Single Fibre Pull-Out Tests
The single fibre pull-out tests were done in a Zwick Z250 universal testing machine. A 500 kg HBM load cell was used together with two 50 mm HBM LVDTs. The setup can be seen in Fig. 1. The average displacement value of the two LVDTs were used for the pull-out displacement. The specimens were cast by inserting a
Fig. 1 The single fibre pull-out test setup (a), and (b), the specimen dimensions single fibre at a depth of 15 mm in a 100 x 100 x 40 mm3 mould. The sample was vibrated before the fibre insertion and then vibrated lightly again after the fibre was carefully inserted. The mould can be seen in Fig. 1b. The fibres were gripped by drilling a small hole in a bolt and tapped a hole from the side to facilitate a gripping screw. The hooked end of the fibre was cut off before fixing the fibre to the test setup.
Single Fibre Pull-Out Creep Test Setup
The single fibre pull-out creep test setup is different to the setup shown in Sect. 2.1 in order to facilitate a number of samples to be tested simultaneously and not occupying a test machine for the duration of the tests. A fibre was inserted in 100 x 100 x 100 mm3 moulds filled with concrete and the sample was tested upside down in order to facilitate weights to be used to apply the creep load. A threaded rod was fixed to a drilled hole in the bottom of the sample using an appropriate glue and this was in turned fixed upside down to a beam from which all the samples were hanged. The fibre was gripped in a similar fashion as shown in Sect. 2.1 and weights were then applied to the fibre. The setup is shown in Fig. 2. The pull-out displacement was measured by using scaled microscope photos taken periodically. A scaled object was placed next to the fibre for each photo to ensure the calibration is consistently accurate.
Fig. 2 The single fibre pull-out creep test setup