The appearance of the fracture surfaces also remained largely unchanged. At higher temperatures, crystallisation reactions within the fibres and the Na-geopolymer matrix, respectively, could be observed along with an increasing embrittlement of the composite.
Softening of the fibres and the development of several distinct reaction zones within the fibres was clearly evident after heating to 800 °C and 1000 °C. The formation of an iron-rich outer reaction zone within the fibre was observed above 800 °C.
The interaction between fibre and matrix resulted in the formation of a crystalline albite phase after heating to 1000 °C. It is suggested that basalt fibres have great potential as reinforcements for the development of cost-efficient geopolymer-matrix composites and may be used for applications up to 600 °C.
M.Welter, K.J.D. MacKenzie
MacDiarmid Institute of Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, New Zealand;
German Aerospace Center, Institute of Materials Research, Cologne, Germany.