A reusable modular block system includes a lightweight structural block having a top, a bottom, a first block end, a second block end, an insulating core, an inside facing and an outside facing wherein the structural block is configured to create internal vertical and horizontal raceways between adjacent blocks, a gasketing system connected to the structural block along a portion of the periphery of the structural block, and a fastening system within and that extends horizontally and vertically through the insulating core where the structural block, the gasketing system and the fastening system form a single, integral block component.