In the work at hand the influence of the mechanical properties as well as the fiber shape by means of polypropylene (PP) fibers, and the influence of the surface modification of alkali resistant (AR) glass fibers on the failure behavior…
In the work at hand the influence of the mechanical properties as well as the fiber shape by means of polypropylene (PP) fibers, and the influence of the surface modification of alkali resistant (AR) glass fibers on the failure behavior of cementitious single fiber model composites were investigated. The specific fibers were produced without sizing on lab spinning equipment and the surface modification of the AR glass fibers was done via dip coating afterwards. The fibers were embedded into a high strength matrix and tested under dynamic and quasi-static loading with the single fiber pull-out (SFPO) test. Additionally, single fiber tensile tests, contact angle measurements and scanning electron microscopy before and after the pull-out were performed to clear up the failure mechanisms. Increased mechanical properties as well as the change of the cross sectional shape of PP fibers from circular to trilobal, lead to changes of the force level and shape of the measured force displacement curves. In case of the surface modified AR glass fibers the shape and force level depends on the chemical composition and mechanical properties of the applied polyurethane based sizings. The aimed modification of the interphase properties due to crosslinking in the sizing resulted in a changed failure behavior. These findings are the basis for further investigations aiming at tailored sizings to improve the energy absorption under dynamic loading.