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Thin‐film‐transistor liquid‐crystal display (TFT‐LCD) waste glass can be used as a raw material in the production of geopolymer because of its amorphous and also contains relatively large amounts of silicon and aluminum. The effects of nano‐SiO2 (NS) addition levels (0%–3%) with 1% increments and the geopolymer replacement levels of TFT‐LCD waste glass (0%–40%) with 10% increments were analyzed quantitatively. The optimal geopolymer proportion was identified based on its mechanical characteristics and flexural strength. The geopolymer samples were also analyzed for changes in weight, and a thermogravimetric analyzer and 29Si magic‐angle spinning nuclear magnetic resonance to measure the short‐range network ordering. The results of this study indicated that the TFT‐LCD waste glass metakaolin (TWGM) geopolymer sample with 10% TFT‐LCD waste glass and 1% NS exhibited greater strength and lower porosity than other samples. Understanding these characteristics is necessary to identify the mechanical strength, thermal stability, and the fundamental structure of a geopolymer system. Applying NS to a geopolymer enhances its compactness, improves its uniformity, and increases its strength. These results show that 10% TFT‐LCD waste glass and 1% NS can be used as a partial substitute for metakaolin (MK) in geopolymer materials. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 947–955, 2014

In this research, the performance of a cementless eco-binder, a mixture of waste materials including slag, circulating fluidized bed combustion ash (CFA), and rice husk ash (RHA) was investigated, in which CFA acted as an activator. One hundred and twenty paste samples were prepared by using the RHA/(slag + RHA) ratios of 0, 15, 30, 45% while keeping a constant ratio of CFA/(slag + RHA) at 25%. The setting period, compressive strength, the ultrasonic pulse velocity (UPV), and drying shrinkage of paste samples were determined at the samples’ age of up to 91 days. In addition, the microstructures of all paste samples were also characterized by scanning electron microscopy (SEM). It was found that the use of cementless eco-binder significantly increased the setting times, lower compressive strength, drying shrinkage, and UPV values compared to the control OPC sample. The maximum 91-day-old compressive strength gained by the binary binder of slag and CFA (R00C25) was 90% of that of the control specimen. Incorporation of RHA with higher replacement levels up to 45% resulted in a significant decrease in compressive strength up to 50%. Moreover, the SEM analysis revealed that there was a large difference in the microstructures of the control and the cementless eco-binder samples, in which the main hydration products were C-S-H/C-A-S-H gels and ettringite (AFt) due to relatively high amount of SO3 and SiO2 in the CFA and RHA, respectively. Thus, it can be realized that the potential for the use of slag, CFA, and RHA as a sustainable cement-free binder is promising in the construction industry, especially for lower strength or no required early high strength structures. Keywords: cementless eco-binder; circulating fluidized bed combustion; rice husk ash; slag; microstructure; compressive strength; drying shrinkage; setting time; ultrasonic pulse velocity.