MECHANICAL-PROPERTIES AND MICROSTRUCTURE OF HIGH-ALUMINA CEMENT-BASEDBINDERS REINFORCED WITH NATURAL WOLLASTONITE MICRO-FIBERS

Results of an investigation to determine the dependence of mechanical properties on microstructure of high alumina cement (HAC)-based binder s reinforced with natural wollastonite micro-fibres are reported. Two composite systems were studied. One was the HAC -wollastonite system t he other the HAC-silica fume-wollastonite system. In both systems, wol lastonite micro-fibres varying from 2% to 15% by volume were blended w ith the base cement matrix. The composite specimens were evaluated by flexural testing and microstructural characterization including mercur y intrusion porosimetry, helium gas pycnometry, and isopropyl alcohol saturation measurements. Flexural strength of both composite systems i ncreased linearly with concentration of wollastonite micro-fibres. The replacement of HAC with silica fume resulted in a small reduction of the flexural strength. Variation in flexural toughness, ductility, tot al porosity and pore size distribution between composite systems is di scussed.