Overview of Autoclaved Aerated Concrete (AAC) Products

Overview of Autoclaved Aerated Concrete (AAC) Products

AAC stands for Autoclaved Aerated Concrete. It was invented in early 1920s by a Swedish architect named J A Eriksson. His purpose for designing AAC was to reduce consumption of timber and provide a cheaper and sustainable building solution. Thanks to his efforts, we have with us a product that offers great opportunities to construction industry across the globe.

AAC has a very flexible naming system. It is also known as Autoclaved Cellular Concrete (ACC) or Autoclaved Lightweight Concrete (ALC). In addition to these names, nomenclature might vary depending on geography. Some of the commonly used names for Autoclaved Aerated Concrete are Siporex, Ytong, Hebel, Thermostone, Planstone, Precast Aerated Concrete (PAC), etc.

AAC is manufactured by a process that involves slurry preparation, foaming/rising, cutting and steam curing (aka autoclaving). Although Autoclaved Aerated Concrete sounds very sci-fi, raw materials used in manufacturing process are very common and easily available across the globe. It is made a mixture of sand or fly ash (or pond ash), lime, cement, gypsum, an aeration agent (usually Aluminium paste or powder) and water. Fly ash or pond ash is an industrial waste generated by thermal power plants. Aeration process releases Hydrogen (H2) creating tiny cells inside greencake. This cellular structure imparts light-weight, thermal insulation and acoustic insulation to AAC products.

AAC products are available in various shapes and sizes. Most commonly used forms are AAC blocks, reinforced and non-reinforced panels, slabs (tongue & groove) etc. to cater to varying requirements of construction industry.

AAC blocks and other products offer superior performance and reduced project cost due to bigger size and light-weight. Bigger size leads to faster laying at site. Reduced weight translates to reduced dead-weight on structure. In addition to this, AAC blocks offer higher thermal insulation compared to clay bricks. This reduces investment as there is no need to install additional insulation products. Better insulation leads to reduction in energy cost for heating/cooling purpose. Walls built using AAC blocks or panels can withstand fire for longer period of times compared to other conventional walling material. You may refer to other articles for advantages of AAC products and a comparison of AAC blocks vs clay bricks.

AAC products offer interesting options for various segments. For an entrepreneur, AAC industry offers a lucrative business. For a construction company or a builder it decreases project cost and project cycle time. For a contractor, it translates to saving in terms of labour required and project completion time. For an occupant, it means that he/she has a safer and more energy efficient home translating to savings in heating/cooling costs.

Usage of AAC products not only leads to constructive use of polluting industrial waste like fly ash or pond ash, but also reduces usage of non-renewable resources like topsoil. AAC industry also reduces pollution as it does not rely on open kilns used for baking clay bricks. Especially in countries like India, Autoclaved Aerated Concrete products offer a sustainable and eco-friendly construction product with reduced project cost. Increased usage of AAC products will offer faster and cost-efficient construction, reduction in pollution and reduced usage of topsoil.

Building using AAC blocks

Building constructed using Autoclaved Aerated Concrete (AAC) blocks

Along with a brief overview of aac blocks, here is a list of common sizes of AAC blocks for quick reference:

Sr. No.Length (mm)Height (mm)Breadth (mm)

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