What is AAC Blocks ?

AAC Blocks (Autoclaved aerated concrete)

What is AAC: 

Autoclaved aerated concrete (AAC), also known as autoclaved  cellular concrete (ACC), autoclaved lightweight concrete (ALC), autoclaved concrete, porous concrete, Ytong, Hebel Block, Aircrete, thermalite.


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 When AAC was first developed

AAC was developed in 1924 by a Swedish architect who was looking for alternative building material with wood-like properties–good thermal insulation, solid structure and easy to work with –but without the inconvenience of combustibility, decay and termitis. It has been refined into a highly thermally insulating concrete material for indoor and outdoor construction. AAC products contain blocks, wall panels, floor and ceiling panels and lintels.

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 Advantages of AAC Blocks

AAC block offers several significant advantages over other cement construction materials, one of the most important being its lower environmental impact.
2. Improved thermal efficiency reduces the heating and cooling load in buildings.
3. The Workability allows accurate cutting, which minimizes the generation of solid waste during use.
4.  It has a lower environmental impact in all phases of its life cycle, from the processing of raw materials to the disposal of waste.
5.  Its Lightweight saves cost and energy in transportation.                                     
6.  Its Lightweight saves labour expenses.                                                                        
7.  Light weight increases chances of survival during seismic activity.
8.  Larger size leads to faster masonry work.
9.  Termite/Pest Resistant, Cost Effective, Precision,
      Earthquake Resistant.
10. Easy Workability and Design Flexibility.
11. Thermally Insulated & Energy Efficient, Fire Resistant, Eco-friendly.

ACC Blocks size       

S.No.
Particulars
     Size (L x B x H) in mm
1
Size 1
         600*200*200
2
Size 2
         600*200*150
3
Size 3
         600*200*100
4
Size 4
         600*300*200
5
Size 5
         600*300*100
6
Size 6
         600*400*250

       Note: Sizes are in millimetre.

Applications

  1. Hotels, Motels & Restaurants
  2. Industrial & Cold Storages 
  3. Hospitals & Medical Clinics 
  4. Retail & Warehouses 
  5. Office & Religious Buildings 
  6. Power Plant & Fire Walls
  7. Public Facilities
  8.  Single & Multi Family Homes 
  9.  Shaft walls     
  10.  Education Institutes Construction     
  11.  Auditorium & Theaters 
  12.   Multi-storey Buildings 
 Technical Comparison of Blocks

Parameter
AAC Block
Concrete Block
Brick
Size
(600x200x100-300) mm
(400x200x100-200) mm
(230x115x75) mm
Compressive Strength
30 - 50/Kg/3Cm2
40 - 50/Kg/Cm2
25 - 30/Kg/Cm2

Dry Density

600-650/Kg/Cum

1800 Kg/Cum

1950 Kg/Cum

Fire Resistance
4-6/Hour Depending On Thickness

42Hours

2Hours
Sound Reduction Index(db)
60 For 200 mm thick wall
_
40 For 230 mmThik Wall
Thermal Conductivity w/(Km)
0.25

0.51

0.81

Physical Properties of Autoclaved Cellular Concrete Blocks Clauses (4.1,8.3,8.4,8.5,11.2,11.3 and 11.4) IS :2185(Part-3) 1984


S.No.
Density in oven dry condition
Compressive strength min grade 1 N/mm2
Compressive strength min grade 2 N/mm2
Thermal conductivity in air dry condition w/mk
1
451 to 550
2
1.5
0.21
2
551 to 650
4
3
0.24
3
651 to 750
5
4
0.30
4
751 to 850
6
5
0.37
5
851 to 1000
7
6
0.42


ACC Block Plant


       
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S.No.
Description
S.No.
Description
1
Material hopper
10
Cutting machine
2
Slurry making tank
11
Tilting crane
3
Slurry making pit tank
12
Windless machine
4
Silo
13
Steam trolley car
5
Pouring section platform
14
Autoclave
6
Pouring mixer
15
Ferry car outlet
7
Ferry cart
16
Side plate return roller system
8
Mould box
17
Finish block dispatch point
9
Ground crane



Raw Material Required

Fly Ash /65-70%
 Fly-ash material is freely available in Thermal power plant. A lot has been said about this raw material in Different forums & Environmentalists. There are no taxes levied on this item.

 Lime / 8-12%

Different qualities of lime are available and depending on the raw materials. The mix design can be chosen to get the optimal quality of production. Quick lime is requirement for giving the real aeration to the product.

 OPC Cement / 10-15%

This Project aims to utilize OPC cement as main binder material. it will give faster strength to the blocks besides giving improved consistent quality. it also ensures a better cost effectiveness for the same. Using OPC cement will be a standardized practice.

 Gypsum / 4.5-5%

This too is an industrial waste. This is available as an industrial by product of Fertilizer plant.gypsum is responsible to give longer term strength to block.

 Aluminum Power / 0.5%

Finely ground aluminum power is used in very limited quantity (less than 0.5%) so that it reacts with active lime, and silica in base material to make the aeration, and swell the product, making it very light in weight. The density of the product reduces to 600-650 kg/cum.


Procedure OF Production:

1.  Firstly, batch the measured raw material.

2.  Feed raw material into pouring mixer for slurry making.

3.  pour the mixer slurry into the mould.

4.  After pre-curing under a certain temperature and time,the block would reach certain hardness & ready for cutting.

5.  Tilting crane separate the already- formed material from the mould and transfer it with side plate to the cutting cart.

6.  Cutting machine horizontally & vertically cut the foamed material.

7.  Group of steam Trolley with cake move in to Autoclaves.

8.  In Autoclaves sustained pressure & temperature is maintained for curing cake.

9.   crane transfer the finished product to the dispatch point.

10. Move the finished blocks out of Autoclaves.

11. Packed for loading.

Also, read - What Is Cavity Wall?

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