Quantitative evaluation of carbon fiber dispersion in cement based composites

To date, carbon fiber cement based composites are gaining popularity in the field of civil engineering. Dispersion degree of carbon fibers (CFs) in the composites plays a significant role in the property improvements. However, it is extremely challengeable to evaluate quantitatively the dispersion of CFs because of their random distribution and low contrast with cement paste. In this paper, X-ray computed tomography (CT) scanner was adopted to capture the images; Optical Microscope (OP) was used to determine the thresholds of different components and mathematical calculation was conducted to compare the degree of fiber dispersion. The dispersion coefficient was introduced to evaluate quantitatively dispersion of the CFs. The higher value of dispersion coefficient, the more uniform distribution the CFs. The value range of dispersion coefficient is concentrated from 84% to 94%. There is no rule for changes of dispersion coefficient with the changes of scanned slices. Meanwhile, variation coefficient was calculated as an index to effectively compare the fiber dispersion for the different scanned slice with the same dispersion coefficient. In addition, the lower variation coefficient of fiber dispersion, the more uniform distribution the CFs.