Crack formation and tensile stress-crack opening behavior of fiber reinforced cementitious composites (FRCC)

摘要

The formation and further development of cracking in strain hardening cementitiouscompos-ites under tensile loading strongly influences their mechanical behavior. The work presented in this paper de-scribes the crack formation in fiber reinforced cement composites (FRCC). The experimental results are ana-lyzed using a digital image analysis technique to gain detailed insight in the cracking process during the propagation and the opening phases under tensile loading. The data and observations obtained from these tests are used to derive the tensile stress-crack opening behavior of different types of FRCC and to analyze and compare the effect of various composite parameters including fiber reinforcement, cementitious matrix, and interfacial bond properties. In the experimental program, the FRCC specimens are notched and tested in direct tension with the purpose of inducing a single crack during testing. Subsequently, the corresponding crack behavior in terms of stress-crack opening for all specimens is derived, allowing a quantitative evalua-tion of the performance of the different fiber reinforcements. The monitoring of the crack formation with the digital image acquisition allows the identification of the stages of crack development. The comparison of the stage sequences among different tensioned specimens contributes to the qualitative assessment of the bridging effect obtained in each composite system and to the description of the features associated with the singular crack generated during testing.