1、Designation: C856 18Standard Practice forPetrographic Examination of Hardened Concrete1This standard is issued under the fixed designation C856; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in
2、 parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice outlines procedures for the petrographicexamination of samples of hardened concrete. The samplesexamined may be taken from concre
3、te constructions, they maybe concrete products or portions thereof, or they may beconcrete or mortar specimens that have been exposed in naturalenvironments, or to simulated service conditions, or subjectedto laboratory tests. The phrase “concrete constructions” isintended to include all sorts of ob
4、jects, units, or structures thathave been built of hydraulic cement concrete.NOTE 1A photographic chart of materials, phenomena, and reactionproducts discussed in Sections 813and Tables 16 are available asAdjunct C856 (ADJCO856).1.2 The petrographic procedures outlined herein are appli-cable to the
5、examination of samples of all types of hardenedhydraulic-cement mixtures, including concrete, mortar, grout,plaster, stucco, terrazzo, and the like. In this practice, thematerial for examination is designated as “concrete,” eventhough the commentary may be applicable to the othermixtures, unless the
6、 reference is specifically to media otherthan concrete.1.3 The purposes of and procedures for petrographic exami-nation of hardened concrete are given in the following sections:SectionQualifications of Petrographers and Use of Technicians 4Purposes of Examination 5Apparatus 6Selection and Use of App
7、aratus 7Samples 8Examination of Samples 9Specimen Preparation 10Visual and Stereomicroscope Examination 11Polarizing Microscope Examination 12Paste Features 13Report 141.4 The values stated in inch-pound units are to be regardedas the standard. The SI units in parentheses are provided forinformation
8、 purposes only.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitatio
9、ns prior to use. Aspecific hazard statement is given in 6.2.10.1.1.6 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 Recom-menda
10、tions 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-gregatesC215 Test Method for Fundamental Transverse,Longitudinal, and Torsional Resonant Frequencies ofConcrete Spe
11、cimensC227 Test Method for Potential Alkali Reactivity ofCement-Aggregate Combinations (Mortar-Bar Method)C342 Test Method for Potential Volume Change of Cement-Aggregate Combinations (Withdrawn 2001)3C441 Test Method for Effectiveness of Pozzolans or GroundBlast-Furnace Slag in Preventing Excessive
12、 Expansion ofConcrete Due to the Alkali-Silica ReactionC452 Test Method for Potential Expansion of Portland-Cement Mortars Exposed to SulfateC457 Test Method for Microscopical Determination of Pa-rameters of the Air-Void System in Hardened ConcreteC496/C496M Test Method for Splitting Tensile Strengt
13、h ofCylindrical Concrete SpecimensC597 Test Method for Pulse Velocity Through ConcreteC803/C803M Test Method for Penetration Resistance ofHardened ConcreteC805 Test Method for Rebound Number of Hardened Con-crete1This practice is under the jurisdiction of ASTM Committee C09 on Concreteand ConcreteAg
14、gregates and is the direct responsibility of Subcommittee C09.65 onPetrography.Current edition approved March 1, 2018. Published April 2018. Originallyapproved in 1977. Last previous edition approved in 2017 as C856 17. DOI:10.1520/C0856-18.2For referenced ASTM standards, visit the ASTM website, www
15、.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 historical standard is referenced onwww.astm.org.*A Summary of Changes section appear
16、s at the end of this standardCopyright 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 Decision on Principle
17、s for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1C823 Practice for Examination and Sampling of HardenedConcrete in ConstructionsC1012 Test Method for Length Change of Hydraulic-Cement Morta
18、rs Exposed to a Sulfate SolutionC1260 Test Method for Potential Alkali Reactivity of Ag-gregates (Mortar-Bar Method)C1723 Guide for Examination of Hardened Concrete UsingScanning Electron MicroscopyE3 Guide for Preparation of Metallographic SpecimensE883 Guide for ReflectedLight Photomicrography2.2
19、ASTM Adjuncts:Adjunct C856 (ADJCO856) A chart of 27 photos43. Terminology3.1 Definitions: For definitions of terms used in thispractice, refer to Terminology C125.4. Qualifications of Petrographers and Use of Technicians4.1 All petrographic examinations of hardened concretedescribed in this practice
20、 shall be performed by or under thetechnical direction of a full time supervising petrographer withat least 5 years experience in petrographic examinations ofconcrete and concrete-making materials. The supervising con-crete petrographer shall have college level courses that includepetrography, miner
21、alogy, and optical mineralogy, or 5 years ofdocumented equivalent experience, and experience in theirapplication to evaluations of concrete-making materials andconcrete products in which they are used and in cementitious-based materials. A resume of the professional background andqualifications of a
22、ll concrete petrographers shall be available.4.2 A concrete petrographer shall be knowledgeable aboutthe following: concrete-making materials; processes ofbatching, mixing, handling, placing, and finishing of hydraulic-cement concrete; the composition and microstructure of ce-mentitious paste; the i
23、nteraction of constituents of concrete;and the effects of exposure of such concrete to a wide varietyof conditions of service.4.3 Sample preparation shall be performed by concretepetrographers or trained technicians pursuant to instructionsfrom and under the guidance of a qualified concrete petrogra
24、-pher. Aspects of the petrographic examination, such as themeasurement of sample dimensions, photography of as-received samples, staining of sample surfaces, that do notrequire the education and skills outlined in 4.1, shall beperformed by concrete petrographers or by trained technicianspursuant to
25、instructions and under the guidance of a qualifiedconcrete petrographer. The analysis and interpretation of thefeatures that are relevant to the investigation and evaluation ofthe performance of the materials represented by the sampleshall be made solely by concrete petrographers with qualifica-tion
26、s consistent with those outlined in 4.1.4.4 A concrete petrographer shall be prepared to provide anoral statement, written report, or both that includes a descrip-tion of the observations and examinations made during thepetrographic examinations, and interpretation of the findingsinsofar as they rel
27、ate to the concerns of the person or agencyfor whom the examination was performed. Supplementaryinformation provided to the petrographer on the concrete andconcrete materials, conditions of service, or other features ofthe concrete construction may be helpful in interpreting thedata obtained during
28、the petrographic examinations.4.5 This practice may form the basis for establishing ar-rangements between a purchaser of the consulting service andthe consulting petrographer. In such cases, the purchaser of theconsulting service and the consulting petrographer shouldtogether determine the kind, ext
29、ent, and objectives of theexaminations and analyses to be made, and may record theiragreement in writing. The agreement may stipulate specificdeterminations to be made, observations to be reported, fundsto be obligated, or a combination of these and other conditions.5. Purposes of Examination5.1 Exa
30、mples of purposes for which petrographic examina-tion of concrete is used are given in 5.2 5.5. The probableusefulness of petrographic examination in specific instancesmay be determined by discussion with an experienced petrog-rapher of the objectives of the investigation proposed orunderway.5.2 Con
31、crete from Constructions:5.2.1 Determination in detail of the condition of concrete ina construction.5.2.2 Determination of the causes of inferior quality,distress, or deterioration of concrete in a construction.5.2.3 Determination of the probable future performance ofthe concrete.5.2.4 Determinatio
32、n whether the concrete in a constructionwas or was not as specified. In this case, other tests may berequired in conjunction with petrographic examination.5.2.5 Description of the cementitious matrix, includingqualitative determination of the kind of hydraulic binder used,degree of hydration, degree
33、 of carbonation if present, evidenceof unsoundness of the cement, presence of supplementarycementitious materials, the nature of the hydration products,adequacy of curing, and unusually high watercement ratio ofthe paste.5.2.6 Determination whether alkalisilica or alkalicarbon-ate reactions, or ceme
34、ntaggregate reactions, or reactionsbetween contaminants and the matrix have taken place, andtheir effects upon the concrete.5.2.7 Determination whether the concrete has been sub-jected to and affected by sulfate attack, or other chemicalattack, or early freezing, or to other harmful effects of freez
35、ingand thawing.5.2.8 Part of a survey of the safety of a structure for apresent or proposed use.5.2.9 Determination whether concrete subjected to fire isessentially undamaged or moderately or seriously damaged.5.2.10 Investigation of the performance of the coarse or fineaggregate in the structure, o
36、r determination of the compositionof the aggregate for comparison with aggregate from approvedor specified sources.4Available from ASTM International Headquarters. Order Adjunct No.ADJC0856. Original adjunct produced in 1995.C856 1825.2.11 Determination of the factors that caused a givenconcrete to
37、serve satisfactorily in the environment in which itwas exposed.5.2.12 Determination of the presence and nature of surfacetreatments, such as dry shake applications on concrete floors.5.3 Test Specimens from Actual or Simulated ServiceConcrete or mortar specimens that have been subjected toactual or
38、simulated service conditions may be examined formost of the purposes listed under Concrete from Constructions.5.4 Concrete Products:5.4.1 Petrographic examination can be used in investigationof concrete products of any kind, including masonry units,precast structural units, piling, pipe, and buildin
39、g modules. Theproducts or samples of those submitted for examination may beeither from current production, from elements in service inconstructions, or from elements that have been subjected totests or to actual or simulated service conditions.5.4.2 Determination of features like those listed underc
40、oncrete from constructions.5.4.3 Determination of effects of manufacturing processesand variables such as procedures for mixing, molding,demolding, consolidation, curing, and handling.5.4.4 Determination of effects of use of different concrete-making materials, forming and molding procedures, types
41、andamounts of reinforcement, embedded hardware, etc.5.5 Laboratory SpecimensThe purposes of petrographicexamination of laboratory specimens of concrete, mortar, orcement paste are, in general, to investigate the effects of the teston the test piece or on one or more of its constituents, toprovide ex
42、amples of the effects of a process, and to provide thepetrographer with visual evidence of examples of reactions inpaste or mortar or concrete of known materials, proportions,age, and history. Specific purposes include:5.5.1 To establish whether alkalisilica reaction has takenplace, what aggregate c
43、onstituents were affected, what evi-dence of the reaction exists, and what were the effects of thereaction on the concrete.5.5.2 To establish whether one or more alkalicarbonatereactions have taken place, which aggregate constituents wereaffected and what evidence of the reaction or reactions exists
44、,and the effects of the reaction on the concrete properties.5.5.3 To establish whether any other cement aggregatereaction has taken place. In addition to alkalisilica andalkalicarbonate reactions, these include hydration of anhy-drous sulfates, rehydration of zeolites, wetting of clays andreactions
45、involving solubility, oxidation, sulfates, and sulfides(see Refs (1-3).55.5.4 To establish whether an aggregate used in a test hasbeen contaminated by a reactive constituent when in fact theaggregate was not reactive.5.5.5 To establish the effects of a freezing and thawing testor other physical or m
46、echanical exposure of concrete on theaggregate and the matrix.5.5.6 To establish the extent of reaction, the nature ofreaction products, and effects of reaction produced in exposureto a chemically aggressive environment such as in Test MethodC452 or Test Method C1012.5.5.7 To determine the character
47、istics of moist-cured con-crete that has not been subjected to chemical attack orcementaggregate reaction or freezing and thawing.5.5.8 By comparison with appropriate laboratoryspecimens, a petrographer may be able to substantiate theexistence of a particular reaction in concrete or determine thatth
48、e reaction cannot be detected.6. Apparatus6.1 The apparatus and supplies employed in making petro-graphic examinations of hardened concrete depend on theprocedures required. The following list includes the equipmentgenerally used. Equipment required for field sampling is notlisted. Any other useful
49、equipment may be added.6.2 For Specimen Preparation:6.2.1 Diamond SawSlabbing saw with an automatic feedand blade large enough to make at least a 7-in. (175-mm) cutin one pass.6.2.2 Cutting Lubricant, for diamond saw.6.2.3 Horizontal Lap Wheel or Wheels, steel, cast iron, orother metal lap, preferably at least 16 in. (400 mm) in diameter,large enough to grind at leasta4by6-in. (100 by 152-mm)area.6.2.4 Free Abrasive Machine, using abrasive grit inlubricant, with sample holders rotating on a rotating table. Thistype of grinding machine greatly increases the speed
