What are light weight blocks? How are they different from the conventional solid concrete blocks or bricks?
The normal solid blocks are made out of concrete. Red bricks are made out of red clay (fired red clay for giving it the stability). There are many different types of light weight blocks. One that is readily available in my place, which is being too common around here, is AAC blocks. I think I will take AAC blocks for consideration with this article. AAC stands for Autoclaved Aerated Clay. It has gypsum as one of its components, and what we have as end result is a light weight block, which from my observation is almost one fourth the weight of a normal solid blocks.
Some advantages of AAC blocks
- It is light weight, which holds the potential for more labor productivity and much more faster execution.
- It has thermal and sound resistivity better than solid blocks or red bricks. I have personally felt that insides of a home in which AAC blocks are used is a bit more cooler (though it is not so very evidently so in my observation) in my observation.
- I love the consistency of the material, visually and structurally. What I mean is the blocks are consistent strength wise. I have tested multiple blocks from the same manufacturer in different locations and I have found that the strength is in the range of 2.5 - 3 KN/cum. I will never be able to say that in the case of solid blocks. Visually too, every block looks the same.
- Wastage during construction is less. Handling AAC blocks is a better experience. You don't lose material due to breakage during unloading or during transportation.
- In case of high rise buildings, there is significant saving in structural costs as the loads are considerably reduced.
Consideration as the structural material for houses
Most of the double storied houses use solid blocks as the structural material. The weight of the slab is transferred to the plinth and further to the foundation through the solid blocks. For such a case too, AAC blocks can be used. I believe that since AAC blocks are manufactured in a controlled facility, there is more reliability on the capacity of the blocks.
Other factors to consider
- When AAC blocks are used, the surface is much more even than in the case of solid blocks or normal red bricks even. Hence plastering material consumptions and labor consumption is much lower and this can be savings in cost.
- In certain cases, putty is directly applied to the AAC blocks by avoiding the plastering itself. I have nor tried this so far, but I am assured of good results. If it is true, then there is considerable savings in terms of labor and material for plastering.
- If adhesives are used, wall tiling may be directly done to the AAC blocks. Let me warn you here, it will not be advisable to directly do wall tiling using cement mortar to AAC blocks because of the even surface and therefore lesser mechanical adhesion.
- AAC blocks can be used with cementitious adhesives. There is considerable savings in cost when this is the method used. Most of the suppliers of AAC blocks will also provide the adhesives. It is available in 20kg bags.
I think if speed of execution is what matters, a home owner can completely rely on AAC blocks. I will be writing another article exclusively for cost comparison as that is a subject that merits exclusive attention and detail analysis.