Use of carbon fibres for reinforcement of thin geopolymer cement sections

An alkali-activated aluminosilicate geopolymer cement was reinforced with polyether ether ketone-wound carbon fibre layers to improve the mechanical properties of the cement in flexion. Such a material, which is heat resistant and has a low coefficient of thermal expansion, will be of use in the development of out-of-autoclave processing routes for large area composite components. The mechanical and physicochemical properties of both the neat and reinforced cement were examined using Charpy impact and three-point bend testing and Fourier transform infrared spectroscopy. A fivefold improvement in flexural strength was observed for the fibre-reinforced geopolymer samples, while a three-fold improvement was observed in the impact strength. The coefficient of thermal expansion of the composite was determined using dilatometry. A number of different curing cycles were also examined using differential scanning calorimetry. The fibre reinforcement led to flexural strength improvement of up to 5 times as well as increasing the strain to failure.