Petrographic Examination of Hardened Concrete

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.