AAC Blocks Manufacturing Line
AAC is Autoclaved Aerated Concrete. The blocks are made to aerate by creating a reaction between silica in base material such as fly ash or sand, active lime, and aluminum power. The block hardness is being achieved by cement strength, and instant curing mechanism by autoclaving. Gypsum acts as a long term strength gainer.
The finished product is a 2.5 times lighter Block compared to conventional Bricks, while providing the similar strengths. The specific gravity stays around 0.6 to 0.65. This is one single most USP of the AAC blocks, because by using these blocks in structural buildings, the builder saves around 30 to 35 % of structural steel, and concrete, as these blocks reduce the dead load on the building significantly.
The major raw material Fly-Ash, an indispensable by-product of Thermal Power Plants, is an environmental threat across the globe. Power plants are facing an ever increasing challenge disposal of this polluting agent. This unit is proposed to manufacture AAC Bricks & Blocks by consuming the Fly-Ash as one of the prime raw material. Secondly, it also helps environment by saving the invaluable top soil by not using them in brick making like conventional brick making. Thirdly, they need no burning, thus further enhancing their Eco-Friendly Brand. The steam curing requires far less fuel, compared to the backing for each cubic meter of Bricks. This is the reason these bricks are also referred as Eco Bricks or popularly Green Bricks, (though the color is gray).
AAC Blocks are largely used in various constructions, such as load bearing and pillar structure Buildings, Boundary walls, Roads, Culverts, Pavements, and wherever conventional bricks can be used. The general AAC blocks fall in the strength zone of 30- 60 Kg/Cm2, thus is having comparable strength as conventional Bricks, and hollow concrete blocks. These Blocks gain strength over a period of time up to 2 years, whereas the conventional bricks tend to lose strength over a period of time.
These green bricks can attain very regular and uniform shapes. As no burning is involved, so the shape also remains unchanged. As a result, the final Brick work with these green bricks consumes less mortar to build, less mortar to plaster. Further, the AAC being a concrete itself, it forms a more uniform bond with cement mortar, giving almost a homogeneous structure. Not only this, even exposed brickwork (without plastering) is a good durable structure. So people prefer to leave the Green Bricks Brickworks in garages, boundary walls etc. un-plastered.
BRIEF PRODUCTION PROCESS:
COAL FLY ASH:
The coal fly ash will be sent to the slurry preparing pond by wheel loader to be prepared required concentration coal fly ash slurry by add rated water, which will be pumped into slurry tank to be stored and ready to be used.
The powder will sent into the lime powder silo for storage and read to be used by bucket elevator, after coming into the factory.
The gypsum in the storage shed will be added into slurry pond according to the required proportion, while preparing slurry.
The cement will be transported into factory by tank truck and directly is pumped into cement silo to be used
ALUMINUM POWDER PAST:
The purchased aluminum powder past in the bucket or bag will be stored in its storehouse, When being used, it will be lifted to second floor of the batching building, then measured and added into aluminum mixer to prepare 5% suspending liquid to be used.
SCRAPE AND WASTE SLURRY:
The cleaning waste water under the casting machine will be pumped to ball mill to be used as grinding water. The scrape from the cutting machine will be prepared to slurry and pumped into waste slurry tank to be used.
BATCHING, MIXING, CASTING:
Coal fly ash will be sent to electronic scale in the batching building by pump at the bottom slurry tank to be measured. When the slurry concentration arrives at batching requirement, the control system will turn of the pump to stop pump slurry. The measured the slurry will be directly discharged into casting mixer.
Lime and cement will be sent to electronic scale in the batching building by single screw conveyer at the bottom of their silos. When measuring arrives at the required quantity, they will be sent to casting mixer by screw conveyer.
Aluminum powder will be measured by manual, and added into aluminum mixer to be prepared suspending liquid one by one for each mould. The finished suspending liquid can be directly added into the casting mixer.
The slurry temperature should be arrived at required process temperature before coasting. And mould will be moved to the bottom of the casting mixer by ferry car.
CUTTING AND GROUPING:
After pre-curing, the green block arrive at the required strength, the crane will take it to the cutting machine section. After remove the mould, the green block will be cut according to the required size.
The green block after cutting will be move to the curing trolley with the bottom plate by crane in front of autoclave for grouping. The seven trolley for each autoclave with 14 pieces of green block.
AUTOCLAVED AND FINISHED PRODUCT:
The green block after grouping, will be move into the autoclave by windlass for curing. The whole curing period is approx. 12h, pressure approx.1.2Mpa, temperature approx. 185
After curing, the product will be pulling out of autoclave, and be sent to the store yard.
THE BOTTOM PLATE RETURNING, COMBINING WITH MOULD AND OILING:
After unloading, the side plate on the trolley will be lifted to returning rail by crane, and be returned to the side of the cutting machine, which will be combined with the mould and sent to mould returning line for cleaning and oiling to be reused.