Designing a New Generation of High-Performance Building Materials: Plasma Functionalisation of Silica Aerogel Particles

The increasing demand for energy-efficient and sustainable building materials has driven research into advanced thermal insulation solutions. Silica aerogels, renowned for their ultra-low density and exceptional thermal insulating properties, present a promising avenue for lightweight cementitious composites. However, their practical application is hindered by poor compatibility with cement matrices, primarily due to their hydrophobic surface chemistry, which leads to weak interfacial bonding and compromised mechanical performance. Addressing this challenge, the present thesis explores the functionalisation of silica aerogel particles using atmospheric pressure plasma and flame treatments to tailor their surface properties and enhance their integration into cement-based composites.The experimental approach involved subjecting commercial silica aerogel particles to controlled plasma and flame treatments, aiming to increase surface polarity and wettability while preserving the core structure of the aerogel. The effectiveness of these treatments was evaluated using the Wilhelmy plate method to measure wettability. Treated and untreated aerogels were then incorporated into cementitious matrices, and the resulting composites were systematically characterised through mechanical testing (compressive and flexural strength), thermal conductivity measurements, water absorption tests, and X-ray computed tomography (XCT) imaging to assess particle size and segregation. Results indicate that flame treatment, in particular, yields a significant improvement in the wettability of aerogel particles, leading to enhanced interfacial adhesion with the cement matrix. However, despite the enhanced surface wetting, the resulting compressive and flexural strength values of the composites remained within the margin of experimental error across all samples. XCT analysis further revealed evidence of particle segregation in both treated and untreated samples, which likely contributed to the variability and lack of statistically significant differences in mechanical performance. Water absorption tests indicate comparable moisture resistance across all samples, ensuring durability against moisture ingress. In conclusion, the study demonstrates that surface functionalisation is a promising strategy to overcome the interfacial challenges associated with silica aerogel-cement composites, enabling the development of lightweight building materials that combine thermal insulation with improved mechanical integrity.