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Transforming waste glass to sodium silicate; an activator for cement-free binders and concrete products

  • Daniel William McCloskey

Student thesis: Doctoral ThesisDoctor of Philosophy

Abstract

The world is in a state of climate emergency. Increasing consumption of natural resources and increasing release of carbon emissions are resulting in clear and present dangers to the planet due to global warming. As the years continue to roll by, the severity of natural disasters as a result of global warming increase. Flash flooding in Spain turned streets into rivers and killed 216 people in October 2024. While on the 21st of July 2024 the world reached its highest global temperature ever recorded. The planet is in uncharted territory and without action on carbon emissions, who knows what the future holds?

Despite the clear and current dangers of climate change, the production of Portland cement (PC), which is responsible for 5-7% of global anthropogenic carbon dioxide emissions, continues to grow reaching over 4 billion tonnes annually, Alkali-Activated Materials (AAMs) are emerging as a promising alterative to PC because they have the potential to consume considerable amounts of waste materials and have been reported to reduce carbon emissions by up to 80% compared with PC binders.

However, the use of AAMs is not a quick fix for Portland cement consumption because these materials rely heavily on chemical activators, such as sodium silicate, these activators are not user, nor eco-friendly. For example, the production of sodium silicate often involves direct fusion which requires the melting of soda ash (Na2CO3) and a source of silica (typically quartz sand SiO2) at temperatures over 1100°C.

Therefore, this thesis has investigated the use of waste glass, destined for landfill, as a silica source for the synthesis of a glass-derived sodium silicate activator. This activator was successfully utilised for AAMs within the construction industry. But was also used for the synthesis of zeolite LTA for the chemical industry
Date of AwardJul 2025
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsRe-Gen Waste Ltd
SupervisorMarios Soutsos (Supervisor) & Gosia Swadzba-Kwasny (Supervisor)

Keywords

  • Alkali activated materials
  • Geopolymer
  • Sodium silicate
  • Glass recycling
  • zeolites

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