Reports
Expandable clay in St. Marys Formation of Southern Maryland
1966, Knechtel, M.M., Hamlin, H.P., and Hosterman, J.W.
Report of Investigations 4
Abstract
Firing tests were made on clay samples representing strata of the Chesapeake Group (Miocene) found in exposures and auger borings at 24 localities in Calvert and St. Mary’s Counties, Maryland. Results suggest that promising sources of raw material for production of bloated, rotary-kiln-fired lightweight aggregate occur in the St. Marys Formation. The deposits sampled include bodies of bloatable clay at sites within moderate distances of populous areas wherein this type of aggregated is in growing demand. At many such sites, excavation of open pits would be feasible. The bloatable materials are composed mainly of clay shown by X-ray analyses to be made up of kaolinite, montmorillonite, and illite in approximately equal amounts. The nonclay fractions, which vary in amount from sample to sample, comprise disseminated grains of quartz, muscovite, and various heavy minerals.
