Fiber orientation distribution in strain hardening cementitious composites (SHCC): Experimental investigation and consideration of processing effect

Tensile performance of strain hardening cementitious composites (SHCC) is determined from uniaxial tensile specimens, in which the fiber orientation can vary with sample size and processing method. However, when interpreting the laboratory-determined tensile behaviors, synthetic fibers in SHCC are usually assumed to be randomly oriented without experimental validation. In this study, an automatic image processing workflow for obtaining accurate fiber orientation distribution over a whole section is proposed. The experimentally obtained fiber orientation distributions in PVA-SHCC tensile samples form a clear peak at around 20 degrees relative to the tensile direction, which is not revealed by any existing model on fiber distribution. A modified fiber orientation analysis considering the sample processing effect (flattening effect) is presented to derive the distribution, with parameters obtained by computational fluid dynamics simulations. The measured or derived orientation distribution can be used to replace random distributions in fiber bridging models to reduce systematic simulation errors.