The present invention relates to a composite concrete building material comprising cementatious materials; and foam glass aggregates. The cementatious materials may comprise cement, sand and fly ash. The cementatious materials may also comprise other materials, including, for example, reinforcing fibers. In one embodiment the reinforcing fibers are comprised of one or more of the following materials: glass, steel, titanium, other metals, carbon, or Kevlar. The foam glass aggregates may have a closed pore structure and average pore size of 1.0 mm or less, wherein said average pore size is measured based on the distance between two farthest points of pore surface. The foam glass aggregate may have an average density of 30 to 100 PCF. The foam glass aggregate may have a compression strength of 2000 PSI or greater. The foam glass aggregates may be on average between 0.1 inches and approximately 2.0 inches in their largest diameter.