The dimensions of the steam-activated fly ash bricks are identical to those of standard solid clay bricks, measuring 240mm x 115mm x 53mm, thus steam-activated bricks can directly replace solid clay bricks.

Fly ash bricks are available in two types: autoclaved fly ash bricks and steam-cured fly ash bricks. Autoclaved fly ash bricks are those produced by high-pressure steam curing. Steam-cured fly ash bricks are those cured under atmospheric pressure with steam. Both types have similar raw materials and production processes, but differ in curing techniques and performance characteristics. Autoclaved fly ash bricks are cured at superheated steam pressure (with steam temperature above 174.5℃ and working pressure above 0.8MPa), allowing for complete hydrothermal reactions of the active components, resulting in high strength and stable performance. Conversely, steam-cured fly ash bricks may experience cracking and other issues commonly found in masonry walls.

Vapor-activated fly ash bricks generally exhibit high compressive strength, reaching up to 20MPa or 15MPa, with a minimum of 10MPa. They can withstand 15 freeze-thaw cycles. Additionally, fly ash bricks are a potentially active hydraulic material that continues to undergo hydration reactions in moist environments, making the brick's internal structure denser and beneficial for strength enhancement.