Development of an eco-friendly composite material for engineering applications
Aly, Marwa (2012) Development of an eco-friendly composite material for engineering applications. PhD thesis, Dublin City University.
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In response to increases in worldwide environmental awareness, there is increasing and encouraging scientific research being done on the development of eco-friendly and more sustainable construction materials. The use of recycled materials and agriculture waste in construction is among the most attractive options because of the increasing need of the construction industry for these materials, their relatively low quality requirements and the industry’s use of widespread construction sites.
The primary objective of this thesis is to assess the performance of flax fibre/waste glass cement composites. Flax fibres are used to reinforce two systems. The first system contains Ordinary Portland Cement (OPC) only as a binder while in the second system a part of OPC is replaced by finely ground waste glass powder. The fibre parameters were selected by applying a Central Composite Design to plan the experiments, develop mathematical models and optimise the fibre parameters. In order to improve the durability and long term performance of these composites, nano clay particles and colloidal nano silica was added in the production of both systems. In order to remove the surface impurities from the fibre surface, to enhance the adhesion between the matrix and the fibres and to improve long term stability of the composites, alkali treatment of the fibres was carried out in the production of both systems. Alkali treatment conditions were selected by applying a Box-Behnken method to design the experiments, develop mathematical models and optimise the treatment conditions.
Several fibre and composite characterisation techniques were utilized in this research. The characterisation was designed to obtain information on surface morphology, fibre crystallinity, mineralogical composition, thermal stability and the mechanical properties of alkali treated flax fibre and its composites. Hence, the following techniques, X-ray diffraction (XRD), thermogravimetry (TGA/TDA), scanning electron microscopy (SEM), tensile, flexure, toughness, fracture energy, impact and compressive properties testing were employed to analyse the results.
The results obtained in this study provide ample evidence that waste glass powder (up to 20% by cement weight) and nano-silica (3% by cement weight) or nano-clay (2.5% by cement weight) can be used together in concrete without any adverse impact. The presence of nanoparticles improves the mechanical and physical properties of waste glass cement systems, enabling the development of high performance cement composites. Moreover, the use of nanoparticles and waste glass powder reduces the CO2 footprint of the cement composites which are produced and is also economically attractive. In brief, the proposed new composite offers superior performance, lower costs and provides better ecological and environmental benefits.
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