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Autoclaved Aerated Concrete
Autoclaved Aerated Concrete
What is AAC?
Autoclaved Aerated Concrete (AAC) has been widely used across the world for the construction projects. AAC is a concrete building material that is light weighted and cut into blocks.
AAC Block is basically made from 5 types of raw materials such asSilica/ Fly ash, Lime, Sand, Water and Gypsum
The combination of the above mentioned raw materials is the reason for the lightness, structural strength, fire resistance and thermal resistance of the AAC block.
What is AAC used for ?
AAC block is suitable and useful in all types of construction projects from schools, hotels, hospitals, industrial projects and residential projects to commercial projects. From internal walls to external walls, framed walls to infill walls, fire break walls, party walls, etc, AAC block could be simply used anywhere.
Autoclaved Aerated Block was developed in early 1990s in Sweden. The German Engineers discovered that if aluminium powder was foamed with the mixture of finely divided quartz and lime and then autoclaved at 180 degree Celsius, a insulating, fire resistant, sound absorbing and lightweight building material was produced. Refining the technology, the Germans have been manufacturing lime silica AAC for more than 50 years.
Due to its relatively low consumption of readily available raw materials, excellent durability, energy efficiency, relative cost effectiveness, and ability to be recycled, AAC is well deserving of its "green" designation.
AAC Application :
Hospitals & Hotels,
Extensions and renovations
For the purpose of insulation
Murals and crafts
Advantages of AAC Block over the conventional Red brick:
- Better structural strength
- Enhanced heat prevention
- Acts as a better heat insulator
- Eco-friendly product
- Great Resistance for fire
- Better sound insulation
- Availability in custom sizes and Flexibility for designing
- Cost Effective Product
- Cost effectiveness
- a. Lower Utility Bills
- b. Lower Maintenance costs
- c. Lower insurance premium
- Fire Resistance
- a. Enhanced protection of individual and the property
- Improved quality of indoor air
- High level of thermal efficiency
- Faster construction
- Workability of the AAC Block
- Competitive Rate
AAC block weighs almost around 80% less as compared to the conventional red brick ultimately resulting into great reduction of deadweight. Further, the reduced
deadweight results into reduction of the use of cement and steel which helps great in cost savings.
As the AAC block is very easy to handle, manipulate and use, ordinary tools for cutting the wood such as the drill, band saws, etc. could be easily used to cut and align the AAC. Moreover, the AAC blocks come with larger sizes and fewer joints. This ultimately results in faster construction work as the installation time is significantly reduced due to fewer amounts of blocks and the masonry amount involved is also lowered resulting into reduced time-to-finish.
The AAC block constitutes of “macro” pores within its structure, unlike the conventional red brick that constitutes of the macro pores. The macro pores significantly blocks the capillary action as well as reduces the absorption of water within the AAC blocks to minimal.
Depending upon the thickness of the AAC blocks, they offer fire resistance from 2 hours up to 6 hours. These blocks are highly suitable for the areas where fire safety is of great priority.
AAC block walls help maintaining the inner and outer temperatures ultimately lowering the energy costs. Thermal insulation is one of the finest features of the AAC blocks.
The light weight property of the AAC blocks results into higher steadiness of the AAC blocks in the structure of the buildings. As the impact of the earthquake is directly proportional to the weight of the building, the building constructed using AAC blocks are more reliable and safer.
AAC blocks are highly superior in terms of the strength. Higher level of strength of these blocks gives higher stability to the structure of the building.
The potential of the AAC blocks of averting 200mn tones of emissions of CO2 within the environment helps saving $20 billion each year.
AAC blocks consist of the inorganic material in its constitution that helps preventing/avoiding termites, damages or losses.
Easy to use
AAC blocks are quickly and accurately cut with a band saw or hand saw to the desired dimension including accurate angles and other shapes. AAC can also be drilled, nailed, grooved, routed, shaped, sculpted, carved, coated, floated, screwed into and milled with common tools and finished with paint, tile, plaster, or veneer.
Simplifies hydro-sanitary and electrical installations, such as pipes or ducts, which can be installed easily inside it.
Its also Available in custom sizes.
That why AAC is extremely workable product. Because it can be shaped by ordinary power tools with ease
Almost any design can be achieved with ACC.
Autoclaved Aerated Concrete products do not contain any toxic gas substances. The product does not harbour or encourage vermin.
AAC blocks are suitable for both external and internal construction. The thermal conductivity of the AAC blocks helps maintaining the inner temperature to be warm during the winters and cool during the summers.
AAC weight approximately 1/3 of clay brick without compromise in strength that Reduces dead weight on the foundations and structural members. Thus economy in constructions .This attribute makes the design and construction of AAC buildings easier and less strenuous. The lighter weight doesn't compromise strength as AAC has a compressive strength of 435 psi.
Moisture from both external and internal sources can cause damage to buildings, therefore, moisture protection is a primary consideration.
External moisture sources include rain and water from the soil. Internal moisture, usually in the form of humidity, can cause condensation on the surface of the walls as well as condensation inside the wall itself.
AAC has a very porous structure which is characterized by "macro" pores. Macro pores are small air bubbles evenly distributed throughout the material. Therefore, absorption of water into the AAC material is minimal.
The porous structure of the AAC blocks results into enhanced sound absorption. The Sound Transmission Class (STC) rating of the AAC blocks up to 45 db. Thus, AAC blocks have been the most ideal material for the construction of walls in auditorium, hotels, hospitals, studios, etc.
AAC Advantages:-Thermal Insulation
Highest thermal rating in the industry R30! Thus provides well insulated interiors, keeping out warm air in summers and cold air in winters. AAc reduces air conditioning cost by 20%.
AAC provides superior thermal insulation due to its cellular structure and results in substantial power savings where air conditioned needs is necessary.Environmentally Sound
AAC is manufactured with abundant Fly ash (which makes it a green Product), unlike traditional clay bricks which uses the fertile top soil which was otherwise used for Agriculture. Manufacturing of AAC blocks produces no waste products or pollution. Its manufacturing enquires little energy as compared to other materials for walling.Go-Green Nature
Least carbon footprint with a potential offset of 0.8 tonne CO2 per m3. In India itself AAC has potential to avert 200mn tones of CO2 emissions into environment – a saving of $20 bn every year. A Green Building material – contributes to LEED rating.Earthquake Resistant
Earthquake forces on structure are proportional to the weight of the building, hence AAC shows excellent resistant to earthquake forces. Regions of the seismic activities like exclusively use AAC. It has been proven to withstand wind loads of category 5 tropical storms.Energy Efficient
AAC is 100% green building material & is a walling material of choice in LEED certified buildings (ITC centre the highest rated green building has been built using AAC) It is most energy and resource efficient in the sense that it uses least amount of energy & material per m3 of product.
Unlike brick manufacturing process which use precious layer too-layer agricultural soil, AAC uses fly ash (65% of its weight), thus provides the most constructive solution to the nation’s fly-ash utilization problem.Fire Resistant
Its unique cellular structure provides excellent fire rating. Due to this Cellular structure AAC blocks do not disintegrate even in fire. It is best in class fire rating of 4 hours. The melting point of AAC is over 1600 degree Celsius, more than twice the typical temperature in building fire 650 degree Celsius.Pest Resistant
With solid wall construction and finishes, there are fewer if any, cavities for insects and rodents to dwell in. Termites and ants do not eat or nest in AAC.
Being made up of inorganic minerals, it does not promote growth of molds.Water Barrier
Its structure does not allow for capability action making it impervious to water. Its water barrier properties are further enhanced by adding silicone based additives.High Strength
High pressure steam-curing autoclaving process gives AAC unmatchable strength to weight ratio, higher than even M 150 concrete, and far exceeds the Indian building Code Requirements.Cost savings
Being light weight AAC drastically reduces the weight of the building. Resulting into reduction in steel (up to 27%) and cement (up to 20%) structural cost savings.
Being 8 times the size of a clay brick, AAC wall construction involves 1/3rd of the joints, thus an overall mortar savings up to 66%.
Its automatic manufacturing process gives AAC an exceptional dimensional accuracy & smooth surfaces, eliminating need of three-coat plaster walls and allows for a final 6mm skin coat (putty/pop).Floor Space Area
Use of thinner blocks (6” instead of 9” exterior walls) because of its excellent water barrio & insulation properties leads to an increase in floor space area between 3-5%.OTHER FEATURES Ease of working
AAC can be drilled, sawed, nailed, and chiselled. Basically, one may work Autoclaved Aerated Concrete like wood, using wood working tools.Long Lasting
AAC being steam cured above 220 Deg C and at 14 kg /cm2 pressure becomes inert and does not have any effect of water damage or weather damage on it.Versatility of usage
Unlike standard concrete, AAC yields readily without chipping.Faster Construction
AAC's advantages in construction is its quick and easy installation since the material can be routed, sanded and cut to size on site using standard carbon tip band saws, hand saws and drills.Light Weight
It weighs approximately 1/3 of the weight of normal walling materials. AAC provides significant benefits where weight is a concern in building design. AAC is the perfect material for renovations. It causes dead weight reduction of the building and hence the reduction in structural costs.Acoustic Properties:
With its closed air pockets, AAC 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.Sound proof
AAC wall has an excellent Sound transmission Class ( STC) rating of 44. Result virtually sound proof interiors.
- AAC consists 80% air by volume, making it lightest available Walling Material (weighs 1/4th that of clay bricks).
- It was formed as a result of reaction of Aluminum on a proportionate blend of Lime, Cement & Flyash; the hydrogen gas that escapes creates millions of tiny air cells giving it a strong honeycomb like structure.
- It is further strengthened by High pressure steam curing in Autoclaves
Cost Impact Analysis - G + 5 Structure ( 50000 Sq. Feet )
|Brick Wall||AAC Wall||Saving in AAC|
|Increased Floor Area*||1250000|
|40 % Saving in Overall Project Cost|
|Size||mm||625 x 240 x thickness|
|Compressive Strength||N / mm 2||> 3 - 4.5 ( IS 2185 )|
|Normal Dry Density||Kg / m 3||450 - 650|
|Sound Absorption||de||upto 42|
|Fire Resistance||Hrs.||4 *|
|Thermal Conductivity "K"||w / mk||0.16 - 0.18|
|Thermal Resistance||K-m2 / W||0.46|
|Heat Transmission Coefficient 'u'||W / m2k||2.17|
|Drying Shrinkage||%||0.04 % ( size of block )|