The design of public buildings in the District of Columbia must be approved by the Fine Arts Commission. The design of the new Georgetown University Medical Center won their approval for construction adjacent to the old medical school buildings of brick and limestone. A key to obtaining approval was the satisfactory matching of the color and texture of the weathered limestone in the old building, achieved by producing a buff-colored exposed crushed limestone concrete made with a buff cement custom-burned for this project. The cements available locally had what was described as a cold, gray color, although the aggregates from nearby Potomac River sources were a warm tone close to the color desired. Capitol Cement Division of Martin Marietta at nearby Martinsburg, West Virginia was asked to produce a Type I cement with normal physical characteristics but with a warm buff tone to match weathered limestone instead of the usual gray. Normally, cement clinker coming out of the Martinsburg kiln is brown in color initially, but exposure to the atmosphere immediately turns it gray. In order to retain the initial color a process was developed in which oil or fine coal powder was sprayed over the clinker and ignited. The clinker treated in this manner could be ground to a warm buff cement, which in turn produced a cast in place concrete that closely matched the original limestone in both color and texture. A sufficient quantity of this cement was purchased and stocked to complete the work. Both coarse and fine aggregates were taken from the same Potomac River source throughout the job.