ABSTRACT
New types of macro-synthetic fibres have been developed in the last few years. Among these is the Barchip Kyodo 48 mm fibre with an embossed surface to maximize bonding to the shotcrete matrix. Postcrack panel performance tests have shown that these fibres make the shotcrete capable of sustaining high energy absorption values. The crack patterns developed in these panel tests seem to depend on fibre dosages: an increase in the number of cracks occurs with increased fibre dosage. This verifies the fibres’ ability to redistribute stress in a cracking FRS membrane. As a result of the demonstrated ability of macro-synthetic fibres to absorb large ampounts of post-crack energy in panel tests, and the improved durability, handling, and cost advantages of these fibres compared to steel fibres, a test length of road tunnel in Norway has been lined with shotcrete reinforced with macro-synthetic fibres.
Panel tests conducted as part of the project showed that requirements with respect to energy absorption class E 700 are fulfilled with dosages of 5 to 6kg/m3 Barchip Kyodo fibres as well as 25 kg/m3 Dramix RC65/35. The requirement with respect to energy absorption class E 1000 is fulfilled with dosages of 7 to 8 kg/m3 Barchip, as well as 35 kg/m3 Dramix. Load-displacement graphs for shotcrete panels reinforced with either type of fibre were almost identical, both at low and high displacements. This shows that both types of fibre are active throughout the whole test period. Long-term tests will be carried out to determine durability after being stored outdoor for a period of 1 year.
