1 BEHAVIOR AND PERFORMANCE OF MONOFILAMENT

The use of monofilament macro-synthetic fibres in wet-mix shotcrete applications has grown significantly worldwide since their introduction in the late 90’s. As opposed to the stiffer steel fibres, which have to be used at relatively short lengths (30mm) to reduce line blockage, the more flexible macro-synthetic fibres can typically be used, in well proportioned wet-mix shotcrete mixtures, at lengths ranging from 50 to 100mm, without significantly reducing the pumpability and shootability of the mixture. Other reported benefits of macro-synthetic fibres over steel fibres in wet-mix shotcrete include reduced equipment wear and fibre rebound, and increased shotcrete layer built-up thickness. However, attempts to date to incorporate macro-synthetic fibres in dry-mix shotcrete have failed for numerous technical reasons. The problems encountered range from the inability to uniformly mix the fibres at the dry-batching plant using a standard mixing sequence, to fibres causing conduit blockage of the batching dispensing unit, fibres causing blockage of the dry material exiting from the bulk bags, fibre