Are you getting blocked on AAC blocks ?

Overview :

off Late we are observing lots of projects coming up where the AAC blocks are being used. the Red clay bricks are now getting replaced with these AAC blocks , also known as Siporex blocks.This article explains the various aspects which strongly favor this choice of the builder.

In this context , author also sought expert’s opinion on these blocks.

The author is doing some fundamental thinking on Auto-claved aerated concrete blocks by Socrates’ method of questions and answers :

1. As a builder what is better choice for me ; bricks or AAC blocks ?

To answer this question , we need to ask :

What are the basic advantages of using Auto-claved aerated blocks ?

1.1 Multiple choice :

The length of block is 625 mm ,height is 240 mm and user has  multiple options in thickness such as :  75 mm , 100 mm , 125 mm , 150 mm and 300 mm.

Whereas ,the bricks are produced in 2 sizes :

200 mm x 100 mm x 75 mm  [ used for internal walls ]

200 mm x 150 mm x 100 mm [ used for external walls ].

1.2 Can AAC blocks bear more load ?

Most important thing to remember is that whereas Red clay bricks can  certainly be used for load bearing wall ,  the AAC blocks are only for Non load bearing applications . So these can only be used as partition walls.

This must be due to the fact that AAC blocks have low crushing strength as compared to red clay bricks . [ First class red clay bricks would have a crushing strength of 75 Kg /Sqcm , the AAC blocks do have a crushing strength of only 40 Kg /

1.3 A Happy Mason :

A mason is ought to be more comfortable in using the AAC blocks due to these reasons :

1.3.1 : Easy to handle :

The AAC weigh only 31 % as compared to Red clay bricks.

[ The dry density of AAC blocks is 600 Kg/ CuM as compared to red clay bricks @ 1900 Kg / CuM.]

1.3.2 : Lesser  blocks to be handled per CuM of masonry :

A mason need to  work only on 44 blocks for getting an output of 1 CuM whereas with red clay bricks at least 514 bricks need to be laid.

1.4.What is the raw material used ?

The Red clay bricks are made using the fertile clay from the farms or green fields whereas the AAC blocks use only cement and/or calcined lime, fly ash , sand quartz and some alumina & ferrous oxide.

Thus AAC blocks are more environment friendly since the fertile land is not damaged

1.5. What about the cost ?

1.5.1 AAC blocks appear to be costlier than Red clay bricks :

AAC blocks are priced around INR 3300 per CuM.

A red brick of size 200 mm x 150 mm x 100 mm would cost INR 7000 per thousand bricks.

Volume of one brick : 0.2 x 0.15 x 0.10 = 0 .003 CuM  is costing INR 7=00 

Thus , per cubic Metre cost for red clay bricks = 7/0.003 = INR 2333 

so as a material , AAC blocks are costlier by 41 % than red clay bricks.

1.6 Why to use AAC blocks if these are costlier ?

1.6.1 : Reduced mortar quantity :

a. 44  AAC blocks make 1 CuM of masonry whereas we need to use 514 Bricks .

b. Thinner mortar joint : AAC blocks have a size variation of ( +/-) 1  mm as compared to Red clay bricks which have a dimensional variation of ( +/-) 5 mm.

1.6.2 : Reduced sizes of the RCC beams and columns and footings ( Not slab ):

The dead weight of walls is reduced from 1900 Kg / CuM in red clay bricks to 600 Kg / CuM.

Suggestions to the builder :

From the preceding discussions, it is clear that AAC blocks are advisable to be adapted . However, would like to make a few suggestions :

1. Make a firm decision on using AAC blocks and communicate to your RCC designer much before the designing is taken up . This is the only way of economizing on the RCC sections and reinforcement weight.This decision if made after completion of RCC works at site , there would not be any  structural advantage.

2. Use chemical bonding for AAC blocks as this does not require any curing later on.

3.While negotiating the rates for Masonry work , do explain the features to the sub contractor and seek a discount on conventional rates. [ This would not be easy. ]

Given the larger dimensions  higher productivity , the light weight and thinner mortar joints , the work of a mason is much more comfortable with AAC blocks.

Authors Note :

Dear reader ,

Need to add some photographs .

Just bear with me for time being.

Happy reading !


3 thoughts on “Are you getting blocked on AAC blocks ?”

  1. Thats a good idea…

    🙂 As It is good with..
    *Earthquake Resistant:due to impact of the earthquake is directly proportional to the weight of the building
    *Fire Resistant: 2/6 hours depends upon the size of blocks
    *Pest Resistant: due to inorganic material used
    *Sound Proof: upto 45db
    *Faster Construction
    *Perfect Size and Shape
    *Light weight
    *Superior Resistance to Water
    *Environment Friendly
    *Thermal Insulation
    *Long Lasting
    *Moisture Resistance


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