AAC Blocks, India

AAC Block Project By Aerocon Buildwell Pvt. Ltd.
(EKIESL- June 2016-02)

Global location of project

Project Number: VCS 1549

Standard: VCS

Technology Type: Energy Efficiency (Autoclaved Aerated Concrete Blocks)

Project Location: Jalal Khedi village, Ujjain district, Madhya Pradesh, India

Project Description

The project manufactures 150,000 m3 of Autoclaved Aerated Concrete (AAC) blocks and 90,000 m3 of Fly Ash bricks.  These products are high-quality walling and wall insulating building materials produced using an efficient, low energy intensive brick production process, instead of high energy intensive production processes like brick trench kilns.

Central to the process is the composition and chemistry of the raw material inputs, with fly ash from thermal plants mixed with lime, cement, gypsum, aluminium powder, stone dust and Plaster of Paris.  This enables the blocks and bricks to acquire the mechanical properties required during the hydration and curing process without being sintered.

Sintering/ firing ‘green’ bricks in a kiln uses large amounts of thermal energy, sourced mainly from coal combustion plus a small amount of fuelwood.  AAC blocks don’t require any sintering or kiln heating for block consolidation, so coal use is eliminated and overall energy use is greatly reduced compared to clay bricks.

AAC does require electricity and steam generation.  The steam production’s energy use is much less than brick kilns use.  The project’s steam is generated using biomass briquettes produced locally from agricultural residues, displacing the carbon intensive coal/ fuel oils typically used in brick kilns.

Leakage of emissions associated with the production of the raw materials used (e.g. cement and lime) are accounted for and netted off from the project’s emission reductions.

Satellite image showing project site
Example of autoclaves used to manufacture AAC blocks
Example of autoclaves used to manufacture AAC blocks

Project With Benefits

Sustainability co-benefits, beyond the carbon, associated with this project include:

67% of the raw materials used are waste materials or by-products from other industries.  Thermal coal’s waste product, fly ash, has the potential to pollute both air and water.  Using fly ash in AAC reduces the consumption of natural resources such as land and water (for fly ash disposal), fossil fuels and limestone.  No waste material is generated during manufacturing.

The project has created employment opportunities for more than 300 skilled-and unskilled people.

It reduces air pollution by introducing robust air treatment facilities compared to brick kiln technology.  Local and regional air quality improvements occur by avoiding local fossil fuel combustion.  Reduced dependence on fossil fuels for brick making helps lower regional dependence on the import and availability of fossil fuels.

The project produces a “green” building material which: is energy efficient; lowers energy consumption per m3 in the production process; is 6 to 10 times better thermal insulation than regular concrete; is non-toxic, fire resistant and has excellent sound absorption.  AAC blocks’ low density enables the building structure to be lightweight.