Valorization of spent fluorescent lamp waste glass powder as an activator for eco-efficient binder materials

Spent fluorescent lamp waste glass is considered hazardous and requires an appropriate management and recycling route. Due to its highly alkali-siliceous nature, the feasibility of using the powdered form of the fluorescent lamp waste glass (FGP) to synthesize an activator for activating the GGBS/FA blend was studied. Additionally, the solubility and reactivity of FGP were compared with waste beverage bottle glass powder (BGP). Results showed that FGP had a higher solubility and reactivity than BGP due to the presence of the higher network modifiers. A significant enhancement in solubility (about 19 %), total heat release (57 - 62 %), and compressive strength (85 - 89 %) was observed in FGP-based mixtures, implying its suitability for activator design. The mechanical and microstructural properties of the alkali-activated pastes (AAP) prepared with the FGP activators were similar to those prepared with the commercially sourced reference activator. Before acti-vator preparation, washing FGP with water or acid enhanced the availability of soluble silicates. The activators prepared with those washed FGP accelerated the alkali-activation process and helped achieve better strengths for the corresponding AAP. Their 28-day compressive strength values were in the range of 36 - 40 MPa and com-parable to the control (FGP-C). In addition, the microstructural analysis showed that the reaction products in these mixtures were of C-(N)-A-S-H gels type with high Si/Al and low Ca/Si ratios. Thus, a recycling route for spent fluorescent lamp waste glass was preliminary demonstrated in this study.