1、Designation: C 856 04Standard Practice forPetrographic Examination of Hardened Concrete1This standard is issued under the fixed designation C 856; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、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 practice outlines procedures for the petrographicexamination of samples of hardened concrete. The samplesexamined may be taken from conc
3、rete 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
4、objects, units, or structures thathave been built of hydraulic cement concrete.NOTE 1A photographic chart of materials, phenomena, and reactionproducts discussed in Sections 7-12 and Tables 1-6 are available asAdjunct C856 (ADJCO856).1.2 The petrographic procedures outlined herein are appli-cable to
5、 the 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 other mix-tures, unl
6、ess the reference is specifically to media other thanconcrete.1.3 Annex A1 outlines an uranyl acetate method for identi-fying locations where alkali-silica gel may be present. It is arequirement that the substances in those locations must beidentified using any other more definitive techniques, such
7、 aspetrographic microscopy.1.4 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 3Purposes of Examination 4Apparatus 5Selection and Use of Apparatus 6Samples 7Examination
8、 of Samples 8Specimen Preparation 9Visual and Stereomicroscope Examination 10Polarizing Microscope Examination 11Paste Features 12Report 131.5 The values stated in inch-pound units are to be regardedas the standard. The SI units in parentheses are provided forinformation purposes only.1.6 This stand
9、ard 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 and health practices and determine the applica-bility of regulatory limitations prior to use. A specific hazardstatement i
10、s given in 5.2.10.1.2. Referenced Documents2.1 ASTM Standards:2C 215 Test Method for Fundamental Transverse, Longitu-dinal, and Torsional Frequencies of Concrete SpecimensC 227 Test Method for Potential Alkali Reactivity ofCement-Aggregate Combinations (Mortar-Bar Method)C 342 Test Method for Potent
11、ial Volume Change ofCement-Aggregate Combinations3C 441 Test Method for Effectiveness of Pozzolans orGround Blast-Furnace Slag in Preventing Excessive Ex-pansion of Concrete Due to the Alkali-Silica ReactionC 452 Test Method for Potential Expansion of Portland-Cement Mortars Exposed to SulfateC 457
12、Test Method for Microscopical Determination ofParameters of the Air-Void System in Hardened ConcreteC 496 Test Method for Splitting Tensile Strength of Cylin-drical Concrete SpecimensC 597 Test Method for Pulse Velocity Through ConcreteC 803/C 803M Test Method for Penetration Resistance ofHardened C
13、oncreteC 805 Test Method for Rebound Number of HardenedConcreteC 823 Practice for Examination and Sampling of HardenedConcrete in ConstructionsC 1012 Test Method for Length Change of Hydraulic-Cement Mortars Exposed to a Sulfate SolutionC 1260 Test Method for Potential Alkali Reactivity ofAggregates
14、 (Mortar-Bar Method)E 3 Practice for Preparation of Metallographic Specimens1This practice is under the jurisdiction of ASTM Committee C09 on Concreteand Concrete Aggregates and is the direct responsibility of Subcommittee C09.65 onPetrography.Current edition approved Jan. 1, 2004. Published Februar
15、y 2004. Originallyapproved in 1977. Last previous edition approved in 2002 as C 856 02.2For 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 Summar
16、y page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.E 883 Guide for Reflected-Light Photomicrography2.2 ASTM Adjuncts:Adjunct C856 (ADJCO856) A chart of 27 photos43. Qualifications of Petrographers an
17、d Use of Technicians3.1 All petrographic examinations of hardened concretedescribed in this practice 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. Th
18、e supervising con-crete petrographer shall have college level courses that includepetrography, mineralogy, 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
19、 and in cementitious-based materials. A resume of the professional background andqualifications of all concrete petrographers shall be available.3.2 A concrete petrographer shall be knowledgeable aboutthe following: concrete-making materials; processes of batch-ing, mixing, handling, placing, and fi
20、nishing of hydraulic-cement concrete; the composition and microstructure of ce-mentitious paste; the interaction of constituents of concrete;and the effects of exposure of such concrete to a wide varietyof conditions of service.3.3 Sample preparation shall be performed by concretepetrographers or tr
21、ained technicians pursuant to instructionsfrom and under the guidance of a qualified concrete petrogra-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 ski
22、lls outlined in 3.1, shall beperformed by concrete petrographers or by trained technicianspursuant to 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
23、 materials represented by the sampleshall be made solely by concrete petrographers with qualifica-tions consistent with those outlined in 3.1.3.4 A concrete petrographer shall be prepared to provide anoral statement, written report, or both that includes a descrip-tion of the observations and examin
24、ations made during thepetrographic examinations, and interpretation of the findingsinsofar as they relate to the concerns of the person or agency4Available from ASTM International Headquarters, 100 Barr Harbor Drive,West Conshohocken, PA 19428. Request Adjunct No. ADJC0856.TABLE 1 Visual Examination
25、 of Concrete (1)6Coarse Aggregate + Fine Aggregate + Matrix + Air + Embedded ItemsComposition:Maximum dimension,Ain. ormm, in the range dType: Type: color, by comparison withNational ResearchCouncil Rock ColorChart (1963)more than 3 % of total, Type, size, location;kinds of metal; otheritems1 Gravel
26、 1 Natural sand predominantly in spherical2 Crushed stone 2 Manufactured sand color distribution: voids?3 Mixed 1 and 2 3 Mixed 1 mottled less than 3 % of total,4 Other (name) 4 Other (name) 2 even abundant nonspherical5 Mixed 1 + /or 2 + /or 4 5 Mixed 1 + /or 2 + /or 4 3 gradational changes voids?I
27、f Type 1, 2, or 4, homogeneousor heterogeneousIf Type 1, 2, or 4,homogeneous orheterogeneouscolor differences betweenvoids and mortar?Lithologic typesCoarse aggregate more than 20,30, 40, or 50 % of totalvoids empty, filled, lined, orpartly filledFabric:ShapeDistributionPackingGrading (even, uneven,
28、distributionparticle shapegradingpreferred orientation6as per-ceptibledistribution shapedistributiongrading (as perceptible)parallelism of long axes ofvoids below horizontalor low-anglereinforcementexcess, or deficiency of irregular voids or sheetssize or sizes) of voids: with each other;Parallelism
29、 of flat sides orlong axes of exposedwith flat sides or longaxes of coarse aggregatesections, normal todirection of placement+ /or parallel to formed andfinished surfacesBCondition:Does it ring when hit lightly with a hammer or give a dull flat sound? Can you break it with your fingers? Cracks? How
30、distributed?Through or around coarse aggregate? With cores or sawed specimens, did the aggregate tear in drilling or sawing? Crack fillings?Surface deposits? If air dry, are there unusually wet or dry looking areas? Rims on aggregate?clean or corroded?Are cracks associatedwith embeddeditems?AA subst
31、antial portion of the coarse aggregate has maximum dimensions in the range shown as measured on sawed or broken surfaces.BSections sawed or drilled close to and parallel to formed surfaces appear to show local turbulence as a result of spading or rodding close to the form. Sections sawedin the plane
32、 of bedding (normal to the direction of placement) are likely to have inconspicuous orientation. Sections broken normal to placement in conventionally placedconcrete with normal bond tend to have aggregate knobs abundant on the bottom of the upper piece as cast and sockets abundant on the top of the
33、 lower piece as cast.C856042for 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 the petrographi
34、c examinations.3.5 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, extent, and object
35、ives 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.4. Purposes of Examination4.1 Examples of purpos
36、es for which petrographic examina-tion of concrete is used are given in 4.2-4.5. 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.4.2 Concrete from Cons
37、tructions:4.2.1 Determination in detail of the condition of concrete ina construction.4.2.2 Determination of the causes of inferior quality, dis-tress, or deterioration of concrete in a construction.4.2.3 Determination of the probable future performance ofthe concrete.4.2.4 Determination whether the
38、 concrete in a constructionwas or was not as specified. In this case, other tests may berequired in conjunction with petrographic examination.4.2.5 Description of the cementitious matrix, includingqualitative determination of the kind of hydraulic binder used,degree of hydration, degree of carbonati
39、on if present, evidenceof unsoundness of the cement, presence of a mineral admix-ture, the nature of the hydration products, adequacy of curing,and unusually high water - cement ratio of the paste.4.2.6 Determination whether alkali - silica or alkali - car-bonate reactions, or cement - aggregate rea
40、ctions, or reactionsbetween contaminants and the matrix have taken place, andtheir effects upon the concrete.4.2.7 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 freezingand thawing.
41、4.2.8 Part of a survey of the safety of a structure for apresent or proposed use.4.2.9 Determination whether concrete subjected to fire isessentially undamaged or moderately or seriously damaged.4.2.10 Investigation of the performance of the coarse or fineaggregate in the structure, or determination
42、 of the compositionof the aggregate for comparison with aggregate from approvedor specified sources.4.2.11 Determination of the factors that caused a givenconcrete to serve satisfactorily in the environment in which itwas exposed.TABLE 2 Outline for Examination of Concrete with a Stereomicroscope (1
43、)NOTE 1ConditionWhen it is examined at 6 to 103 under good light, the freshly broken surface of a concrete in good physical condition that stillretains most of its natural moisture content has a luster that in mineralogical terms is subtranslucent glimmering vitreous.AThin edges of splinters of thep
44、aste transmit light; reflections appear to come from many minute points on the surface, and the quality of luster is like that from broken glass but lessintense. Concrete in less good physical condition is more opaque on a freshly broken surface, and the luster is dull, subvitreous going toward chal
45、ky. Aproperly cured laboratory specimen from a concrete mixture of normal proportions cured 28 days that has shown normal compressive or flexural strengthand that is broken with a hammer and examined on a new break within a week of the time that it finished curing should provide an example of concre
46、tein good physical condition.Under the same conditions of examination, when there is reasonable assurance that the concrete does not contain white portland cement or slag cement,the color of the matrix of concrete in good physical condition is definitely gray or definitely tan, except adjoining old
47、cracks or original surfaces.Coarse Aggregate Fine Aggregate Matrix VoidsLithologic types and mineralogy as percep- Lithologic types and miner- Color Gradingtible alogy as perceptible Fracture around or through aggregate Proportion of spherical to nonsphericalSurface texture Shape Contact of matrix w
48、ith aggregate: Nonspherical, ellipsoidal, irregular, disk-Within the piece: Surface texture close, no opening visible on sawed shapedGrain shape Grading or broken surface; aggregate not Color change from interior surface toGrain size extreme range observed, mm Distribution dislodged with fingers or
49、probe; matrixMedian within range _ to _ mm boundary openings frequent, Interior surface luster like rest of ma-Textureless (too fine to resolve) common, rare trix, dull, shiningUniform or variable within the piece Width Linings in voids absent, rare, common,From piece to piece: Empty in most, complete, partial, colorless,Intergranular bond Filled colored, silky tufts, hexagonal tab-Porosity and absorptionBCracks present, absent, result of spec- lets, gel, otherIf concrete breaks through aggregate, imen preparation, preceding spec- Underside voids or sheets of voids un-through how m
