Design development of coal-based fly ash geopolymer brick using orthogonal array design of experiment

Abstract

ABSTRACT The world produces billions of fired-clay bricks annually, but their manufacturing process adversely affects the environment. The present article investigates the alternative and sustainable approach for manufacturing coal-based fly ash geopolymer bricks by L9 orthogonal array design of experiment. Three factors and three levels were considered against a single response. The physical, mechanical, and thermal properties of bricks were evaluated and reported in the paper. The optimal ratio to produce fly ash geopolymer brick was 12 Molarity (M) NaOH solution, 2.5 alkaline solution ratio (ASR), and 60°C curing temperature (CT). The experiment’s confirmation and prediction were made and found within the limit. The significance of different levels of factors in enhancing the strength of brick specimens was analyzed using Analysis of Variance (ANOVA) through a General Linear Model. The results indicated that Molarity, ASR, and CT were the crucial factors in improving the strength of the brick specimens. Moreover, to investigate the morphology, mineralogy, phase structure, and thermal resistance of the brick specimens, microstructural properties such as Field Emission Scanning Electron microscopy (FESEM) – Energy dispersive spectra (EDS), X-Ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Thermal Gravimetric Analysis (TGA) were carried out and reported in the paper.