(Received 9 August 2015; accepted 10 February 2016)
Published Online: 2016
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Molded gypsum has been commonly used as a replica rock in rock-mechanics research, whereas its brittleness is higher than that of many natural rocks. To better understand the mechanical behavior of such a highly brittle material under dynamic loadings, its dependence of the strength on the strain rate is investigated in the present study. A uniaxial loading rig and a split Hopkinson pressure bar (SHPB) setup are used to test the quasi-static and the dynamic compressive and Brazilian tensile strength of the molded-gypsum specimens, respectively. The test results reveal that both the compressive and the tensile strengths increase with the strain rate similar to other brittle materials. The compressive and the tensile dynamic increase factors (CDIF and TDIF, respectively) are obtained to evaluate the extent of strength increase with the strain rate. The rate of increase of the TDIF versus the strain rate is higher than that of the CDIF under dynamic loadings, which indicates that the tensile strength of the molded gypsum is more sensitive to the strain rate than the compressive strength. Moreover, the strain rate is also found to influence the crack-initiation and propagation pattern, which, consequently, affects the fragmentation style of specimens.
School of Earth Sciences and Engineering, Nanjing Univ., Nanjing,
Wong, L. N. Y.
School of Civil and Environmental Engineering, Nanyang Technological Univ.,
Stock #: GTJ20150174