Fly ash bricks development using concrete waste debris and self-healing bacteria

In this study, an effort has been made to use concrete waste debris for the manufacturing of fly ash bricks as a sustainable material. Though in earlier studies, attempts have been made to use concrete waste debris to manufacture fly ash bricks however it becomes inferior as mechanical properties in comparison to regular fly ash brick have always been a concern. To overcome the problem, self-healing bacteria (SHB) has been amalgamated in the manufacturing process. Various tests have been performed to evaluate the mechanical properties, microstructure and morphology of four different compositions of brick samples. The study revealed that brick made with concrete debris and SHB was having mechanical properties at par with red clay brick with an initial rate of absorption of about 4.8 kg/m²/min, water absorption as 15.72% and compressive strength of 10.29 MPa observed to be even higher than red clay bricks. Further X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) study revealed the presence of lesser micro-cracks over the bricks structure made up with concrete debris and SHB in comparison to other samples. This investigation revealed that the use of SHB results in a higher strength with the lesser void formation which helps in achieving higher performance quality parameters for brick manufacturing using concrete waste debris as sustainable materials.