AAC & AVANTTA
Being in the construction related business since the last 20+ years, the promoters of Avantta have undertaken an extensive study of various construction techniques, new products being introduced and used in the construction industry. During the course of this study, they have also interacted with eminent consultants in the field from various parts of the country. Though the basic construction material being used all over the country was more or less similar, the Northern and Western parts of India were found to be using different walling material popularly known as Autoclave Aerated Concrete bricks (AAC). Further investigation revealed that AAC Bricks is a much superior material as compared to the conventional Clay Bricks and generated substantial economy in the cost of construction.
AERATED AUTOCLAVED CONCRETE BRICKS (AAC)
The raw materials of AAC bricks is a mixture of Fly Ash, Cement, Gypsum and Lime which is aerated by adding certain chemicals. The bricks are then cured under a pressurized steam atmosphere. The presence of Cement ensures bonding of material while Gypsum ensures continued strength in the material. High pressure steam curing provides additional compressive strength to the product. Due to aeration the product becomes substantially lighter in weight when compared to the conventional Red Brick / Fly Ash Brick.
The conventional bricks are made of clay and burnt in Coal. Both the items are of immense importance to the ecological balance of Mother Earth as well as the environment. Clay Bricks consume the very precious top soil of the earth which is made during thousands of years by nature. It also burns substantial quantity of Coal which creates huge Carbon-di-oxide emissions resulting in an irreversible destruction of the environment. Also, such coal can be used for manufacturing items which are of more economic and of national importance.
Fly Ash has become a huge environment hazard because of its huge generation in the Thermal Power Plants and limited use. Disposal of Fly Ash has become a major issue with the Thermal Power Plants and Government of India is encouraging usage of Fly Ash in various ways. The result of such encouragement is its use in Cement Manufacturing, Brick Manufacturing and similar products.
One of the main components in the manufacture of AAC bricks is Fly Ash. The Fly Ash content in the AAC is around 70% and the balance comprises of Cement, Lime, Gypsum and few additives. The basic advantages of AAC bricks are compiled as under:
1. Eco-friendly
- Makes productive use of recycled industrial waste (Fly Ash).
- Non-polluting manufacturing process – the only by-product is steam.
- Made of non-toxic ingredients.
- Does not exude gases.
- Total energy consumption for producing AAC is less than / of what it takes to produce other building material.
2. Lightweight
- 3-4 times lighter than traditional bricks therefore, easier and cheaper to transport.
- An AAC block weighs approximately 50% less than a standard CMU block. An AAC panel weighs approximately 30% of standard cast-in-place AAC concrete.
- Usage reduces overall dead load of a building, thereby allowing construction of taller buildings.
3. Thermally Insulated & Energy Efficient
- Tiny air pores and thermal mass of blocks provide excellent thermal insulation, thus reducing heating and air conditioning costs of a building.
- Non-combustible and fire resistant up to 1600° C.
- Can withstand up to 6 hours of direct fire exposure.
5. Acoustic Performance
- Superior sound absorption qualities due to porous structure of blocks.
- Offers sound attenuation of about 42 dB, blocking out all major sounds and disturbances.
- Ideal for schools, hospitals, hotels, offices, multi-family housing and other structures that require acoustic insulation.
6. Easy Workability and Design Flexibility
- Blocks can be easily cut, drilled, nailed, milled and grooved to fit individual requirements.
- Available in custom sizes
- Simplifies hydro-sanitary and electrical installations, such as pipes or ducts, which can be installed after the main construction is complete.
7. Sustainable
- Retains properties over time.
- Made of non-allergenic material.
- Use of AAC improves indoor air quality.
8. Earthquake Resistant
- Lightweight blocks reduce mass of a structure, thus decreasing the impact of an earthquake on a building.
- Non-combustible nature provides an advantage against fires, which commonly accompany earthquakes.
9. Precision
- Available in custom sizes.
- Results in smooth walls with perfect contact between different elements.
- Reduces cement and steel usage.
10. Termite/Pest Resistant
- Due to structure of blocks, AAC cannot be damaged of infested by termites and other pests.
11. Cost Effective
- Reduces operating cost by 30% to 40%.
- Reduces overall construction cost by 2.5% as it requires less jointing and reduces need for cement and steel.
- High-insulation blocks save up to 30% in energy costs.
- Variety in sizes of blocks helps increase carpet area.
- Wall painting and plastering last longer as almost zero efflorescence affects AAC. This translates into lower maintenance costs.
12. Faster Construction
- Reduces construction time by 20%.
- Different sizes of blocks help reduce the number of joints in wall masonry.
- Lighter blocks make construction easier and faster.
- Easy to install. Sets and hardens quickly.
13. Salient features of AAC block: Leading to increasing acceptance of the product
The following salient features of AAC block make it user-friendly product over other construction materials:
| Environment friendly |
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| Light weight |
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| Cost saving |
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| Energy Efficient |
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| Easy workability |
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| Other Factors |
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A quick comparison between AAC Block and Clay Brick
| Parameter | AAC Block | Clay Brick |
| Production facility | State-of-the-art production facility | Unhealthy working conditions due to emission of toxic gases |
| Production cost beak-up |  |
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| Sector and labour | Organised sector with statutory labour laws | Unorganised sector with rampant use of child labour. |
| Soil consumption | Zero soil consumption. Primary raw material for AAC block is fly ash which is industrial waste generated by coal/lignite-based thermal power plants (TPP). | One Sq. Ft. of carpet area with clay brick walling consumes 25.5 KG of top soil. |
| Fuel consumption | One Sq. Ft. of AAC block consumes 1 KG of coal. Lower greenhouse gas emission. | One Sq. Ft. of clay brick consumes 8 KG of coal. Higher greenhouse gas emission. |
| CO2 emission | One Sq. Ft. of carpet area emits 2.2 KG of CO2. | One Sq. Ft. of carpet area emits 17.6 KG of CO2. |
| Energy Saving | Approximately 30% for heating and cooling | None |
| Size | Available in custom sizes to fit individual requirements. | Available in fixed size. |
| Density | 550-700 KG per cubic meter | Around 1,800 KG per cubic meter |
| Availability | Available throughout the year. | Since the drying and firing is done in open, the brick cannot be manufactured in rainy season; hence, it is mostly seasonal and operating for around 8 months in a year. |
| Tax contribution to exchequer | Contributes to taxes in form of GST, etc. | Clay brick is non-excisable product. However, it contributes in form of VAT and royalty on earth mining to the state government. |
Technical Data
The technical data of the product manufactured along with the various sizes in which it can be manufactured as under:
| Technical Specification | ||
| Property | Units | Sizes |
| Size | mm | 625 x 240 x Thickness (± 1.5 mm) |
| Thickness | mm | 50,75,100,125,150,200,225 |
| Compressive Strength | N / mm2 | > 2.5 – 7.0 (IS 2185) |
| Normal Dry Density | KG / m3 | 550 – 800 |
| Sound Absorption | Decibels | Up to 42 |
| Fire Resistance | Hrs. | 4 * |
| Thermal Conductivity “K” | W / mk | 0.09 – 0.18 |
| Thermal Resistance | K-m2 / W | 0.46 – 0.52 |
| Heat Transmission Coefficient ‘u’ | W / m2k | 2.17 |
| Drying Shrinkage | % | 0.04 % (Size of Block) |