IIT-M develops process to recycle building debris using solar power

CHENNAI: Researchers at the Indian Institute of Technology Madras (IIT Madras) have developed a process involving solar thermal energy to recycle construction and demolition debris.

The waste concrete from demolition was heated using solar radiation to produce recycled concrete aggregate (RCA) that was higher in quality when compared to those obtained from mechanical crushing. The concrete made using this technology met the requirements for typical structural applications, said a release from IIT-M.

By using concentrated solar energy for heating, the thermo-mechanical beneficiation of the concrete waste results in high-quality recyclable materials, which can substitute stone (blue metal) aggregates and sand in concrete. In this study, concrete from a demolition site was heated using solar radiation concentrated through large reflectors and cast-iron receivers to more than 550 °C. It was scrubbed mechanically to yield coarse and fine RCA, with properties similar to those of pristine aggregates.

Prof Ravindra Gettu, department of civil engineering, IIT Madras, said, “The aim was to develop the proof-of-concept that solar radiation could be used in the thermomechanical beneficiation of concrete waste to produce good quality recyclable material for new concrete.”

He added that the study presents strong evidence supporting the use of concentrated solar energy for recycling waste concrete, with promise for large-scale waste concrete recycling. “This would reduce the energy footprint of construction and demolition waste processing, and lead to savings in raw material and electricity, towards the circular economy.”