1、Designation: C 638 92 (Reapproved 2002)Standard Descriptive Nomenclature ofConstituents of Aggregates for Radiation-ShieldingConcrete1This standard is issued under the fixed designation C 638; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This nomenclature is intended to give accurate descrip-tions of some common or important natura
3、lly occurring andsynthetic constituents of aggregates for radiation-shieldingconcrete, that, at the same time, are not common or importantconstituents of concrete aggregates in general use. While mostof the minerals and rocks discussed below may occur in smallquantities in aggregates in general use,
4、 they are not majorconstituents of such aggregates. Common constituents ofaggregates in general use are described in Descriptive Nomen-clature C 294. Radiation-shielding concrete often contains suchaggregates, but other special aggregates are used in somecircumstances.1.2 The synthetic aggregates in
5、cluded 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 bemade by a qualified geologist, mineralogist, or petrographer,using the appa
6、ratus and procedures of those sciences.2. Referenced Documents2.1 ASTM Standards:C 294 Descriptive Nomenclature for Constituents of Con-crete Aggregates23. Types of Materials3.1 Two classes of materials are described below. The firstclass consists of minerals and rocks formed from them, andsynthetic
7、 materials, that have high specific gravity and inaddition contain substantial proportions of atoms of high ormoderately high atomic weight. They are referred to as heavyor high-density aggregates. The second class consists ofminerals and synthetic glasses of substantial boron content thatare partic
8、ularly effective in absorbing thermal neutrons withoutproducing highly penetrating gamma rays. The boron-fritglasses are included because of their frequent use.HEAVY AGGREGATES4. Descriptions of Naturally Occurring Constituents4.1 Members of this group have higher specific gravitiesthan aggregates i
9、n general use. Six are iron minerals, of whichfive are important iron ore minerals and the sixth is an ore oftitanium. Two are barium minerals worked as the principalsources of barium salts. The other is ferrophosphorus, amixture of synthetic iron phosphides.4.2 The constituents are described below
10、first as minerals,and then as major constituents of ores when their aspect asmajor constituents of ores affects the behavior of ores asconcrete aggregates.5. Iron Minerals and Ores5.1 Hematite (Fe2O3)Hematite has a hardness of 5 to 6 onMohs scale (will be scratched by hard steel), and a specificgrav
11、ity of 5.26 when pure. The color varies from bright red todull red to steel gray; luster varies from metallic to submetallicto dull; the streak is cherry red or reddish brown; it isnonmagnetic.5.1.1 Hematite OresRocks of which hematite is the majorconstituent vary from one deposit to another, and wi
12、thin thedeposit, 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 the LakeSuperior region are banded sedimentary ores consis
13、ting 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 Birmingham, AL ores areoolitic with hematite replacements of olit
14、es 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 4/6 to 5R 3/4 to 10R4/6).35.2 Ilmenite (FeTiO3with minor
15、Mg and Mn)Ilmenite hasa hardness of 5 to 6 and specific gravity of 4.72 6 0.04 when1This nomenclature is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.41on Concrete for Radiation Shielding.Current edition approved
16、Dec. 10, 2002. Published February 2003. Originallyapproved in 1973. Last previous edition approved in 1992 as C 638 92.2Annual Book of ASTM Standards, Vol 04.02.3National Research Council, Washington, DC, Rock Color Chart (1948)reissued 1964 by Geological Soc. Am., New York, NY.1Copyright ASTM Inter
17、national, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.pure. The color is iron black with metallic to submetallic luster;the streak is black; it is feebly magnetic.5.2.1 Ilmenite OresThese ores consist of crystalline il-menite with either magnetite or hematite
18、and constituents ofthe associated gabbroic or anorthositic rocks. Massive ilmeniteores can form coarsely crystalline massive tough rocks butvary, from deposit to deposit, and within a deposit, in specificgravity, composition, hardness, and suitability for use asconcrete aggregate. Many ilmenite ores
19、 consist of ilmenitedisseminated in rock rather than concentrated as a majorrock-forming mineral. Ilmenite concentrated from beach sandsis usually altered to a variable degree, and its mechanicalproperties probably differ from those of unaltered ilmenite.One of the most widely used types of heavy ag
20、gregates isilmenite ore.5.3 Lepidocrocite (FeO(OH)Lepidocrocite has a hard-ness of 5 and specific gravity of 4.09 when pure. The colorvaries from ruby red to reddish brown and the streak is dullorange. Lepidocrocite and goethite occur together, and lepi-docrocite may be a constituent of goethite and
21、 limonite ores.5.4 Goethite (HFeO2)Goethite has the same chemicalcomposition as lepidocrocite but crystallizes differently. Thehardness is 5 to 512 and the specific gravity is 4.28 6 0.01when pure and 3.3 to 4.3 in massive goethite. The color varieswith the form, from crystals that are blackish brow
22、n withimperfect adamantine-metallic luster, to dull or silky luster infibrous varieties; massive goethite is yellowish brown toreddish brown; clayey material is brownish yellow to ocheryellow. The streak is brownish yellow to ocher yellow.5.4.1 Goethite OresThese ores range from hard toughmassive ro
23、cks to soft crumbling earths; these alterationsfrequently occur within fractions of an inch.5.5 LimoniteA general name for hydrous iron oxides ofunknown composition frequently cryptocrystalline goethitewith adsorbed and capillary water, and probably mixtures ofsuch goethite with similar lepidocrocit
24、e or hematite, or both,with adsorbed and capillary water4. The specific gravity rangesfrom 2.7 to 4.3 and the color from brownish black throughbrowns to yellows. Limonite deposits range from recognizablecrystalline goethite to dull massive material of indefinitecomposition, and therefore, properly l
25、imonite. Limonites ofhigh iron content are also called brown iron ores. Frequentlythey contain sand, colloidal silica, clays, and other impurities.5.6 Magnetite (FeFe2O4)Magnetite has a hardness of 512to 612and specific gravity of 5.17 when pure. It is stronglymagnetic; the color is black with metal
26、lic to semimetallicluster; the streak is black.5.6.1 Magnetite OresThese ores can form dense, tough,usually coarse-grained rocks with few impurities. Magnetiteores are associated with metamorphic or igneous or sedimen-tary rocks, and therefore, the impurities associated with mag-netite ores may incl
27、ude a wide variety of rock-forming andaccessory minerals. Magnetite occurs in association withhematite and ilmenite; magnetic ores are widely distributed,but many are not suitable for use as heavy aggregate becausethe magnetite occurs disseminated through rock rather than asa major rock-forming mine
28、ral. One of the most widely usedtypes of heavy aggregates is magnetite ore.6. Barium Minerals6.1 Witherite (BaCO3)Witherite has a hardness of 3 to 312and a specific gravity of 4.29 when pure. The color ranges fromcolorless to white to grayish or many pale colors. Like calciteand aragonite, witherite
29、 is decomposed with effervescence bydilute hydrochloric acid (HCl). Witherite, the second mostcommon barium mineral, occurs with barite and galena.England is the chief producer of witherite, and barium-containing heavy aggregates in Great Britain might be ex-pected to contain witherite as a major co
30、nstituent.6.2 Barite (BaSO4) (also, but improperly, called barytes)Barite has a hardness of 3 to 312 and a specific gravity of 4.50when pure. The color ranges from colorless to white to manyusually pale colors.6.2.1 Barite is the most common barium mineral and themajor barium ore. It occurs in veins
31、 transecting many kinds ofrocks, concentrated in sedimentary rocks, and as residualnodules in clays formed by 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 o
32、ften weathered, it ispossible to obtain clean, well-graded barite aggregate.7. Ferrophosphorus7.1 Ferrophosphorus, 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 sp
33、ecific gravities range from 5.72to 6.50 for coarse aggregate. The coarse aggregate is reportedto degrade easily and has been associated with extremeretardation of set in concrete. Ferrophosphorus in concretereleases flammable, and possibly toxic, gases which candevelop high pressures if confined5.7.
34、2 Several iron phosphides are known, including silvergray to blue gray Fe2P, with specific gravity of 6.50, FeP2withspecific gravity of 5.07, and Fe3P and FeP. Ferrophosphorusaggregates are silver gray but develop some rusty staining onexposure.BORON-CONTAINING MATERIALS8. Boron Minerals8.1 The gamm
35、a rays that result from neutron capture by thelighter isotope of boron, boron-10, are much less penetratingthan those which result from neutron capture by hydrogen; andfor this reason boron and boron compounds are often used in4Palache, Charles, et al., The System of Mineralogy of J. D. Dana and E.
36、S.Dana, Vol 1, Elements, Sulfides, Sulfosalts, Oxides, Ed. 7, New York, NY, 1944, p685.5Clendenning, T. G., Kellam, B., and MacInnis, C., “Hydrogen Evolution fromFerrophosphorous Aggregate in Portland Cement Concrete,” Journal of the Ameri-can Concrete Institute, No 12, December 1968, Proceedings, V
37、ol 65, pp.10211028.Mather, Bryant, discussion of Davis, Harold S., “Concrete for RadiationShielding-In Perspective,” and closure by author in“ Concrete for NuclearReactors,” ACI SP-34, Vol 1, 1972, pp 1113.C 638 92 (2002)2neutron shields. The unusually high capture capability ofboron-10 permits its
38、use in relatively small quantities. Boron ismost frequently incorporated 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. Theexperie
39、nce recorded in the United States suggests that the costof synthetic 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.8.2 Minerals that are commercially important sources ofboro
40、n are principally sodium, calcium, and magnesium borateprecipitates 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 p
41、artly decomposed by cold water. Clay, gypsum, and salt arefound 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 workabilit
42、y,aside from the problem of varying degrees of retardation as thetime composition, and thus the solubility, of the borate ore mayrange from lot to lot or within a lot.8.3 Borate production in the United States is virtuallylimited to borax and borax derivates obtained from naturalbrines at Searles La
43、ke, CA, and brines produced by treatingborates from the Kramer 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 referr
44、ed to as “borocalcite,” but probably areulexite or colemanite or mixtures of the two, have been used inshielding concrete in Germany and Japan7.8.4 Boron minerals that are stable and insoluble are usuallynot available in large quantities for use as aggregates. Therecorded exceptions are described be
45、low.8.4.1 Paigeite(Fe+Mg)Fe+BO5)Paigeite has a hard-ness of 5 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 mag
46、ne-tite in contact metamorphic deposits. Paigeite has been used asa heavy boron-containing aggregate in Japan.8.4.2 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 a
47、re brown or black. It is characteristically amineral of granites, 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 tou
48、rmaline sand concentrate.9. Boron-Frit Glasses9.1 Boron-frit glasses are clear, colorless, synthetic glassesproduced by fusion and quenching used in making ceramicglazes. They may be obtained in many compositions, but thosemost useful in shielding concrete contain calcium, relativelyhigh amounts of
49、silica and alumina, and low amounts ofalkalies. Increased silica and alumina decrease the solubility ofthe frits and thus diminish their retarding effect in shieldingconcrete. When there is a hazard from secondary radiation,limits on allowable proportions of sodium and potassium maybe imposed.10. Keywords10.1 aggregates; boron; concrete; iron; minerals6Compiled from: Smith, W. C., “Borax and Borates,” Gillson, J. L., ed.,Industrial Rocks and Minerals, 3rd Ed., American Institute of Mining, Metallurgi-cal, and Petroleum Engineers, New York, NY, 1960, pp
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