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1 Static Mechanical Properties of UHPCC
Fig. 1.17 Representative four-point flexural load–deflection curves of UHPCC with a microstraight fiber b hooked fiber, Ren et al. (2018), copyright 2020, with permission from Elsevier
of four-point flexural load–deflection curves turns to be deflection hardening. While
for the UHPCC with hooked steel fiber, the behavior of deflection hardening occurs
when the steel fiber content is larger than 0.5%. The crack pattern of UHPCC specimens in the four-point flexural test is shown in Fig. 1.18, which indicates that only
one major crack occurs, and the distributed cracking behavior is not emerged.
As shown in Fig. 1.16, several parameters are used to describe the flexural behavior
of UHPCC. The first cracking point of UHPCC is defined as the Limit of proportionality (LOP) in ASTM C1018-97 (1998), and the point where deflection softening
behavior starts to occur after the point LOP is defined as Modulus of rupture (MOR).
The definitions of LOP and MOR are introduced by Kim et al. (2008) in detail. P LOP ,
δ LOP and P MOR , δ MOR are the loads and the corresponding deflections at LOP and
MOR, respectively. Besides, the other two points L/600 and L/150 are also adopted
Fig. 1.18 Four-point flexural crack pattern of UHPCC specimens with a no mixing fiber b microstraight fiber c hooked fiber, Ren et al. (2018), copyright 2020, with permission from Elsevier