Firstly fly ash is mixed with water in order to form slurry, and that slurry is mixed with other ingredients like lime powder, cement, gypsum and aluminum powder as per the quantities consistent with the recipe. Lime powder which aids strength development as well as helps in the aeration effect is another important ingredient of these blocks.
It is crucial to maintain the ratio of all ingredients. Fly ash is used in a slurry form by mixing it with water in a certain proportion and mixed with lime powder and cement which are weighed on load cells with a control system and then discharged into the mixing drum. Steam might also be fed to the unit to maintain the temperature in the range of 40-42°C.
The ready mix is poured into the moulds which vary in size as per the capacity of the plant. Aluminum reacts with Calcium Hydroxide and water to form Hydrogen gas which releases millions of tiny Hydrogen bubbles. Once the rising process is over, the green cake is allowed to settle and cure for some time.
A horizontal cutting machine, is used in the first stage, while a vertical cutting machine used in the second stage has a cutting assembly mounted on columns and it moves up and down at a set speed.
The cut cakes are then sent to the autoclave for a high temperature and high-pressure steam curing. The cycle time is 12 hours after which the blocks achieve their required strength and are sent to the packing line.
After autoclaving, the hardened cakes are sent to the packing line. Here they are packed into cubes, loaded in the trucks with a robotic grabber crane and dispatched to the sites of the clients.