Lightweight structual concrete block and methods of use

A method of forming a lightweight concrete wall comprising:

• vertically stacking one or more lightweight concrete blocks, the one or more lightweight concrete blocks comprising:
• a first side and a second side joined by a plurality of interposing walls, the interposing walls defining one or more inner cavities and one or more outer cavities,
• wherein the first side, the second side, and the plurality of interposing walls are formed from a lightweight concrete comprising lightweight aggregates (LWA) suspended in a mixture of calcium sulfoaluminate (CSA) cement and specialized grout,
• aligning the one or more inner cavities and one or more outer cavities of each of the one or more lightweight concrete blocks, such that one or more vertical columns are formed;
• inserting fiberglass rebar vertically in at least a portion of the one or more vertical columns;
• inserting fiberglass rebar horizontally through a hole in one or more of the interposing walls of the one or more lightweight concrete blocks;
• and
• filling the one or more vertical columns with one or more materials.