Mechanical behavior of strain-hardening cement-based composites (SHCC) subjected to torsional loading and to combined torsional and axial loading

Highlights: • Axial confinement substantially increases the torsional capacity of strain-hardening cement-based composites (SHCC); • SHCC's torsional performance reduces considerably in combination with axial tension; • The fiber material and geometric properties define both the axial and torsional behavior of SHCC; • 3D optical measurements are essential in quantifying the crack-flank displacement histories in torsioned SHCC specimens. Strain-hardening cement-based composites (SHCC) are a novel class of fiber-reinforced concretes which exhibit high tensile strain capacity prior to failure localization. Although the tensile behavior of SHCC has been a matter of study in numerous research works, the behavior of these composites under other loading modes has scarcely been investigated. The article at hand addresses the mechanical behavior of two types of normal-strength SHCC subject to uniaxial tension, torsion, and combinations of torsional and axial loading. The SHCC under investigation were made with polyvinyl-alcohol (PVA) and ultra-high molecular weight polyethylene (UHMWPE) fibers, respectively. Digital Image Correlation (DIC) was applied to evaluate the multiple cracking process and crack opening modes in conjunction with the axial and torsional loading histories. The study demonstrates the suitability of torsion experiments to assess the multi-axial and shear performance of SHCC, highlights the relation between multiple cracking and transfer capacity for shear forces, and emphasizes the importance of the type of reinforcing fibers on the shear strength and ductility of such composites.