The Indian Institute of Technology (IIT) Madras researchers have developed a treatment process involving solar thermal energy to recycle construction and demolition debris. The demonstration was done at the ‘India One Solar Thermal Power Plant,’ located in ‘Shantivan,’ the headquarters of the Brahma Kumaris organization in Rajasthan.
It has 770 solar concentrators to produce electricity using steam generated at high pressure. 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. The plant has been operational since 2017 and provides power to a community of about 25,000 people at a reasonable cost and low maintenance.
The objectives addressed in this study is divided into three parts— the use of concentrated solar energy in the thermomechanical beneficiation of concrete waste, the production of high-quality RCA from the waste and assessing the performance of the RCA in concrete to establish the fact that waste can be recycled. The main conclusions from the study is as follows:
It was observed that the required temperature of about 500 °C could be achieved and maintained for a long duration with the reflector-receiver setup used. The properties of the aggregates produced were found to be comparable with those of RCA produced in an electric furnace, with the total yield of recycled products being [90 per cent of the feed concrete). Preliminary results on concrete made with the RCA indicate its suitability for typical concrete applications.
Concrete is the most common material used in construction universally with an annual production estimated to be 10–30 billion tonnes. The present study attempts to mitigate the limitations of conventional thermomechanical techniques with regard to harmful emissions through the utilization of concentrated solar energy.
