4.4 Results and Analysis
81
Fig. 4.3 Failure patterns of recovered UHPCC specimens a 95 MPa, b 129 MPa, reprinted from
Ren et al. (2016), copyright 2020, with permission from Elsevier
fibers. For the specimens with relatively lower confining pressure, the shear failure
induced by several minor cracks occurred. With further increasing the confining
pressure, no visible cracks emerged and apparent swelling occurred around the specimens due to the axial contractions. Therefore, adding fibers can improve the failure
mode of UHPCC when the confining pressure is relatively low. While for the high
confining pressure, the fiber enhancing effect becomes marginal. It should be pointed
out that the broken specimen TC1-4 was induced by the careless operations in taking
off the rubber membrane after the test.
4.4.2 Stress–Strain Curve
Behavior of UHPCC specimens subjected to various levels of confining pressure is
shown in Fig. 4.4. It can be seen obviously that the triaxial strength and the ductility
of specimens increase with the rising of confining pressure. In the pre-peak phase, the
slope of the curves also gradually increase. For the confining pressure σ 3 ≤ 60 MPa,
the deviatoric stress–strain curves show softening behavior. As the confining pressure
increases, the behavior of the deviatoric stress–strain curves become more plastic,
and the stress slightly drops after the peak stress.
Based on Figs. 4.4 and 4.5 further illustrates the relationships of volumetric strain
81
Fig. 4.3 Failure patterns of recovered UHPCC specimens a 95 MPa, b 129 MPa, reprinted from
Ren et al. (2016), copyright 2020, with permission from Elsevier
fibers. For the specimens with relatively lower confining pressure, the shear failure
induced by several minor cracks occurred. With further increasing the confining
pressure, no visible cracks emerged and apparent swelling occurred around the specimens due to the axial contractions. Therefore, adding fibers can improve the failure
mode of UHPCC when the confining pressure is relatively low. While for the high
confining pressure, the fiber enhancing effect becomes marginal. It should be pointed
out that the broken specimen TC1-4 was induced by the careless operations in taking
off the rubber membrane after the test.
4.4.2 Stress–Strain Curve
Behavior of UHPCC specimens subjected to various levels of confining pressure is
shown in Fig. 4.4. It can be seen obviously that the triaxial strength and the ductility
of specimens increase with the rising of confining pressure. In the pre-peak phase, the
slope of the curves also gradually increase. For the confining pressure σ 3 ≤ 60 MPa,
the deviatoric stress–strain curves show softening behavior. As the confining pressure
increases, the behavior of the deviatoric stress–strain curves become more plastic,
and the stress slightly drops after the peak stress.
Based on Figs. 4.4 and 4.5 further illustrates the relationships of volumetric strain