The AAC block( autoclaved aerated concrete block) is a porous and lightweight aerated concrete product made from siliceous and calcareous materials with aluminum powder through a series of processing(raw material processing, dosing and mixing, Casting, Rinsing and Pre-curing, Demoulding and cutting, autoclave curing).

Raw Material Processing

A: Siliceous materials: Fly ash / Sand /Tailings containing silicon

B: Calcareous material: Lime block + cement + gypsum

C: Gas  former: Aluminum powder

Flyash or sand is first ground by ball mills and transferred to a slurry tank for later use. Crushed lime stones by jaw crusher are sent into a ball mill for fine grinding to make powder lime and storage in a silo. Aluminum powder is conveyed to a mixer to form a suspension with water.

Dosing and Mixing

The critical material fly ash is turned into slurry first. Fyl ash slurry, lime powder, and cement are measured separately and added to the pouring mixer for mixing. A certain amount of steam will be added when necessary to make sure the temperature for mixing reaches 40-45 ℃. The blending process lasts for  2-3 minutes. Before pouring, the aluminum suspension will be poured into the slurry and mixed for less than 40 seconds. The whole batching system adopts centralized computer control to realize automatic batching control, remote control, and fault diagnosis.

Moulding, Rinsing, and Pre-curing

The well-stirred slurry is poured into the molds which are painted with oil in advance to prevent sticky. Bubbles are first eliminated after the pouring. The molds are transferred by a trolley to the pre-curing room which leaves time for the expansion of the slurry resulting in aluminum reacting with lime and water. It takes about 90-130 minutes with an automatically controlled temperature of 40-45℃.

Demoulding and Cutting

When the slurry reaches strength, the mold will be moved out from the curing room. The crane hoist lifts up the mold and releases the green cake after a 90-degree tilting. Then the green cake is cut by horizontal and vertical cutting machines. Before going into autoclaves, it is hoisted to the turning and peeling device, and the bottom waste is recycled.

Autoclaving

The hauling machine transfer and stack the cut green cake together with the side plate on the rails to enter the autoclave. The autoclave curing will last 8-12 hours to ensure the hardness and chemical properties of the final blocks.

Packing and Loading

The finished blocks out from the autoclave will be packed with waterproof materials and loaded on trucks for delivery.