Fracture process zone characterizations of multi-scale fiber reinforced cementitious composites

Abstract

This research investigates the toughening effect of a multi-scale steel fiber reinforcement, consisting of a micro-macro fiber combination, within the fracture process zone (FPZ) of a cementitious composite. The reinforcement schemes investigated include: no fiber, micro-fiber only, macro-fiber only, and multi-scale fiber reinforcement. Fracture energy (Gf) experiments were performed to characterize the energy dissipation in the FPZ. Three different FPZ length (lFPZ) measurement methods were employed using digital image correlation (DIC) post-processing - one established and two novel - to further understand the effects of multi-scale fiber reinforcement on the FPZ. The steel wool micro-fiber increased the Gf of a micro-fiber-only cementitious composite over a non-reinforced composite by approximately 200%. The steel wool also increased the Gf of a multi-scale fiber cementitious composite over a macro-fiber only version by 19–23%. These gains were achieved through a toughening of the FPZ, as indicated by corresponding increases in lFPZ.