SEDL / STP / STP169-EB / STP39438S

Petrographic Examination

Mielenz, RC
Head, Petrographic Laboratory, Bureau of Reclamation, Denver, Colo.

Pages: 21    Published: Jan 1956

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Abstract

Petrographic examination of concrete aggregate is visual examination and analysis of the material in terms of both lithology and properties of the individual particles. The procedure requires use of a hand lens and petrographie and stereo-scopic microscopes; less commonly, X-ray diffraction or differential thermal analysis is a necessary part of the procedure. By petrographie examination, the relative abundance of specific types of rocks and minerals is established; the physical and chemical attributes of each, such as particle shape, surface texture, pore characteristics, hardness, and potential alkali reactivity, are described; coatings are identified and described; and the presence of contaminating substances is determined.