Quasi-static and dynamic compressive behavior of ultra-high toughness cementitious composites in dry and wet conditions

This paper investigated the quasi-static and dynamic compressive behavior of ultra high toughness cementitious composites (UHTCC) in dry and wet conditions. The presence of water decreased the quasi-static compressive strength and peak strain of UHTCC, whereas that led to the increase in the elasticity modulus and Poisson's ratio. Under dynamic loading, the reduction of compressive strength and the strain rate sensitivity in terms of strength in UHTCC were observed after water immersion, which was different to those in normal concrete. The underlying mechanism for such phenomenon may attribute to the bridging effect of polyvinyl alcohol (PVA) fibers in the matrix. In order to verify this assumption, the specimens reinforced with different volume fractions (0%, 0.75%, 1.5%, 2.0%) of PVA fiber were tested in this study. Test results showed that, in the case of the specimens without fiber, wet specimens exhibited higher dynamic compressive strength compared with dry specimens, which was consistent with the previous results for normal concrete. Moreover, the influence effect of free water on the strain rate sensitivity in terms of strength of composites was relative to the fiber content. (C) 2019 Elsevier Ltd. All rights reserved.