Mechanical properties and pore structure of carbon fiber reinforced cementitious composites

Abstract

The development of high strength cementitious composites by the use of silica fume, together with the development of high performance synthetic fibers, open the way to the production of new cementitious composites of superior performance. The purpose of the present research was to study the performance of dense cement-silica fume matrices reinforced with high performance PAN type carbon fibers, in order to determine the influence of matrix composition on the characteristics of the composite. Special attention was given to the short term mechanical properties (flexural strength and toughness), and the internal pore structure. Composites with water to binder ratio of 0.40 and silica-fume (SF) content of 0% to 28% were tested at the ages of 1,3 and 28 days. Test results indicate that at the early age of one day, the mechanical properties increase with the increase in the SF contents, while the internal structure remains quite the same. At 28 days the mechanical properties increase with the addition of SF up to a maximum at 7%, and decrease with higher content of SF. The internal pore structure, however, becomes finer as the SF content increases.