AAC Blocks – Autoclaved Aerated Cement Blocks

AAC Blocks – Autoclaved aerated concrete (AAC) is a cellular concrete material with a low density, high compressive strength, and excellent thermal insulation properties. It is made from cement, water, lime, sand, and an expanding agent, and is cured under heat and pressure in an autoclave. AAC is an eco-friendly building material with a low embodied energy, and is also a certified green building material.

Autoclaved aerated concrete (AAC) was developed in 1924 by a Swedish architect, who was looking for an alternative building material with the same properties as wood: good thermal insulation, solid structure, and ease of use. However, AAC does not have the disadvantages of wood, such as combustibility, decay, and termite damage.

is code for aac block

Yes, there is a code for AAC blocks. In India, the code for AAC blocks is IS 2185: Part 3. This code specifies the properties and permissible values for AAC blocks. It also covers the manufacturing process, testing methods, and quality control requirements for AAC blocks.

The code is divided into three parts:

  • Part 1: General requirements
  • Part 2: Test methods
  • Part 3: Permissible properties

Part 1 of the code defines the terms and describes the general requirements for AAC blocks. It also covers the raw materials, mixing, casting, curing, and storage of AAC blocks.

Part 2 of the code describes the test methods for determining the properties of AAC blocks. These properties include compressive strength, flexural strength, water absorption, and thermal conductivity.

Part 3 of the code specifies the permissible properties for AAC blocks. These properties are based on the intended use of the blocks. For example, blocks that are used for load-bearing walls have different permissible properties than blocks that are used for non-load-bearing walls.

The IS 2185: Part 3 code is an important document for manufacturers, suppliers, and users of AAC blocks. It ensures that AAC blocks meet the required quality standards and are safe for use.

Here are some other codes for AAC blocks in different countries:

  • BS EN 12524:2009 (Europe)
  • ASTM C1386 (United States)
  • AS 1735.1 (Australia)
  • NZS 4285 (New Zealand)

Technical Specification of AAC Blocks

PropertyUnitsAAC Block
Sizemm600 x 200 x (75 to 300),
Size Tolerancemm± 1.5
Compressive StrengthN/mm 23 – 4.5 (IS 2185 part 3)
Normal Dry DensityKg / m 3550 – 650
Sound Reduction IndexDb45 for 200 mm Thick Wall
Fire ResistanceHrs.2 to 6 (Depending on Thickness)
Thermal Conductivity “K”W / m-k0.16 – 0.18
Drying Shrinkage%0.04% (Size of block)

AAC Blocks Manufacturing Process

The manufacturing process of AAC blocks involves the following steps:

  1. Raw material preparation: The raw materials for AAC blocks are fly ash, cement, lime, gypsum, and water. The fly ash is a byproduct of coal combustion, while the cement, lime, and gypsum are all common building materials. The water is used to hydrate the cement and lime.
  2. Mixing: The raw materials are mixed together in a concrete mixer. The mixing process is critical to ensure that the materials are evenly distributed and that the air bubbles are evenly distributed throughout the mixture.
  3. Casting: The mixed slurry is then poured into molds. The molds are typically made of steel or aluminum.
  4. Curing: The molds are then placed in an autoclave, which is a high-pressure, high-temperature chamber. The curing process causes the aluminum powder to react with the water, creating tiny air bubbles in the concrete. These air bubbles give AAC blocks their lightweight and insulating properties.
  5. Demolding: After the curing process is complete, the blocks are demolded and cut to size.
  6. Storage: The blocks are then stored in a cool, dry place.

The manufacturing process of AAC blocks is relatively simple and can be automated. This makes AAC blocks a cost-effective and efficient building material.

Here are some of the key factors that affect the quality of AAC blocks:

  • The quality of the raw materials
  • The mixing process
  • The casting process
  • The curing process
  • The storage conditions

By carefully controlling these factors, manufacturers can produce high-quality AAC blocks that meet the required standards.

Advantages of AAC blocks

Here are the advantages of AAC blocks:

  • Lightweight: AAC blocks are much lighter than traditional building materials, such as concrete blocks and bricks. This makes them easier to transport and handle, and it also reduces the load on the foundation.
  • Good thermal insulation: AAC blocks have excellent thermal insulation properties, which can help to reduce heating and cooling costs. This is because the air bubbles in the blocks trap air, which is a poor conductor of heat.
  • Soundproofing: AAC blocks are also good at soundproofing, which can create a more comfortable and quiet living environment. This is because the air bubbles in the blocks absorb sound waves.
  • Fire resistant: AAC blocks are fire resistant, making them a safe choice for building walls and other structures. This is because the aluminum powder in the blocks reacts with the water in the event of a fire, forming a layer of foam that insulates the blocks and prevents them from burning.
  • Durable: AAC blocks are durable and can withstand a lot of wear and tear. They are also resistant to moisture and pests.
  • Eco-friendly: AAC blocks are made from recycled materials, such as fly ash, which makes them a more environmentally friendly choice than other building materials. The use of recycled industrial waste (fly ash), non-toxic materials, zero-emission, and low energy consumption make AAC blocks eco-friendly and sustainable.

Overall, AAC blocks offer a number of advantages over traditional building materials. They are lightweight, have good thermal insulation properties, are soundproof, fire resistant, durable, and eco-friendly. These factors make them a good choice for a variety of construction applications.

Here are some of the specific applications of AAC blocks:

  • Walls: AAC blocks are commonly used for building walls, both load-bearing and non-load-bearing.
  • Floors: AAC blocks can also be used for building floors, as they are strong enough to support the weight of furniture and people.
  • Roofs: AAC blocks can also be used for building roofs, as they are lightweight and can be easily cut to size.
  • Insulation: AAC blocks can also be used as insulation, as they trap air and prevent heat from escaping.
  • Forms: AAC blocks can also be used as forms for concrete, as they are strong and durable.

Disadvantages of AAC Blocks

Here are some of the disadvantages of AAC blocks:

  • Low compressive strength: AAC blocks have a lower compressive strength than traditional building materials, such as concrete blocks and bricks. This means that they are not suitable for all applications, such as load-bearing walls.
  • Susceptible to moisture damage: AAC blocks are susceptible to moisture damage if they are not properly sealed. This can lead to the blocks swelling and cracking.
  • Can be brittle: AAC blocks can be brittle if they are not properly cured. This can make them more susceptible to damage from impact.
  • Requires specialized skills: The installation of AAC blocks requires specialized skills. This can make it more difficult and expensive to use AAC blocks than traditional building materials.
  • Not readily available: AAC blocks are not as readily available as traditional building materials. This can make it more difficult to find AAC blocks, and it can also make them more expensive.

Overall, AAC blocks offer a number of advantages over traditional building materials, but they also have some disadvantages. It is important to weigh the pros and cons of AAC blocks before deciding whether or not to use them in your construction project.

Here are some tips for minimizing the disadvantages of AAC blocks:

  • Use AAC blocks for applications where their strengths outweigh their weaknesses. For example, AAC blocks are a good choice for non-load-bearing walls, but they are not a good choice for load-bearing walls.
  • Seal AAC blocks properly to prevent moisture damage. This can be done by using a sealant or by painting the blocks with a water-resistant paint.
  • Use AAC blocks that have been properly cured. This will help to prevent the blocks from being brittle.
  • Hire a contractor who is experienced in installing AAC blocks. This will help to ensure that the blocks are installed correctly and that they will last for many years.

AAC Blocks Price


Some times people asked similar questions to following. so we compile the list of questions related to AAC Block and answered the following in appropriate way possible.

  • What is the full form of AAC?
  • What is AAC block made of?
  • How are AAC blocks made?
  • What are the advantages of AAC blocks?
  • What are the disadvantages of AAC blocks?
  • Where are AAC blocks used?
  • What is the cost of AAC blocks?
  • How to install AAC blocks?
  • What is the maintenance of AAC blocks?
  • What are the different types of AAC blocks?
  • What is the future of AAC blocks?

How many AAC Blocks in 1 square meter?

The number of AAC blocks in 1 square meter depends on the size of the blocks. The most common size of AAC blocks is 600 x 200 x 100 mm (24 x 8 x 4 inches). In this case, the number of blocks in 1 square meter is: 1 square meter / 0.6 x 0.2 x 0.1 = 50 blocks | So, you will need 50 AAC blocks to cover an area of 1 square meter.

which is better clc or aac block?

AAC and CLC blocks are both lightweight concrete blocks that are used in construction. They have some similarities, but also some key differences. The best block for you will depend on your specific needs and budget. If you need a lightweight block with good thermal insulation properties and fire resistance, then either AAC or CLC blocks would be a good choice. If you need a block with high compressive strength, then AAC blocks are the better option. If you are on a budget, then CLC blocks are the more affordable option.

what is the size of aac block?

AAC blocks are available in a variety of sizes, but the most common sizes are:
600 x 200 x 100 mm (24 x 8 x 4 inches) | 400 x 200 x 100 mm (16 x 8 x 4 inches) |300 x 200 x 100 mm (12 x 8 x 4 inches) | 200 x 200 x 100 mm (8 x 8 x 4 inches)
The size of the block you need will depend on the type of wall you are building and the load it will be carrying. For example, if you are building a load-bearing wall, you will need to use larger blocks than if you are building a non-load-bearing wall.

is code for aac block masonry work

In India, the code for aac block masonry work is IS 6041- 1985. (IS 6041 (1985): Code of practice for construction of autoclaved cellular concrete block masonry). This code specifies the methods and materials for constructing AAC block masonry walls. It also covers the design, construction, and quality control of AAC block masonry walls.

About the Author
Er. Mukesh Kumar
Er. Mukesh Kumar is Editor in Chief and Co-Fonder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.