Study on Evaluation Method for PVA Fiber Distribution in Engineered Cementitious Composite

The distribution of fibers in Engineered Cementitious Composite (ECC) is one of the most important factors in terms of the mechanical performance of the composite. However, estimation of fiber distribution in ECC has been a difficult problem because of the lower contrast of organic fiber in the cement material. To overcome this problem, we demonstrated a new evaluation method for the distribution of discontinuous Polyvinylalcohol (PVA) fibers in ECC. By using a fluorescence technique on the ECC, we were able to observe PVA fibers as green to yellow dots in the cross section of the composite. After capturing the fluorescence image with a CCD camera through a microscope, the image was divided into small units of the appropriate pixel size. Then, the degree of distribution was calculated with the deviation from the average number of fibers in one unit. By adjusting the preferable unit size, we found a relationship between the degree of distribution and the ultimate tensile strain of the composite.