Aerated Concrete Blocks: Building with Innovation | Features & Advantages

In the realm of modern construction, innovation plays a crucial role in shaping the future of our buildings and infrastructure. One groundbreaking building material that has been gaining immense popularity is Autoclaved Aerated Concrete blocks or AAC blocks. In this article, we will delve into the characteristics, manufacturing process, physical attributes, installations, advantages, and disadvantages of Aerated Concrete Blocks, highlighting their role in creating sustainable and eco-friendly buildings.

1. What is Autoclaved Aerated Concrete (AAC)?

Autoclaved Aerated Concrete (AAC) is a lightweight, precast, and foam concrete material made from a blend of sand, lime, cement, gypsum, and an expanding agent, typically aluminium powder. As a result, this creates porous structure filled with air bubbles, giving AAC blocks their remarkable lightweight, strength, and durability.

Autoclaved Aerated Concrete Blocks
Image of Autoclaved Aerated Concrete Blocks (Source: iStock)

2. AAC Block Features

  • Lightweight: Aerated Concrete Blocks are significantly lighter than traditional clay bricks, making them easier to handle and transport during construction. Their reduced weight also leads to cost savings in terms of transportation and foundation requirements.
  • Thermal Insulation: The porous structure of AAC blocks provides excellent thermal insulation, which reduces the need for additional insulation materials. This characteristic ensures that buildings made with AAC blocks remain cool in summers and warm in winters, leading to a comfortable living environment and energy savings.
  • Soundproofing: AAC blocks offer impressive soundproofing capabilities, making buildings quieter and more comfortable. Their high sound absorption properties ensure that external noises are minimized, creating a peaceful indoor atmosphere.
  • Fire Resistance: AAC blocks have excellent fire-resistant properties, adding an extra layer of safety to buildings. Their inorganic composition and low thermal conductivity make them highly resistant to fire, making them suitable for fire-rated walls and partitions.
  • Environmentally Friendly: The manufacturing process of AAC blocks involves minimal carbon emissions, making them environmentally friendly and sustainable. Moreover, the use of fly ash, a byproduct from coal-fired power plants, as a raw material further improves their eco-friendliness.

3. Sizes of Aerated Concrete Blocks

Aerated Concrete Blocks come in various sizes to suit diverse construction needs, offering architects and builders flexibility in design and construction. The common sizes include:

  • Standard Blocks: These measure 600mm x 200mm x 100mm, and they are often used for interior walls.
  • Large Blocks: Measuring 600mm x 300mm x 200mm, these blocks are commonly utilized for exterior walls and load-bearing applications.
  • U-Blocks: Measuring 600mm x 200mm x 250mm, these blocks have a unique shape that provides excellent thermal and acoustic insulation.

Moreover, custom sizes can also be manufactured according to project requirements, providing architects and builders with the flexibility to design innovative and creative structures.

Different sizes of ACC Blocks
Image of AAC Block with different Sizes (Source: civilsolution)

4. Manufacturing Process of Aerated Concrete Blocks

The manufacturing process of AAC blocks involves precise raw material preparation, followed by autoclaving, a curing process that uses steam and high pressure.

Detailed step in the manufacturing process of Aerated Concrete Blocks
Manufacturing Process of AAC Blocks (Source:
  1. Raw Material Preparation

The first step is to prepare the raw materials. Sand, cement, lime, and gypsum are carefully mixed in the correct proportions to form a slurry.

  1. Mixing and Pouring

Thereafter, Aluminium powder is added to the slurry, and the mixture is poured into molds. The aluminium powder acts as an expanding agent that releases hydrogen gas during the curing process.

  1. Aerating

As the hydrogen gas is released, the slurry rises and expands, creating air bubbles that give the blocks their cellular structure.

  1. Curing

The molded blocks are placed in an autoclave, where they are exposed to steam pressure and high temperature. This curing process enhances the blocks’ strength and durability.

Advanced manufacturing techniques ensure the uniform distribution of air voids, resulting in consistent quality across all AAC blocks. The process also consumes less energy compared to traditional brick firing, making it more sustainable.

5. Physical Properties of Aerated Concrete Blocks

Aerated Concrete Blocks possess several essential physical properties that make them ideal for modern construction:

• Density of AAC blocks

AAC blocks typically have a density of 550 to 650 kg/m³, making them one of the lightest construction materials available. Their low density significantly reduces the structural load on foundations and ensures ease of handling and installation.

• Compressive Strength of AAC blocks

The compressive strength of AAC blocks ranges from 3.5 to 5 N/mm², providing structural stability to buildings. Despite being lightweight, AAC blocks offer excellent load-bearing capacity, making them suitable for both low-rise and high-rise constructions.

• Thermal Conductivity of AAC blocks

With a thermal conductivity of approximately 0.11 W/mK, AAC blocks provide excellent thermal insulation. Thus, their thermal properties help maintain a consistent indoor temperature, reducing the dependence on heating and cooling systems and promoting sustainability.

• Water Absorption of AAC blocks

AAC blocks have a water absorption rate of 10-15%, resisting moisture and preventing dampness. As a result, their resistance to water absorption minimizes the risk of efflorescence and mold formation on walls.

• Workability of AAC blocks

AAC blocks are easy to cut, shape, and work with, reducing construction time and labour costs. They can be easily sawed, drilled, and shaped using standard construction tools, thus allowing for precise customization as per design requirements.

6. Installations, Connections, and Finishes

Uncurated AAC Blocks
Image of Uncurated AAC Blocks (Source:

Installing AAC blocks is easy using thin-bed mortar, significantly speeding up the construction process. Their accurate dimensions and lightweight nature facilitate quick and efficient laying, resulting in shorter construction periods and lower labour costs.

The tongue-and-groove interlocking system of AAC blocks ensures seamless connections between blocks, reducing the need for additional mortar and enhancing the wall’s overall stability. Properly installed AAC walls exhibit minimal shrinkage and settlement, ensuring long-term durability.

AAC blocks are compatible with various finishes, including plastering, tiling, and cladding. Additionally, their smooth surface and consistent shape provide an excellent base for various exterior and interior finishes, allowing architects and designers to achieve the desired aesthetics.

7. Suitability and Energy Considerations

AAC blocks are highly suitable for both residential and commercial constructions. Due to their lightweight and excellent insulating properties, buildings made with AAC blocks consume less energy for heating and cooling, leading to reduced energy bills and a smaller carbon footprint.

The high thermal mass of AAC blocks helps in stabilizing indoor temperatures by absorbing and slowly releasing heat, further enhancing energy efficiency. Moreover, the use of fly ash in the manufacturing process helps in recycling industrial waste and contributes to sustainable construction practices.

8. Comparison of AAC Block and Clay Bricks

When comparing AAC blocks with traditional clay bricks, AAC blocks offer several advantages:

  • Weight: AAC blocks are lighter than clay bricks, making them easier to handle and transport, resulting in reduced labour costs and construction time.
  • Thermal Insulation: AAC blocks provide superior thermal insulation compared to clay bricks, reducing the need for additional insulation materials and enhancing energy efficiency.
  • Soundproofing: AAC blocks have better soundproofing capabilities than clay bricks, creating a quieter and more comfortable living environment.
  • Uniformity: AAC blocks have a more uniform shape and size compared to clay bricks, ensuring consistent quality and ease of construction.
  • Sustainability: The use of fly ash in AAC blocks contributes to sustainable construction practices, while clay bricks rely on finite clay resources.

However, it is essential to note that each material has its unique applications, and the choice between AAC blocks and clay bricks should be based on project requirements and design considerations.

9. Uses of Aerated Concrete Blocks

AAC blocks find extensive use in a wide range of construction projects, including:

  • Residential Buildings: AAC blocks are common in constructing individual houses, apartments, and housing complexes due to their lightweight, insulation, and ease of construction.
  • Commercial Complexes: Offices, shopping malls, and retail outlets often use AAC blocks for their speed of construction and energy-efficient properties.
  • Industrial Structures: The thermal insulation and fire resistance of AAC blocks make them suitable for industrial buildings and warehouses.
  • Schools and Hospitals:
    The soundproofing and thermal properties of AAC blocks create a comfortable and peaceful environment, making them an ideal choice for educational and healthcare facilities.
  • High-Rise Buildings: The lightweight and compressive strength of AAC blocks make them an excellent choice for high-rise constructions, thus reduces structural loads and construction time.
Modern minimal Texas Hill Country farmhouse constructed using Aerated Concrete Blocks)
Image of Construction using AAC Blocks (Source: pinterest)

10. Advantages of Aerated Concrete Blocks

The advantages of using AAC blocks in construction include:

  • Reduced Dead Load on Structures:

AAC blocks’ light weight decreases foundation and structural load, allowing higher and more complex constructions.

  • Excellent Thermal Insulation:

The porous structure retains air, providing thermal insulation, energy savings, and a comfortable indoor environment.

  • Superior Soundproofing:

The blocks have excellent sound absorption which minimizes outside noise, making living or working spaces serene.

  • Environmentally Friendly and Sustainable:

AAC blocks are eco-friendly because fly ash recycles waste and reduces carbon footprint.

  • Faster Construction Process:

AAC blocks‘ huge size and ease of installation make building projects faster and cheaper.

  • Cost-Effective in the Long Run:

Aerated Concrete Blocks cost more than ordinary bricks, but their energy efficiency saves money over time.

11. Disadvantages of Aerated Concrete Blocks

While AAC blocks offer various benefits, it’s essential to consider their limitations, such as:

  • Higher Initial Cost:

Despite the numerous benefits of AAC blocks, it is essential to consider the higher initial cost compared to traditional clay bricks.

  • Specialized Installation Techniques:

Construction using AAC blocks requires skilled labor familiar with AAC construction techniques to ensure proper installation and structural stability.

  • Limited Availability in Some Regions:

While AAC blocks are gaining popularity, their availability might be limited in certain areas, leading to higher transportation costs for projects in those regions.


In brief, AAC blocks have emerged as a revolutionary building material, changing the construction sector with their outstanding qualities. Also, AAC blocks have several advantages, ranging from their lightweight and thermal insulation to their environmental friendliness. Although they may have a higher initial cost and require professional installation, the long-term benefits outweigh the disadvantages. AAC blocks will become even more common in ecological and energy-efficient construction as technology progresses.

How do AAC blocks contribute to sustainable construction?

AAC blocks contribute to sustainable construction through their use of fly ash, a waste byproduct, and their excellent thermal insulation properties. The reduction in energy consumption for heating and cooling ensures lower carbon emissions and a smaller environmental impact.

Can AAC blocks be recycled?

While AAC blocks are not directly recyclable due to the curing process, they contribute to sustainability by utilizing fly ash, a recycled waste material. The manufacturing process also consumes less energy compared to traditional brick firing, further reducing the environmental impact.

Are AAC blocks suitable for earthquake-prone areas?

Yes, AAC blocks possess excellent earthquake-resistant properties due to their lightweight and flexible nature, making them an ideal choice for such regions. The ability to withstand seismic forces enhances the safety and structural integrity of buildings.

Are AAC blocks easy to cut and shape during construction?

Absolutely, AAC blocks are easy to work with, and builders can easily saw, drill, and shape them using standard construction tools. This ease of customization allows architects and builders to achieve intricate designs with ease.