As a specialist in the evaluation of riprap and armor stone and in the petrographic analysis of concrete aggregates, drill core, riprap, and forensic evaluation of hardened concrete, D A Lienhart is the developer of the "systems approach" in the determination of "true rock quality" for riprap and armor stone. In the performance of petrographic evaluations, Mr. Lienhart uses all of the many petrographic techniques including standardized thin sections and the universal stage in the measurement of optical properties and identification of minerals.

David A. Lienhart was named ". . the U.S. armourstone expert. . ." by the Geoscientist magazine of the Geological Society of London (January 1997). He served as a consultant on riprap and armor stone to various Corps of Engineers district offices during his 30 years with the Corps. Between 1995 and 2000 he was employed as a partner/sole geologist with Rock Products Consultants. In the year 2000 he formed his own consulting service. His papers on riprap and armor stone have been published by ASCE, ASTM, AEG, GS (of London), Wiley Publishing and A.A. Balkema Publishing. Mr. Lienhart is a Fellow of GSA and GS (of London) and a member of ASTM, AEG, ASCE, Kentucky Society of Professional Geologists, International Society for Rock Mechanics, American Rock Mechanics Association, American Shore & Beach Preservation Society and is a registered professional geologist in IN and NC. In 2001 he was promoted to the grade of Chartered Geologist by the Geological Society (of London). Mr. Lienhart's graduate level (M.Sc.) specialty is petrography/optical mineralogy. Through additional education at MIT, Univ. of IL, Univ. of TX and University of Cincinnati (Department of Army Fellow), Mr. Lienhart also developed a second specialty in rock mechanics. The combination of these specialties has enabled him to develop his expertise in the prediction of behavior of rock under various climatic conditions.