The concrete waste after a building is demolished mostly ends up in landfills, in unauthorized places or simply dumped on the roadside. If the attempts of a team of engineering students from Erode succeeds, then this concrete waste could well turn out to be building block to a new structure. The team from Kongu Engineering College, Erode recently won an award in the Carbon Zero Challenge competition organised by IIT Madras for developing blocks from concrete debris.
Professor of civil engineering, G S Rampradheep, said the debris can be recycled into construction material like hollow or paver blocks. “We have tested the blocks for compressive strength and found that they are stronger and more durable than conventional bricks and concrete blocks.”
The professor said they have come up with a simple and economical process where concrete waste is carefully segregated from the C&D debris and is crushed to produce recycled aggregates of different particle sizes. The crushed material is then mixed with sodium silicate, which will act an agent to reduce porosity, increase durability and for help the material bind well. The mixture is then put through carbonation process where carbon dioxide is injected into it at varying pressures in a chamber. It is then mixed with cement and water, moulded into blocks before they are sprayed with water again and sundried for curing.
“Injection of CO2 will improve the physical properties including the density of the aggregate. Such properties are important for the durability of the block, as most recycled bricks are known to crack faster,” said Rampradheep. “Also, there is no need to add water for curing, as we have added sodium silicate to the crushed particles.”
The city generates about 1,200 tonnes of C&D waste every day. Recently, the Chennai corporation identified two erstwhile landfill sites in Athipattu and Pallikaranai to process the waste. The technology of converting debris to construction material has been widely adopted in the West while civic body officials said less than 1% of the C&D waste is processed or recycled in the city.
Rampradheep said the technology, if adopted, will convert waste into wealth and also cut down on CO2 emissions.The team has applied for a patent for both the technology and for the equipment used for processing the waste.