Sustainable valorization through the reuse of incinerated paper mill sludge ash in building brick production

In recent years in India, fly ash-lime-gypsum (FaL-G) brick production has been adversely affected by the scarcity of fly ash and lime. Consequently, the current study aims to mitigate this problem. It delves into leveraging incinerated paper mill sludge ash (IPMSA) as a supplement to fly ash and lime in FaL-G brick production, aiming to present an eco-conscious alternative to conventional burnt clay bricks. It focuses on two blends: blend 1, replacing fly ash with IPMSA (2.5-30 wt%), and blend 2 substituting lime entirely with IPMSA (2.5-15 wt%). A thorough material analysis preceded brick manufacturing, involving techniques like energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, thermogravimetry differential thermal analysis, scanning electron microscopy, and X-ray diffraction spectroscopy. Subsequent tests evaluated compressive strength, water absorption, weight density, percentage of voids, initial rate of suction and chemical resistance of the resulting bricks. According to the XRD results, the higher IPMSA levels didn't induce any phase transformation. Remarkably, bricks incorporating IPMSA in blend 1 (2.5-20 wt%) and blend 2 (2.5-7.5 wt%) met the mechanical properties specified for 'class 10' bricks according to Indian and ASTM standards. Incorporating IPMSA increases the porosity of bricks, making them lighter. This aids in minimizing construction expenses by reducing labour and transportation costs as well as lowering expenditure on foundation construction. This sustainable approach efficiently uses resources, reduces landfill wastes, shows potential for industrial-scale production, making ecofriendly bricks a promising alternative to traditional methods and promoting greener construction practices.