Direct assessment of the shear behavior of strain-hardening cement-based composites under quasi-static and impact loading: Influence of shear span and notch depth

Strain-hardening cement-based composites (SHCC) represent a new frontier for improving the resistance of concrete structures against highly dynamic loading regimes, e.g., in the case of impact. A novel testing device was designed to characterize the shear behavior of such pseudo-ductile cementitious composites, whose dynamic response is extremely complex. The newly developed shear testing device was adapted to investigate the performance of fiber-reinforced, cementitious composites under both quasi-static and impact regimes. In the framework of setup validation and standardization, this article focuses on the investigation of the shear behavior of SHCC specimens and spotlights the influence of two main experimental shear parameters: shear span and notch depth. The purpose-specific shear device was integrated into a hydraulic testing machine and a gravity Split-Hopkinson tension bar (SHTB) for quasi-static and impact shear experiments, respectively. Shear spans of 2 mm and 5 mm were introduced by modifying the test setup. Furthermore, the specimens were shaped through sawn U-notches with varying depths of 3 mm, 5 mm, and 7 mm. The shear response of the SHCC specimens was monitored by means of Digital Image Correlation (DIC), which enabled the accurate derivation of strain fields, cracking behavior, and fracture modes on the specimen surface. The results showed that both shear span length and notch depth regulate the shear/tension fracture propagation. With an appropriate shear specimen shape, the desired dominant shear fracture could be obtained.