MECHANICAL-PROPERTIES AND MICROSTRUCTURE OF HIGH-ALUMINA CEMENT-BASED BINDERS 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 binders reinforced with natural wollastonite micro-fibres are reported. Two composite systems were studied. One was the HAC -wollastonite system the other the HAC-silica fume-wollastonite system. In both systems, wollastonite micro-fibres varying from 2% to 15% by volume were blended with the base cement matrix. The composite specimens were evaluated by flexural testing and microstructural characterization including mercury intrusion porosimetry, helium gas pycnometry, and isopropyl alcohol saturation measurements. Flexural strength of both composite systems increased 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, total porosity and pore size distribution between composite systems is discussed.