Effect of carbon nano and microfibers on the mechanical properties and durability of cement pastes

Abstract

Cement is one of the world’s most widely used building materials and as such great lengths have been taken over the years to further improve the mechanical properties and durability of cementitious materials in order to increase reliability and decrease maintenance costs. The mechanical properties of carbon microfibers (CF) have made them attractive candidates for the reinforcement of several matrices including cement. Technological advancements have led to the development of carbon nanofibers (CNF) with even more advantageous mechanical properties due to their smaller size and therefore show tremendous promise as reinforcement in cementitious materials. This research studied the effects of carbon fiber type (CF vs. CNF) and CNF loading on Portland cement pastes and silica fume Portland cement pastes. CNF loading up to 0.5 wt% had no significant effect on the compressive and tensile strength of the pastes. In contrast, 2 wt% CNF loading was found to decrease the compressive strength of the Portland cement paste. Addition of 2 wt% CNF enhanced the water penetration resistance of the cement pastes and improved the durability with respect to decalcification and leaching.