Tension and shear behavior of hybrid-fiber pseudo-ductile cementitious composites (PDCC)

Abstract

Through proper material design, Pseudo-Ductile Cementitious Composites (PDCC) can exhibit tensile hardening behavior up to several percent strain, accompanied by the formation of multiple cracks with very small openings. With these properties, PDCC can be employed to make structural components with high deformation capacity and energy absorption as well as good durability through the control of cracks. This paper focuses on the development of PDCC with hybrid PVA and steel fibers. With total fiber volume fraction kept at 2.5%, specimens were prepared with three different fiber combinations for the performance of (i) single-crack tension test on notched specimens, (ii) uniaxial direct tension test on un-notched samples, and (iii) shear test on modified Iosipescu beams. The Digital Image Processing technique is utilized to analysis the crack pattern of PDCC under direct tension. Based on the test results, single-crack tension tests show that the same bridging stress can be obtained in hybrid-fiber composites at a much smaller crack opening, indicating the possibility to reduce crack width under service load, which is beneficial to durability. In terms of the ultimate strength, PDCC without steel fibers behave better in direct tension but worse in shear when compared to hybrid-fiber PDCC. The findings of this work can provide insights on the optimal design of PDCC for structural applications.