THE FLEXURAL TOUGHNESS AND DUCTILITY OF PORTLAND CEMENT-BASED BINDERSREINFORCED WITH WOLLASTONITE MICRO-FIBERS

An analysis of the flexural toughness and ductility of Portland cement -based binders reinforced with natural wollastonite micro-fibres is re ported. The flexural toughness was calculated as the sum of finite are a increments under the entire load-deflection curve and the ductility was determined from the deflection in the post-peak region. Load-defle ction curves were created with numerical data obtained in flexural tes ts employing the computer controlled MT'S system. Five series of speci mens were investigated. A series of specimens made with cement and ble nded with different amounts of silica fume served as reference systems . The other four series of specimens contained seven different concent rations of wollastonite micro-fibres, each series having a different a mount of silica fume. Results showed that the flexural toughness of th e cement-silica fume system decreased non-linearly as the amount of si lica fume in the mixture increased. The flexural toughness of the ceme nt-wollastonite composite system and the cement-silica fume-wollastoni te composite system was observed to increase almost linearly as the co ncentration of the wollastonite micro-fibres in the composite matrices increased. The increase of the flexural toughness with increasing con centration of wollastonite micro-fibres in the composite mixtures was influenced by the amount of silica fume. The ductility of the composit e matrices increased nonlinearly with increase in concentration of wol lastonite micro-fibres in the composite mixtures. The amount of silica fume in the composite matrix had no significant role in modification of ductility in the composite system. Differences in observed properti es are discussed.