Hybrid effects of carbon fibers on mechanical properties of Portland cement mortar

This study investigates the effects of carbon fiber with different sizes on the mechanical properties of Portland cement mortar through laboratory testing. To achieve the goal, Portland cement mortars reinforced with hybrid-sized carbon fibers were tested for potential improvement in mechanical properties. The sizes of carbon fibers used in the study include micro-length (in micrometers), macro-length (in millimeters), and a combination of both. The properties of the mortar mixes were evaluated based on the results from indirect tension test, semicircular notch fracture test, mortar cube compression test, as well as unit weight and specific gravity tests. The laboratory test results show that the hybrid fiber mix exhibited superior tensile performance to the microfiber mix. Although all three types of fiber reinforcement improved the pre-peak load energy absorbing capacity of the mortar, only hybrid fiber blend improved the mortar's fracture resistance. The test results also showed that the hybrid fiber mix had lower air-to-cement mortar ratio than the macrofiber mix. (C) 2014 Elsevier Ltd. All rights reserved.