1、Designation: C294 12 (Reapproved 2017)Standard Descriptive Nomenclature forConstituents of Concrete Aggregates1This standard is issued under the fixed designation C294; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st 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. Scope1.1 This descriptive nomenclature prov
3、ides brief descrip-tions of some of the more commonly occurring, or moreimportant, natural and artificial materials of which mineralaggregates are composed. The descriptions provide a basis forunderstanding these terms as applied to concrete aggregates.When appropriate, brief observations regarding
4、the potentialeffects of using the natural and artificial materials in concreteare discussed.NOTE 1These descriptions characterize minerals and rocks as theyoccur in nature and blast-furnace slag or lightweight aggregates that areprepared by the alteration of the structure and composition of naturalm
5、aterial. Information about lightweight aggregates is given in Specifica-tions C330, C331, and C332.1.2 This standard does not include descriptions of constitu-ents of aggregates used in radiation shielding concrete. SeeDescriptive Nomenclature C638.1.3 The values stated in SI units are to be regarde
6、d asstandard. No other units of measurement are included in thisstandard.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Rec
7、om-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C125 Terminology Relating to Concrete and Concrete Ag-gregatesC227 Test Method for Potential Alkali Reactivity ofCement-Aggregate Combinations (Mortar-Bar Method
8、)C289 Test Method for Potential Alkali-Silica Reactivity ofAggregates (Chemical Method) (Withdrawn 2016)3C330 Specification for Lightweight Aggregates for Struc-tural ConcreteC331 Specification for Lightweight Aggregates for ConcreteMasonry UnitsC332 Specification for Lightweight Aggregates for Insu
9、lat-ing ConcreteC638 Descriptive Nomenclature of Constituents of Aggre-gates for Radiation-Shielding Concrete3. Terminology3.1 For definitions of terms in this standard, refer toTerminology C125.4. Significance and Use4.1 This descriptive nomenclature provides information onterms commonly applied to
10、 concrete aggregates. This standardis intended to assist in understanding the meaning and signifi-cance of the terms.4.2 Many of the materials described frequently occur inparticles that do not display all the characteristics given in thedescriptions, and most of the described rocks grade fromvariet
11、ies meeting one description to varieties meeting anotherwith all intermediate stages being found.4.3 The accurate identification of rocks and minerals can, inmany cases, be made only by a qualified geologist,mineralogist, or petrographer using the apparatus and proce-dures of these sciences. Referen
12、ce to these descriptions may,however, serve to indicate or prevent gross errors in identifi-cation. Identification of the constituent materials in an aggre-gate may assist in characterizing its engineering properties, butidentification alone cannot provide the sole basis for predictingbehavior of ag
13、gregates in service. Aggregates of any type orcombination of types may perform well or poorly in servicedepending upon the exposure to which the concrete issubjected, the physical and chemical properties of the matrix inwhich they are embedded, their physical condition at the time1This descriptive n
14、omenclature is under the jurisdiction of ASTM CommitteeC09 on Concrete and Concrete Aggregatesand is the direct responsibility ofSubcommittee C09.65 on Petrography.Current edition approved May 1, 2017. Published June 2017. Originallyapproved in 1952. Last previous edition approved in 2012 as C29412.
15、 DOI:10.1520/C0294-12R17.2For referenced ASTM standards, visit the ASTM website, 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.3The last approved version of this h
16、istorical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the De
17、cision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1they are used, and other factors. Constituents that may occuronly in minor amounts in the aggregate may or may notdecisiv
18、ely influence its performance. Information about con-crete aggregate performance in concrete has been published byASTM.4CONSTITUENTS OF NATURAL MINERALAGGREGATES5. Classes and Types5.1 The materials found as constituents of natural mineralaggregates are minerals and rocks.5.2 Minerals are naturally
19、occurring inorganic substances ofmore or less definite chemical composition and usually of aspecific crystalline structure. The physical nature of the rock-forming minerals and aspects of crystal chemistry determinethe important physical and chemical properties of naturalmineral aggregates. Certain
20、assemblages of rock-forming min-erals possess desirable qualities for use as aggregates incementitious materials.5.2.1 Minerals are characterized by their crystallographic,physical, and optical properties and their chemical composi-tion. The crystallographic properties of minerals may bedetermined b
21、y x-ray diffraction and optical properties (1-6).The physical properties of minerals include but are not limitedto crystal habit, cleavage, parting, fracture, hardness, specificgravity, luster, color, streak, magnetism, luminescence, andpyroelectricity (7). The optical properties of minerals include
22、but are not limited to refractive index, birefringence, optic sign,pleochroism, and sign of elongation (2-5). Methods to deter-mine the chemical composition of minerals include but are notlimited to optical properties (5), flame photometry (7,8),chemical spot tests (9,10), various staining technique
23、s (11),x-ray fluorescence, and electron microscopy (12-14).5.2.2 Different minerals may have the same chemical com-position but different crystallographic and physical properties.Such sets of minerals are known as polymorphs. Distinguish-ing between some polymorphs can be important for determin-ing
24、the suitability of aggregates for use in cementitiousmaterials.5.3 Rocks are classified according to origin into three majordivisions: igneous, sedimentary, and metamorphic. These threemajor groups are subdivided into types according to mineraland chemical composition, texture, and internal structur
25、e. Mostrocks are composed of several minerals but some are composedof only one mineral. Certain examples of the rock quartzite arecomposed exclusively of the mineral quartz, and certainlimestones are composed exclusively of the mineral calcite.Individual sand grains frequently are composed of partic
26、les ofrock, but they may be composed of a single mineral, particu-larly in the finer sizes.5.3.1 Igneous rocks form from molten matter either at orbelow the earths surface.5.3.2 Sedimentary rocks form near the earths surface by theaccumulation and consolidation of the products of weatheringand erosi
27、on of existing rocks, or by direct chemical precipita-tion. Sedimentary rocks may form from pre-existing igneous,metamorphic, or sedimentary rocks.5.3.3 Metamorphic rocks form from pre-existing igneous,sedimentary, or metamorphic rocks by the action of heat orpressure or both.6. Silica Minerals6.1 Q
28、uartza very common hard mineral composed ofsilica (SiO2). It will scratch glass and is not scratched by aknife. When pure it is colorless with a glassy (vitreous) lusterand a shell-like (conchoidal) fracture. It lacks a visible cleav-age (the ability to break in definite directions along evenplanes)
29、 and, when present in massive rocks such as granite, itusually has no characteristic shape. It is resistant to weatheringand is therefore an important constituent of many sand andgravel deposits and many sandstones. It is also abundant inmany light-colored igneous and metamorphic rocks. Somestrained
30、, or intensely fractured (granulated), and microcrystal-line quartz may be potentially deleteriously reactive with thealkalies in the hydraulic cement paste.6.2 Opala hydrous form of silica (SiO2 nH2O) whichoccurs without characteristic external form or internal crystal-line arrangement as determine
31、d by ordinary visible lightmethods. When X-ray diffraction methods are used, opal mayshow some evidences of internal crystalline arrangement. Opalhas a variable water content, generally ranging from 3 to 9 %.The specific gravity and hardness are always less than those ofquartz. The color is variable
32、 and the luster is resinous to glassy.It is usually found in sedimentary rocks, especially somecherts, and is the principal constituent of diatomite. It is alsofound as a secondary material filling cavities and fissures inigneous rocks and may occur as a coating on gravel and sand.The recognition of
33、 opal in aggregates is important because it ispotentially deleteriously reactive with the alkalies in hydrauliccement paste or with the alkalies from other sources, such asaggregates containing zeolites, and ground water.6.3 Chalcedonychalcedony has been considered both as adistinct mineral and a va
34、riety of quartz. It is frequentlycomposed of a mixture of microscopic fibers of quartz with alarge number of submicroscopic pores filled with water and air.The properties of chalcedony are intermediate between those ofopal and quartz, from which it can sometimes be distinguishedonly by laboratory te
35、sts. It frequently occurs as a constituent ofthe rock chert and is potentially deleteriously reactive with thealkalies in hydraulic cement paste.6.4 Tridymite and cristobalitehigh temperature crystallineforms of silica (SiO2) sometimes found in volcanic rocks. Theyare metastable at ordinary temperat
36、ures and pressures. They arerare minerals in aggregates except in areas where volcanicrocks are abundant. A type of cristobalite is a commonconstituent of opal. Tridymite and cristobalite are potentiallydeleteriously reactive with the alkalies in hydraulic cementpaste.7. Feldspars7.1 The minerals of
37、 the feldspar group are the most abun-dant rock-forming minerals in the crust of the earth. They are4Klieger, P., and Lamond, J. F., editors, Significance of Tests and Properties ofConcrete and Concrete-Making Materials, ASTM STP 169C, 1994.C294 12 (2017)2important constituents of all three major ro
38、ck groups, igneous,sedimentary, and metamorphic. Since all feldspars have goodcleavages in two directions, particles of feldspar usually showseveral smooth surfaces. Frequently, the smooth cleavagesurfaces show fine parallel lines. All feldspars are slightly lesshard than, and can be scratched by, q
39、uartz and will, when fresh,easily scratch a penny. The various members of the group aredifferentiated by chemical composition and crystallographicproperties. The feldspars orthoclase, sanidine, and microclineare potassium aluminum silicates, and are frequently referredto as potassium feldspars. The
40、plagioclase feldspars includethose that are sodium aluminum silicates and calcium alumi-num silicates, or both sodium and calcium aluminum silicates.This group, frequently referred to as the “soda-lime” group,includes a continuous series, of varying chemical compositionand optical properties, from a
41、lbite, the sodium aluminumfeldspar, to anorthite, the calcium aluminum feldspar, withintermediate members of the series designated oligoclase,andesine, labradorite, and bytownite. Potassium feldspars andsodium-rich plagioclase feldspars occur typically in igneousrocks such as granites and rhyolites,
42、 whereas, plagioclasefeldspars of higher calcium content are found in igneous rocksof lower silica content such as diorite, gabbro, andesite, andbasalt.8. Ferromagnesian Minerals8.1 Many igneous and metamorphic rocks contain darkgreen to black minerals that are generally silicates of iron ormagnesiu
43、m, or of both. They include the minerals of theamphibole, pyroxene, and olivine groups. The most commonamphibole mineral is hornblende; the most common pyroxenemineral is augite; and the most common olivine mineral isforsterite. Dark mica, such as biotite and phlogopite, are alsoconsidered ferromagn
44、esian minerals. The amphibole and py-roxene minerals are brown to green to black and generallyoccur as prismatic units. Olivine is usually olive green, glassyin appearance, and usually altered. Biotite has excellent cleav-age and can be easily cleaved into thin flakes and plates. Theseminerals can b
45、e found as components of a variety of rocks, andin sands and gravels. Olivine is found only in dark igneousrocks where quartz is not present, and in sands and gravelsclose to the olivine source.9. Micaceous Minerals9.1 Micaceous minerals have perfect cleavage in one direc-tion and can be easily spli
46、t into thin flakes. The mica mineralsof the muscovite group are colorless to light green; of thebiotite group, dark brown to black or dark green; of thelepidolite group, white to pink and red or yellow; and of thechlorite group, shades of green. Another mica, phlogopite, issimilar to biotite, common
47、ly has a pearl-like luster and bronzecolor, and less commonly is brownish red, green, or yellow.The mica minerals are common and occur in igneous,sedimentary, and metamorphic rocks, and are common asminor to trace components in many sands and gravels. Themuscovite, biotite, lepidolite, and phlogopit
48、e minerals cleaveinto flakes and plates that are elastic; the chlorite minerals, bycomparison, form inelastic flakes and plates. Vermiculite (amica-like mineral) forms by the alteration of other micas and isbrown and has a bronze luster.9.2 Because micaceous materials have a high surface area,they c
49、an influence the properties of freshly mixed and hardenedconcrete. Aggregates with a high mica content can reduceworkability and increase the water demand of the concrete(15). The shape and perfect cleavage of micaceous mineralsmay result in a poor bond to the cementitious paste (16).10. Clay Minerals10.1 The term “clay” refers to natural material composed ofparticles in a specific size range less than 2 m (0.002 mm).Mineralogically, clay refers to a group of layered silicateminerals including the clay-micas (illites), the kaolin group,very finely divided chlorites, and the
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