Compressive Strength of Concrete
100% recycled and virgin PP fibre reinforced concrete cylinder’s compressive strength is shown in Fig. 4.9. This shows no significant effect on compressive strength through addition of fibres. This can be contributed to the concrete matrix containing fibres in quantities low enough (4 and 6 kg/m3) to have no effect on the compressive strength (Hasan et al. 2011). However, larger fibre doses (i.e. 1318 kg/m3) can lead to improper distribution resulting in balling of fibres and air pockets which adversely affect the compressive strength of concrete (Ochi et al. 2007). This correlates with the outcomes of many researchers (Choi and Yuan 2005; Ochi et al. 2007; Soroushian et al. 2003; Wang et al. 1994), who have recorded no significant variation to compressive strength of concrete with PP fibre addition. Moreover, recycled fibre and virgin fibre reinforced concrete cylinders had comparable compressive strength results, as shown in Fig. 4.9. It should also be noted
Fig. 4.9 Compressive strength of the PP fibre reinforced concrete cylinders
Fig. 4.10 Failure behaviour of a plain concrete and b fibre reinforced concrete in the compression test that during the compression tests PP fibre reinforced concrete cylinder failure was characterised by numerous minor surface cracks while plain concrete cylinders failed catastrophically, at peak load, with a large single crack, as shown in Fig. 4.10. In other words, the fibre samples displayed a more ductile mode of failure.