ASTM C638-14 pdf download.Standard Descriptive Nomenclature of Constituents of Aggregates for Radiation-Shielding Concrete.
4. Types of Materials
4.1 Two classes of materials are described below. The first class consists of minerals and rocks formed from them, and synthetic materials, that have high relative density (specific gravity) and in addition contain substantial proportions of atoms of high or moderately high atomic weight. They are referred to as heavy or high-density aggregates. The second class consists of minerals and synthetic glasses of substantial boron content that are particularly effective in absorbing thermal neutrons without producing highly penetrating gamma rays. The boron-frit glasses are included because of their frequent use. HEAVY AGGREGATES
5. Descriptions of Naturally Occurring Constituents
5.1 Members of this group have higher relative density (specific gravity) than aggregates in general use. Six are iron minerals, of which five are important iron ore minerals and the sixth is an ore of titanium. Two are barium minerals worked as the principal sources of barium salts. The other is ferrophosphorus, 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 as major constituents of ores affects the behavior of ores as concrete aggregates.
6. Iron Minerals and Ores 6.1 Hematite (Fe 2 O 3 )—Hematite has a hardness of5 to 6 on Mohs’ scale (will be scratched by hard steel), and a relative density (specific gravity) of 5.26 when pure. The color varies from bright red to dull red to steel gray; luster varies from metallic to submetallic to dull; the streak is cherry red or reddish brown; it is nonmagnetic.
6.1.1 Hematite Ores—Rocks of which hematite is the major constituent vary from one deposit to another, and within the deposit, in specific gravity, toughness, compactness, amount of impurities, degree of weathering, and suitability for use as concrete aggregate. Hematite appears to be the iron ore mineral most exploited as a source of iron. The ores of the Lake Superior region are banded sedimentary ores consisting of layers rich in hematite, and sometimes goethite, iron silicates, such as stilpnomelane, minnesotaite, greenalite, grunerite, and iron carbonate, alternating with silica-rich layers of chert or fine-grained quartz or a mixture. The Birmingham, AL ores are oolitic with hematite replacements of oölites and fossils in a matrix that ranges from fine-grained earthy hematite, with or without calcite, to crystalline calcite. Hematite ores dust in handling, with the dust ranging in color from moderate red to dusky red to moderate reddish brown (5R 4/6 to 5R 3/4 to 10R 4/6). 3
6.2 Ilmenite (FeTiO 3 with minor Mg and Mn)—Ilmenite has a hardness of 5 to 6 and relative density (specific gravity) of 4.72 6 0.04 when pure. The color is iron black with metallic to submetallic luster; the streak is black; it is feebly magnetic.
6.2.1 Ilmenite Ores—These ores consist of crystalline ilme- nite with either magnetite or hematite and constituents of the associated gabbroic or anorthositic rocks. Massive ilmenite ores can form coarsely crystalline massive tough rocks but vary, from deposit to deposit, and within a deposit, in relative density (specific gravity), composition, hardness, and suitabil- ity for use as concrete aggregate. Many ilmenite ores consist of ilmenite disseminated in rock rather than concentrated as a major rock-forming mineral. Ilmenite concentrated from beach sands is usually altered to a variable degree, and its mechanical properties probably differ from those of unaltered ilmenite. One of the most widely used types of heavy aggregates is ilmenite ore.
6.3 Lepidocrocite (FeO(OH))—Lepidocrocite has a hard- ness of 5 and relative density (specific gravity) of 4.09 when pure. The color varies from ruby red to reddish brown and the streak is dull orange. Lepidocrocite and goethite occur together, and lepidocrocite may be a constituent ofgoethite and limonite ores. 6.4 Goethite (HFeO 2 )—Goethite has the same chemical composition as lepidocrocite but crystallizes differently. The hardness is 5 to 5 1 ⁄ 2 and the relative density (specific gravity) is 4.28 6 0.01 when pure and 3.3 to 4.3 in massive goethite. The color varies with the form, from crystals that are blackish brown with imperfect adamantine-metallic luster, to dull or silky luster in fibrous varieties; massive goethite is yellowish brown to reddish brown; clayey material is brownish yellow to ocher yellow. The streak is brownish yellow to ocher yellow.
6.4.1 Goethite Ores—These ores range from hard tough massive rocks to soft crumbling earths; these alterations frequently occur within fractions of an inch. 6.5 Limonite—A general name for hydrous iron oxides of unknown composition frequently cryptocrystalline goethite with adsorbed and capillary water, and probably mixtures of such goethite with similar lepidocrocite or hematite, or both, with adsorbed and capillary water 4 . The relative density (specific gravity) ranges from 2.7 to 4.3 and the color from brownish black through browns to yellows. Limonite deposits range from recognizable crystalline goethite to dull massive material of indefinite composition, and therefore, properly limonite. Limonites of high iron content are also called brown iron ores. Frequently they contain sand, colloidal silica, clays, and other impurities.ASTM C638 pdf download.