Toughness of large-scale shotcrete panels loaded in flexure

Quasi-static and mechanical shock testing of reinforced shotcrete surface support

“…In these tests, although some of the fibres were observed to pull through the shotcrete, the primary mode of failure appears to be fibre rupture, as is shown in Figure 14(b). This result contrasts with the quasi-static HEHD tests, using the same mix design, in which the primary failure mechanism was fibre pull-out (Raffaldi et al 2016). Figure 15 shows the deceleration of the loading-mass versus time for the welded-wire and chain-link (reinforcement below neutral axis) panels and a fibre-mix panel resulting from an initial 3.2 m/s drop.…”

“…The photogrammetric analysis techniques used to perform these calculations are described in detail by Benton et al (2015aBenton et al ( , 2015b. Further detail on the HEHD panel testing machine and photogrammetric methods is available in previous publications (Martin et al 2015;Raffaldi et al 2016).…”

“…The combination of both fibres and chain-link mesh was also tested. Construction methodology and 28 day concrete compressive and tensile strengths are provided by Martin et al (2015) and Raffaldi et al (2016). All reinforcement types significantly outperformed the polyurea-lined panels, which provided no increase in peak strength.…”

“…Researchers at SMRD initially responded to this deficiency by designing a full-scale testing device (Martin et al 2015) and beginning a testing program (Raffaldi et al 2016) to assess the mechanical behaviour and energy capacity of shotcrete reinforced with a variety of products used in practice including: fibres, chain-link mesh, welded-wire mesh, spray-on polyurea liners, and combinations of these products.…”

“…This deficiency can be overcome by reinforcing shotcrete with steel mesh to form a composite surface support (Morgan et al 1989;Kirsten 1993;Ortlepp & Stacey 1998) with quasi-static energy capacities as large as 10 kJ/m² (Raffaldi et al 2016). However, the applicability of quasi-static test results to rockburst support design is not universally accepted and quantitative test results concerning the behaviour of reinforced shotcrete subjected to dynamic loading are limited.…”