Predicting pull-out behaviour based on the bond mechanism of arch-type steel fibre in cementitious composite

In this study, we investigated the bond mechanism associated with the pull-out behaviour of arch-type steel fibre in cementitious composite. Prediction model development and bond mechanism analysis were conducted in parallel on hooked-end-type steel fibre having the same tensile strength. Pull-out tests were performed using the single fibre-single-sided method, according to JCI SF-8. The bond mechanism analysis of arch-type steel fibre, from the pull-out test results using a transparent epoxy matrix, confirmed that pull-out resistance was maintained, without a drastic decrease in the pull-out load under plastic bending or frictional forces; these forces acted simultaneously throughout all pull-out stages until completion. Based on our results, the pull-out behaviour of arch-type steel fibre was classified into three pull-out stages: debonding and pull-out initiation, achievement of maximum pull-out load while passing through the bend section, and the final pull-out stage as the fibre passed through the arch. The proposed model for the pull-out behaviour of arch-type steel fibre was verified by a pull-out test using a cement matrix. The maximum pull-out resistance strength and interfacial toughness differed by 2.0% and 17.0%, respectively, from values given by the prediction model, and coincided with three-stage pull-out behaviour.