MICROMECHANICAL MODELING OF TENSILE STRENGTH OF SHORT RANDOM CARBON FIBER REINFORCED CONCRETE

Abstract

The accurate prediction on the response of the composite material is difficult to achieve due to
the complexity of its mechanical properties. However, such complexity can be understood well using the
micromechanical analysis. One of the most important goals of micromechanical analysis is to predict the failure
and strength of the composite material on the basis of the geometries and properties of the matrix and the fibers.
This study aims to develop a simplified micromechanical model that predicts the direct tensile strength of a
randomly oriented short Carbon Fiber Reinforced Concrete (CFRC) using the modified rule of mixtures based
on the assumptions that CFRC will fail by fiber failure mode and with the perfect interfacial bond between the
matrix and the fibers. PAN-based High Tensile short carbon fibers distributed randomly in 3D with low fiber
volume fractions (Vf) of 0.10%, 0.15%, 0.20%, 0.25% and 0.30% were used in this study. Fiber lengths (Lf) of
sizes 19mm, 30mm, and 38mm were used. The designed compressive strength considered for each fiber volume
fraction and fiber length was 21MPa, 28MPa, and 35MPa. There were three samples of specimens considered
for each case. Each case was tested for its cylindrical compressive strength and its direct tensile strength. Test
results showed that the tensile strength of CFRC was optimum at Vf = 0.10% and Lf = 38mm. Finally, good
agreement has been observed between the experimental tensile strength and predicted tensile strength using
the micromechanical model.