A novel method for the determination of polymeric micro-fiber distribution of cementitious composites exhibiting multiple cracking behavior under tensile loading

• A methodology is proposed to determine cross-sectional micro-fiber distribution.
• Fiber distribution coefficients and fiber density maps were determined.
• The validity of method is checked by comparing two distinctive HTPP-ECCs.
• Relatively low matrix viscosity is beneficial for homogeneous fiber distribution.

A methodology is proposed to measure the micro-fiber distribution of high tenacity polypropylene fiber reinforced engineered cementitious composites (HTPP-ECC). For this purpose, scanning electron microscope (SEM) images of failure section were captured at backscattered electron mode (BEC) and analyzed via a consecutive set of image processing algorithms. Fiber distribution coefficients and fiber density maps of each section were determined. The validity of fiber distribution parameters is checked by comparing the multiple cracking potential of two distinctive HTPP-ECCs from the view point of tensile ductility (M24: 3.1%, M37: 0.8%) and matrix rheology (modified Marsh cone flow time; M24: 23 s, M37: 40 s). Results showed that a better fiber distribution at failure section and relatively porous matrix structure improved the multiple cracking potential of composites. The proposed methodology is capable of detecting the fiber distribution variation at micro-scale. Relatively high matrix viscosity was found responsible for the undesirable polymeric micro-fiber distribution of HTPP-ECCs.