1.1 本指南概述了代表拟用作水泥混合物骨料或生产此类骨料的原材料的样品的岩相检查程序。本指南基于Ref ( 1. ) . 2. 1.2 本指南概述了应在多大程度上使用岩相技术，应寻找的特性的选择，以及在混凝土骨料样品检查中使用此类技术的方式。 1.3 描述命名法中给出的岩石和矿物名称 C294型 在适当的情况下，应在根据本指南编制的报告中使用。 1.4 以国际单位制或英寸-磅单位表示的数值应单独视为标准值。每个系统中规定的值可能不是精确的等效值；因此，每个系统应相互独立使用。将两个系统的值合并可能会导致不符合标准。 1.5 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 岩相检查的目的如下: 5.1.1 确定可通过岩相方法观察到的材料的物理和化学特性，以及对材料在其预期用途中的性能有影响的物理和化学特性。 5.1.2 为了描述和分类样本的成分， 5.1.3 当成分的性质与材料在其预期用途中的性能有显著差异时，确定样品成分的相对数量，这对于正确评估样品至关重要，以及 5.1.4 将新来源的骨料样本与一个或多个来源的骨料样本进行比较，测试数据或性能记录可用。 5.2 本指南可供检查对象直接雇用的岩学家使用。 雇主应尽可能详细地告诉岩学家检查的目的和目标、所需信息的种类以及所需检查的范围。应提供相关背景信息，包括之前测试的结果。应就检查范围征求岩学家的意见和判断。 5.3 本指南可构成咨询岩相服务购买者与岩相学家之间达成协议的基础。在这种情况下，买方和顾问应共同确定要进行的检查和分析的种类、范围和目标，并以书面形式记录其协议。 协议可以规定要作出的具体决定、要报告的观察结果、要承担的资金，或这些或其他条件的组合。 5.4 水硬性水泥混凝土中使用的骨料的岩相检查是骨料评估的一个方面，但岩相检查也用于许多其他目的。岩相检查可确定潜在骨料中存在的岩石的类型和种类。然而，如上所述，不需要识别骨料来源中存在的每种岩石和矿物。 5.5 岩相检查应确定骨料是否含有化学不稳定的矿物（如可溶性硫酸盐）或体积不稳定的材料，如蒙脱石（以前称为蒙脱石皂石矿物组或膨胀粘土）。规范可能会限制混凝土中使用的骨料的石英含量，因为混凝土在573°C[1063°F]下转化为β石英，可能会受到高温（有意或无意）的影响，并伴随体积增加。 5.6 岩相检查应确定骨料是否含有可能在混凝土内氧化的硫化铁矿物。 如果在混凝土表面附近存在黄铁矿、水镁石或磁黄铁矿，则可能会导致爆裂和锈斑。一些岩石类型中的磁黄铁矿在有水分的情况下会氧化和膨胀，导致混凝土内出现明显裂缝。混凝土中的硫化铁矿物氧化可导致硫酸侵蚀、硫酸盐侵蚀或两者兼而有之。 5.7 岩相检查应确定由风化或其他蚀变颗粒组成的每种粗骨料的部分，以及风化或蚀变的程度，无论是严重、中度还是轻微，并应确定每种岩石类型在每种条件下的比例。 如果可能使用骨料的混凝土将在临界饱和条件下暴露于冻融，则应确定细多孔、高度风化或其他蚀变岩石，因为它们特别容易受到冻融破坏，并会导致混凝土的骨料部分无法冻融。这将最终破坏混凝土，因为此类骨料无法通过适当的引气砂浆进行保护。混凝土表面附近的细多孔骨料也可能形成突出物，即路面和墙壁上的瑕疵。 5.8 岩相检查也可用于确定骨料样品中立方体、球形、椭球体、棱锥体、板状、扁平和细长颗粒的比例。骨料中扁平、细长和薄片状颗粒增加了搅拌用水需求，因此降低了混凝土强度。 5.9 岩相检查应确定并提请注意潜在的碱-硅反应性成分和碱-碳酸盐反应性成分，定量测定此类成分，并建议进行额外测试，以确认或反驳混凝土中大量能够发生碱反应的骨料成分的存在。 见规范 C33/C33M . 在骨料中发现的碱-硅反应性成分包括:蛋白石、玉髓、方石英、鳞石英、高应变石英、微晶石英、隐晶质石英、火山玻璃和合成硅质玻璃。含有这些成分的骨料材料包括:玻璃质至隐晶质中间至酸性火山岩、一些泥质岩、千枚岩、灰岩、片麻岩、片岩、片麻状花岗岩、脉石英、石英岩、砂岩、燧石和含有碱反应形式二氧化硅的碳酸盐岩。 可以通过光学性质或XRD来识别上述列表中的矿物 ( 2. ) , ( 3. ) . 根据矿物成分和结构识别岩石的标准是可用的 ( 4. ) . 可能需要对反射光和透射光进行检查，以便为这些标识提供数据。使用带扫描电子显微镜（SEM/EDX）的能量色散X射线光谱仪或电子探针（EMPA/WDX）中的波长色散X射线光谱仪进行X射线显微分析，可以提供有关矿物和岩石化学成分的有用信息。 潜在有害的碱性碳酸盐活性岩通常为钙质白云石或含粘土不溶残渣的白云质石灰岩。一些基本上不含粘土的白云石和一些不含粘土且含有少量不溶残渣（主要为石英）的极细粒石灰岩也能发生一些碱碳酸盐反应，然而，此类反应不一定有害。 5.10 岩相检查可专门针对骨料中可能存在的污染物，如合成玻璃、炉渣、熟料或煤灰、氧化镁、氧化钙或两者，石膏、土壤、碳氢化合物、可能影响混凝土凝结行为或骨料性质的化学品、动物粪便、植物或腐烂植被，以及混凝土中可能不需要的任何其他污染物。 5.11 如果参与评估混凝土施工中使用的骨料材料的人员能够合理地保证，无论何时何地获得的岩相检查结果都可以可靠地进行比较，那么就可以实现本指南所针对的这些目标。

1.1 This guide outlines procedures for the petrographic examination of samples representative of materials proposed for use as aggregates in cementitious mixtures or as raw materials for use in production of such aggregates. This guide is based on Ref ( 1 ) . 2 1.2 This guide outlines the extent to which petrographic techniques should be used, the selection of properties that should be looked for, and the manner in which such techniques may be employed in the examination of samples of aggregates for concrete. 1.3 The rock and mineral names given in Descriptive Nomenclature C294 should be used, insofar as they are appropriate, in reports prepared in accordance with this guide. 1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Petrographic examinations are made for the following purposes: 5.1.1 To determine the physical and chemical characteristics of the material that may be observed by petrographic methods and that have a bearing on the performance of the material in its intended use. 5.1.2 To describe and classify the constituents of the sample, 5.1.3 To determine the relative amounts of the constituents of the sample that are essential for proper evaluation of the sample when the constituents differ significantly in properties that have a bearing on the performance of the material in its intended use, and 5.1.4 To compare samples of aggregate from new sources with samples of aggregate from one or more sources, for which test data or performance records are available. 5.2 This guide may be used by a petrographer employed directly by those for whom the examination is made. The employer should tell the petrographer, in as much detail as necessary, the purposes and objectives of the examination, the kind of information needed, and the extent of examination desired. Pertinent background information, including results of prior testing, should be made available. The petrographer's advice and judgment should be sought regarding the extent of the examination. 5.3 This guide may form the basis for establishing arrangements between a purchaser of consulting petrographic service and the petrographer. In such a case, the purchaser and the consultant should together determine the kind, extent, and objectives of the examination and analyses to be made, and should record their agreement in writing. The agreement may stipulate specific determinations to be made, observations to be reported, funds to be obligated, or a combination of these or other conditions. 5.4 Petrographic examination of aggregate considered for use in hydraulic-cement concrete is one aspect of the evaluation of aggregate, but petrographic examination is also used for many other purposes. Petrographic examinations provide identification of types and varieties of rocks present in potential aggregates. However, as noted above, identification of every rock and mineral present in an aggregate source is not required. 5.5 The petrographic examination should establish whether the aggregate contains chemically unstable minerals (such as soluble sulfates) or volumetrically unstable materials, such as smectites (formerly known as the montmorillonite-saponite group of minerals or swelling clays). Specifications may limit the quartz content of aggregates for use in concrete that may be subject to high temperature (purposefully or accidentally) because of the conversion to beta-quartz at 573 °C [1063 °F], with accompanying volume increase. 5.6 The petrographic examination should establish whether the aggregate contains iron sulfide minerals that may potentially oxidize within the concrete. Pyrite, marcasite, or pyrrhotite may cause popouts and rust staining if present near the surface of the concrete. Pyrrhotite within some rock types, in the presence of moisture, has been found to oxidize and expand causing significant cracking within concrete. Oxidation of iron sulfide minerals within concrete can lead to sulfuric acid attack, sulfate attack, or both. 5.7 Petrographic examination should identify the portion of each coarse aggregate that is composed of weathered or otherwise altered particles and the extent of that weathering or alteration, whether it is severe, moderate, or slight, and should determine the proportion of each rock type in each condition. If the concrete in which the aggregate may be used will be exposed to freezing and thawing in a critically saturated condition, finely porous and highly weathered or otherwise altered rocks should be identified because they will be especially susceptible to damage by freezing and thawing and will cause the aggregate portion of the concrete to fail in freezing and thawing. This will ultimately destroy the concrete because such aggregates cannot be protected by adequately air-entrained mortar. Finely porous aggregates near the concrete surface are also likely to form popouts, which are blemishes on pavements and walls. 5.8 Petrographic examinations may also be used to determine the proportions of cubic, spherical, ellipsoidal, pyramidal, tabular, flat, and elongated particles in an aggregate sample or samples. Flat, elongated, and thin chip-like particles in aggregate increase the mixing water requirement and hence decrease concrete strength. 5.9 Petrographic examination should identify and call attention to potentially alkali-silica reactive and alkali-carbonate reactive constituents, determine such constituents quantitatively, and recommend additional tests to confirm or refute the presence in significant amounts of aggregate constituents capable of alkali reaction in concrete. See Specification C33/C33M . Alkali-silica reactive constituents found in aggregates include: opal, chalcedony, cristobalite, tridymite, highly strained quartz, microcrystalline quartz, cryptocrystalline quartz, volcanic glass, and synthetic siliceous glass. Aggregate materials containing these constituents include: glassy to cryptocrystalline intermediate to acidic volcanic rocks, some argillites, phyllites, graywacke, gneiss, schist, gneissic granite, vein quartz, quartzite, sandstone, chert, and carbonate rocks containing alkali reactive forms of silica. Criteria are available for identifying the minerals in the list above by their optical properties or by XRD ( 2 ) , ( 3 ) . Criteria are available for identifying rocks by their mineral composition and texture ( 4 ) . Examination in both reflected and transmitted light may be necessary to provide data for these identifications. X-ray microanalysis using energy-dispersive x-ray spectrometers with scanning electron microscopy (SEM/EDX) or wavelength-dispersive x-ray spectrometers in electron microprobes (EMPA/WDX) may provide useful information on the chemical composition of minerals and rocks. Potentially deleterious alkali-carbonate reactive rocks are usually calcareous dolomites or dolomitic limestones with clayey insoluble residues. Some dolomites essentially free of clay and some very fine-grained limestones free of clay and with minor insoluble residue, mostly quartz, are also capable of some alkali-carbonate reactions, however, such reactions are not necessarily deleterious. 5.10 Petrographic examination may be directed specifically at the possible presence of contaminants in aggregates, such as synthetic glass, cinders, clinker, or coal ash, magnesium oxide, calcium oxide, or both, gypsum, soil, hydrocarbons, chemicals that may affect the setting behavior of concrete or the properties of the aggregate, animal excrement, plants or rotten vegetation, and any other contaminant that may prove undesirable in concrete. 5.11 These objectives, for which this guide was prepared, will have been attained if those involved with the evaluation of aggregate materials for use in concrete construction have reasonable assurance that the petrographic examination results wherever and whenever obtained may confidently be compared.