Experimental investigation of industrial wastes in concrete: Mechanical and microstructural evaluation of pumice powder and Fly Ash in concrete

Abstract

Industrial wastes have been widely used worldwide in the construction industry as a pozzolana aiming to reduce Portland cement utilization and to produce economical, energy-efficient, and environment-friendly concrete. Fly ash is a well-recognized and extensively used pozzolana in concrete, whereas pumice has been scarcely used for this purpose. This study intends to experimentally investigate the beneficial utilization of textile industry waste-derived pumice powder (PP) and its comparison with Fly Ash (FA) in concrete. A total of ten mixes of concrete were prepared with PP, FA, and their ternary mixes (PF) by replacing cement with 15 %, 25 %, and 35 %, respectively. The results show that PP possesses higher pozzolanic potential attributed to the presence of higher content of amorphous silica (SiO2) as detected in the X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD) test and justified by the Strength Activity Index (SAI). Moreover, the addition of both pozzolana enhances rheological properties along with the workability of fresh concrete. In the case of Mechanical properties, the inclusion of 25 % PP shows better performance among all mixes, whereas FA mixes gain strength in later ages. Furthermore, the hydration products assessed by thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FTIR) analysis justified the formation of secondary hydration products and higher pozzolanic potential of PP.