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

ABSTRACTThe 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.KEYWORDS: Fly ash brickalkaline solutionmolaritycuring temperatureorthogonal array AcknowledgementsThe authors would like to thank NCESS Trivandrum for helping it to characterize the particle size distribution and WD-XRF of raw material. The authors are grateful to MRC MNIT for carrying out the microstructural properties of the raw material and sample. The authors are thankful to Tribology Lab MNIT Jaipur for investigating the thermal conductivity of the specimens.