The corrosion behaviors of partially and fully debonded steel fibers embedded in ultra-high-performance concrete (UHPC) and their impact on the pullout behavior were investigated. For this purpose, pre-loaded dog-bone samples were immersed in a 3.5% standard sodium chloride (NaCl) solution for 4, 10, and 20 weeks and then pull-out tested. The degree of corrosion on the fiber surface was determined by energy-dispersive X-ray spectroscopy. The test results indicated that the bond strength and pullout energy are improved by 54% and 90% maximally due to surface corrosion up to an immersion duration of 20 weeks. The effect of surface corrosion on the pullout properties was insignificantly influenced by the fiber pullout state (partially or fully debonded) up to 10 weeks, but the fully debonded fiber was prematurely ruptured at the longest duration of 20 weeks. The corrosion resistance of steel fiber in UHPC was earlier deteriorated, given the full debonding state (or the larger slip). The chemically debonded region was evidently corroded due to ferric oxide formation even after the shortest immersion duration of 4 weeks, whereas the bonded region with highly densified microstructures was insignificantly corroded. By surface corrosion, the pullout energy of the steel fiber in UHPC increased more significantly as compared with the average bond strength, owing to the twice or more frictional shear stress acting at the fiber–matrix interface.

研究了嵌入超高性能混凝土 (UHPC) 的部分和完全脱粘钢纤维的腐蚀行为及其对拔出行为的影响。为此，将预加载的狗骨样品浸入 3.5% 标准氯化钠 (NaCl) 溶液中 4、10 和 20 周，然后进行拉出测试。纤维表面的腐蚀程度通过能量色散 X 射线光谱法测定。测试结果表明，由于表面腐蚀长达 20 周，粘合强度和拉拔能最大提高了 54% 和 90%。长达 10 周的纤维拔出状态（部分或完全脱粘）对表面腐蚀对拔出性能的影响微不足道，但完全脱粘的纤维在最长 20 周的持续时间内过早破裂。鉴于完全脱粘状态（或较大的滑移），UHPC 中钢纤维的耐腐蚀性较早恶化。即使在最短的 4 周浸泡时间后，由于氧化铁的形成，化学脱粘区域明显被腐蚀，而具有高度致密微结构的结合区域则没有明显腐蚀。由于表面腐蚀，UHPC 中钢纤维的拉拔能与平均结合强度相比增加更显着，这是由于作用在纤维-基体界面上的两倍或更多的摩擦剪应力。即使在最短的 4 周浸泡时间后，由于氧化铁的形成，化学脱粘区域明显被腐蚀，而具有高度致密微结构的结合区域则没有明显腐蚀。由于表面腐蚀，UHPC 中钢纤维的拉拔能与平均结合强度相比增加更显着，这是由于作用在纤维-基体界面上的两倍或更多的摩擦剪应力。即使在最短的 4 周浸泡时间后，由于氧化铁的形成，化学脱粘区域明显被腐蚀，而具有高度致密微结构的结合区域则没有明显腐蚀。由于表面腐蚀，UHPC 中钢纤维的拉拔能与平均结合强度相比增加更显着，这是由于作用在纤维-基体界面上的两倍或更多的摩擦剪应力。