What are AAC blocks?
Autoclaved Aerated Concrete (AAC) blocks are lightweight and durable building products. First conceptualized and invented by Swedish architect and inventor Johan Axel Eriksson in 1924, AAC blocks are particularly known for their fire, heat and sound-resistant properties.
Air being the major constituent (almost 80-85% by volume), these building products are typically lightweight, weighing only a third of the more common red clay bricks.
How are they made?
Common ingredients used in the production of AAC blocks include lime, cement, sand, water, gypsum, fly ash, and Calcium oxide (commonly known as quicklime). Aluminum powder reacts chemically with these and hydrogen gas escapes into the air towards the end of the procedure. It is this chemical reaction that lends AAC blocks their distinct honeycomb structure, lightness, and other insulation properties.
Having undergone necessary molding and mixing, these are further cured in an autoclave (subject to high heat and pressure) that imparts them the desired strength and durability.
What are the advantages of using AAC Blocks?
On an average, AAC blocks are 9 times the size of regular clay bricks. This translates to superior construction speed and quality, coupled with the formidable reduction of costs - on plaster and mortar - at the site. Importantly, best-in-class thermal insulation results in increased savings of Heating, Ventilation, and Air-conditioning (HVAC) costs.
Because of its high workability and flexibility standards, AAC material is widely used across the construction of residential buildings, healthcare facilities, schools, hotels, and other industrial/commercial structures.
Earthquake forces on structure are proportional to weight of the building, hence light weight blocks show excellent resistant to earthquake forces. Regions of high siesmic activities like Japan exclusively use AAC Fly Ash Blocks. It has been proven to withstand wind loads of category 5 tropical storms.
With closed air pockets, AAC lightweight fly ash blocks can provide very good sound insulation/sound absorption with an STC(Sound Transmission Class) rating of 44. It can also be used as a sound barrier wall along busy roads. AAC wall has an excellent sound transmission class (STC) rating of 44. Result, virtually sound proof interiors.
Microscopic structure of lightweight block does not allow for capillary action making it impervious to water. Its water barrier properties are further enhanced by adding silicone based additives.
Highest thermal rating in the industry R30!. Its cellular structure provides well insulated interiors, keeping out warm air in summers and cold air in winters. AAC reduces air conditioning cost upto 30%.
High pressure steam-curing autoclaving process gives AAC fly ash blocks unmatchable strength to weight ratio, higher than even M 150 concrete, and far exceeds the Indian Building code requirements.
Its unique cellular structure provides excellent fire rating. Due to this cellular structure AAC fly ask blocks do not disintegrate even in fire. It is best in class in fire rating of 4 hours. the melting point of AAC fly ash blocks are over 1600 degree celsius, more than twice the typical temperature in building 650 degree celcius.
|Density Oven Dry||550-650 kg/m3|
|Compressive strength||4N/mm2 (MPa)|
|Shear Strength||0.6 N/m2|
|Modulus of Elasticity||2040 Mpa|
|Coefficient of Thermal Expansion|
|Thermal Conductivity||0.16 w/moK|
|Thermal resistance||0.46 m2 - 0k/w|
|Fire resistance||4 Hrs (for 200 mm wall)|
|Sound Transmission class rating||44db for 200 mm wall|