ASTM C856

ASTM C856 – Standard Practice for Petrographic Examination of Hardened Concrete

Description:

Abstract

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.

Scope

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.

1.2 The petrographic procedures outlined herein are applicable to the examination of samples of all types of hardened 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 The purposes of and procedures for petrographic examination of hardened concrete are given in the following sections:

	Section
Qualifications of Petrographers and Use of Technicians	4
Purposes of Examination	5
Apparatus	6
Selection and Use of Apparatus	7
Samples	8
Examination of Samples	9
Specimen Preparation	10
Visual and Stereomicroscope Examination	11
Polarizing Microscope Examination	12
Paste Features	13
Report	14

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 are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.

NOTE 1: Sieve size is identified by its standard designation in Specification E11. The alternative designation given in parentheses is for information only and does not represent a different standard sieve size.