IISc-Bengaluru scientists develop low-carbon bricks using construction waste

BENGALURU: Researchers from Indian Institute of Science (IISc) have developed a technology to produce energy-efficient walling materials using construction and demolition waste (CDW) and alkali-activated binders.
These low-carbon (low-C) bricks, as the team calls them, do not require high-temperature firing and avoid the use of high-energy materials such as Portland cement. The technology, researchers believe, will also solve the disposal problems associated with construction waste.The project was funded by the department of science and technology (DST).
Prof BV Venkatarama Reddy, who led the team, said a startup will be functional within 6-9 months to manufacture low-C bricks and blocks with IISc’s technical help. “The startup will act as a technology dissemination unit through training, capacity building and providing technical knowhow for establishing such commercial units across India,” Reddy, who recently retired from IISc, added.
The major beneficiary of this development will be the construction industry in general and the building sector in particular. DST pointed out that conventionally, building envelopes consist of masonry walls built with burnt clay bricks, concrete blocks, hollow clay blocks, fly ash bricks, lightweight blocks, and so on, which spend energy during their production, incurring carbon emission (i.e., possess embodied carbon) and consuming mined raw material resources, which lead to unsustainable constructions.
The masonry units are manufactured either through the process of firing or using high-energy/embodied carbon binders such as Portland cement. DST added that annual consumption of bricks and blocks in India is about 900 million tonnes.
“Besides, the construction industry generates vast amounts (70-100 million tonnes per annum) of CDW. To promote sustainable construction, two important issues need to be addressed while manufacturing masonry units: Conserving mined raw material resources and emission reduction. Moving towards this target, IISc scientists developed a technology for producing alkali-activated bricks/blocks by utilising fly ash and furnace slag,” DST said.
After ascertaining the physico-chemical and compaction characteristics of CDW, the team obtained the optimum mix ratios of materials before the production process was evolved to produce low-C bricks.