History of AAC Block
AAC was perfected in the mid-1920s by the Swedish architect and inventor, Dr. Johan Axel Eriksson working with Professor Henrik Kreuger. It was patented in 1924 & production started in Sweden city Yxhult in 1929. Again “SIPOREX” brand started in 1939.
In 1943 Josef Hebel from Memmingen started his first plant in Germany. In 1978 LCC sSIPOREX” plant started in Saudi Arabia. In this way, AAC industries slowly started to grow all over the world from 1978 & rapidly cover the market from 2012.
What Is AAC Blocks?
Another building material we have used in GreenWay Subdivision is autoclaved aerated concrete blocks (AAC blocks) for exterior walls. AAC blocks can be an excellent Green building material. They provide a solid substrate for exterior stucco or siding and interior plaster or sheetrock.
- It is porous, non-toxic, reusable, renewable, and recyclable.
- AAC Block full form: Autoclaved Aerated Concrete Blocks
- Other names ACC Block
- ACC Block full form: Autoclaved Cellular Concrete Block
AAC Blocks Technical Specifications
| Sr.No. | Detail | Sizes | Units |
| 1 | Size | 600 X 200 X Thickness | mm |
| 2 | Thickness | 50,75,100,125,150,200,225 | mm |
| 3 | Compressive Strength | > 3 – 4.5 ( IS 2185 ) | N / mm2 |
| 4 | Normal Dry Density | 450 – 650 | Kg / m3 |
| 5 | Thermal Conductivity “K” | 0.16 – 0.18 | W / MK |
| 6 | Thermal Resistance | 0.46 | K-m2 / W |
| 7 | Heat Transmission Coefficient ‘U’ | 2.17 | W / m2k |
| 8 | Drying Shrinkage | 0.04 % ( Size Of Block ) | % |
| 9 | Sound Absorption | Up to 42 | De |
| 10 | Fire Resistance | 2 to 6 | Hrs. |
Uses of AAC Blocks
AAC is well suited for high-rise buildings and those with high-temperature variations. Due to its lower density, high-rise buildings constructed using AAC require less steel and concrete for structural members. The mortar needed for the laying of AAC blocks is reduced due to the lower number of joints. Similarly, the material required for rendering is also lower due to the dimensional accuracy of AAC.
The increased thermal efficiency of AAC makes it suitable for use in areas with extreme temperatures, as it eliminates the need for separate materials for construction and insulation, leading to faster construction and cost savings.
Disadvantages of AAC Blocks
list of AAC blocks Disadvantage
- Cost
- Crack in Walls
- Nailing vs. Drilling
- Installation During Rainy Weather
- Brittle Nature
- Attachments
- Insulation Requirements
| Sr.No. | Detail | Disadvantages of AAC Block |
| 1 | Cost | Cost of production higher than the ordinary concrete block or brick. |
| 2 | Crack in walls | We need to take precautions to eliminate drying shrinkage cracks and stress concentration cracks.
See my answer on the cracking of the AAC block wall. |
| 3 | Nailing vs. Drilling | If you need to fix furniture in the AAC Blocks wall, you need to use a drill bit and a raw plug. You can’t just put a nail. |
| 4 | Installation During Rainy Weather | AAC Blocks are known to crack after installation, which can be avoided by reducing the strength of the mortar and ensuring the blocks are thy during and after installation. |
| 5 | Brittle Nature | They need to be handled more carefully than clay bricks to avoid breakage. |
| 6 | Attachments | The brittle nature of the blocks requires longer, thinner screws when fitting cabinets and wall hangings and wood-suitable drill bits or hammering in.
Special, large-diameter wall plugs are available at a higher mat than common wall plugs. |
| 7 | Insulation Requirements | In newer building codes of northern European countries would require very thick walls when using MC alone.
Thus many builders choose to use traditional building methods, installing an extra layer of insulation around the entire building. |
Advantage of AAC Blocks
list of AAC blocks Advantage
- Structural Saving
- Faster Construction
- Acoustic Insulation
- Light Weight
- Eco Friendly
- Water Proof
- High Strength
- Workability and Flexibility
- Fire Resistant
- Pest Resistant / Anti Termite
- Earthquake Resistant
- Non-Toxic
- Great Ventilation
- Precision
- Cost-Effective
| Sr.No. | Detail | Advantage of Block |
| 1 | Structural Saving | AAC blocks reduce the dead weight, which leading to reduce steel consumption in the construction of building due to its lightweight as well as its reduced the consumption of cement and mortar. |
| 2 | Eco Friendly | It produces at least 30% less solid waste than traditional concrete. There is a decrease of 50% of greenhouse gas emissions.
AAC blocks are made by Fly ash or Pond Ash or Sand via a non-polluting process of steam curing comprising of non¬toxic elements. Hence AAC blocks are a more eco-friendly product for construction. |
| 3 | Cost-Effective |
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| 4 | Acoustic Insulation | AAC blocks offer unmatched acoustic insulation. Boost high sound absorption. |
| 5 | Precision |
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| 6 | Light Weight | AAC blocks are 3 times lighter than traditional bricks, making it easier to transport and reduce the construction time. |
| 7 | Faster Construction | AAC block cut down on construction time by 25 % due to its dimension, lightweight, and leas number of joints. |
| 8 | Earthquake Resistant | The effect of earthquake is proportional to the weight of the structure.
AAC blocks being a lightweight subdues any damage by quakes or high winds largely. |
| 9 | Water Proof | MC blocks have a microscopic cellular structure of aerated pores, which has less water absorption property than regular bricks.
Hence, building built by AAC blocks almost 80 % water-resistant. |
| 10 | High Strength | AAC Blocks have higher strength than regular bricks as compared to regular bricks due to steam curing at high pressure and high temperature. |
| 11 | Workability and Flexibility | MC blocks can be cut easily, drilled easily, nailed easily, and grooved easily.
This allows the installation of electrical and sanitary fitting even after structure construction is complete. |
| 12 | Fire Resistant | Owing to the unique cellular bee-hives like structure, the fire resistance quotient of AAC blocks is very high.
It can withstand up to 1400 ‘C and has a fire rating of 4 to 5 hours. |
| 13 | Non-Toxic | There are no toxic gases or other toxic substances in autoclaved aerated concrete.
It neither attracts rodents or other pests, nor can it be damaged by such. |
| 14 | Great Ventilation | This material is very airy and allows diffusion of water. This reduces the humidity inside the building.
AAC will absorb moisture and release humidity. This helps to prevent condensation and other problems that are related to mildew. |
| 15 | Pest Resistant / Anti Termite | With the precision ratio of AAC Blocks being very high, it results in smooth finishing preventing pests.
The use of inorganic material also inherently prevents algae and fungi growth |
Why AAC Blocks Get Cracks?
Below reason of AAC blocks get cracks
- Poor Workmanship.
- Improper curing.
- Higher thickness of plaster.
- Use of very fine sand to make mortar i.e., higher silt content or use of sand, which is not graded properly.
- Shrinkage in blocks or poor quality of blocks may also cause a crack in a wall
- Continuous vibration or frequent hit by a hammer for nailing may also be a reason for cracks in a wall.
- The temperature at the time of the application of plaster. i.e., shrinkage cracks are more prone in the summer season than the winter.
FAQs on Autoclaved Aerated Concrete (AAC) Blocks
What Are Aac Blocks?
AAC blocks, or Autoclaved Aerated Concrete blocks, are lightweight, precast building materials that provide structure, insulation, and fire resistance in a single unit. They are made from natural raw materials and are highly sustainable.
Who Invented Aac Blocks and When?
AAC blocks were perfected in the mid-1920s by the Swedish architect Dr. Johan Axel Eriksson, in collaboration with Professor Henrik Kreuger. They were patented in 1924 and production began in 1929 in Yxhult, Sweden.
What Are the Primary Uses of Aac Blocks?
AAC blocks are used for constructing exterior and interior walls, high-rise buildings, and structures in areas with high-temperature variations. They are known for their thermal insulation, sound absorption, and fire resistance.
What Are the Technical Specifications of Aac Blocks?
- Size: 600 x 200 x Thickness (mm)
- Thickness: 50, 75, 100, 125, 150, 200, 225 mm
- Compressive Strength: >3 – 4.5 N/mm² (IS 2185)
- Normal Dry Density: 450 – 650 Kg/m³
- Thermal Conductivity: 0.16 – 0.18 W/mK
- Thermal Resistance: 0.46 K-m²/W
- Heat Transmission Coefficient: 2.17 W/m²K
- Drying Shrinkage: 0.04%
- Sound Absorption: Up to 42 dB
- Fire Resistance: 2 to 6 hours
What Are the Advantages of Using Aac Blocks?
- Structural saving
- Faster construction
- Acoustic insulation
- Lightweight
- Eco-friendly
- Waterproof
- High strength
- Workability and flexibility
- Fire resistant
- Pest resistant/anti-termite
- Earthquake resistant
- Non-toxic
- Great ventilation
- Precision
- Cost-effective
What Are the Disadvantages of Aac Blocks?
- Higher production cost compared to traditional concrete blocks or bricks
- Potential for cracks in walls
- Requires drilling rather than nailing for attachments
- Installation challenges during rainy weather
- Brittle nature requires careful handling
- Specific insulation requirements in colder climates
Why Do Aac Blocks Get Cracks?
Cracks in AAC blocks can occur due to poor workmanship, improper curing, higher plaster thickness, use of fine sand in mortar, shrinkage in blocks, continuous vibration, frequent hammering, and temperature variations during plaster application.
How Do Aac Blocks Contribute to Eco-Friendly Construction?
AAC blocks produce at least 30% less solid waste than traditional concrete and reduce greenhouse gas emissions by 50%. They are made using fly ash, pond ash, or sand through a non-polluting steam curing process and consist of non-toxic elements.
Are Aac Blocks Fire Resistant?
Yes, AAC blocks have a high fire resistance due to their unique cellular structure. They can withstand temperatures up to 1400°C and have a fire rating of 4 to 5 hours.
Can Aac Blocks Be Used in Earthquake-Prone Areas?
Yes, AAC blocks are earthquake resistant. Their lightweight nature reduces the overall weight of the structure, thereby minimizing the impact of seismic forces.
What Are the Common Dimensions of Aac Blocks?
AAC blocks are typically available in sizes of 600 x 200 mm with varying thicknesses of 50, 75, 100, 125, 150, 200, and 225 mm.
How Do Aac Blocks Improve Construction Speed?
Due to their lightweight and larger size, AAC blocks reduce the number of joints and the amount of mortar needed. This, combined with their precise dimensions, speeds up the construction process by up to 25%.
What Makes Aac Blocks Cost-Effective in the Long Run?
AAC blocks reduce operating costs by 30-40
What Makes Aac Blocks Cost-Effective in the Long Run?
AAC blocks reduce operating costs by 30-40% due to their insulation properties, which lead to energy savings. The reduced need for jointing, cement, and steel also lowers overall construction costs. Additionally, their durability and resistance to pests, fire, and water reduce maintenance costs over time.
Can Aac Blocks Be Used for Soundproofing?
Yes, AAC blocks provide excellent acoustic insulation. Their porous structure helps absorb sound, making them ideal for use in buildings where soundproofing is important.
How Do Aac Blocks Help in Thermal Insulation?
AAC blocks have low thermal conductivity, which means they can retain heat in colder climates and stay cool in warmer climates. This reduces the need for additional insulation materials and helps in maintaining energy efficiency in buildings.
Are Aac Blocks Suitable for High-Rise Buildings?
Yes, AAC blocks are well-suited for high-rise buildings. Their lightweight nature reduces the load on structural members, thereby decreasing the amount of steel and concrete required for the structure.
What Should Be Considered During the Installation of Aac Blocks?
During installation, it is important to ensure proper curing, avoid excessive plaster thickness, use well-graded sand for mortar, and handle the blocks carefully to prevent cracks and breakage. Ensuring that the blocks are dry during and after installation is also crucial, especially in rainy weather.
What Is the Environmental Impact of Aac Block Production?
The production of AAC blocks has a lower environmental impact compared to traditional concrete blocks. The process uses less energy, generates less solid waste, and reduces greenhouse gas emissions. Additionally, AAC blocks are made from industrial by-products like fly ash, contributing to waste reduction.
Can Aac Blocks Be Recycled?
Yes, AAC blocks are recyclable. They can be crushed and reused as a base material for road construction or as aggregate in new concrete mixtures.
How Do Aac Blocks Contribute to Healthier Indoor Environments?
AAC blocks are non-toxic and do not release harmful gases, contributing to better indoor air quality. Their ability to absorb and release moisture helps in regulating humidity levels, preventing mold and mildew growth.
