'Upon hydration, FaL-G exhibits properties similar to those of Ordinary Portland Cement (OPC), so it can be effectively used as a cement replacement (or cementitious media) in the production of bricks and blocks, and as a value-add material in concrete. When added to cement, fly-ash enhances the durability and strength of concrete by chemically reacting with the excess lime released during hydration. It is this surplus lime which reacts with deleterious chemicals in the atmosphere or ground, causing concrete to deteriorate.'
The lime for FaL-G was traditionally sourced from the acetylene industry and later from mineral sources. FaL-G, made of lime procured from the acetylene industry, costs about Rs 2,500 per tonne as against Rs 6,000-7,000 per tonne of OPC, which shows how much the cost of construction can be reduced by FaL-G concrete. Since FaL-G has become more popular and procuring lime has become cumbersome and expensive, an alternative FaL-G has been developed, wherein, cement is the source of lime. 'FaL-G in the cement route is more popular nowadays as standard quality cement is more widely and readily available than mineral lime,' adds Kalidas.
- CHARU BAHRI
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