CONSTRUCTION AND BUILDING MATERIALS, vol.258, 2020 (SCI-Expanded)
This paper investigated the incorporation of ceramic tile waste (CTW) in optimized combinations of geopolymer binders, while using curing at ambient temperature. For this reason, a new algorithmic mix design method was evaluated by pre-targeting values of SiO2/Al2O3, Na2O/SiO2 and liquid/solid. The relation between the predetermined chemical ratios and the flowability, setting times and mechanical properties were assessed at fresh and hardened states of CTW-geopolymers. In addition, the influence of subjecting the optimized compositions to a 24 h curing at elevated temperatures of 50 degrees C, 75 degrees C, and 100 degrees C and the addition of 15%, 30% and 45% of Class C fly ash (FA/C), Class F fly ash (FA/F), metakaolin (MK) and ground granulated blast furnace slag (GGBS) was also considered. As microstructural analyses, X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) and Fourier transformed infrared (FTIR) spectroscopy were performed on the optimized binders in order to characterize their microstructural change at different SiO2/Al2O3 and Na2O/SiO2 ratios. The results demonstrate that it is possible to achieve CTW binders with normal and high compressive strengths at room temperature curing, especially with the addition of calcium source materials such as Class C fly ash and GGBS. However, well-proportioned ratios of SiO2/Al2O3 of 11.1 and Na2O/SiO2 of 0.2 was necessary to reach advanced dissolution of precursor powders and greater quantity and quality C (N)-A-S-H geopolymer products. (C) 2020 Elsevier Ltd. All rights reserved.