Effect of matrix self-healing on the bond-slip behavior of micro steel fibers in ultra-high-performance concrete

Effect of matrix self-healing on the bond-slip behavior of micro steel fibers in ultra-high-performance concrete

Al-Obaidi, S.M.J. (TU Delft Materials and Environment; Politecnico di Milano; University of Al-Qadisiyah)
He, S. (TU Delft Materials and Environment)
Schlangen, E. (TU Delft Materials and Environment)
Ferrara, Liberato (Politecnico di Milano)

2023

This study investigates the bond-slip behavior of micro steel fibers embedded into an Ultra-High-Performance Concrete (UHPC) matrix as affected by the self-healing of the same matrix in different exposure conditions. The UHPC matrix contains a crystalline admixture as a promoter of the autogenous self-healing specially added to enhance the durability in the cracked state. For the aforesaid purpose, some samples were partially pre-damaged with controlled preload (fiber pre-slip at different levels) and subjected to one-month exposure in 3.5% NaCl aqueous solution and in tap water to study the fiber corrosion, if any, and the effects of self-healing; after that, they were subjected to a pull-out test, to be compared with the behavior of analogous non-pre-slipped samples undergoing the same curing history. Moreover, some samples were cured in the chloride solution, intended to simulate a marine environment, to study the effect of marine curing on the pull-out behavior of steel fiber. The steel fiber corrosion and self-healing products attached to the surface of the steel fiber were analyzed via Scanning Electron Microscopy (SEM), and Energy -Dispersive Spectroscopy (EDS). The results indicate that the newly healed particles formed on the highly damaged fiber-matrix interface significantly enhance the friction phase of the bond-slip behavior and result in a significant residual capacity compared to non-pre-slipped specimens. On the other hand, the self-healing effect in specimens subjected to low damage pre-slip contributed more to the chemical adhesion region of the bond-slip behavior. Owning to the dense microstructure of the matrix, curing in 3.5% NaCl aqueous solution was not found to significantly affect the pull-out resistance as compared to the samples cured in tap water.

Bond-slip behavior of steel fibers
Self-healing
Steel fiber corrosion
UHPFRC composites

http://resolver.tudelft.nl/uuid:e7d0aec9-02b2-4148-aa6c-f6575ff15ffd

https://doi.org/10.1617/s11527-023-02250-5

2024-04-11

1359-5997

Materials and Structures, 56 (9)

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

journal article

© 2023 S.M.J. Al-Obaidi, S. He, E. Schlangen, Liberato Ferrara