CA2457765A1 - Settable composition containing cement kiln dust - Google Patents
Settable composition containing cement kiln dust Download PDFInfo
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- CA2457765A1 CA2457765A1 CA002457765A CA2457765A CA2457765A1 CA 2457765 A1 CA2457765 A1 CA 2457765A1 CA 002457765 A CA002457765 A CA 002457765A CA 2457765 A CA2457765 A CA 2457765A CA 2457765 A1 CA2457765 A1 CA 2457765A1
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- 239000000203 mixture Substances 0.000 title claims abstract description 115
- 239000004568 cement Substances 0.000 title claims abstract description 82
- 239000000428 dust Substances 0.000 title claims abstract description 18
- 239000010881 fly ash Substances 0.000 claims abstract description 124
- 239000002893 slag Substances 0.000 claims abstract description 54
- 239000010754 BS 2869 Class F Substances 0.000 claims abstract description 47
- 239000004567 concrete Substances 0.000 claims abstract description 40
- 239000011398 Portland cement Substances 0.000 claims abstract description 34
- 238000000034 method Methods 0.000 claims description 30
- 239000004576 sand Substances 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 7
- 238000004890 malting Methods 0.000 claims description 4
- 238000010276 construction Methods 0.000 abstract description 9
- 239000011178 precast concrete Substances 0.000 abstract description 2
- 230000007306 turnover Effects 0.000 abstract description 2
- 239000000463 material Substances 0.000 description 16
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 12
- 239000002956 ash Substances 0.000 description 11
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 9
- 235000011941 Tilia x europaea Nutrition 0.000 description 9
- 239000003245 coal Substances 0.000 description 9
- 238000007906 compression Methods 0.000 description 9
- 230000006835 compression Effects 0.000 description 9
- 239000004571 lime Substances 0.000 description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 239000006227 byproduct Substances 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 238000012360 testing method Methods 0.000 description 7
- 239000000654 additive Substances 0.000 description 6
- 235000019738 Limestone Nutrition 0.000 description 5
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 5
- 239000010440 gypsum Substances 0.000 description 5
- 229910052602 gypsum Inorganic materials 0.000 description 5
- 239000006028 limestone Substances 0.000 description 5
- 239000011404 masonry cement Substances 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 4
- 239000000292 calcium oxide Substances 0.000 description 4
- 239000004615 ingredient Substances 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 238000006467 substitution reaction Methods 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 3
- 230000005611 electricity Effects 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 3
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 2
- 235000002918 Fraxinus excelsior Nutrition 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- RHZUVFJBSILHOK-UHFFFAOYSA-N anthracen-1-ylmethanolate Chemical compound C1=CC=C2C=C3C(C[O-])=CC=CC3=CC2=C1 RHZUVFJBSILHOK-UHFFFAOYSA-N 0.000 description 2
- 239000003830 anthracite Substances 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 239000001110 calcium chloride Substances 0.000 description 2
- 229910001628 calcium chloride Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000010883 coal ash Substances 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000003546 flue gas Substances 0.000 description 2
- 238000009472 formulation Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- -1 i.e. Substances 0.000 description 2
- 239000003077 lignite Substances 0.000 description 2
- 239000004570 mortar (masonry) Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 229910021487 silica fume Inorganic materials 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 239000003476 subbituminous coal Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 229910000323 aluminium silicate Inorganic materials 0.000 description 1
- 239000010426 asphalt Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000002802 bituminous coal Substances 0.000 description 1
- 239000010882 bottom ash Substances 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005367 electrostatic precipitation Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 239000011133 lead Substances 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000001151 other effect Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000012265 solid product Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000010421 standard material Substances 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
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- 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
- C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B18/04—Waste materials; Refuse
- C04B18/16—Waste materials; Refuse from building or ceramic industry
- C04B18/162—Cement kiln dust; Lime kiln dust
-
- 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
- C04B28/02—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 hydraulic cements other than calcium sulfates
- C04B28/021—Ash cements, e.g. fly ash cements ; Cements based on incineration residues, e.g. alkali-activated slags from waste incineration ; Kiln dust cements
-
- 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
- C04B28/02—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 hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
-
- 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
-
- 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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S106/00—Compositions: coating or plastic
- Y10S106/01—Fly ash
Abstract
The present invention relates to settable compositions for general purpose concrete construction containing Class-F fly ash, Class-C fly ash or slag, and cement kiln dust (CKD) as a substantial replacement for Portland cement conventionally used in such compositions. The compositions of the present invention provide high early strength thereby allowing the concrete structure to be put into service sooner, reducing labor cost, and allowing precast concrete and concrete masonry manufacturers to achieve rapid form and mold turnover.
Description
SETTAELE COMPOSITION CONTAINING CEMENT HILN DUST
Field Of The Invention This invention relates to the field of settable compositions for general purpose concrete construction containing Class-F fly ash, Class-C fly ash or slag, and cement kiln dust (CID) as a substantial replacement for Portland cement conventionally used in such compositions.
Background Of The Invention This invention is concerned with the utilization of four industrial by-products;
namely, Class-F fly ash, Class-C fly ash, blast furnace slag, and cement kiln dust (CID) in general purpose concrete-making composition. When finely divided or pulverized coal is combusted at high temperatures, for example, in boilers for the steam generation of electricity, the ash consisting of the incombustible residue plus a small amount of residual combustible matter, is made up of two fractions, a bottom ash recovered from the furnace or boiler in the form of a slag-like material and a fly ash which remains suspended in the flue gases from the combustion until separated therefrom by lcnown separation techniques, such as electrostatic precipitation. This fly ash is an extremely finely divided material generally in the form of spherical bead-like particles, with at least 70% by weight passing a 200 mesh sieve and has a generally glassy state, resulting from fusion or sintering during combustion. As recognized in the American Society of Testing Materials (ASTM) specification designations C61 ~-00 entitled "Fly Ash and Raw or Calcined Natural Pozzolan for Use as a Mineral Admixture in Portland Cement Concrete" and D5370-96 entitled "Standard Specification for Pozzolanic Blended Materials in Construction Application," fly ash is subdivided into two distinct classifications; namely, Class-F and Class-C. The definitions of these two classes are as follows:
"Class-F--Fly ash normally produced from burning anthracite or bituminous coal that meets the applicable requirements for this class as given herein. This class fly ash has pozzolanic properties.
Class-C--Fly ash normally produced from lignite ar subbituminous coal that meets the applicable requirements for this class as given herein. This class of fly ash, in addition to having pozzolanic properties, also has some cementitious properties. Some Class-C fly ashes may contain lime contents higher than 10°l0."
The latter reference to "pozzolanic properties" refers to the capability of certain mixtures that are not in themselves cementitious, but are capable of undergoing a cementitious reaction when mixed with calcium hydroxide in the presence of water. Class-C
fly ash possesses direct cementitious properties as well as pozzolanic properties. ASTM
C618-00 is also applicable to natural pozzolanic materials that are separately classified as Class N but are not pertinent here.
As the above quotation indicates, the type of coal to be combusted generally determines which class fly ash results, and the type of coal~in turn is often dependent on its geographic origin. Thus, Class-C fly ash frequently results from coals mined in the Midwest;
whereas Class-F fly ash often comes from coals mined in the Appalachian region. The ASTM
specification imposes certain chemical and physical requirements upon the respective fly ash classifications which are set forth in US 5,520,730 which is incorporated herein by reference.
CID, on the other hand, is a by-product of the production of Portland cement clinkers by the high temperature furnacing of appropriate raw materials, typically mixtures of limestone and clay or a low grade limestone already containing a sufficient quantity of argillaceous materials often with added quantities of lime to adjust the final composition. The resultant clinkers are pulverized by grinding with gypsum to a high degree of fineness aald these particles upon admixture with sand gravel and sufficient water undergo a cementitious reaction and produce the solid product generally referred to as concrete, which exhibits high compressive strength and is thus highly useful in construction of a great variety of building or supporting structures. Generally, rotary furnaces are used for producing Portland cement clinkers and a certain quantity of finely divided dust is produced as a by-product that is carried off in the flue gases from such furnaces. The dust content can range from about 5% of the clinkers output in so-called wet process plants up to as high as 15% in dry process plants.
The suspended dust is removed by various separating techniques and remains as a by-product of the cement malting operation. Part of the CIA can be returned to the furnace as recycled raw material, but it is not readily reincorporated into clinker formation and, in addition, tends to excessively elevate the allcalinity of the ultimate Portland cement.
Blast furnace slag is a by-product from the production of iron in a blast furnace;
silicon, calcium, aluminum, magnesium and oxygen are the major elemental components of the slag. Blast furnace stags include air-cooled slag resulting from solidification of molten blast fmmace slag under atmospheric conditions; granulated blast furnace slag, a glassy granular material formed when molten blast furnace slag is rapidly chilled as by immersion in water; and pelletized blast furnace slag produced by passing molten slag over a vibrating feed plate where it is expanded and cooled by water sprays, whence it passes onto a rotating drum from which it is dispatched into the air where it rapidly solidifies to spherical pellets. In general the glass content of the slag determines the cementitious character, rapidly cooled stags have a higher glass content and are cementitious; slowly cooled stags are non-glassy and crystalline and thus do not have significant cementitious properties.
The quantities of these by-product materials that are produced annually are enormous and are lileely only to increase in the future. As petroleum oil as the fuel for the generation of electricity is reduced because of conservation efforts and unfavorable economics, and as political considerations increasingly preclude the construction of new nuclear power electrical generating facilities, or even the operation of already completed units of this type, greater reliance will necessarily fall on coal as the fuel for generating electricity. As of 1979, the amount of CKD was estimated as accumulating at a rate of 4-12 million tons per year in the United States alone, whereas the amount of Class-F fly ash that is available is estimated to be about five times what can be readily utilized. The estimated yearly total production of coal ash in the U.S. is about 66.8 million tons, wlule the yearly total coal ash sales in the U.S.
is about 14.5 million tons. Further, in Canada, the recovery of copper, nickel, lead and zinc from their ores produces over twelve million tons of slag per year, which usually accumulated near the smelters without significant use. Obviously, there is an urgent growing need to find effective ways of employing these unavoidable industrial by-products since otherwise they will collect at a staggering rate and create crucial concerns over their adverse environmental effect.
Various proposals have already been made for utilizing both fly ash and CKD.
According to Lea (1971), The Chemistry of Cej~zefat ahd Coract~ete, Chemical Publishing Company, Inc., page 421 et seq., fly ash, i.e., Class-F type, from boilers was first reported to be potentially useful as a partial replacement for Portland cement in concrete construction about 50 years ago, and its utilization for that purpose has since become increasingly widespread. It is generally accepted that the proportion of Portland cement replaced by the usual fly ash should not exceed about 20% to avoid significant reduction in the compressive strength of the resultant concrete, although some more cautious jurisdictions may impose lower limits, e.g., the 15% maximum authorized by the Virginia Department of Highways and Transportation (VDHT). As described in Lea on page 437, the substitution of fly ash tends to retard the early rate of hardening of the concrete so that the concrete shows up to a 30% lower strength after seven days testing and up to a 25% lower strength after 28 days of testing, but in time the strength levels equalize at replacement levels up to 20%. Increasing the substitution quantity up to 30% gives more drastic reduction in the early compression values plus an ultimate reduction of at least about 15% after one year.
The limited substitution of fly ash for Portland cement in concrete formulations has other effects beyond compressive strength changes, both positive and negative.
The fly ash tends to increase the workability of the cement mix and is recogiuzed as desirably reducing the reactivity of the Portland cement with so-called reactive aggregates. On the other hand, fly ash contains a minor content of uncombusted carbon that acts to absorb air entrained in the concrete. Because entrained air increases the resistance of the hardened concrete to freezing, such reduction is undesirable but can be compensated for by the inclusion as an additive of so-called air-entraining agents.
l~odson, et al. in US 4,210,457, while recognizing the accepted limit of 20%
replacement with fly ash of the Portland cement in concrete mixes, proposed the substitution of larger amounts, preferably 50% or more, of the Portland cement with particular selected fly ashes having a combined content of silica, alumina and ferric oxide content, less than 80%
by weight, and a calcium oxide content exceeding 10%, based on five samples of such ashes, varying from about 58-72% combined with a calcium oxide range of about 18-30%.
Six other fly ash samples that are not suitable at the high replacement levels of 50% or more were shown to vary in the combined oxide content from about 87-92% and in calcium oxide content from about 4 to about 8%. Evaluating these values against the ASTM
C618-00, one observes that the acceptable fly ashes came wider the Class-C specifications, while the unacceptable ashes fell in the Class-F specification. Thus, this patent in effect establishes that Class-C fly ashes are suitable for substantially higher levels of replacement for Portland cement in concrete mixes than are Class-F fly ashes, and this capacity is now generally recognized, with Class-C fly ashes being generally permitted up to about a 50%
replacement level while maintaining the desirable physical properties of the concrete especially compressive strength.
In US 4,240,952, Hulbert, et al. while also acknowledging the generally recognized permissible limit of Class-F fly ash replacement for Portland cement of 20%, proposed replacement of at lest 50% up to 80%, provided the mix contained as special additives about 2% of gypsum and about 3% of calcium chloride by weight of the fly ash. The fly ash described for this purpose, however, was a Class-C fly ash analyzing about 28%
calcium oxide and combined silica, alumina and ferric oxide content of about 63%. With up to 80% of this fly ash and the specified additives, compressive strengths comparable to straight Portland cement were said to be generally acluevable. In one example using 140 pounds Portland cement and 560 pounds of fly ash (20:80 ratio) with conventional amounts of coarse and fine aggregate, and water and including t~ requisite additives, compressive strengths tested at 3180 psi for 7 days, 4200 psi for 14 dalys and about 5000 psi at 28 days.
In US 4,018,617 and US 4,101,332, Nicholson proposed the use of mixtures of fly ash (apparently Class-F in type), cement kiln dust and aggregate for creating a stabilized base supporting surface replacing conventional gravel or asphalt aggregate stabilized bases in road construction wherein the useful ranges were fly ash 6-24%, CI~1D 4-16% and aggregate 60-90%, with 8% CKD, 12% fly ash and 80% aggregate preferred. Compressive strength values for such measures as revealed in the examples varied rather erratically and generally exhibited only small increases in compression strength over the 7 to 28 day test period.
Among the better results were for the preferred mixture wherein the values increased from about 1100 psi at 7 days to 1400 psi at 28 days. The addition of a small amount of calcium chloride improved those values by about 200 psi. On the other hand, the addition of 3% of lime staclc dust recovered from a lime kiln significantly reduced the results to about 700 psi at 7 days to 900-1300 psi at 28 days. Elimination of the aggregate reduced the strength to a fraction of the values otherwise obtained, a mixture of 12% CID and 88% fly ash alone showing strength values of only about 190-260 psi over the 28-day test period.
Similarly, the choice of a finely divided aggregate such as fill sand resulted in about the same fractional level of strength values in the range of about 140-230 psi. A combination of finely divided and coarse aggregate in approximately equal amounts reduced the compressive strength values by about 1/2 with virtually no change over the test period, giving values ranging from 650-750 psi, except where 1 % of Type 1 Portland cement was included which restored the strength values to about their original level, except at the initial 7 days period where the strength values were about 800-900 psi, increasing at 28 days to about 1200-1600 psi.
Curiously, the best strength results were attained when 11.6% fly ash was combined with 3.4% lime with the balance crushed aggregate, the CKD being omitted entirely, for which the strength values while starting at a lower level of about 850-950 at 7 days increased to about 1700 psi at 28 days.
The combination of fly ash aazd lime stack dust incidentally mentioned in the later patent was explored further by Nicholson in US 4,038,095 which concerns mixtures of about 10-14% fly ash, about 5-15% lime stack dust with the balance aggregate in the range of 71-85%. Somewhat inexplicably, the compressive results reported here for such mixtures do not reach the high level specified in the first two patents, the strength values specified being only about 1000 psi with the more general levels well below that depending on particular proportions.
In US 4,268,316, Wills, Jr., discloses the use of mixtures of kiln dust and fly ash as a replacement for ground limestone and gypsum for forming a mortar or masonry cement, using proportions of about 25-55% Portland cement, about 25-65% CI~1D and 10-25% fly ash.
When these mortar formulations were mixed with damp sand in the proportions of about one part cement mixture to 2.5-3 parts sand, compression strengths comparable to those of standard masonry cement composed of 55% cement clinkers 40% limestone and 5%
gypsum were shown for mixtures containing 50% cement, 24-40% CKD and 15-25% fly ash.
hzexplicably, in one example, when the cement content was increased to 55%
with 35% CKD
and 10-% fly ash, the compressive strengths dropped by about 30-40% at both the 7 day and 28 day ages to levels inferior to the standard material. As the cement content was decreased, with corresponding increases in the CKD, the compressive strength values dropped drastically. On the other hand, in another similar example mixtures containing 55% cement, 35% CKD and 10% fly ash proved superior, particularly at the 28 day age, in compressive strength, to mixtures containing 50% cement, 35% fly ash and 15% CKD as well as other standard masonry cements containing 50% cement, 47% limestone and 3% gypsum.
Indeed, strength values dropped about 40% for the mixtures having a 5% reduction in cement and a corresponding 5% increase in the fly ash to values definitely inferior to the standard cements.
Similar variations were shown under laboratory test conditions for comparable mixtures dependent on the source of the fly ash while under actual construction conditions for the same mixtures, compressive strength values were reduced by about 50% for both the conventional masonry cement containing 55% Portland cement and comparable mixtures within the patented concept. The fly ash here was preferably Class-F with Class-C materials being less desirable.
In US 4,407,677, Wills, Jr., went on to teach that in the manufacture of concrete products such as blocks or bricks, the fly ash usually employed in combination with Portland cement therein could be replaced in its entirety by CKD with modest improvement in early compressive strength values for such products. Thus, at one day and two day tests compressive strength values were shown of about 500-800 psi, but were said to increase to about 1200 psi after 28 days. The mixes disclosed here contained 0.4-0.9 parts cement, about 0.1-0.6 parts CKD and 10-12 parts aggregate combining both fine and coarse materials, such as expanded shale and natural sand in a weight ratio of 80/20. Masonry cements generally develop at~ least about 95% of their strength properties at 28 days age so that additional aging of the patented products would not be expected to result in any significant increase in their compressive strength values.
fii US 5,106,422, Bemlett et al. teaches a self hardening backfill material that utilizes Class-C fly ash as a primary constituent in conjunction with other fly ashes, such as Class-F
fly ash, or other filler materials. The material can attain compressive strength of about 20 psi within about four hours, which is about 25 to 40 percent of its 28-day strength. The material, however, does not use cement and thus has low strength and is not useful in applications requiring concrete.
None of the above patents addresses the issue of early strength of concrete;
therefore, there remains a need for concrete mixes containing fly ash with high early strength, because the addition of fly ash to concrete often results in slow setting. There are many advantages for having high early strength, such as allowing the concrete structure to be put into service sooner, thereby reducing labor cost, and allowing precast concrete and concrete masonry manufacturers to achieve rapid form and mold turnover.
Summary Of The Invention An object of the instant invention relates a settable composition for improved early strength comprising cement, Class-F fly ash, Class-C fly ash, and CKD. In a preferred embodiment, the cement is present in an amount greater than about SO% by weight, the Class-F fly ash is present in an amount of about 1 percent to about 10 percent by weight, the Class-C fly ash is present in an amount of about 5 percent to about 25 percent by weight, and CKD is present in an amount of about 1 percent to about 15 percent by weight.
A further obj ect of the instant invention relates a settable composition for improved early strength comprising cement, Class-F fly ash, slag, and CKD. In a preferred embodiment, the cement is present in an amount greater than about 50% by weight, the Class-F fly ash is present in an amount of about 2 percent to about 11 percent by weight, the slag is present in an amount of about 1 percent to about 15 percent by weight, and CID is present in an amount of about 3 percent to about 20 percent by weight.
Methods of malting concrete from the above compositions are also disclosed.
Detailed Description Of The Invention Several different types of Portland cement are available and all are useful with the present invention. Type I is the general purpose variety and is most commonly employed but Type III is preferable for early strength application. Cormnercial blended cements, such as Type I-P, wherein 20% Class-F fly ash is blended with 80% by weight Portland cement clinleer during pulverization should be avoided.
Any standard or common Class-F fly ash obtained from boilers and like furnaces used for the combustion of pulverized coal, particularly of a bituminous or anthracite type, and especially from coal-fired, steam-generating pla~lts of electrical utilities, is suitable for use as the Class-F fly ash component of this invention. Such fly ash should have a combined silica, alumina and ferric oxide content of at least about 70% and preferably 80% or higher by weight and a lime (Ca0) content below about 10%, usually about 6% by weight or less.
Any standard or common Class-C fly ash obtained from the burning of lignite or subbituminous coal is suitable fox use as the Class-C fly ash component of this invention.
Such Class-C fly ash generally contains more calcium and less iron than Class-F fly ash and has a lime content in the range of 15% to 30%.
Similarly, any common cement kihl dust (CID) that is produced as a by-product during the industrial production of Portland cement would in principle be suitable for purposes of this invention. One specific CKD, obtained as a matter of convenience, from the Tarmac Lone Star Cement Company cement plant at Roanoke, Va., has previously been found useful in the cement composition. Other various CKD can be found in the patent literature. For example, US 4,018,617 to Nicholson mentioned previously, analyzed nine different samples of CKD.
Likewise, any blast furnace slag is appropriate for the present invention.
Slag is a non-metallic coproduct produced in the production of iron in a blast furnace.
It consists primarily of silicates, aluminosilicates and calcimn-alumina-silicates. The molten slag usually comprises about twenty percent by mass of iron production. Different fortes of slag products are produced depending on the method used to cool the molten slag.
These products include air-cooled blast furnace slag, expanded or foamed slag, palletized slag, and granulated blast furnace slag. Granulated blast furnace slag satisfying ASTM
specification is preferred.
As will be established later, within the above limits for the compositions of the invention, the concrete produced therefrom exhibit substantially comparable or superior properties for use in general purpose cement construction, especially one-day compressive strength to corresponding all Portland cement mixes. This being the case, economic considerations may be an important factor in selecting a specific mix within such ranges.
Under present marlcet conditions, and dependent upon transportation distances from the available sources of the two components, CKD can be purchased somewhat more cheaply than can a standard Class-F fly ash. For example, fly ash might be purchased at a cost of $20.00 per ton including transportation expense of about $7.00 per ton;
whereas CKD can be purchased for about $9.00 per ton including about $4.00 transportation expense. Where the relative expense sigiuficantly favors one of the products, such as CKD, it is economically advantageous to utilize a larger amount of the cheaper constituent. Thus a mix having CID
and Class-F fly ash would be cheaper to produce than a mix having only Class-F
fly ash.
Concrete mixes using the present invention may also contain aggregate materials.
The choice of aggregate material for concrete mixes using the present blends will pose not problem to the person slcilled in the design of such mixes. The coarse aggregate should have a minimum size of about 3/8 inch and can vary in size from that minimum up to one inch or larger, preferably in gradations between these limits. Crushed limestone, gravel and the life are desirable coarse aggregates, and the material selected in any case should exhibit a considerable hardness and durability inasmuch as crumbly, friable aggregates tend to significantly reduce the strength of the ultimate concrete. The finely divided aggregate is smaller than 3/S inch in size and again is preferably graduated in much finer sizes down to 200-sieve size or so. Ground limestone, sand and the life axe common useful fme aggregates.
Tn accordance with the present invention, silica fume can also be added to the cement mixture to achieve high strength and chloride protection for the concrete.
Silica fume is preferably used from 3-12 percent of the amount of cement that is being use in the mixture.
Other additives can also be used in accordance with the present invention, including, but is not limited to, water reducers, accelerators, air entrainment agents, as well as other additives that is commonly used in the concrete industry.
The mixes of the invention are prepared by homogeneously and uniformly mixing all of the mix ingredients including the Class-F fly ash, Class-C fly ash, slag, and CID. The Class-F fly ash has a specific gravity of about 2.25, while that of CKD is around 2.70. These relatively small differences in specific gravities do not create any unusual problems in the preparation of the present compositions and any of the usual mixing techniques commonly employed in the concrete mix industry axe suitable. The ultimate compositions are no more susceptible to undergo separation during handling and storage than are ordinarily concrete mixes. They can be transported and stored in the same manner as the ordinary mixes, as can the individual ingredients. The storage containers should, of course, be closed to protect the contents thereof from weather.
The following examples are given to illustrate the present invention. It should be understood that the invention is not limited to the specific conditions or details described in these examples.
The results in the following examples were actually obtained by preliminarily blending, in each case, the Class-F fly ash, Class-C fly ash, slag, and CKD
together in accordance with the concept of the prior application and combining the blend with the other mix ingredients. However, the results would be identical if the same proportionate amount for each of the component was added separately to the remaining mix ingredients and the proportionate amounts of the Class-F fly ash, Class-C fly ash, slag, and CKD
have been expressed in each case in terms of their relative weight percentages of the particular mix.
Example 1 TABLE
Mix Cement Class-F fly Class-C fly CIA 1 day PSI
# ash ash 1 100% 0 0 0 2450 2 80% 20% 0 0 1920 90% 0 10% 0 2190 6 70% 0 30% 0 1480 7 50% 0 50% 0 400 8 90% 1% 7.5% 1.5% 2860 9 70% 3% 22.5% 4.5% 2730 50% 5% 37.7% 7.5% 1510 35 90% 1.5% 5% 3.5% 3060 36 70% 4.5% 15% 10.5% 3090 37 50% 7.5% 25% 17.5% 2080 11 90% 2% 5% 3% 2870 12 70% 6% 15% 9% 2700 13 50% 10% 25% 15% 2010 14 90% 3.5% 5% 1.5% 2730 70% 10.5% 15% 4.5% 2390 16 50% 17.5% 25% 7.5% 1840 17 70% 27% 3% 0 1630 18 70% 22.5% 7.5% 0 1500 19 70% 15% 15% 0 1410 70% 7.5% 22.5% 0 1510 21 70% 3% 27% 0 1520 TAELE
Mix 1 Day PSI 7 Day PSI 28 Day PSI
#
In Example l, the cement mixes comprising Class-F fly ash, Class-C fly ash, and CI~1D (Mix #8-10, 35-37, and 11-16) are compared with cement mixes without CID
(Mix #1-2, 5-7, and 17-21). Samples were tested for compression strength in accordance with ASTM
C-109. Table 1 compares 1 day strength of the mixes; and Table 2 compares 1 day, 7 day, and 28 day strengths of the mixes.
Example 2 TABLE
Mix Cement CF fly ash CIA 1 Day PSI 7 Day 28 Day # PSI PSI
1 100% 0 0 2450 5860 7750 3 70% 20% 10% 2690 4970 6360 4 70% 30% 0 1940 4810 6480 In Example 2, cement mixes comprising CF fly ash and CKD (Mix #3) are compared with the same mix without CID (Mix #4) and all Portland cement (Mix #1).
Samples were tested for compression strength in accordance with ASTM C-109.
CF ash is the product of a mixture of western and eastern coal. An all-western coal produces Class-C fly ash; and an all-eastern coal produces Class-F fly ash.
Because of emissions and environmental concerns, power plants may burn a mixture of eastern and western coals. Further, the percentages of eastern and westenl coals may vary according to the needs of the individual power plant. The CF ash used in Example 2 is the product of a 50/50 blend of eastern and western coal.
Example 3 TABLE
Mix Cement Class-F fly Slag CIA 1 Day 7 Day 28 Day # ash PSI PSI PSI
22 100% 0 0 0 2560 5900 7270 23 90% 0 10% 0 2340 5400 6700 24 70% 0 30% 0 1860 4920 7030 25 50% 0 50% 0 1190 4150 6840 26 90% 3.6% 1% 5.4% 3520 6020 6810 27 70% 10.8% 3% 16.2% 3070 4940 5830 28 50% 18% 5% 27% 1610 3240 4290 29 90% 2.8% 3% 4.2% 3360 6050 6950 30 70% 8.4% 9% 12.6% 3020 5430 6910 31 50% 14% 15% 21% 1780 3930 5550 32 90% 2% 5% 3% 3200 6140 7230 33 70% 6% 15% 9% 2880 5730 7170 34 50% 10% 25% 15% 1880 4910 6720 52 90% 0.6% 9% 0.4% 2510 5790 7790 53 70% 1.8% 27% 1.2% 2360 5500 6950 54 50% 3% 45% 2% 1330 4270 7240 55 90% 6.3% 1% 2.7% 2620 5600 7050 56 70% 18.9% 3% 8.1% 2330 4900 5790 57 50% 31.5% 5% 13.5% 1530 3440 5010 58 90% 4.9% 3% 2.1% 2670 5500 7310 59 70% 14.7% 9% 6.3% 2290 5040 6450 60 50% 24.5% 15% 10.5% 1610 3890 5640 61 90% 3.5% 5% 1.5% 2500 5650 7330 62 70% 10.5% 15% 4.5% 2130 5010 6920 63 50% 17.5% 25% 7.5% 1640 4320 6360 In Example 3, cement mixes comprising Class-F fly ash, slag, and CKD (Mix #26-and 52-63) are compared with all Portland cement (Mix #22) and mixes comprising just slag (Mix #23-25). Samples were tested for compression strength in accordance with ASTM C-109.
Example 4 TABLE
Mix Cement Slag CKD 1 Day PSI 7 Day 28 Day # PSI PSI
23 90% 10% 0 2340 5400 6700 24 70% 30% 0 1860 4920 7030 25 50% 50% 0 1190 4150 6840 38 90% 9% 1% 2720 5640 6840 39 70% 27% 3% 2340 5480 7220 40 50% 45% 3% 1710 4950 6890 41 90% 7% 3% 3030 5810 6760 42 70% 21 % 9% 2920 5720 7050 In Example 4, cement mixes comprising slag and CKD (Mix #38-42) are compared with mixes comprising just slag (Mix #23-25). Samples were tested for compression strength in accordance with ASTM C-109.
Example 5 TABLE
Mix Cement Class-C fly Slag CKD 1 Day 7 Day 28 Day # ash PSI PSI PSI
23 90% 0 10% 0 2340 5400 6700 24 70% 0 30% 0 1860 4920 7030 25 50% 0 50% 0 1190 4150 6840 5 90% 10% 0 0 2190 5830 7880 6 70% 30% 0 0 1480 5450 7350 7 50% 50% 0 0 400 4270 6250 43 90% 1% 8% 1% 2590 5690 6890 44 70% 3% 24% 3% 2340 5580 7150 45 50% 5% 40% 5% 1720 5230 6990 46 90% 1.5% 7% 1.5% 2730 5710 7150 47 70% 4.5% 21% 4.5% 2440 5660 7590 48 50% 7.5% 35% 7.5% 1640 5090 7130 49 .90% 2.5% 5% 2.5% 2690 5500 7090 50 70% 7.5% 15% 7.5% 2570 5500 6890 51 50% 12.5% 25% 12.5% 1980 5180 6830 Tn Example 5, cement mixes comprising Class-C fly ash, slag, and CID (Mix #43-51) are compared with mixes comprising just slag (Mix #23-25) and mixes comprising just Class-C fly ash (Mix #5-7). Samples were tested for compression strength in accordance with ASTM C-109.
Example 6 TABLE
Mix Cement Class-C fly Class-F fly Slag CIA 1 Day # ash ash PSI
23 90% 0 0 10% 0 2340 24 70% 0 0 30% 0 1860 25 50% 0 0 50% 0 1190 90% 10% 0 0 0 2190 6 70% 30% 0 0 0 1480 7 50% 50% 0 0 0 400 64 90% 1.5% 0.9% 7% 0.6% 2450 65 70% 4.5% 2.7% 21% 1.8% 2210 66 50% 7.5% 4.5% 35% 3% 1470 67 90% 2.5% 1.5% 5% 1% 2450 68 70% 7.5% 4.5% 15% 3% 2220 69 50% 12.5% 7.5% 25% 5% 1510 TABLE
Field Of The Invention This invention relates to the field of settable compositions for general purpose concrete construction containing Class-F fly ash, Class-C fly ash or slag, and cement kiln dust (CID) as a substantial replacement for Portland cement conventionally used in such compositions.
Background Of The Invention This invention is concerned with the utilization of four industrial by-products;
namely, Class-F fly ash, Class-C fly ash, blast furnace slag, and cement kiln dust (CID) in general purpose concrete-making composition. When finely divided or pulverized coal is combusted at high temperatures, for example, in boilers for the steam generation of electricity, the ash consisting of the incombustible residue plus a small amount of residual combustible matter, is made up of two fractions, a bottom ash recovered from the furnace or boiler in the form of a slag-like material and a fly ash which remains suspended in the flue gases from the combustion until separated therefrom by lcnown separation techniques, such as electrostatic precipitation. This fly ash is an extremely finely divided material generally in the form of spherical bead-like particles, with at least 70% by weight passing a 200 mesh sieve and has a generally glassy state, resulting from fusion or sintering during combustion. As recognized in the American Society of Testing Materials (ASTM) specification designations C61 ~-00 entitled "Fly Ash and Raw or Calcined Natural Pozzolan for Use as a Mineral Admixture in Portland Cement Concrete" and D5370-96 entitled "Standard Specification for Pozzolanic Blended Materials in Construction Application," fly ash is subdivided into two distinct classifications; namely, Class-F and Class-C. The definitions of these two classes are as follows:
"Class-F--Fly ash normally produced from burning anthracite or bituminous coal that meets the applicable requirements for this class as given herein. This class fly ash has pozzolanic properties.
Class-C--Fly ash normally produced from lignite ar subbituminous coal that meets the applicable requirements for this class as given herein. This class of fly ash, in addition to having pozzolanic properties, also has some cementitious properties. Some Class-C fly ashes may contain lime contents higher than 10°l0."
The latter reference to "pozzolanic properties" refers to the capability of certain mixtures that are not in themselves cementitious, but are capable of undergoing a cementitious reaction when mixed with calcium hydroxide in the presence of water. Class-C
fly ash possesses direct cementitious properties as well as pozzolanic properties. ASTM
C618-00 is also applicable to natural pozzolanic materials that are separately classified as Class N but are not pertinent here.
As the above quotation indicates, the type of coal to be combusted generally determines which class fly ash results, and the type of coal~in turn is often dependent on its geographic origin. Thus, Class-C fly ash frequently results from coals mined in the Midwest;
whereas Class-F fly ash often comes from coals mined in the Appalachian region. The ASTM
specification imposes certain chemical and physical requirements upon the respective fly ash classifications which are set forth in US 5,520,730 which is incorporated herein by reference.
CID, on the other hand, is a by-product of the production of Portland cement clinkers by the high temperature furnacing of appropriate raw materials, typically mixtures of limestone and clay or a low grade limestone already containing a sufficient quantity of argillaceous materials often with added quantities of lime to adjust the final composition. The resultant clinkers are pulverized by grinding with gypsum to a high degree of fineness aald these particles upon admixture with sand gravel and sufficient water undergo a cementitious reaction and produce the solid product generally referred to as concrete, which exhibits high compressive strength and is thus highly useful in construction of a great variety of building or supporting structures. Generally, rotary furnaces are used for producing Portland cement clinkers and a certain quantity of finely divided dust is produced as a by-product that is carried off in the flue gases from such furnaces. The dust content can range from about 5% of the clinkers output in so-called wet process plants up to as high as 15% in dry process plants.
The suspended dust is removed by various separating techniques and remains as a by-product of the cement malting operation. Part of the CIA can be returned to the furnace as recycled raw material, but it is not readily reincorporated into clinker formation and, in addition, tends to excessively elevate the allcalinity of the ultimate Portland cement.
Blast furnace slag is a by-product from the production of iron in a blast furnace;
silicon, calcium, aluminum, magnesium and oxygen are the major elemental components of the slag. Blast furnace stags include air-cooled slag resulting from solidification of molten blast fmmace slag under atmospheric conditions; granulated blast furnace slag, a glassy granular material formed when molten blast furnace slag is rapidly chilled as by immersion in water; and pelletized blast furnace slag produced by passing molten slag over a vibrating feed plate where it is expanded and cooled by water sprays, whence it passes onto a rotating drum from which it is dispatched into the air where it rapidly solidifies to spherical pellets. In general the glass content of the slag determines the cementitious character, rapidly cooled stags have a higher glass content and are cementitious; slowly cooled stags are non-glassy and crystalline and thus do not have significant cementitious properties.
The quantities of these by-product materials that are produced annually are enormous and are lileely only to increase in the future. As petroleum oil as the fuel for the generation of electricity is reduced because of conservation efforts and unfavorable economics, and as political considerations increasingly preclude the construction of new nuclear power electrical generating facilities, or even the operation of already completed units of this type, greater reliance will necessarily fall on coal as the fuel for generating electricity. As of 1979, the amount of CKD was estimated as accumulating at a rate of 4-12 million tons per year in the United States alone, whereas the amount of Class-F fly ash that is available is estimated to be about five times what can be readily utilized. The estimated yearly total production of coal ash in the U.S. is about 66.8 million tons, wlule the yearly total coal ash sales in the U.S.
is about 14.5 million tons. Further, in Canada, the recovery of copper, nickel, lead and zinc from their ores produces over twelve million tons of slag per year, which usually accumulated near the smelters without significant use. Obviously, there is an urgent growing need to find effective ways of employing these unavoidable industrial by-products since otherwise they will collect at a staggering rate and create crucial concerns over their adverse environmental effect.
Various proposals have already been made for utilizing both fly ash and CKD.
According to Lea (1971), The Chemistry of Cej~zefat ahd Coract~ete, Chemical Publishing Company, Inc., page 421 et seq., fly ash, i.e., Class-F type, from boilers was first reported to be potentially useful as a partial replacement for Portland cement in concrete construction about 50 years ago, and its utilization for that purpose has since become increasingly widespread. It is generally accepted that the proportion of Portland cement replaced by the usual fly ash should not exceed about 20% to avoid significant reduction in the compressive strength of the resultant concrete, although some more cautious jurisdictions may impose lower limits, e.g., the 15% maximum authorized by the Virginia Department of Highways and Transportation (VDHT). As described in Lea on page 437, the substitution of fly ash tends to retard the early rate of hardening of the concrete so that the concrete shows up to a 30% lower strength after seven days testing and up to a 25% lower strength after 28 days of testing, but in time the strength levels equalize at replacement levels up to 20%. Increasing the substitution quantity up to 30% gives more drastic reduction in the early compression values plus an ultimate reduction of at least about 15% after one year.
The limited substitution of fly ash for Portland cement in concrete formulations has other effects beyond compressive strength changes, both positive and negative.
The fly ash tends to increase the workability of the cement mix and is recogiuzed as desirably reducing the reactivity of the Portland cement with so-called reactive aggregates. On the other hand, fly ash contains a minor content of uncombusted carbon that acts to absorb air entrained in the concrete. Because entrained air increases the resistance of the hardened concrete to freezing, such reduction is undesirable but can be compensated for by the inclusion as an additive of so-called air-entraining agents.
l~odson, et al. in US 4,210,457, while recognizing the accepted limit of 20%
replacement with fly ash of the Portland cement in concrete mixes, proposed the substitution of larger amounts, preferably 50% or more, of the Portland cement with particular selected fly ashes having a combined content of silica, alumina and ferric oxide content, less than 80%
by weight, and a calcium oxide content exceeding 10%, based on five samples of such ashes, varying from about 58-72% combined with a calcium oxide range of about 18-30%.
Six other fly ash samples that are not suitable at the high replacement levels of 50% or more were shown to vary in the combined oxide content from about 87-92% and in calcium oxide content from about 4 to about 8%. Evaluating these values against the ASTM
C618-00, one observes that the acceptable fly ashes came wider the Class-C specifications, while the unacceptable ashes fell in the Class-F specification. Thus, this patent in effect establishes that Class-C fly ashes are suitable for substantially higher levels of replacement for Portland cement in concrete mixes than are Class-F fly ashes, and this capacity is now generally recognized, with Class-C fly ashes being generally permitted up to about a 50%
replacement level while maintaining the desirable physical properties of the concrete especially compressive strength.
In US 4,240,952, Hulbert, et al. while also acknowledging the generally recognized permissible limit of Class-F fly ash replacement for Portland cement of 20%, proposed replacement of at lest 50% up to 80%, provided the mix contained as special additives about 2% of gypsum and about 3% of calcium chloride by weight of the fly ash. The fly ash described for this purpose, however, was a Class-C fly ash analyzing about 28%
calcium oxide and combined silica, alumina and ferric oxide content of about 63%. With up to 80% of this fly ash and the specified additives, compressive strengths comparable to straight Portland cement were said to be generally acluevable. In one example using 140 pounds Portland cement and 560 pounds of fly ash (20:80 ratio) with conventional amounts of coarse and fine aggregate, and water and including t~ requisite additives, compressive strengths tested at 3180 psi for 7 days, 4200 psi for 14 dalys and about 5000 psi at 28 days.
In US 4,018,617 and US 4,101,332, Nicholson proposed the use of mixtures of fly ash (apparently Class-F in type), cement kiln dust and aggregate for creating a stabilized base supporting surface replacing conventional gravel or asphalt aggregate stabilized bases in road construction wherein the useful ranges were fly ash 6-24%, CI~1D 4-16% and aggregate 60-90%, with 8% CKD, 12% fly ash and 80% aggregate preferred. Compressive strength values for such measures as revealed in the examples varied rather erratically and generally exhibited only small increases in compression strength over the 7 to 28 day test period.
Among the better results were for the preferred mixture wherein the values increased from about 1100 psi at 7 days to 1400 psi at 28 days. The addition of a small amount of calcium chloride improved those values by about 200 psi. On the other hand, the addition of 3% of lime staclc dust recovered from a lime kiln significantly reduced the results to about 700 psi at 7 days to 900-1300 psi at 28 days. Elimination of the aggregate reduced the strength to a fraction of the values otherwise obtained, a mixture of 12% CID and 88% fly ash alone showing strength values of only about 190-260 psi over the 28-day test period.
Similarly, the choice of a finely divided aggregate such as fill sand resulted in about the same fractional level of strength values in the range of about 140-230 psi. A combination of finely divided and coarse aggregate in approximately equal amounts reduced the compressive strength values by about 1/2 with virtually no change over the test period, giving values ranging from 650-750 psi, except where 1 % of Type 1 Portland cement was included which restored the strength values to about their original level, except at the initial 7 days period where the strength values were about 800-900 psi, increasing at 28 days to about 1200-1600 psi.
Curiously, the best strength results were attained when 11.6% fly ash was combined with 3.4% lime with the balance crushed aggregate, the CKD being omitted entirely, for which the strength values while starting at a lower level of about 850-950 at 7 days increased to about 1700 psi at 28 days.
The combination of fly ash aazd lime stack dust incidentally mentioned in the later patent was explored further by Nicholson in US 4,038,095 which concerns mixtures of about 10-14% fly ash, about 5-15% lime stack dust with the balance aggregate in the range of 71-85%. Somewhat inexplicably, the compressive results reported here for such mixtures do not reach the high level specified in the first two patents, the strength values specified being only about 1000 psi with the more general levels well below that depending on particular proportions.
In US 4,268,316, Wills, Jr., discloses the use of mixtures of kiln dust and fly ash as a replacement for ground limestone and gypsum for forming a mortar or masonry cement, using proportions of about 25-55% Portland cement, about 25-65% CI~1D and 10-25% fly ash.
When these mortar formulations were mixed with damp sand in the proportions of about one part cement mixture to 2.5-3 parts sand, compression strengths comparable to those of standard masonry cement composed of 55% cement clinkers 40% limestone and 5%
gypsum were shown for mixtures containing 50% cement, 24-40% CKD and 15-25% fly ash.
hzexplicably, in one example, when the cement content was increased to 55%
with 35% CKD
and 10-% fly ash, the compressive strengths dropped by about 30-40% at both the 7 day and 28 day ages to levels inferior to the standard material. As the cement content was decreased, with corresponding increases in the CKD, the compressive strength values dropped drastically. On the other hand, in another similar example mixtures containing 55% cement, 35% CKD and 10% fly ash proved superior, particularly at the 28 day age, in compressive strength, to mixtures containing 50% cement, 35% fly ash and 15% CKD as well as other standard masonry cements containing 50% cement, 47% limestone and 3% gypsum.
Indeed, strength values dropped about 40% for the mixtures having a 5% reduction in cement and a corresponding 5% increase in the fly ash to values definitely inferior to the standard cements.
Similar variations were shown under laboratory test conditions for comparable mixtures dependent on the source of the fly ash while under actual construction conditions for the same mixtures, compressive strength values were reduced by about 50% for both the conventional masonry cement containing 55% Portland cement and comparable mixtures within the patented concept. The fly ash here was preferably Class-F with Class-C materials being less desirable.
In US 4,407,677, Wills, Jr., went on to teach that in the manufacture of concrete products such as blocks or bricks, the fly ash usually employed in combination with Portland cement therein could be replaced in its entirety by CKD with modest improvement in early compressive strength values for such products. Thus, at one day and two day tests compressive strength values were shown of about 500-800 psi, but were said to increase to about 1200 psi after 28 days. The mixes disclosed here contained 0.4-0.9 parts cement, about 0.1-0.6 parts CKD and 10-12 parts aggregate combining both fine and coarse materials, such as expanded shale and natural sand in a weight ratio of 80/20. Masonry cements generally develop at~ least about 95% of their strength properties at 28 days age so that additional aging of the patented products would not be expected to result in any significant increase in their compressive strength values.
fii US 5,106,422, Bemlett et al. teaches a self hardening backfill material that utilizes Class-C fly ash as a primary constituent in conjunction with other fly ashes, such as Class-F
fly ash, or other filler materials. The material can attain compressive strength of about 20 psi within about four hours, which is about 25 to 40 percent of its 28-day strength. The material, however, does not use cement and thus has low strength and is not useful in applications requiring concrete.
None of the above patents addresses the issue of early strength of concrete;
therefore, there remains a need for concrete mixes containing fly ash with high early strength, because the addition of fly ash to concrete often results in slow setting. There are many advantages for having high early strength, such as allowing the concrete structure to be put into service sooner, thereby reducing labor cost, and allowing precast concrete and concrete masonry manufacturers to achieve rapid form and mold turnover.
Summary Of The Invention An object of the instant invention relates a settable composition for improved early strength comprising cement, Class-F fly ash, Class-C fly ash, and CKD. In a preferred embodiment, the cement is present in an amount greater than about SO% by weight, the Class-F fly ash is present in an amount of about 1 percent to about 10 percent by weight, the Class-C fly ash is present in an amount of about 5 percent to about 25 percent by weight, and CKD is present in an amount of about 1 percent to about 15 percent by weight.
A further obj ect of the instant invention relates a settable composition for improved early strength comprising cement, Class-F fly ash, slag, and CKD. In a preferred embodiment, the cement is present in an amount greater than about 50% by weight, the Class-F fly ash is present in an amount of about 2 percent to about 11 percent by weight, the slag is present in an amount of about 1 percent to about 15 percent by weight, and CID is present in an amount of about 3 percent to about 20 percent by weight.
Methods of malting concrete from the above compositions are also disclosed.
Detailed Description Of The Invention Several different types of Portland cement are available and all are useful with the present invention. Type I is the general purpose variety and is most commonly employed but Type III is preferable for early strength application. Cormnercial blended cements, such as Type I-P, wherein 20% Class-F fly ash is blended with 80% by weight Portland cement clinleer during pulverization should be avoided.
Any standard or common Class-F fly ash obtained from boilers and like furnaces used for the combustion of pulverized coal, particularly of a bituminous or anthracite type, and especially from coal-fired, steam-generating pla~lts of electrical utilities, is suitable for use as the Class-F fly ash component of this invention. Such fly ash should have a combined silica, alumina and ferric oxide content of at least about 70% and preferably 80% or higher by weight and a lime (Ca0) content below about 10%, usually about 6% by weight or less.
Any standard or common Class-C fly ash obtained from the burning of lignite or subbituminous coal is suitable fox use as the Class-C fly ash component of this invention.
Such Class-C fly ash generally contains more calcium and less iron than Class-F fly ash and has a lime content in the range of 15% to 30%.
Similarly, any common cement kihl dust (CID) that is produced as a by-product during the industrial production of Portland cement would in principle be suitable for purposes of this invention. One specific CKD, obtained as a matter of convenience, from the Tarmac Lone Star Cement Company cement plant at Roanoke, Va., has previously been found useful in the cement composition. Other various CKD can be found in the patent literature. For example, US 4,018,617 to Nicholson mentioned previously, analyzed nine different samples of CKD.
Likewise, any blast furnace slag is appropriate for the present invention.
Slag is a non-metallic coproduct produced in the production of iron in a blast furnace.
It consists primarily of silicates, aluminosilicates and calcimn-alumina-silicates. The molten slag usually comprises about twenty percent by mass of iron production. Different fortes of slag products are produced depending on the method used to cool the molten slag.
These products include air-cooled blast furnace slag, expanded or foamed slag, palletized slag, and granulated blast furnace slag. Granulated blast furnace slag satisfying ASTM
specification is preferred.
As will be established later, within the above limits for the compositions of the invention, the concrete produced therefrom exhibit substantially comparable or superior properties for use in general purpose cement construction, especially one-day compressive strength to corresponding all Portland cement mixes. This being the case, economic considerations may be an important factor in selecting a specific mix within such ranges.
Under present marlcet conditions, and dependent upon transportation distances from the available sources of the two components, CKD can be purchased somewhat more cheaply than can a standard Class-F fly ash. For example, fly ash might be purchased at a cost of $20.00 per ton including transportation expense of about $7.00 per ton;
whereas CKD can be purchased for about $9.00 per ton including about $4.00 transportation expense. Where the relative expense sigiuficantly favors one of the products, such as CKD, it is economically advantageous to utilize a larger amount of the cheaper constituent. Thus a mix having CID
and Class-F fly ash would be cheaper to produce than a mix having only Class-F
fly ash.
Concrete mixes using the present invention may also contain aggregate materials.
The choice of aggregate material for concrete mixes using the present blends will pose not problem to the person slcilled in the design of such mixes. The coarse aggregate should have a minimum size of about 3/8 inch and can vary in size from that minimum up to one inch or larger, preferably in gradations between these limits. Crushed limestone, gravel and the life are desirable coarse aggregates, and the material selected in any case should exhibit a considerable hardness and durability inasmuch as crumbly, friable aggregates tend to significantly reduce the strength of the ultimate concrete. The finely divided aggregate is smaller than 3/S inch in size and again is preferably graduated in much finer sizes down to 200-sieve size or so. Ground limestone, sand and the life axe common useful fme aggregates.
Tn accordance with the present invention, silica fume can also be added to the cement mixture to achieve high strength and chloride protection for the concrete.
Silica fume is preferably used from 3-12 percent of the amount of cement that is being use in the mixture.
Other additives can also be used in accordance with the present invention, including, but is not limited to, water reducers, accelerators, air entrainment agents, as well as other additives that is commonly used in the concrete industry.
The mixes of the invention are prepared by homogeneously and uniformly mixing all of the mix ingredients including the Class-F fly ash, Class-C fly ash, slag, and CID. The Class-F fly ash has a specific gravity of about 2.25, while that of CKD is around 2.70. These relatively small differences in specific gravities do not create any unusual problems in the preparation of the present compositions and any of the usual mixing techniques commonly employed in the concrete mix industry axe suitable. The ultimate compositions are no more susceptible to undergo separation during handling and storage than are ordinarily concrete mixes. They can be transported and stored in the same manner as the ordinary mixes, as can the individual ingredients. The storage containers should, of course, be closed to protect the contents thereof from weather.
The following examples are given to illustrate the present invention. It should be understood that the invention is not limited to the specific conditions or details described in these examples.
The results in the following examples were actually obtained by preliminarily blending, in each case, the Class-F fly ash, Class-C fly ash, slag, and CKD
together in accordance with the concept of the prior application and combining the blend with the other mix ingredients. However, the results would be identical if the same proportionate amount for each of the component was added separately to the remaining mix ingredients and the proportionate amounts of the Class-F fly ash, Class-C fly ash, slag, and CKD
have been expressed in each case in terms of their relative weight percentages of the particular mix.
Example 1 TABLE
Mix Cement Class-F fly Class-C fly CIA 1 day PSI
# ash ash 1 100% 0 0 0 2450 2 80% 20% 0 0 1920 90% 0 10% 0 2190 6 70% 0 30% 0 1480 7 50% 0 50% 0 400 8 90% 1% 7.5% 1.5% 2860 9 70% 3% 22.5% 4.5% 2730 50% 5% 37.7% 7.5% 1510 35 90% 1.5% 5% 3.5% 3060 36 70% 4.5% 15% 10.5% 3090 37 50% 7.5% 25% 17.5% 2080 11 90% 2% 5% 3% 2870 12 70% 6% 15% 9% 2700 13 50% 10% 25% 15% 2010 14 90% 3.5% 5% 1.5% 2730 70% 10.5% 15% 4.5% 2390 16 50% 17.5% 25% 7.5% 1840 17 70% 27% 3% 0 1630 18 70% 22.5% 7.5% 0 1500 19 70% 15% 15% 0 1410 70% 7.5% 22.5% 0 1510 21 70% 3% 27% 0 1520 TAELE
Mix 1 Day PSI 7 Day PSI 28 Day PSI
#
In Example l, the cement mixes comprising Class-F fly ash, Class-C fly ash, and CI~1D (Mix #8-10, 35-37, and 11-16) are compared with cement mixes without CID
(Mix #1-2, 5-7, and 17-21). Samples were tested for compression strength in accordance with ASTM
C-109. Table 1 compares 1 day strength of the mixes; and Table 2 compares 1 day, 7 day, and 28 day strengths of the mixes.
Example 2 TABLE
Mix Cement CF fly ash CIA 1 Day PSI 7 Day 28 Day # PSI PSI
1 100% 0 0 2450 5860 7750 3 70% 20% 10% 2690 4970 6360 4 70% 30% 0 1940 4810 6480 In Example 2, cement mixes comprising CF fly ash and CKD (Mix #3) are compared with the same mix without CID (Mix #4) and all Portland cement (Mix #1).
Samples were tested for compression strength in accordance with ASTM C-109.
CF ash is the product of a mixture of western and eastern coal. An all-western coal produces Class-C fly ash; and an all-eastern coal produces Class-F fly ash.
Because of emissions and environmental concerns, power plants may burn a mixture of eastern and western coals. Further, the percentages of eastern and westenl coals may vary according to the needs of the individual power plant. The CF ash used in Example 2 is the product of a 50/50 blend of eastern and western coal.
Example 3 TABLE
Mix Cement Class-F fly Slag CIA 1 Day 7 Day 28 Day # ash PSI PSI PSI
22 100% 0 0 0 2560 5900 7270 23 90% 0 10% 0 2340 5400 6700 24 70% 0 30% 0 1860 4920 7030 25 50% 0 50% 0 1190 4150 6840 26 90% 3.6% 1% 5.4% 3520 6020 6810 27 70% 10.8% 3% 16.2% 3070 4940 5830 28 50% 18% 5% 27% 1610 3240 4290 29 90% 2.8% 3% 4.2% 3360 6050 6950 30 70% 8.4% 9% 12.6% 3020 5430 6910 31 50% 14% 15% 21% 1780 3930 5550 32 90% 2% 5% 3% 3200 6140 7230 33 70% 6% 15% 9% 2880 5730 7170 34 50% 10% 25% 15% 1880 4910 6720 52 90% 0.6% 9% 0.4% 2510 5790 7790 53 70% 1.8% 27% 1.2% 2360 5500 6950 54 50% 3% 45% 2% 1330 4270 7240 55 90% 6.3% 1% 2.7% 2620 5600 7050 56 70% 18.9% 3% 8.1% 2330 4900 5790 57 50% 31.5% 5% 13.5% 1530 3440 5010 58 90% 4.9% 3% 2.1% 2670 5500 7310 59 70% 14.7% 9% 6.3% 2290 5040 6450 60 50% 24.5% 15% 10.5% 1610 3890 5640 61 90% 3.5% 5% 1.5% 2500 5650 7330 62 70% 10.5% 15% 4.5% 2130 5010 6920 63 50% 17.5% 25% 7.5% 1640 4320 6360 In Example 3, cement mixes comprising Class-F fly ash, slag, and CKD (Mix #26-and 52-63) are compared with all Portland cement (Mix #22) and mixes comprising just slag (Mix #23-25). Samples were tested for compression strength in accordance with ASTM C-109.
Example 4 TABLE
Mix Cement Slag CKD 1 Day PSI 7 Day 28 Day # PSI PSI
23 90% 10% 0 2340 5400 6700 24 70% 30% 0 1860 4920 7030 25 50% 50% 0 1190 4150 6840 38 90% 9% 1% 2720 5640 6840 39 70% 27% 3% 2340 5480 7220 40 50% 45% 3% 1710 4950 6890 41 90% 7% 3% 3030 5810 6760 42 70% 21 % 9% 2920 5720 7050 In Example 4, cement mixes comprising slag and CKD (Mix #38-42) are compared with mixes comprising just slag (Mix #23-25). Samples were tested for compression strength in accordance with ASTM C-109.
Example 5 TABLE
Mix Cement Class-C fly Slag CKD 1 Day 7 Day 28 Day # ash PSI PSI PSI
23 90% 0 10% 0 2340 5400 6700 24 70% 0 30% 0 1860 4920 7030 25 50% 0 50% 0 1190 4150 6840 5 90% 10% 0 0 2190 5830 7880 6 70% 30% 0 0 1480 5450 7350 7 50% 50% 0 0 400 4270 6250 43 90% 1% 8% 1% 2590 5690 6890 44 70% 3% 24% 3% 2340 5580 7150 45 50% 5% 40% 5% 1720 5230 6990 46 90% 1.5% 7% 1.5% 2730 5710 7150 47 70% 4.5% 21% 4.5% 2440 5660 7590 48 50% 7.5% 35% 7.5% 1640 5090 7130 49 .90% 2.5% 5% 2.5% 2690 5500 7090 50 70% 7.5% 15% 7.5% 2570 5500 6890 51 50% 12.5% 25% 12.5% 1980 5180 6830 Tn Example 5, cement mixes comprising Class-C fly ash, slag, and CID (Mix #43-51) are compared with mixes comprising just slag (Mix #23-25) and mixes comprising just Class-C fly ash (Mix #5-7). Samples were tested for compression strength in accordance with ASTM C-109.
Example 6 TABLE
Mix Cement Class-C fly Class-F fly Slag CIA 1 Day # ash ash PSI
23 90% 0 0 10% 0 2340 24 70% 0 0 30% 0 1860 25 50% 0 0 50% 0 1190 90% 10% 0 0 0 2190 6 70% 30% 0 0 0 1480 7 50% 50% 0 0 0 400 64 90% 1.5% 0.9% 7% 0.6% 2450 65 70% 4.5% 2.7% 21% 1.8% 2210 66 50% 7.5% 4.5% 35% 3% 1470 67 90% 2.5% 1.5% 5% 1% 2450 68 70% 7.5% 4.5% 15% 3% 2220 69 50% 12.5% 7.5% 25% 5% 1510 TABLE
Mix 1 Day PSI 7 Day PSI 28 Day # PSI
In Example 6, the cement mixes comprising Class-F fly ash, Class-C fly ash, slag, and CKD (Mix #64-69) are compared with cement mixes comprising only Class-C fly ash (Mix #5-7) and mixes comprising only slag (Mix #23-27). Samples were tested for compression strength in accordance with ASTM C-109. Table 1 compares 1 day strength of the mixes;
and Table 2 compares 1 day, 7 day, and 28 day strengths of the mixes.
The invention has been disclosed broadly and illustrated in reference to representative embodiments described above. Those skilled in the art will recognize that various modifications can be made to the present invention without departing from the spirit and scope thereof.
In Example 6, the cement mixes comprising Class-F fly ash, Class-C fly ash, slag, and CKD (Mix #64-69) are compared with cement mixes comprising only Class-C fly ash (Mix #5-7) and mixes comprising only slag (Mix #23-27). Samples were tested for compression strength in accordance with ASTM C-109. Table 1 compares 1 day strength of the mixes;
and Table 2 compares 1 day, 7 day, and 28 day strengths of the mixes.
The invention has been disclosed broadly and illustrated in reference to representative embodiments described above. Those skilled in the art will recognize that various modifications can be made to the present invention without departing from the spirit and scope thereof.
Claims (54)
1. A settable composition comprising cement, Class-F fly ash, Class-C fly ash, and cement kiln dust (CKD).
2. The settable composition of claim 1, wherein the cement is Portland cement.
3. The settable composition of claim 1, wherein the cement is present in an amount greater than about 50 percent by weight.
4. The settable composition of claim 1, wherein the Class-C fly ash is present in an amount of about 5 percent to about 25 percent by weight.
5. The settable composition of claim 1, wherein the Class-F fly ash is present in an amount of about 1 percent to about 10 percent by weight.
6. The settable composition of claim 1, wherein the CKD is present in an amount of about 1 percent to about 15 percent by weight.
7. The settable composition of claim 1, wherein the cement is present in an amount greater than about 50 percent by weight, the Class-C fly ash is present in an amount of about percent to about 25 percent by weight, the Class-F fly ash is present in an amount of about 1 percent to about 10 percent by weight, and the CKD is present in an amount of about 1 percent to about 15 percent by weight.
8. A settable composition comprising cement, Class-F fly ash, slag, and cement kiln dust (CKD).
9. The settable composition of claim 8, wherein the cement is Portland cement.
10. The settable composition of claim 8, wherein the cement is present 111 all amount greater than about 50 percent by weight.
11. The settable composition of claim 8, wherein the Class-F fly ash is present in an amount of about 2 percent to about 11 percent by weight.
12. The settable composition of claim 8, wherein the slag is present in an amount of about 1 percent to about 15 percent by weight.
13. The settable composition of claim 8, wherein the CKD is present in an amount of about 3 percent to about 20 percent by weight.
14. The settable composition of claim 8, wherein the cement is present in an amount greater than about 50 percent by weight, the Class-F fly ash is present in an amount of about 2 percent to about 11 percent by weight, the slag is present in an amount of about 1 percent to about 15 percent by weight, and the CKD is present in an amount of about 3 percent to about 20 percent by weight.
15. A settable composition comprising cement, slag, and cement kiln dust (CKD).
16. The settable composition of claim 15, wherein the cement is Portland cement.
17. The settable composition of claim 15, wherein the cement is present in an amount greater than about 50 percent by weight.
18. The settable composition of claim 15, wherein the slag is present in an amount of about 9 percent to about 45 percent by weight.
19. The settable composition of claim 15, wherein the CKD is present in an amount of about 1 percent to about 10 percent by weight.
20. The settable composition of claim 15, wherein the cement is present in an amount greater than about 50 percent by weigh, the slag is present in an amount of about 9 percent to about 45 percent by weight, and the CKD is present in an amount of about 1 percent to about percent by weight.
21. A settable composition comprising cement, Class-C fly ash, slag, and cement kiln dust (CKD).
22. The settable composition of claim 21, wherein the cement is Portland cement.
23. The settable composition of claim 21, wherein the cement is present in an amount greater than about 50 percent by weight.
24. The settable composition of claim 21, wherein the Class-C fly ash is present in an amount of about 1 percent to about 15 percent by weight.
25. The settable composition of claim 21, wherein the slag is present in an amount of about 8 percent to about 45 percent by weight.
26. The settable composition of claim 21, wherein the CID is present in an amount of about 1 percent to about 15 percent by weight.
27. The settable composition of claim 21, wherein the cement is present in an amount greater than about 50 percent by weight, the Class-C fly ash is present in an amount of about 1 percent to about 15 percent by weight, the slag is present in an amount of about 8 percent to about 45 percent by weight, and the CKD is present in an amount of about 1 percent to about 15 percent by weight.
28. A method of malting concrete comprising steps of i) mixing cement, Class-F fly ash, Class-C fly ash, and CKD with water, sand, and gravel to form a mixture;
ii) pouring the mixture into a form; and iii) allowing the mixture to harden to form concrete.
ii) pouring the mixture into a form; and iii) allowing the mixture to harden to form concrete.
29. The method of claim 28, wherein the cement is Portland cement.
30. The method of claim 28, wherein the cement is present in an amount greater than about 50 percent by weight.
31. The method of claim 28, wherein the Class-C fly ash is present in an amount of about percent to about 25 percent by weight.
32. The method of claim 28, wherein the Class-F fly ash is present in an amount of about 1 percent to about 10 percent by weight.
33. The method of claim 28, wherein the CKD is present in an amount of about 1 percent to about 15 percent by weight.
34. The method of claim 28, wherein the cement is present in an amount greater than about 50 percent by weight, the Class-C fly ash is present in an amount of about 5 percent to about 25 percent by weight, the Class-F fly ash is present in an amount of about 1 percent to about 10 percent by weight, and the CKD is present in an amount of about 1 percent to about percent by weight.
35. A method of making concrete comprising steps of i) mixing cement, Class-F fly ash, slag, and CKD with water, sand, and gravel to form a mixture;
ii) pouring the mixture into a form; and iii) allowing the mixture to harden to form concrete.
ii) pouring the mixture into a form; and iii) allowing the mixture to harden to form concrete.
36. The method of claim 35, wherein the cement is Portland cement.
37. The method of claim 35, wherein the cement is present in an amount greater than about 50 percent by weight.
38. The method of claim 35, wherein the Class-F fly ash is present in an amount of about 2 percent to about 11 percent by weight.
39. The method of claim 35, wherein the slag is present in an amount of about 1 percent to about 15 percent by weight.
40. The method of claim 35, wherein the CKD is present in an amount of about 3 percent to about 20 percent by weight.
41. The method of claim 35, wherein the cement is present in an amount greater than 50 percent by weight, the Class-F fly ash is present in an amount of about 2 percent to about 11 percent by weight, the slag is present in an amount of about 1 percent to about 15 percent by weight, and the CKD is present in an amount of about 3 percent to about 20 percent by weight.
42. A method of making concrete comprising steps of i) mixing cement, slag, and CKD with water, sand, and gravel to form a mixture;
ii) pouring the mixture into a form; and iii) allowing the mixture to harden to form concrete.
ii) pouring the mixture into a form; and iii) allowing the mixture to harden to form concrete.
43. The method of claim 35, wherein the cement is Portland cement.
44. The method of claim 42, wherein the cement is present in an amount greater than about 50 percent by weight.
45. The method of claim 42, wherein the slag is present in an amount of about 9 percent to about 45 percent by weight.
46. The method of claim 42, wherein the CKD is present in an amount of about 1 percent to about 10 percent by weight.
47. The method of claim 42, wherein the cement is present in an amount greater than about 50 percent by weight, the slag is present in an amount of about 9 percent to about 45 percent by weight, and the CKD is present in an amount of about 1 percent to about 10 percent by weight.
48. A method of malting concrete comprising steps of i) mixing cement, Class-C fly ash, slag, and CKD with water, sand, and gravel to form a mixture;
ii) pouring the mixture into a form; and iii) allowing the mixture to harden to form concrete.
ii) pouring the mixture into a form; and iii) allowing the mixture to harden to form concrete.
49. The method of claim 48, wherein the cement is Portland cement.
50. The method of claim 48, wherein the cement is present in an amount greater than about 50 percent by weight.
51. The method of claim 48, wherein the Class-C fly ash is present in an amount of about 1 percent to about 15 percent by weight.
52. The method of claim 48, wherein the slag is present in an amount of about 8 percent to about 45 percent by weight.
53. The method of claim 48, wherein the CKD is present in an amount of about 1 percent to about 15 percent by weight.
54. The method of claim 48, wherein the cement is present in an amount greater than about 50 percent by weight, the Class-C fly ash is present in an amount of about 1 percent to about 15 percent by weight, the slag is present in an amount of about 8 percent to about 45 percent by weight, and the CKD is present in an amount of about 1 percent to about 15 percent by weight.
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US09/972,153 | 2001-10-09 | ||
PCT/US2002/032064 WO2003031364A1 (en) | 2001-10-09 | 2002-10-08 | Settable composition containing cement kiln dust |
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-
2001
- 2001-10-09 US US09/972,153 patent/US6645290B1/en not_active Expired - Fee Related
-
2002
- 2002-10-08 WO PCT/US2002/032064 patent/WO2003031364A1/en not_active Application Discontinuation
- 2002-10-08 CA CA002457765A patent/CA2457765A1/en not_active Abandoned
- 2002-10-08 EP EP02800946A patent/EP1441998A4/en not_active Withdrawn
Also Published As
Publication number | Publication date |
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EP1441998A1 (en) | 2004-08-04 |
EP1441998A4 (en) | 2008-07-16 |
US6645290B1 (en) | 2003-11-11 |
WO2003031364A1 (en) | 2003-04-17 |
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