1、Designation: C638 14Standard Descriptive Nomenclature ofConstituents of Aggregates for Radiation-ShieldingConcrete1This standard is issued under the fixed designation C638; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope*1.1 This descriptive nomenclature
3、 is intended to give accu-rate descriptions of some common or important naturallyoccurring and synthetic constituents of aggregates forradiation-shielding concrete, that, at the same time, are notcommon or important constituents of concrete aggregates ingeneral use. While most of the minerals and ro
4、cks discussedbelow may occur in small quantities in aggregates in generaluse, they are not major constituents of such aggregates.Common constituents of aggregates in general use are de-scribed in Descriptive Nomenclature C294. Radiation-shielding concrete often contains such aggregates, but otherspe
5、cial aggregates are used in some circumstances.1.2 The synthetic aggregates included are ferrophosphorusand boron frit.1.3 The descriptions are not adequate to permit the identi-fication of materials, since accurate identification of naturaland synthetic aggregate constituents in many cases can only
6、 bemade by a qualified geologist, mineralogist, or petrographer,using the apparatus and procedures of those sciences.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.2. Referenced Documents2.1 ASTM Standards:2C125 Terminology
7、 Relating to Concrete and Concrete Ag-gregatesC219 Terminology Relating to Hydraulic CementC294 Descriptive Nomenclature for Constituents of Con-crete Aggregates3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this standard, refer toTerminologies C125 and C219.4. Types of Materia
8、ls4.1 Two classes of materials are described below. The firstclass consists of minerals and rocks formed from them, andsynthetic materials, that have high relative density (specificgravity) and in addition contain substantial proportions ofatoms of high or moderately high atomic weight. They arerefe
9、rred to as heavy or high-density aggregates. The secondclass consists of minerals and synthetic glasses of substantialboron content that are particularly effective in absorbingthermal neutrons without producing highly penetrating gammarays. The boron-frit glasses are included because of theirfrequen
10、t use.HEAVY AGGREGATES5. Descriptions of Naturally Occurring Constituents5.1 Members of this group have higher relative density(specific gravity) than aggregates in general use. Six are ironminerals, of which five are important iron ore minerals and thesixth is an ore of titanium. Two are barium min
11、erals worked asthe principal sources of barium salts. The other isferrophosphorus, a mixture of synthetic iron phosphides.5.2 The constituents are described below first as minerals,and then as major constituents of ores when their aspect asmajor constituents of ores affects the behavior of ores asco
12、ncrete aggregates.6. Iron Minerals and Ores6.1 Hematite (Fe2O3)Hematite has a hardness of 5 to 6 onMohs scale (will be scratched by hard steel), and a relativedensity (specific gravity) of 5.26 when pure. The color variesfrom bright red to dull red to steel gray; luster varies frommetallic to submet
13、allic to dull; the streak is cherry red orreddish brown; it is nonmagnetic.6.1.1 Hematite OresRocks of which hematite is the majorconstituent vary from one deposit to another, and within the1This descriptive nomenclature is under the jurisdiction of ASTM CommitteeC09 on Concrete and Concrete Aggrega
14、tes and is the direct responsibility ofSubcommittee C09.41 on Hydraulic Cement Grouts.Current edition approved June 1, 2014. Published June 2014. Originallyapproved in 1973. Last previous edition approved in 2009 as C638 09. DOI:10.1520/C0638-14.2For referenced ASTM standards, visit the ASTM website
15、, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Driv
16、e, PO Box C700, West Conshohocken, PA 19428-2959. United States1deposit, in specific gravity, toughness, compactness, amount ofimpurities, degree of weathering, and suitability for use asconcrete aggregate. Hematite appears to be the iron ore mineralmost exploited as a source of iron. The ores of th
17、e LakeSuperior region are banded sedimentary ores consisting oflayers rich in hematite, and sometimes goethite, iron silicates,such as stilpnomelane, minnesotaite, greenalite, grunerite, andiron carbonate, alternating with silica-rich layers of chert orfine-grained quartz or a mixture. The Birmingha
18、m, AL ores areoolitic with hematite replacements of olites and fossils in amatrix that ranges from fine-grained earthy hematite, with orwithout calcite, to crystalline calcite. Hematite ores dust inhandling, with the dust ranging in color from moderate red todusky red to moderate reddish brown (5R 4
19、/6 to 5R 3/4 to 10R4/6).36.2 Ilmenite (FeTiO3with minor Mg and Mn)Ilmenite hasa hardness of 5 to 6 and relative density (specific gravity) of4.72 6 0.04 when pure. The color is iron black with metallicto submetallic luster; the streak is black; it is feebly magnetic.6.2.1 Ilmenite OresThese ores con
20、sist of crystalline ilme-nite with either magnetite or hematite and constituents of theassociated gabbroic or anorthositic rocks. Massive ilmeniteores can form coarsely crystalline massive tough rocks butvary, from deposit to deposit, and within a deposit, in relativedensity (specific gravity), comp
21、osition, hardness, and suitabil-ity for use as concrete aggregate. Many ilmenite ores consist ofilmenite disseminated in rock rather than concentrated as amajor rock-forming mineral. Ilmenite concentrated from beachsands is usually altered to a variable degree, and its mechanicalproperties probably
22、differ from those of unaltered ilmenite.One of the most widely used types of heavy aggregates isilmenite ore.6.3 Lepidocrocite (FeO(OH)Lepidocrocite has a hard-ness of 5 and relative density (specific gravity) of 4.09 whenpure. The color varies from ruby red to reddish brown and thestreak is dull or
23、ange. Lepidocrocite and goethite occurtogether, and lepidocrocite may be a constituent of goethite andlimonite ores.6.4 Goethite (HFeO2)Goethite has the same chemicalcomposition as lepidocrocite but crystallizes differently. Thehardness is 5 to 512 and the relative density (specific gravity)is 4.28
24、6 0.01 when pure and 3.3 to 4.3 in massive goethite.The color varies with the form, from crystals that are blackishbrown with imperfect adamantine-metallic luster, to dull orsilky luster in fibrous varieties; massive goethite is yellowishbrown to reddish brown; clayey material is brownish yellow too
25、cher yellow. The streak is brownish yellow to ocher yellow.6.4.1 Goethite OresThese ores range from hard toughmassive rocks to soft crumbling earths; these alterationsfrequently occur within fractions of an inch.6.5 LimoniteA general name for hydrous iron oxides ofunknown composition frequently cryp
26、tocrystalline goethitewith adsorbed and capillary water, and probably mixtures ofsuch goethite with similar lepidocrocite or hematite, or both,with adsorbed and capillary water4. The relative density(specific gravity) ranges from 2.7 to 4.3 and the color frombrownish black through browns to yellows.
27、 Limonite depositsrange from recognizable crystalline goethite to dull massivematerial of indefinite composition, and therefore, properlylimonite. Limonites of high iron content are also called browniron ores. Frequently they contain sand, colloidal silica, clays,and other impurities.6.6 Magnetite (
28、FeFe2O4)Magnetite has a hardness of 512to 612 and relative density (specific gravity) of 5.17 when pure.It is strongly magnetic; the color is black with metallic tosemimetallic luster; the streak is black.6.6.1 Magnetite OresThese ores can form dense, tough,usually coarse-grained rocks with few impu
29、rities. Magnetiteores are associated with metamorphic or igneous or sedimen-tary rocks, and therefore, the impurities associated with mag-netite ores may include a wide variety of rock-forming andaccessory minerals. Magnetite occurs in association withhematite and ilmenite; magnetic ores are widely
30、distributed,but many are not suitable for use as heavy aggregate becausethe magnetite occurs disseminated through rock rather than asa major rock-forming mineral. One of the most widely usedtypes of heavy aggregates is magnetite ore.7. Barium Minerals7.1 Witherite (BaCO3)Witherite has a hardness of
31、3 to 312and a relative density (specific gravity) of 4.29 when pure. Thecolor ranges from colorless to white to grayish or many palecolors. Like calcite and aragonite, witherite is decomposedwith effervescence by dilute hydrochloric acid (HCl).Witherite, the second most common barium mineral, occurs
32、with barite and galena. England is the chief producer ofwitherite, and barium-containing heavy aggregates in GreatBritain might be expected to contain witherite as a majorconstituent.7.2 Barite (BaSO4) (also, but improperly, called barytes)Barite has a hardness of 3 to 312 and a relative density (sp
33、ecificgravity) of 4.50 when pure. The color ranges from colorless towhite to many usually pale colors.7.2.1 Barite is the most common barium mineral and themajor barium ore. It occurs in veins transecting many kinds ofrocks, concentrated in sedimentary rocks, and as residualnodules in clays formed b
34、y the solution of sedimentary rocks.In many of its occurrences it is accompanied by clay or acalcium sulfate mineral (gypsum or anhydrite) or both. Al-though barite from residual deposits is often weathered, it ispossible to obtain clean, well-graded barite aggregate.8. Ferrophosphorus8.1 Ferrophosp
35、horus, a material produced in the productionof phosphorus, consists of a mixture of iron phosphides, andhas been used as coarse and fine aggregate in radiation-shielding concrete. Published relative density (specific gravity)range from 5.72 to 6.50 for coarse aggregate. The coarse3National Research
36、Council, Washington, DC, Rock Color Chart , 1948,reissued 1964 by Geological Soc. Am., New York, NY.4Palache, Charles, et al., The System of Mineralogy of J. D. Dana and E. S.Dana, Vol 1, Elements, Sulfides, Sulfosalts, Oxides, Ed. 7, New York, NY, 1944, p685.C638 142aggregate is reported to degrade
37、 easily and has been associatedwith extreme retardation of set in concrete. Ferrophosphorus inconcrete releases flammable, and possibly toxic, gases whichcan develop high pressures if confined5.8.2 Several iron phosphides are known, including silvergray to blue gray Fe2P, with relative density (spec
38、ific gravity)of 6.50, FeP2with relative density (specific gravity) of 5.07,and Fe3P and FeP. Ferrophosphorus aggregates are silver graybut develop some rusty staining on exposure.BORON-CONTAINING MATERIALS9. Boron Minerals9.1 The gamma rays that result from neutron capture by thelighter isotope of b
39、oron, boron-10, are much less penetratingthan those which result from neutron capture by hydrogen; andfor this reason boron and boron compounds are often used inneutron shields. The unusually high capture capability ofboron-10 permits its use in relatively small quantities. Boron ismost frequently i
40、ncorporated in the concrete as borate mineralsor synthetic boron frits. Both methods of incorporating boroncause some retardation of time of setting of the concrete, whichcan be counteracted by the use of a suitable accelerator. Theexperience recorded in the United States suggests that the costof sy
41、nthetic frits, which is higher than the cost of borate, maybe counterbalanced by uniform composition of the frits, whichpermits effective control of the properties of the concrete.9.2 Minerals that are commercially important sources ofboron are principally sodium, calcium, and magnesium borateprecip
42、itates from waters in arid volcanic regions, or alterationproducts of such precipitates (Table 1)6. These hydratedminerals include some that are easily altered by changes inrelative humidity and temperature. Some of them are soluble inor partly decomposed by cold water. Clay, gypsum, and salt arefou
43、nd in borate deposits. The presence of one or more of thesein varying unknown amounts in a borate ore used in shieldingconcrete may cause problems in making concrete with con-trolled strength, setting time, volume stability, and workability,aside from the problem of varying degrees of retardation as
44、 thetime composition, and thus the solubility, of the borate ore mayrange from lot to lot or within a lot.9.3 Borate production in the United States is virtuallylimited to borax and borax derivates obtained from naturalbrines at Searles Lake, CA, and brines produced by treatingborates from the Krame
45、r deposit at Boron, CA. Californiacolemanite deposits, which also contain ulexite, are apparentlynot regularly worked but colemanite ores have been obtainedfrom them for use in shielding concrete. Turkish borate ores,which have been referred to as “borocalcite,” but probably areulexite or colemanite
46、 or mixtures of the two, have been used inshielding concrete in Germany and Japan7.9.4 Boron minerals that are stable and insoluble are usuallynot available in large quantities for use as aggregates. Therecorded exceptions are described below.9.4.1 Paigeite(Fe+Mg)Fe+BO5)Paigeite has a hard-ness of 5
47、 and specific gravity ranging from 4.7 at the paigeiteend to 3.6 at the ludwigite end of the paigeite-ludwigite series.It is coal black or greenish black and insoluble in water, andtough. It is a high-temperature mineral occurring with magne-tite in contact metamorphic deposits. Paigeite has been us
48、ed asa heavy boron-containing aggregate in Japan.9.4.2 Tourmaline (Na(Mg, Fe, Mn, Li, Al)3Al6Si6O18(BO3)3(OH,F)4)Tourmaline has a hardness of 7 and specificgravity ranging from 3.03 to 3.25; it ranges widely in color, butcommon varieties are brown or black. It is characteristically amineral of grani
49、tes, pegmatites, and pneumatolytic veins, butpersists as a detrital mineral in sediments. Concrete havingeffective neutron-shielding characteristics has been describedin which the coarse aggregate was serpentine and the fineaggregate a tourmaline sand concentrate.10. Boron-Frit Glasses10.1 Boron-frit glasses are clear, colorless, synthetic glassesproduced by fusion and quenching used in making ceramic5Clendenning, T. G., Kellam, B., and MacInnis, C., “Hydrogen Evolution fromFerrophosphorous Aggregate in Portland Cement Concrete,” Journal of the Ameri-ca
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