This study investigated the effects of various chemical treatments on the pullout behavior of steel fibers in ultra-high-performance concrete (UHPC). Various methods used in previous studies were adopted and reproduced using macro straight steel fibers. The methods included acetone and acid washing, zinc phosphating, nanosilica coating, and ethylenediaminetetraacetic acid (EDTA) electrolyte solution treatment. The surface conditions and roughness of each treated fiber were analyzed using scanning electron microscopy and atomic force microscopy. The fiber pullout test results indicated that the surface roughness increased between 1.5 and 24.9 times, and that a roughened fiber surface leads to an improvement in the average bond strength. Acetone washing was the most effective in improving the pullout resistance of the fiber due to its cleansing effect. Acid washing resulted in a slip-hardening behavior, which improved the pullout energy significantly. The zinc phosphating treatment exhibited the lowest average bond strength increase rate. Nanosilica coating was found to considerably improve adhesion; however, it caused fractures as inclined. EDTA electrolyte solution treatment significantly improved the average bond strength in proportion to the surface roughness. By considering the energy absorption capacity, the optimum treatment time of EDTA electrolyte solution was proposed to be less than 6 h.
|Journal||Construction and Building Materials|
|Publication status||Published - 2021 Aug 2|
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2021R1A2C4001503 ).
© 2021 Elsevier Ltd
All Science Journal Classification (ASJC) codes
- Civil and Structural Engineering
- Building and Construction
- Materials Science(all)