This practice outlines the standard procedures for performing petrographic examination of hardened concrete samples. The samples examined may be taken from concrete constructions, that is, all sorts of objects, units, or structures that have been built of hydraulic cement concrete. They may also be concrete products or portions thereof, or concrete or mortar specimens that have been exposed in natural environments or simulated service conditions, or subjected to laboratory tests. This practice applies to samples of all types of hardened hydraulic-cement mixtures, including concrete, mortar, grout, plaster, stucco, terrazzo, and the like. The equipments generally used for specimen preparation are diamond saw, cutting lubricant, horizontal lap wheels, free abrasive machine, polishing wheel, hot plate or oven, prospector's pick and/or bricklayer's hammer, abrasives, plate-glass squares, suitable media, and microscope slides. For specimen examination, the equipments needed are stereomicroscope, dollies, petrographic or polarizing microscope, metallographic microscope, eyepiece micrometer, stage micrometer, microscope lamps, needleholders and points, bottles with droppers, assorted forceps, lens paper, refractometer, and immersion media. Appropriate procedures for the sampling, preparation, and examination of specimens are detailed methodically.
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1.1 This practice outlines procedures for the petrographic examination of samples of hardened concrete. The samples examined may be taken from concrete constructions, they may be concrete products or portions thereof, or they may be concrete or mortar specimens that have been exposed in natural environments, or to simulated service conditions, or subjected to laboratory tests. The phrase “concrete constructions” is intended to include all sorts of objects, units, or structures that have been built of hydraulic cement concrete.
Note 1—A photographic chart of materials, phenomena, and reaction products discussed in Sections 8-13 and Tables 1-6 are available as Adjunct C856 (ADJCO856).
1.2 The petrographic procedures outlined herein are applicable to the examination of samples of all types of hardened hydraulic-cement mixtures, including concrete, mortar, grout, plaster, stucco, terrazzo, and the like. In this practice, the material for examination is designated as “concrete,” even though the commentary may be applicable to the other mixtures, unless the reference is specifically to media other than concrete.
1.3 Annex A1 outlines an uranyl acetate method for identifying locations where alkali-silica gel may be present. It is a requirement that the substances in those locations must be identified using any other more definitive techniques, such as petrographic microscopy.
1.4 The purposes of and procedures for petrographic examination of hardened concrete are given in the following sections:
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
C125 Terminology Relating to Concrete and Concrete Aggregates
C215 Test Method for Fundamental Transverse, Longitudinal, and Torsional Resonant Frequencies of Concrete Specimens
C227 Test Method for Potential Alkali Reactivity of Cement-Aggregate Combinations (Mortar-Bar Method)
C342 Test Method for Potential Volume Change of Cement-Aggregate Combinations
C441 Test Method for Effectiveness of Pozzolans or Ground Blast-Furnace Slag in Preventing Excessive Expansion of Concrete Due to the Alkali-Silica Reaction
C452 Test Method for Potential Expansion of Portland-Cement Mortars Exposed to Sulfate
C457 Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete
C496/C496M Test Method for Splitting Tensile Strength of Cylindrical Concrete Specimens
C597 Test Method for Pulse Velocity Through Concrete
C803/C803M Test Method for Penetration Resistance of Hardened Concrete
C805 Test Method for Rebound Number of Hardened Concrete
C823 Practice for Examination and Sampling of Hardened Concrete in Constructions
C1012 Test Method for Length Change of Hydraulic-Cement Mortars Exposed to a Sulfate Solution
C1260 Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method)
E3 Guide for Preparation of Metallographic Specimens
E883 Guide for Reflected-Light Photomicrography
AdjunctC856(ADJCO856 A chart of 27 photos Available from ASTM International Headquarters. Order Adjunct No. . Original adjunct produced in 1995.
aggregates; air voids; alkali-silica reaction; analysis; deterioration; examination; fire effects; hardened concrete; microscopy; paste; petrographic; secondary deposits; Fire testing--building materials; Hardened concrete; Microscopic examination--concrete; Petrographic analysis; Stereomicroscopy; Visual examination--concrete; Alkali reactivity;
ICS Number Code 91.100.30 (Concrete and concrete products)
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