High fly ash content autoclaved cellular concrete is produced by adding calibrated quantities of aluminum powder to a mixture of fly ash (60% wt/wt), cement, and water. The foamed product is hardened in an autoclave with pressurized steam at about 180-degrees-C. Block material for samples tested originated from a mobile pilot plant that toured sites of United States-based electric utilities. Compressive strengths of the foamed product were controlled to the range of 300-600 psi, with dry weight densities on the order of 32-37 lb/cu ft. Heavy metal concentrations in TCLP, ASTM, and synthetic acid rain leachates were on the order one to 10 times that found in Pittsburgh tap water, and never approached 100 times drinking water standards. Organic contents of leachates were not detectable. Controlling pore distributions appears to influence density, moisture accumulation rates, and mechanical/physical properties that are significant for construction.
