Date of Award

11-27-2025

Thesis Type

PhD

Document Type

Thesis

Divisions

Faculty of Engineering

Department

Department of Civil Engineering

Institution

Universiti Malaya

Abstract

The growing global demand for sustainable materials has driven extensive research into lightweight insulating materials, such as self-foaming glass ceramics (SFGCs), which align closely with the principles of a circular economy. While the alkali activation of aluminosilicates offers an environmentally friendly alternative to conventional, energy-intensive industrial methods for producing glass-based foams, current approaches often depend on synthetic foaming agents, high-speed agitation, and elevated sintering temperatures. These factors adversely affect slurry rheology, resulting in suboptimal microstructures, reduced mechanical strength, increased production costs, and negative environmental impacts. This study contributes to the advancement of the field by developing eco-friendly SFGCs using soda-lime glass and hazardous secondary aluminium dross (SAD) as self-foaming precursors. The SFGCs were successfully synthesized via alkali activation using sodium hydroxide (NaOH). Key process parameters including alkali concentration, surfactant type, and foaming temperature were systematically investigated. Optimal foaming performance was achieved at 850 ℃ with a 3M NaOH solution and 0.05 wt.% sodium dodecyl sulphate, which significantly enhanced aluminosilicate dissolution and microstructural evolution. Subsequently, the effect of varying SAD content on the properties of the SFGCs was examined using these optimized parameters. Results indicated that the incorporation of SAD and its associated metal oxides promoted solid-solid reactions and partial crystallization, facilitating gas bubble formation. A formulation containing 2.5 wt.% SAD exhibited the best performance, with a high specific strength (14.44 MPa·cm3/g) and low thermal conductivity (0.125 W/m·K), alongside a broad pore size distribution (0.002–180 μm), consisting of both open and closed pores. Toxicity leaching tests yielded values between 90.86 and 141.59 μg/L (SA2.5-S to SA10-S), well below the USEPA regulatory limit of 5000 μg/L, confirming the environmental safety of the synthesized materials. To evaluate the environmental performance of the developed SFGCs, a comparative life cycle assessment (LCA) was conducted in accordance with ISO 14040 and ISO 14044 standards. The study compared two emerging laboratory-scale alkali activation methods against conventional industrial foaming processes. The combined foaming approach presented in this study offers substantial environmental benefits, reducing global warming potential by approximately 50% compared to the gel-casting method. It also achieves around 30% lower emissions and a 23% decrease in fossil resource consumption relative to traditional industrial processes, as confirmed through comprehensive sensitivity analyses. Overall, this research establishes a scalable and sustainable pathway for producing high-performance SFGCs from valorised hazardous waste. The resulting SFGCs demonstrate strong potential for diverse applications, including wastewater treatment, lightweight thermal insulation, and low-energy absorption systems.

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Thesis (PhD) - Faculty of Engineering, Universiti Malaya, 2025.

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