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Home arrow Engineering arrow Creep Behaviour in Cracked Sections of Fibre Reinforced Concrete: Proceedings of the International RILEM Workshop FRC-CREEP 2016

Single Fibre Tests

The results of the time-dependent fibre pull-out and fibre creep tests have shown that these phenomena are majorly responsible for the creep of cracked macro-synthetic FRC. Figure 9a, b shows the results of the time-dependent pull-out and fibre creep tests. For the pull-out test, all the fibres pulled out of the specimens at all load level without any fibre rupture. It is also evident from Fig. 9a that the fibre pull-out creep is also dependent on the stress level.

The result of the single fibre creep test (Fig. 9b) shows significant creep of 40 % strain in less than 4 days at a load of 30 % of the fibre’s tensile capacity. Due to

Time-dependent fibre pull-out a and fibre creep b results [8]

Fig. 9 Time-dependent fibre pull-out a and fibre creep b results [8]

Poisson’s effect, this lengthening will result in the fibre’s cross section reducing over time. The transfer of load between the fibre and the matrix when the matrix is cracked is dependent on the frictional bond and mechanical interlock between the fibre and the matrix. When the fibre contracts laterally, both the frictional bond and the mechanical bond will weaken and this will result in partial fibre pull-out. This process will continue until this debonding stabilises or the fibre pulls out completely which in turn leads to failure. Hence, it is evident that the creep of the fibre is a contributor to the crack widening of cracked macro-synthetic FRC under sustained loading which results in partial of full fibre pull-out.

 
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