AAC Block Manufacturing Process

Step 1 – Raw Material Preparation

The processing of raw materials is the first step in the production of AAC blocks. The following is a list of raw materials:-

Cement- 53-grade cement For manufacturing, Ordinary Portland Cement (OPC) from a manufacturer is necessary. Plant-supplied cement is not recommended due to quality differences between batches of cement.

Fly ash- Fly ash slur Limestone powder is obtained for AAC manufacturing by crushing limestone to a fine powder at the AAC facility or by obtaining it in powder form from a variety of companies. 

Gypsum- Gypsum is a common building material.

Step 2: Mixing and Dosing 

Dosing and mixing are the next steps in the AAC block manufacturing process after raw material preparation. Process Dosing and mixing quality refer to the end product's quality. Maintaining the following ingredient ratios:

• FLY ASH : LIME:CEMENT: GYPSUM - 69:20:8:3 
• Aluminum accounts for around 0.08 percent of the total dry ingredients in the mix.
• Ratio of water = 0.60-0.65

The mixing and pouring cycle take 5.5 minutes. To make the right mix for AAC blocks, a dosing and mixing unit is used. A container is filled with fly ash. Pumping is turned off once the desired weight has been pumped in. Similarly, conveyors are used to distribute lime powder, cement, and gypsum into individual containers. The control mechanism releases all ingredients into the mixing drum once the required amount of each ingredient has been loaded into their separate containers. A container is filled with fly ash. Pumping begins when the desired weight has been poured in. Similarly, conveyors are used to distribute lime powder, cement, and gypsum into individual containers.

                                  Once the proper amount of each component has been placed in their respective containers, the control system releases all of the ingredients into a mixing drum. A smaller bowl-like device is also used to feed Aluminum powder, a component of the mixing unit After the mixture has been churned for the specified amount of time, it is ready to be put into the mold. The dosing unit is used to make molds. The dosing unit disperses the mixture into the molds in predetermined amounts. Because residual mixture can solidify and choke up the entire unit if there is a gap between charging and discharging of materials, the dosing and mixing operation must be done continually. The entire dosing and mixing operation for AAC blocks is completely automated, requiring very little human participation.

Step 3 – Casting, Rising, and Curing

Once the raw material mixture is complete, it is poured into molds. Molds come in a variety of sizes, depending on the application. The size of the installed capacity is 4.2m x 1.2m x 0.65m. Molds are covered with a thin layer of oil before casting. To keep the green cake from sticking to the molds During the mixing and pouring of the slurry into greased molds, Aluminum produces hydrogen gas when it combines with Calcium Hydroxide and water. As a result, small crystals develop. The slurry mix expands due to the presence of cells. This extension might be three times its initial size. Bubbles range in size from 2 to 5mm. As a result, the lightweight and insulating qualities of AAC blocks can be attributed to this. The green cake is allowed to settle and cure when the rising phase is completed. The rising and pre-curing procedure typically takes 60-240 minutes. The rate of rising is determined by the raw material mix and meteorological conditions. As a result, pre-curing is also known as "heated room pre-curing." The green cake is firm enough to be wire sliced as needed at the end of the securing procedure. 

An autoclave is a massive pressure vessel that is used to cure aerated concrete. An autoclave is a steel tube with a diameter of 3 meters and a length of 45 meters. Steam is supplied into the autoclave at high pressure, often between 800 and 1200 kPa, and at a temperature of 180°C

Step 4 – Demoulding and Cutting

Then the green cake has attained cutting strength, it becomes ready to be demoulded and cut. Once a mold is out of the pre-curing room, it is lifted by a crane for demoulding operation. While all previous processes like raw material preparation, dosing & mixing, and casting are pretty much the same across all technologies, demoulding and cutting processes vary vastly depending on the technology provider.

Differences in the demoulding and cutting process are also evident in different types of molds required by different technology providers. Primarily the cutting process may be classified as flat-cake and tilt-cake based on how green cake is demoulded and sent to the cutting line.

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