By examining hardened concrete cores, petrographers can provide information regarding the concrete's composition and serviceability. ASTM C 856, "Standard Practice for Petrographic Examination of Hardened Concrete," outlines procedures for the petrographic examination of hardened concrete samples. But sometimes petrographers report information that's not specifically covered by the ASTM standard procedures, such as an estimate of the slump of the concrete when it was plastic.

Concrete Construction asked Richard Stehly of American Engineering Testing Inc., St. Paul, Minn., and Bernard Erlin of The Erlin Company, Latrobe, Pa., some questions regarding the determination of concrete slump by petrographic examination.