AAC blocks replace traditional bricks that are presently used in construction. We will in this article discuss in detail the advantages, features, benefits, and other technical information of autoclaved aerated concrete blocks.

AAC blocks full form

The full form is autoclaved aerated concrete blocks. The name comes from the material they are made from and the process involved in making them.

What are they?

Autoclaved Aerated Concrete blocks are a second-generation building material that provides many benefits and features compared to traditional bricks.

Autoclaved Aerated Concrete blocks are

  • Larger when compared to bricks
  • Lighter than bricks and float on water
  • AAC blocks can be used for interior and exterior, non load bearing walls
  • Made from Fly ash, calcinated gypsum, lime, cement, water, and aluminum powder
  • Concrete is autoclaved under heat and pressure and thus gains distinctive properties


Is AAC blocks better than brick?

Colour Greyish-white
Lightweight Approximately 67% lighter than red bricks
Fire resistance Between four and six hours, based on the thickness; almost twice that of brick
Energy efficiency Up to 30% reduction in air-conditioning electricity costs
Thermal efficiency 200% more than bricks
Water absorption 8 to 12% at equilibrium for AAC & more than 20% for Brick
Sound insulation 44db(for 200mm thick wall)
Affordable cost Nearly half of the cost of regular bricks


AAC block sizes

The final product of Autoclaved Aerated Concrete blocks comes in the form of a big block cut into different sizes using advanced cutting technology.

If you have a bulk order, you can customize your size as agreed by the manufacturer.

But here are a few standard sizes that are available (length * width * height)

  1. 600mm x 200 mm x 100 mm
  2. 600mm x 200 mm x 150 mm
  3. 600mm x 200 mm x 200 mm

AAC blocks arrangement

The arrangement is just like the traditional brick. The layout used for regular masonry can also be used for blocks..

AAC blocks shapes

  • Cuboid shaped blocks
  • U blocks and O blocks

What are the advantages of AAC blocks?

Autoclaved Aerated Concrete blocks are manufactured using fly ash, a waste material from thermal plants. AAC blocks provide many advantages like

  1. Easily workable with faster construction
  • Blocks are approximately nine times bigger than brick; hence the construction becomes four times faster compared to brick
  • Have fewer joints and thus less mortar
  • Easy to transport
  • Labor costs are less as work is quickly over
  • As logistics depend on weight, AAC blocks that have less weight have a logistics advantage
  1. AAC blocks are Earthquake-resistant
  • As blocks are light, it reduces the load on the structure
  • With fewer loads, the horizontal and vertical forces generated on the building will be low

3. AAC blocks provide Thermal insulation and are energy-efficiency

  • Autoclaved aerated concrete blocks have excellent insulation properties
  • They do not allow external heat to the interiors, reducing air conditioning costs by up to 30%. They keep the interiors cooler by 5 degrees in summer
  • Keep your winters warm as blocks do not allow interior heat to escape
  1. AAC blocks have better Fire-resistance

The material is non-combustible and provides fire resistance of up to six hours, depending on the block thickness. Thus, it also has importance from a fire safety point of view.

  1. AAC blocks are Sustainable and affordable
  • Eco-friendly material uses fly ash, a waste by-product for block production.
  • Bricks use soil and hence destroy the topsoil
  • As blocks are lighter than bricks, the weight of the building decreases. Lower weight reduces the cost of making the foundation.
  1. AAC blocks have High compressive strength
  • Have a compressive strength of 3-5 N/mm2
  • Thus, they are much stronger than bricks of the same density.
  1. AAC blocks are Pest-resistant
  • AAC blocks are prepared from inorganic materials, which help in protecting the structure from pests such as termites, rodents, etc.
  1. AAC blocks are Soundproof
  • Blocks insulate the interior from external sounds. They can reduce the exterior noise by 44dB (For 200mm thick wall)
  1. AAC blocks are Moisture-proof
  • Blocks are made of micro-pores that are not connected.
  • As water does not seep in, water absorption is low.
  • They provide better waterproofing to the structure as a whole

åáåÊåÊåÊåÊåÊåÊåÊåÊ Disadvantages: Why is AAC block not used in the foundation?

    • Can be used for non-load bearing walls only
    • When using nails, special care needs to be taken as you may need to use a drilling machine and apply fasteners. It would be best if you did not directly use the nail on AAC blocks.

AAC blocks installation

  • Installation is quite similar to that of brick.
  • Installation is faster than brick.

Where are they used?

Autoclaved aerated concrete blocks can be widely used for construction purposes like residential properties, and industrial and commercial buildings. They can be used in both interior and exterior environments.

åÊAAC blocks vs. Red bricks

  • Autoclaved aerated concrete blocks are more eco-friendly than bricks as they save soil
  • Labor costs are lower for block laying
  • High strength, better fire resistance, and other factors make blocks a better choice than bricks

AAC blocks vs. CLC blocks: Which is better?

CLC (lightweight cellular concrete) blocks are produced from lightweight cellular concrete (CLC) or foam concrete. It is a lightweight concrete that combines cement and fly-ash slurry with pre-formed foam. CLC blocks are comparatively cheaper than AAC blocks. However, in terms of compressive strength, autoclaved aerated concrete blocks are better than CLC blocks.

Background and history

Autoclaved aerated concrete blocksåÊwere developed by Dr Johan Axel Erikkson, in 1920 and were patented by him. The production started in full swing in 1929 in Sweden and went on to spread to other countries like USA, Russia, Germany, India, etc