AERATED AUTOCLAVED CONCRETE (AAC) BLOCKS:
Autoclaved Aerated Concrete (AAC) is an ultra-light concrete masonry product. It
can weigh as little as 1/5 as much as ordinary concrete due to its distinct cellular structure featuring millions of tiny pockets of trapped air. This cellular structure gives AAC a number of exceptional physical characteristics.
AAC consists of basic materials that are widely available.
These include sand, cement, lime, fly ash, gypsum, aluminium powder paste, water
and an expansion agent. Silica sand, the raw material used in the greatest volume in AAC, is one of the world's most abundant natural resources.
The finished product is up to five times
the volume of the raw materials used, with an air content of 70% to 80% (depending on the required strength and density.) Due to this large increase in volume, AAC is very resource efficient.
The high consumption of raw materials by the construction sector, results in chronic
shortage of building materials and the associated environmental damage.
In the last decade, construction industry has been conducting various researches on the utilization of easily available raw materials in construction. AAC is one of the materials which can cope up with the shortage of building raw materials and can produce a light weight, energy efficient and environmentally friendly concrete. This study deals with the introduction to the process of the autoclaved aerated concrete and its advantages compared to the normal concrete.
Advantages of AAC BLOCK
- Fire Resistant
- Breathable
- Good Sound Insulation Property
- Easily Workable
- Durable
- Attractive Finishing
- Economic
Disadvantages of AAC BLOCK
Some disadvantages of AAC blocks and panels are that they do contain Portland cement,
they are made in so few place which means more transportation cost and using gas resources.
Builders must learn how to use them since the mortaring is different, some of the blocks
are made to European standards and have to be cut.
They are porous so must have stucco or cladding on the exterior to keep out water. For
load-bearing, AAC may need rebar reinforcement.
In some states, they have yet to be accepted in building codes due to lack of test results.
What is not green about Portland cement is that it is about 60 percent limestone, or calcium carbonate, and must be burned at high temperatures in kilns using lots of energy and creating carbon dioxide (CO2), a greenhouse gas linked to global warming.
The newer magnesia-based cement can be burned at lower temperatures using less energy and creating less CO2.
Magnesium carbonate and calcium carbonate are both obtained by mining, but lower alkaline
magnesia concrete is able to remain strong when recycled materials are added to the mix and can insulate better when organic materials are added. Magnesia concrete can also absorb CO2
through a carbonation process while it is being manufactured and used, reducing the
greenhouse gas.
