Recycling of Fly Ash and Waste Glass to Fabricate Environment Friendly Fly Ash Bricks

Fly ash is the most abundantly produced waste material from thermal power plants and steel industries. Management of this fly ash is a tedious task as it creates economic and environmental problems for society. One popular way to recycle fly ash is to produce fly ash-based bricks for construction. However, as the binding capacity of fly ash is significantly less, it pollutes the surrounding environment of the working site. Fly ash brick is usually made using cement as a binder by cold compaction technique. Cement manufacturing is an expensive industrial process that releases carbon dioxide into the atmosphere. Therefore, the scrap glass powder is used here as an alternate binder. The glass powder is mixed with the fly ash to prepare glass-ceramic brick to reduce the brick firing temperature and trap the pollutants within the silica-rich glassy phase. The glass used in this work was the scrap glass collected from the chemical laboratory of the ceramic department (NIT Rourkela). Different batches were studied concerning the glass percentage and fly ash percentage. The fabricated green bodies were sintered at 900 and 1000°C for 2 h. X-ray diffraction study revealed the presence of mullite and cristobalite phases in the sintered brick. FESEM microstructure confirms the presence of the glassy phase in the sintered brick. It is found that with an increase in glass content, the bulk density increases, and apparent porosity decreases. The mechanical properties of the glass-ceramic composite bricks are also superior to the fly ash brick.