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 be directly used as a substitute for 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 made by steam curing under normal pressure. Both types have similar raw materials and production processes, but differ in curing techniques and performance characteristics. Autoclaved fly ash bricks are cured under saturated steam pressure (with steam temperature above 174.5℃ and working pressure above 0.8MPa), allowing the active components in the bricks to undergo full hydrothermal reactions, resulting in high strength and stable performance. Conversely, steam-cured fly ash bricks may experience cracking and other issues commonly found in masonry walls.

The steam-activated fly ash bricks generally have high compressive strength, reaching up to 20MPa or 15MPa, at least 10MPa, and can withstand 15 freeze-thaw cycles. Additionally, fly ash bricks are a potentially active hydraulic material that can continue to undergo hydration reactions in moist environments, making the internal structure of the bricks denser and beneficial for strength enhancement.