A method of making a rapid setting lightweight homogeneous foamed fly ash based cementitious aggregate composition with improved compressive strength for products such as panels is disclosed. The method mixes fly ash, alkali metal salt of citric acid, foaming agent for entraining air, optional foam stabilizing agent, a calcium sulfate such as stucco or gypsum, and water. Compositions are also disclosed which include mixtures of fly ash, particularly Class C fly ash alone or in mixtures with Class F fly ash, alkali metal salts of citric acid, foaming agents, a calcium sulfate such as calcium sulfate dihydrate or hemihydrate and an optional portland cement.