Surface refinement of steel fiber using nanosilica and silver and its effect on static and dynamic pullout resistance of reactive powder concrete

• Published in: Journal of Building Engineering Vol. 51; p. 104269
• Main Authors: Lee, Seung Kyun, Oh, Taekgeun, Chun, Booki, Chu, S.H., Sukontasukkul, Piti, Yoo, Doo-Yeol
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2022
• Subjects: Bond behavior; Rate sensitivity; Reactive powder concrete; Silver and nanosilica coating; Straight steel fiber; Silver and nanosilica coating; Bond behavior; Rate sensitivity; Reactive powder concrete; Straight steel fiber
• ISSN: 2352-7102; 2352-7102
• DOI: 10.1016/j.jobe.2022.104269

This study investigated the effects of steel fibers, surface-reformed by silver and nanosilica coatings, on the static and dynamic pullout behaviors of reactive powder concrete (RPC). To consider the fiber orientation effect, two different inclination angles of 0° and 45° were adopted. The static bond strength of straight steel fiber in RPC significantly increased because of the nanosilica coating but was marginally affected by the silver coating. More than twice the bond strength and pullout energy were achieved by the nanosilica coating compared to the pristine steel fiber. The loading rate sensitivity on the pullout resistance of straight steel fibers from RPC was found regardless of the surface refinement. However, under inclined conditions, the pullout resistances of the silvered and nanosilica-coated steel fibers in RPC were almost insensitive to the loading rate or were even reduced at impact loads. Thus, although the nanosilica-coated steel fiber led to the best pullout resistance from RPC under impact loads, the deposited silver and nanosilica particles negatively affected the rate sensitivity of the pullout resistance of RPC. When the fibers were coated with nanosilica and inclined or impact loads were applied, more scratches and matrix debris were found on the surface of the pulled-out steel fibers, verifying the enhancement of interfacial frictional resistance at the fiber-matrix interface. •More than twice the bond strength and pullout energy of steel fiber are achieved by nanosilica coating.•Bond properties of steel fiber in RPC are marginally influenced by silver coating.•Pullout resistance of straight steel fiber from RPC is obviously rate sensitive.•Nanosilica-coated steel fiber provides the best pullout resistance from RPC under impact loads.•Silver and nanosilica particles on the fiber surface negatively affect the rate sensitivity of bond strength at inclined condition.