Reducing the environmental impact from tunnel construction put focus on finding alternative designs for rock support based on fibre reinforced shotcrete (sprayed concrete). Different types and materials for fibres for use in shotcrete are developed and new methods for control of the load-bearing capacity and new techniques for material investigation in laboratory environments are tested. In an ongoing project the behaviours under flexural loading for shotcrete with some fibres of typical geometries and materials are compared through testing of Round Determinate Panels. For the tested dosages of fibres, the highest energy absorption capacity was for steel fibres, with macro synthetic and basalt fibres showing similar but lower results. The efficiency of fibres depends on the numbers crossings a crack and how these are oriented vs tensile stresses. Computed tomography (CT) X-ray scanning is now used in the laboratory for visualization of the interior of shotcrete samples. Examples from examination of steel fibre orientation in test cores are given.
Part of proceedings ISBN 978-294064315-8
QC 20221025