Title: On the Rate Sensitive Fracture Behavior of Strain-Hardening Cement-Based Composites (SHCC) Depending on Fiber Type and Matrix Composition
Author(s): Iurie Curosu, Viktor Mechtcherine, Daniele Forni, Simone Hempel and Ezio Cadoni
Publication: Symposium Paper
Appears on pages(s): 1-20
Keywords: SHCC, fiber reinforcement, strain-hardening, PVA, UHMWPE, impact, split Hopkinson tension bar, fracture energy
Synopsis: Strain-hardening cement-based composites (SHCC) represent a special type of fiber reinforced concretes,
whose post-elastic tensile behavior is characterized by the formation of multiple, fine cracks under increasing loading
up to failure localization. The high inelastic deformability in the strain-hardening phase together with the high damage
tolerance and energy dissipation capacity make SHCC promising for applications involving dynamic loading
scenarios, such as earthquake, impact or blast.
However, the main constitutive phases of SHCC, i.e. matrix, fibers and interphase between them, are highly rate
sensitive. Depending on the SHCC composition, the increase in loading rates can negatively alter the balanced
micromechanical interactions, leading to a pronounced reduction in strain capacity. Thus, there is need for a detailed
investigation of the strain rate sensitivity of SHCC at different levels of observation for enabling a targeted material
design with respect to high loading rates.
The crack opening behavior is an essential material parameter for SHCC, since it defines to a large extent the tensile
properties of the composite. In the paper at hand, the rate effects on the crack opening and fracture behavior of SHCC
are analyzed based on quasi-static and impact tensile tests on notched specimens made of three different types of
SHCC. Two SHCC consisted of a normal-strength cementitious matrix and were reinforced with polyvinyl-alcohol
(PVA) and ultra-high molecular weight polyethylene (UHMWPE) fibers, respectively. The third type consisted of a
high-strength cementitious matrix and UHMWPE fibers. The dynamic tests were performed in a split Hopkinson
tension bar and enabled an accurate description of the crack opening behavior in terms of force-displacement
relationships at displacement rates of up to 6 m/s (19.7 ft/s).