LIGHTWEIGHT STRUCTURAL CONCRETE, LIGHTWEIGHT CONCRETE, AND CONCRETE; LIGHTWEIGHT AGGREGATES, NAMELY, LIGHTWEIGHT CONCRETE AGGREGATE, LIGHTWEIGHT STRUCTURAL CONCRETE AGGREGATE, LIGHTWEIGHT AGGREGATE CONCRETE BUILDING BLOCKS; AGGREGATE FOR REFRACTORY CONCRETE, SAID AGGREGATE BEING ESSENTIALLY A HEAT TREATED, EXPANDED LIGHTWEIGHT, GRANULAR SHALE OR SLATE MATERIAL; LIGHTWEIGHT AGGREGATE MADE FROM MINERAL SUBSTANCES FOR USE IN CONSTRUCTION FOR LOW-, MID-, AND HIGH-RISE BUILDING CONSTRUCTION OF CON...