/en
Application filed by M. Gold Investments (1999) Ltd., Friedman, Mark, M. filed Critical M. Gold Investments (1999) Ltd.
Priority to AU71245/00A priority Critical patent/AU766242B2/en
Priority to IL14399600A priority patent/IL143996A0/xx
Priority to NZ517474A priority patent/NZ517474A/en
Priority to JP2001523335A priority patent/JP2003509322A/ja
Priority to EP20000960020 priority patent/EP1242329A1/fr
Priority to CA 2384747 priority patent/CA2384747A1/fr
Priority to MXPA02002631A priority patent/MXPA02002631A/es
Publication of WO2001019751A1 publication Critical patent/WO2001019751A1/fr
Publication of WO2001019751A9 publication Critical patent/WO2001019751A9/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/14—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements
    • C04B28/145—Calcium sulfate hemi-hydrate with a specific crystal form
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

  • the present invention relates generally to cementitious compositions and, in particular, to gypsum-containing cementitious construction materials for high strength concrete, blocks, grout, floor underlayments, road-patching materials, backer boards, fiberboard and roofing tiles.
  • Ordinary Portland cement is the main cementitious material of the building industry. It is the main binder in concrete, blocks, roofing tiles, grouts, fiberboard, mortar, tile adhesives, etc. Disadvantages of OPC include low early strength and high shrinkage on drying.
  • Gypsum (CaS0 4 -2H 2 0) is an inexpensive, available material that is commonly used as an additive for OPC and for the production of gypsum-based products such as plasterboard, fiberboard, plaster, etc.
  • Calcined gypsum (calcium sulfate hemihydrate - CaS0 4 -/ H 2 0) forms gypsum upon wetting and sets within minutes, displaying excellent early-strength characteristics.
  • the set gypsum has very low strength relative to OPC.
  • ettringite (3CaO-Al 2 0 3 -CaS0 4 -32H 2 0) formation. It is known that a major factor in the long-term deterioration of concrete is the formation of ettringite. This results from the reaction of tricalcium aluminate (3CaO-Al 2 0 3 ) present in OPC with sulfate. The formation of ettringite increases the volume of the concrete, causing splitting, cracking and crumbling.
  • U.S. Patent No. 3,852,051 deals with special formulations of Portland cement having low concentrations of tricalcium aluminate. Such formulations are expensive, however, and exhibit low ultimate compressive strength.
  • U.S. Patent No. 4,494,990 to Harris discloses a cementitious composition containing OPC and alpha gypsum.
  • the composition also includes a pozzolan source, such as silica fume, fly ash or blast-furnace slag.
  • the Harris patent teaches that the pozzolan blocks the interaction between the tricalcium aluminate and the sulfate in the gypsum.
  • U.S. Patent No. 4,661,159 discloses a floor underlayment composition that includes calcium sulfate alpha-hemihydrate (alpha gypsum), calcium sulfate beta-hemihydrate (beta gypsum), fly ash, and Portland cement.
  • the patent also discloses that the floor underlayment material can be used with water and sand or other aggregate to produce a fluid mixture that may be applied to a substrate.
  • a cementitious composition useful for water-resistant construction materials is disclosed in U.S. Patent No. 5,685,903 to Stav, et al.
  • the composition includes beta gypsum, OPC, silica fume, and pozzolanic aggregate as filler.
  • the OPC component may also contain fly ash and/or ground blast slag.
  • compositions according to the invention that include both a pozzolanic aggregate and a finely divided pozzolan result in cementitious materials in which the transition zone between the aggregate and a cement paste is densified and thus produces a cured product of higher compressive strength than compositions which utilize a pozzolanic aggregate alone or a finely- divided pozzolan alone.
  • a cementitious binder composition useful for water-resistant, high- strength construction materials is disclosed by Stav, et al. in U.S. Patent No. 5,858,083.
  • the binder includes calcium sulfate beta-hemihydrate, a cement component comprising Portland cement, and either silica fume or rice-husk ash.
  • the silica fume or rice-husk ash component is at least about 92% amorphous silica and has an alumina content of about 0.6 wt.% or less.
  • the silica fume component is an extremely active pozzolan and prevents the formation of ettringite.
  • the silica fume component includes at most 0.6 wt.% alumina in the form of aluminum oxide.
  • U.S. Patent No. 5,858,083 cites Malhotra, M., and Mehta, P. Kumar, Pozzolanic and Cementitious Materials. Advances in Concrete Technology. Vol. 1. who report typical oxide analyses of silicon fumes made from the ferrosilicon alloy industry having Si0 2 amounts of as low as 83% and A1 2 0 3 amounts from between 1.00% and 2.5%.
  • U.S. Patent No. 4,350,533 to Galer et al. discloses a cementitious composition containing high-alumina cement, calcium sulfate, and Portland cement and/or lime. The reaction is rapid, and the only significant factor contributing to strength during the very early stages of hydration (i.e., a few minutes to a few hours) is the formation of ettringite.
  • Portland cement is not a necessary component of the composition and can be replaced by lime.
  • a pozzolanic material such as montmorillonite clay, diatomaceous earth, pumice, and fly ash may be included in the cement powder as an optional ingredient. When used, it usually replaces part or all of the Portland cement.
  • High alumina cement known also as Calcium Aluminate Cement
  • Calcium Aluminate Cement has an alumina content of 36-42%, the bulk of which is in the form of various calcium aluminates.
  • Calcium aluminate cements containing high levels of sulfate are known for their susceptibility to DEF and to deterioration over the long-term.
  • a commercial disclosure of LaFarge Fondu International A.S. reports that the addition of calcium sulfate to calcium aluminate cement should be limited to a maximum of 15-20% S0 3 (25-34%) calcium sulfate) to avoid excessive expansion which could disrupt the material.
  • U.S. Patent 5,788,762 to Barger et al. discloses cementitious compositions comprised of gypsum (CaS0 4 -2H 2 0), calcined clay and clinker. Novel methods of preparing these compositions are also disclosed.
  • the pozzolanic material, calcined clay has specified Fe and quartz contents, and contains kaolinites, montmorillonites, illites, halloysites, and mixtures thereof.
  • the cementitious systems disclosed have a water demand of less than about 33%o, one-day strengths of at least 1000 PSI, and low alkali functionality.
  • the cementitious compositions reported are not fast-setting and have early compressive strengths that are comparable to those of ordinary Portland cements.
  • Patent 5,788,762 reports that an advantage of the novel cementitious system disclosed therein is that it allows for the addition of more gypsum than is normally added to the cement clinker, such that the calcium sulfate component amounts to 4-10 wt.% of the cementitious mixture.
  • U.S. Patent No. 5,958,131 to Asbridge et al. discloses water-resistant cementitious compositions comprising calcium sulfate hemihydrate, portland cement and calcined clay, for use in applications in which water-resistance, good surface finish and a rapid gain in strength in the early stages following application are important.
  • a hydrated mixture of calcium sulfate hemihydrate and portland cement might be expected to give the advantages of each of these two cementitious materials, however, deleterious chemical reactions occur between sulfate ions, which are supplied principally by the calcium sulfate, and aluminum compounds in the hydrated portland cement.
  • sulfate ions which are supplied principally by the calcium sulfate, and aluminum compounds in the hydrated portland cement.
  • tricalcium aluminate and hydrated calcium aluminosulfate produce ettringite, a hydrated calcium aluminosulfate of large crystal volume.
  • the expansive, forces introduced into a hardened cementitious product by the formation of ettringite can cause cracking and subsequent terminal deterioration of the product.
  • the water resistance is achieved because of the reactivity of the calcined clay towards chemical compounds such as hydroxides of calcium and sodium and sulfates of calcium and sodium, which are produced during the hydration of mixtures of calcium sulfate hemihydrate and portland cement.
  • Calcined clays such as metakaolin react with and immobilize chemical compounds that would otherwise take part in a reaction to form ettringite, which would cause expansion and deterioration of the hydrated hydraulic composition after setting.
  • U.S. Patent No. 5,958,131 to Asbridge et al. claims water- resistance over an extremely wide range of percentages and ratios of OPC, hemihydrate, and calcined clay.
  • the cementitious compositions disclosed that are deemed suitable for adding to water to form a water-resistant hydraulic solid composition comprise from 20% to 98% by weight of calcium sulfate hemihydrate, from 1% to 50% by weight of portland cement, and from 1% to 30% by weight of calcined clay having pozzolanic activity (e.g., metakaolin).
  • the preferred ratio of hemihydrate to OPC is in the range of 2: 1 to 10: 1; the preferred ratio of OPC to calcined clay is in the range of 2:1 to 10:1.
  • the proportion of calcium sulfate hemihydrate is preferably in the range of from 47.5% to 91% by weight
  • the proportion of portland cement is preferably in the range of from 7% to 40% by weight
  • the proportion of calcined clay is preferably in the range of from 2% to 12.5% by weight.
  • cementitious mixtures having the preferred calcined gypsum to OPC weight ratios of 2 to 1 to 10 to 1, as disclosed by U.S. Patent No. 5,958,131 are subject to dissolution and deterioration due to the relatively-high solubility of the exposed sulfate.
  • cementitious mixtures having calcined gypsum to OPC weight ratios of 2 to 1 to 10 to 1 do not enjoy the full compressive strength contribution of the cement hydration reaction.
  • cementitious mixtures containing OPC, calcined gypsum, and a source of amorphous silica and amorphous alumina require a calcined gypsum to OPC weight ratio of more than about 0.5 to 1 in order for the mixture to be fast setting.
  • the present invention provides a cementitious composition containing OPC (Types I, II, III, IV and white cement), calcined gypsum, a source of amorphous silica and a source of amorphous alumina in a particular ratio as delineated below.
  • OPC Types I, II, III, IV and white cement
  • calcined gypsum a source of amorphous silica
  • source of amorphous alumina in a particular ratio as delineated below.
  • the cementitious composition by itself or mixed with aggregates such as sand, is fast-setting, exhibiting good early compressive strength within the first hour; good medium-term strength, that is, within 7-28 days; and very high late compressive strength; that is, compressive strength after at least 28 days and typically 6 months or more of curing.
  • the cementitious composition is essentially waterproof, and exhibits excellent strength characteristics. Even under exposure to water for at least ' ⁇ year to 2 years, the cementitious material shows dimensional stability, without any sign of splitting, cracking or crumbling.
  • the use of calcined gypsum in place of alumina cement or even OPC is of great economic advantage, and in addition, provides the cementitious composition with quick- setting characteristics.
  • the cementitious binder of the present invention comprises OPC, calcium sulfate hemihydrate (beta or alpha or both), a source of amorphous silica and a source of amorphous alumina, wherein the ratio of calcium sulfate hemihydrate to OPC is 0.7-1.8, the ratio of amorphous silica and amorphous alumina to OPC is 0.26-0.4, and the ratio of amorphous alumina to amorphous silica is 0.3-1.5.
  • the ratio of calcium sulfate hemihydrate to OPC is 0.75-1.3
  • the ratio of amorphous silica and amorphous alumina to OPC is 0.3-0.35
  • the ratio of amorphous alumina to amorphous silica is 0.6-1.2.
  • the cementitious binder of the present invention comprises about 30-55% by weight OPC, about 35-58% by weight calcium sulfate hemihydrate, about 5-12% by weight amorphous silica, and about 3-9%o by weight amorphous alumina.
  • the cementitious binder further comprises filler selected from the group consisting of pozzolanic aggregate, non-pozzolanic aggregate, and fibers, to form a cementitious mixture containing up to about 95% by weight of filler.
  • metakaolin is utilized as a source of amorphous silica and as a source of amorphous alumina.
  • the source of amorphous silica and the source of amorphous alumina includes calcined clay.
  • amorphous silica is provided from materials selected from the group consisting of silica fume and rice-husk ash.
  • the amounts of OPC, calcium sulfate hemihydrate, amorphous silica, amorphous alumina, and filler are selected such that said mixture has a compressive strength of at least about 300 PSI after 10-60 minutes and an ultimate compressive strength that compares favorably with that of OPC and reaches at least 4,500 PSI after 28 days.
  • the ultimate compressive strength after 28 days can easily reach at least 7,000 PSI, and as much as 12,000 to 18,000 PSI.
  • soluble calcium sulfate anhydrite can be used as a raw material in place of some or all of the calcium sulfate hemihydrate.
  • Initial laboratory tests have revealed that cementitious mixtures of anhydrite, (OPC), a source of amo ⁇ hous silica and a source of amo ⁇ hous alumina have ultimate compressive strengths that are comparable to, or superior than, the equivalent mixtures containing calcium sulfate hemihydrate.
  • OPC anhydrite
  • a source of amo ⁇ hous silica a source of amo ⁇ hous alumina
  • Such materials had improved setting characteristics relative to the equivalent mixtures containing calcium sulfate hemihydrate. This is attributed to the reaction of the anhydrite with water.
  • the anhydrite in all of its various mo ⁇ hologies, reacts with water in a qualitatively similar manner to that of calcium sulfate hemihydrate. However, the reaction is faster and more potent, because of the greater instability of the anhydrite in the presence of water, and the ability of the anhydrite to absorb additional water (relative to the hemihydrate) in reacting to form calcium sulfate dihydrate.
  • the cementitious binder comprises OPC, calcium sulfate anhydrite, a source of amo ⁇ hous silica and a source of amo ⁇ hous alumina, wherein the ratio of anhydrite to OPC is 0.6-1.98, the ratio of amo ⁇ hous silica and amo ⁇ hous alumina to OPC is 0.26-0.4, and the ratio of amo ⁇ hous alumina to amo ⁇ hous silica is 0.3-1.5.
  • the ratio of calcium sulfate anhydrite to OPC is 0.7-1.3
  • the ratio of amo ⁇ hous silica and amo ⁇ hous alumina to OPC is 0.3-0.35
  • the ratio of amo ⁇ hous alumina to amo ⁇ hous silica is 0.6-1.2.
  • the cementitious binder of the present invention comprises about 28-57% by weight OPC, about 32-60%o by weight calcium sulfate anhydrite, about 5-12% by weight amo ⁇ hous silica, and about 3-9%o by weight amo ⁇ hous alumina.
  • the cementitious binder of the present invention comprises about 28-57%> by weight OPC, about 32-60% by weight calcium sulfate anhydrite and calcium sulfate hemihydrate (total), about 5-12% by weight amo ⁇ hous silica, and about 3-9% by weight amo ⁇ hous alumina.
  • the cementitious binder of the present invention comprises: (a) Ordinary Portland Cement (OPC); (b) calcium sulfate anhydrite; (c) calcium sulfate hemihydrate; (d) amo ⁇ hous silica; (e) amo ⁇ hous alumina; wherein the weight ratio of calcium sulfate anhydrite and calcium sulfate hemihydrate (total) to OPC is about 0.6: 1.0 to 1.98: 1.0, the ratio of amo ⁇ hous silica and amo ⁇ hous alumina to OPC is about 0.26: 1.0 to 0.4:1.0 and wherein the ratio of amo ⁇ hous alumina to amo ⁇ hous silica is about 0.3: 1.0 to 1.5: 1.0.
  • OPC Ordinary Portland Cement
  • soluble anhydrite is used to replace up to 50% by weight of the hemihydrate, and more preferably, soluble anhydrite is used to replace from 5% to 50%) by weight of the hemihydrate, such that the ratio of hemihydrate to soluble anhydrite is from 1 : 1 to 19: 1.
  • Ordinary Portland Cement refers to Portland cement Types I, II, III, IV and white cement.
  • Calcined gypsum refers to calcium sulfate hemihydrate (CaS0 4 -! 2H 2 0), including the alpha and beta structures.
  • anhydrite refers to the form of anhydrite commonly known as "soluble anhydrite”.
  • a pozzolan or pozzolanic material is defined as a finely- divided siliceous material that reacts chemically with slaked lime at ordinary temperature and in the presence of moisture to form a strong slow-hardening cement.
  • the lime may be generated in the cement mixture containing OPC.
  • the pozzolans as used herein should have a pozzolanic reactivity with calcium hydroxide of at least 700 mg of calcium hydroxide per gram. Typically, the reactivity of pozzolanic materials utilized in the present invention ranges from 700-1100 mg of calcium hydroxide per gram.
  • amo ⁇ hous alumina component should have a pozzolanic reactivity with calcium hydroxide of at least 600 mg of calcium hydroxide per gram.
  • the term "stucco" refers to calcium beta hemi-hydrate.
  • alpha hemi-hydrate is known to be advantageous in many respects, however, the alpha hemi-hydrate is significantly more expensive.
  • calcium hemi-hydrate as used herein, includes all mo ⁇ hologies of calcium hemi-hydrate, including the alpha form.
  • FIG. 1 is a graph of compressive strength developed over time for the cement composition of the present invention as compared with compositions according to the prior art
  • FIG. 2 is a graph of the early compressive strength developed over time for a cement composition according to the present invention as compared with the prior art Portland cement-containing compositions of FIG. 1;
  • FIG. 3 exhibits the compressive strength developed over 1-28 days for a cementitious mixture according to the present invention as compared with the compressive strength of a reference mixture containing solely OPC as binder and ordinary sand as filler;
  • FIGS. 4a-4d are X-ray diffraction (XRD) scans of a cementitious mixture according to the present invention, in which the scans show the development of the crystalline structures within the cement over time (6 hours - 6 months);
  • XRD X-ray diffraction
  • FIGS. 5a-5b are SEM (scanning electron microscope) micrographs depicting the microstructure of the cement matrix of the inventive cement binder
  • FIGS. 6a-6e are SEM micrographs depicting the microstructure of the cement matrix, aggregate particles, and the matrix-aggregate interface of a cementitious mixture according to the present invention
  • FIG. 7 is a graph of 28-day dry compressive strength of cementitious mixtures as a function of weight ratio of calcined gypsum to OPC (and with a constant ratio of metakaolin to OPC), in which the narrow range of optimal, high-compressive strength mixtures of the present invention is demonstrated.
  • the present invention provides a cementitious composition containing OPC, calcined gypsum, a source of amo ⁇ hous silica and a source of amo ⁇ hous alumina, wherein the ratio of calcium sulfate hemihydrate to OPC is 0.7: 1.0 to 1.8: 1.0, the ratio of amo ⁇ hous silica and amo ⁇ hous alumina to OPC is 0.26: 1.0 to 0.4: 1.0, and the ratio of amo ⁇ hous alumina to amo ⁇ hous silica is 0.3: 1.0 to 1.5: 1.0.
  • the cementitious composition by itself or mixed with aggregates such as sand, is fast-setting, exhibiting good early compressive strength within the first hour; good medium-term strength, that is, within 7-28 days; and very high late compressive strength; that is, compressive strength after at least 28 days and typically 3 months or more of curing.
  • the ratio of calcium sulfate hemihydrate to OPC is 0.75:1.0 to 1.3:1.0
  • the ratio of amo ⁇ hous silica and amo ⁇ hous alumina to OPC is 0.3:1.0 to 0.35:1.0
  • the ratio of amo ⁇ hous alumina to amo ⁇ hous silica is 0.6:1.0 to 1.2: 1.0.
  • the cementitious composition is essentially wate ⁇ roof, and exhibits excellent strength characteristics. Even under exposure to water for at least / ⁇ year to 2 years, the cementitious material shows no sign of splitting, cracking or crumbling. Even samples immersed in hot water (45°C) for up to Vi year exhibit no signs of deterioration.
  • the use of calcined gypsum in place of alumina cement or even OPC is of great economic advantage, and in addition, provides the cementitious composition with quick-setting characteristics. It has been discovered that the combination of desirable properties in the cementitious mixtures of the present invention is attainable only over a relatively narrow range of compositions.
  • the mixture For the cementitious mixture to be substantially wate ⁇ roof, the mixture must contain less than about 60%) calcined gypsum. It has been assumed in the above-mentioned ratios that enough amo ⁇ hous silica and amo ⁇ hous alumina have been added to neutralize the lime from OPC. It is known in the art that effective neutralization of lime is achieved in cementitious mixtures containing pozzolan and OPC in a weight ratio of at least about 0.3:1 for pozzolanic materials with typical reactivity.
  • the cementitious material further comprises 0-95%) by weight of filler selected from a group consisting of pozzolanic aggregate (such as pumice, perlite, fly-ash, etc.), non-pozzolan aggregate (such as calcium carbonate, quartz), and fibers.
  • pozzolanic aggregate such as pumice, perlite, fly-ash, etc.
  • non-pozzolan aggregate such as calcium carbonate, quartz
  • the source of amo ⁇ hous silica in the cementitious material is selected from the group consisting of silica fume, rice- husk ash or metakaolin.
  • U.S. Patent No. 5,858,083 to Stav et al. teaches that while the amo ⁇ hous silica component is an extremely active pozzolan and prevents the formation of ettringite, the amo ⁇ hous silica component must include no more than 0.6 wt.% alumina to be effective.
  • compositions according to the present invention are designed to promote the early formation of ettringite, which provides strength to the cementitious mixture.
  • sha ⁇ contrast to the teachings of the prior art, it has been discovered that with binders containing amo ⁇ hous alumina along with amo ⁇ hous silica, the ultimate compressive strength of the cementitious mixture is improved appreciably relative to cementitious mixtures with binders containing amo ⁇ hous silica with little or no amo ⁇ hous alumina.
  • pozzolanic materials with high levels of amo ⁇ hous alumina, such as metakaolin are particularly appropriate for formulating these novel cementitious mixtures.
  • the microstructure of cementitious mixtures according to the present invention is different from the microstructure of cementitious mixtures according to the prior art: in OPC mixtures with a high sulfate content and containing amo ⁇ hous silica (U.S. Patent Nos. 4,494,990, 5,858,083), the pozzolanic reaction with calcium hydroxide produces hydrated calcium silicate, which essentially coats the abundant, crystalline gypsum phase in the cementitious mixture sulfate.
  • the microstructure of the novel cementitious mixture is largely homogeneous and amo ⁇ hous, with a greatly- reduced presence of crystalline sulfate phases (gypsum and ettringite). This feature is described in further detail below. Without wishing to be limited by the theoretical explanations above, it is believed that such differences in the microstructure account for much of the improvement in physical characteristics over prior art cementitious mixtures.
  • the cementitious binder of the present invention comprises: about 30-55 % by weight OPC, about 35-58% by weight calcium sulfate hemihydrate, about 5-12%o by weight amo ⁇ hous silica, and about 3-9% by weight amo ⁇ hous alumina.
  • the amounts of OPC, calcium sulfate hemihydrate, amo ⁇ hous silica, amo ⁇ hous alumina, and filler are selected such that the mixture has a compressive strength of at least about 300 PSI after 10-60 minutes and an ultimate compressive strength that compares favorably with that of OPC and reaches as much as about 18,000 PSI after 28 days.
  • Figure 1 is a graph of the compressive strength developed over time for the cement composition of the present invention as compared with compositions as disclosed in the prior art.
  • Curve No. 1 shows typical compressive strength development for ordinary Portland cement mixed with sand as filler
  • Curve No. 2 shows typical compressive strength development for a binder containing ordinary Portland cement, calcium aluminate and calcium sulfate mixed with sand as a filler, according to U.S. Patent No. 3,997,353;
  • Curve No. 3 shows typical compressive strength development for a binder containing ordinary Portland cement, calcium aluminate and calcium sulfate mixed with sand as a filler, according to U.S. Patent No. 4,350,533;
  • Curve No. 4 shows typical compressive strength development for a binder containing ordinary Portland cement, calcium sulfate (alpha hemihydrate), and a pozzolanic material mixed with sand as a filler, according to U.S. Patent No. 4,494,990;
  • Curve No. 5 shows typical compressive strength development for a binder containing clinker, calcined clay and calcium sulfate mixed with sand as a filler, according to U.S. Patent No. 5,788,762;
  • Curve No. 6 shows typical compressive strength development for a binder containing ordinary Portland cement, calcium sulfate (beta hemihydrate), and metakaolin mixed with sand as a filler, according to the present invention
  • Curve No. 7 shows typical dry compressive strength development for a binder containing ordinary Portland cement, calcium sulfate (beta) hemihydrate, and metakaolin mixed with sand as a filler, according to the present invention.
  • the cementitious mixtures containing calcium aluminate cement (Curve Nos. 2, 3) display excellent early compressive strength.
  • the ultimate compressive strength may be higher (Curve No. 3) or lower (Curve No. 2) than the ultimate compressive strength of a typical cementitious mixture in which the binder consists solely of OPC (Curve No. 1).
  • calcium aluminate cements are expensive relative to OPC, and the maximum content of calcium sulfate is limited to about 20- 30% to prevent excess expansion leading to deterioration of the cement over the long term.
  • the cementitious mixture in which the binder contains ordinary Portland cement, alpha calcium sulfate hemihydrate and a pozzolan displays excellent ultimate strength (Curve No. 4) relative to OPC (Curve No. 1).
  • the early strength is also good (see also Figure 2), due to the hydration of alpha calcium sulfate hemihydrate to calcium sulfate dihydrate (gypsum).
  • this composition is formulated to substantially inhibit the reaction of gypsum with tricalcium aluminate in the OPC, such that ettringite is not formed.
  • the cementitious mixture according to the present invention displays unique compressive strength development.
  • Curve No. 6 the mixture is fast-setting, with a compressive strength of 400 PSI within the first 3 hours (see also Figure 2).
  • the compressive strength increases to about 10,000 PSI within 7 days.
  • the dry compressive strength development is shown in Curve No. 7.
  • the compressive strength reaches about 8,000 PSI after only 3 days, and after 28 days, a compressive strength of over 11 ,000 PSI is attained.
  • Figure 4b is an XRD scan of the novel cement mixture after 6 days.
  • a large ettringite peak has formed, even though the presence of Ca(OH) 2 is not detected.
  • the total peak intensity decreases from 6033 to 4456, which appears to be due to the formation of CSH gel and the amo ⁇ hization of the system.
  • Crystalline sources of alumina in cement clinker such as tricalcium aluminate, are hydrated in the presence of water to form hexagonal plate crystals consisting essentially of 4CaO A1 2 0 3 19H 2 0 and 2CaO A1 2 0 3 8H 2 0. These hydrates are metastable and are transformed over time into a less soluble and more stable crystalline hydrate of the composition 3CaO A1 2 0 3 6H 2 0, which has a cubic structure.
  • the mo ⁇ hological evolution of the crystalline alumina coupled with the formation of ettringite in the presence of sulfate, cause expansive pressures within the cementitious mixture that, over the long term, lead to swelling, cracking, and crumbling of the cement.
  • amo ⁇ hous alumina eliminates the problems associated with the mo ⁇ hological evolution of crystalline alumina.
  • amo ⁇ hous alumina in the cementitious mixture reduces the amount of crystalline sulfate - gypsum and ettringite - in the cementitious mixture over the long term.
  • the cement structure is more amo ⁇ hous, homogeneous, and densely-packed, and is essentially free of the expansive pressures that typically develop in the known cementitious mixtures of the prior art.
  • the stability of the cementitious system according to the present invention was verified in a dimensional stability test conducted according to Israeli Standard No. 896.
  • the sample contracted by 0.07% after 30 days in water, and no expansion was detected, indicating that the ettringite in this system is stable and does not continue to form and expand as in other high- sulfate, high-alumina systems.
  • Figures 6a-6e are SEM micrographs for a cementitious mixture containing aggregate particles. The interface of the cement matrix and aggregate particle is clearly seen in Figures 6b-6c. Whereas in high-alumina, high-sulfate cementitious mixtures according to the prior art, ettringite crystals typically abound, or are expected to abound, in the interface region, in the cementitious mixture according to the present invention, no ettringite crystals are observed in the interface of the cement matrix and aggregate particle.
  • the XRD data is supported and complemented by the SEM micrographs. Together, they provide a firm theoretical basis for the excellent measured characteristics of long-term dimensional stability and compressive strength for the cementitious system according to the present invention.
  • the amount of pozzolanic material in cementitious mixtures of the present invention must be sufficient to neutralize the calcium hydroxide and other basic compounds that evolve during the hydration of the cement.
  • a ratio of approximately 0.3 weight units of metakaolin per weight unit of OPC is required.
  • a slight stoichiometric excess of the pozzolanic material is desirable.
  • the influence of the pozzolan to OPC ratio on compressive strength is clearly evident in Table 1.
  • the samples were cured in plastic bags for 28 days and subsequently dried.
  • Composition 1 which has an appropriate ratio of metakaolin to OPC (0.30: 1.0), displays excellent compressive strength (33 MPa).
  • Compositions 2-4 which possess less-than stoichiometric ratios of metakaolin to OPC (0.05: 1.0 to 0.15: 1.0), disintegrated upon testing.
  • U.S. Patent No. 5,958,131 to Asbridge et al. teaches a composition suitable for adding to water to produce a water-resistant hydraulic solid which comprises calcium sulfate hemihydrate, portland cement and calcined clay having a pozzolanic activity, wherein the percentages by weight of the components range from 20-98% calcium sulfate hemihydrate, 1-50% portland cement, and 1-30% of said calcined clay.
  • the proportion of calcium sulfate hemihydrate is preferably in the range of from 47.5% to 91% by weight; the proportion of portland cement is preferably in the range of from 7% to 40% by weight; the proportion of calcined clay is preferably in the range of from 2% to 12.5% by weight.
  • the desired ratio of hemihydrate to OPC is in the range of 2: 1 to 10: 1 ; the preferred ratio of OPC to calcined clay is in the range of 2: 1 to 10: 1.
  • Composition Nos. 2-4 which disintegrated upon testing, are within the range of water-resistant compositions taught by U.S. Patent No. 5,958,131. Moreover, Composition Nos. 2 and 3 fall within the preferred range of weight ratios. Table 2 provides the compositions of samples with calcined-gypsum (stucco) to OPC ratios of 1.6: 1.0 to 3.9: 1.0. The Metakaolin/OPC ratio was kept constant at 0.30: 1.0. Table 3 provides the compressive strength for samples of composition numbers 5-8 during the first 24 hours of curing. The wet cement cubes were cured in a plastic bag at room temperature. The early compressive strengths of the samples are fairly similar, with those samples containing higher levels of calcined gypsum attaining slightly higher strengths.
  • Figure 7 is a graph of 28-day dry compressive strength of cementitious mixtures as a function of weight ratio of calcined gypsum to OPC and with a fixed weight-ratio of metakaolin to OPC of 0.3:1.0.
  • the compressive strength of the cementitious mixtures increases sha ⁇ ly and monotonically until a maximum is attained at a calcined gypsum to OPC ratio of about 0.8: 1.0 to about 1.0: 1.0.
  • the ratio of calcined gypsum to OPC is further increased, the compressive strength of the cementitious mixtures decreases rapidly.
  • water-resistance is indicated by comparing the wet compressive strength of metakaolin-containing cementitious mixtures with the wet compressive strength of cementitious mixtures of similar compositions, but not containing metakaolin.
  • a more correct evaluation method of water resistance is to compare the wet compressive strength of metakaolin-containing cementitious mixtures with the dry compressive strength of the same metakaolin-containing cementitious mixtures.
  • cement cubes 25mm x 25mm x 25mm
  • the cementitious mixture contained 25%> binder and 75% filler.
  • the cubes were removed from the molds after a setting time of 15 minutes. Two different curing procedures were performed: 1) curing in an oven at 45° C for 18 days;
  • soluble calcium sulfate anhydrite can be used as a raw material in place of some or all of the calcium sulfate hemihydrate.
  • Initial laboratory tests have revealed that cementitious mixtures of soluble anhydrite, OPC, a source of amo ⁇ hous silica and a source of amo ⁇ hous alumina have ultimate compressive strengths that are comparable to, or superior than, the equivalent mixtures containing calcium sulfate hemihydrate.
  • such materials were found to have improved setting characteristics relative to the equivalent mixtures containing calcium sulfate hemihydrate. Without wishing to be limited by theory, this is attributed to the reaction of the soluble anhydrite with water.
  • the soluble anhydrite reacts with water in a qualitatively similar manner to that of calcium sulfate hemihydrate. However, the reaction is faster and more potent, because of the greater instability of the soluble anhydrite in the presence of water, and the ability of the soluble anhydrite to absorb additional water (relative to the hemihydrate) in reacting to form calcium sulfate dihydrate.
  • the cementitious binder comprises OPC, soluble calcium sulfate anhydrite, a source of amo ⁇ hous silica and a source of amo ⁇ hous alumina, wherein the ratio of soluble anhydrite to OPC is 0.6-1.98, the ratio of amo ⁇ hous silica and amo ⁇ hous alumina to OPC is 0.26-0.4, and the ratio of amo ⁇ hous alumina to amo ⁇ hous silica is 0.3-1.5.
  • the ratio of soluble calcium sulfate anhydrite to OPC is 0.7- 1.3
  • the ratio of amo ⁇ hous silica and amo ⁇ hous alumina to OPC is 0.3-0.35
  • the ratio of amo ⁇ hous alumina to amo ⁇ hous silica is 0.6-1.2.
  • the cementitious binder of the present invention comprises about 28-57%> by weight OPC, about 32-60% by weight soluble anhydrite, about 5-12% by weight amo ⁇ hous silica, and about 3-9% by weight amo ⁇ hous alumina.
  • calcium sulfate hemi-hydrate can be subsituted for soluble anhydrite, approximately on a per weight basis.
  • the dry components were mixed thoroughly to obtain a homogeneous blend.
  • the dry blend weighing 600 grams, was mixed with 111 ml. of water for 3 minutes in a HOBART mixer.
  • the cementitious mixture was poured into a 40x40x160 mm mold and was cured in a plastic bag for 28 days.
  • the wet compressive strength of the cementitious mixture, over time, is presented in Table 10.
  • An exemplary composition according to the present invention is given in Table 11.
  • the composition of the binder is identical to that of Example 1 ; the calcium carbonate filler used in Example 1 was replaced with a fine silica sand.
  • the dry components were mixed thoroughly to obtain a homogeneous blend.
  • the dry blend weighing 600 grams, was mixed with 147 ml. of water for 3 minutes in a HOBART mixer.
  • the cementitious mixture was poured into a 40x40x160 mm mold and was cured in a plastic bag for 28 days.
  • the wet compressive strength of the cementitious mixture, over time, is presented in Table 12.
  • An exemplary composition according to the present invention is provided in Table 13, and tested according to standard procedure EN- 196-1.
  • the dry components were mixed thoroughly to obtain a homogeneous blend.
  • the dry blend weighing 1800 grams, was mixed with 900 ml. of water for 3 minutes in a HOBART mixer.
  • the cementitious mixture was poured into a 40x40x160 mm mold and was cured in a plastic bag for 28 days.
  • Both the wet and dry compressive strengths of the cementitious mixture, over time, are presented in Table 14.
  • the compressive strength of an ordinary OPC mixture is provided for comparative pu ⁇ oses.
  • inventive cementitious mixtures and the physical characteristics thereof that these mixtures are particularly suitable where water resistance is an important consideration, such as for blocks, backer boards for baths and showers and floor underlay applications.
  • inventive composition are for materials such as fiberboard, siding, trim boards, structural framing, self-leveling, and road patching materials.
  • compositions made with binders according to the invention produce construction materials that set up quickly, exhibit high strength and durability, and display excellent water resistance. Products produced from compositions according to the invention can be produced on a continuous line. As these compositions set extremely quickly (typically in 2-10 minutes), building compositions made from such compositions can be handled much faster than products made from OPC alone.
  • compositions made with binders according to the invention produce construction materials that set up quickly, exhibit high strength and durability, and display excellent water resistance. Products produced from compositions according to the invention can be produced on a continuous line. As these compositions set extremely quickly (typically in 2-10 minutes), building compositions made from such compositions can be handled much faster than products made from OPC alone.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)

Abstract

La présente invention concerne une composition à base de ciment contenant du ciment Portland ordinaire (CPO), du plâtre, une source de silice amorphe et une source d'alumine amorphe. Le rapport de sulfate de calcium hémihydraté au CPO est de 0.7 :1.0 à 1.8 :1.0, le rapport de silice amorphe et d'alumine amorphe au CPO est de 0.26 :1.0 à 0.4 :1.0, et le rapport d'alumine amorphe au silice amorphe est de 0.3 :1.0 à 1.5 :1.0. Cette composition à base de ciment, utilisée seule ou mélangée à des agrégats, offre une prise rapide, et présente une bonne résistance précoce à la rupture en compression et une résistance élevée à la rupture après hydratation. Malgré la teneur élevée ce sulfate de calcium par rapport aux précédentes formulations de CPO, selon cette invention, cette composition à base de ciment est sensiblement imperméable et présente des caractéristiques de résistance excellentes, même après deux années d'immersion. L'utilisation de plâtre remplacent le ciment alumineux ou même le CPO offre à cette composition à base de ciment un grand avantage économique et des caractéristiques de prise rapide. De l'anhydrite soluble peut remplacer une partie ou l'ensemble du plâtre
PCT/US2000/024621 1999-09-13 2000-09-08 Ciment portland riche en gypse WO2001019751A1 (fr)

Priority Applications (7)

Application Number Priority Date Filing Date Title
AU71245/00A AU766242B2 (en) 1999-09-13 2000-09-08 Gypsum-rich portland cement
IL14399600A IL143996A0 (en) 1999-09-13 2000-09-08 Gypsum-rich portland cement
NZ517474A NZ517474A (en) 1999-09-13 2000-09-08 Gypsum-rich Portland cement
JP2001523335A JP2003509322A (ja) 1999-09-13 2000-09-08 高セッコウ含有率のポルトランドセメント
EP20000960020 EP1242329A1 (fr) 1999-09-13 2000-09-08 Ciment portland riche en gypse
CA 2384747 CA2384747A1 (fr) 1999-09-13 2000-09-08 Ciment portland riche en gypse
MXPA02002631A MXPA02002631A (es) 1999-09-13 2000-09-08 Cemento portland rico en yeso..

Applications Claiming Priority (4)

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US39432299A 1999-09-13 1999-09-13
US09/394,322 1999-09-13
US09/538,217 2000-03-30
US09/538,217 US6197107B1 (en) 1999-09-13 2000-03-30 Gypsum-rich Portland cement

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Cited By (4)

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Publication number Priority date Publication date Assignee Title
US20090229492A1 (en) * 2006-04-25 2009-09-17 Minova International Limited Cement-containing compositions and method of use
WO2013191526A1 (fr) * 2012-06-22 2013-12-27 Escamilla Gonzalez Martin Composition de revêtement et scellage pour différentes applications dans les arts plastiques et l'industrie de la construction
AU2012280400B2 (en) * 2011-07-01 2014-09-25 Wacker Chemie Ag Gypsum-containing construction material compounds
CN116693321A (zh) * 2023-04-13 2023-09-05 重庆交通大学 一种改性磷石膏基自流平砂浆制备方法

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JP6866685B2 (ja) * 2016-03-09 2021-04-28 日本製鉄株式会社 エトリンガイトの許容生成量の推定方法及び硫黄の許容含有量の決定方法

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US4443260A (en) * 1982-06-14 1984-04-17 Chiyoda Chemical Engineering & Constr., Co., Ltd. Method for strengthening soft soil
US5858083A (en) * 1994-06-03 1999-01-12 National Gypsum Company Cementitious gypsum-containing binders and compositions and materials made therefrom
US5958131A (en) * 1996-12-19 1999-09-28 Ecc International Ltd. Cementitious compositions and their uses

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US443260A (en) * 1890-12-23 Knob attachment

Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
US4443260A (en) * 1982-06-14 1984-04-17 Chiyoda Chemical Engineering & Constr., Co., Ltd. Method for strengthening soft soil
US5858083A (en) * 1994-06-03 1999-01-12 National Gypsum Company Cementitious gypsum-containing binders and compositions and materials made therefrom
US5958131A (en) * 1996-12-19 1999-09-28 Ecc International Ltd. Cementitious compositions and their uses

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090229492A1 (en) * 2006-04-25 2009-09-17 Minova International Limited Cement-containing compositions and method of use
AU2012280400B2 (en) * 2011-07-01 2014-09-25 Wacker Chemie Ag Gypsum-containing construction material compounds
US9216927B2 (en) 2011-07-01 2015-12-22 Wacker Chemie Ag Gypsum-containing construction material compounds
EP2726436B1 (fr) * 2011-07-01 2018-04-11 Wacker Chemie AG Matériaux de construction contenant du plâtre
WO2013191526A1 (fr) * 2012-06-22 2013-12-27 Escamilla Gonzalez Martin Composition de revêtement et scellage pour différentes applications dans les arts plastiques et l'industrie de la construction
CN116693321A (zh) * 2023-04-13 2023-09-05 重庆交通大学 一种改性磷石膏基自流平砂浆制备方法
CN116693321B (zh) * 2023-04-13 2024-05-10 重庆交通大学 一种改性磷石膏基自流平砂浆制备方法

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IL143996A0 (en) 2002-04-21
MXPA02002631A (es) 2003-10-14
CA2384747A1 (fr) 2001-03-22
AU766242B2 (en) 2003-10-09
WO2001019751A9 (fr) 2002-11-21
JP2003509322A (ja) 2003-03-11
AU7124500A (en) 2001-04-17
EP1242329A1 (fr) 2002-09-25

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