Bond durability of basalt-fiber-reinforced-polymer (BFRP) bars embedded in concrete in aggressive environments
Bond durability of basalt-fiber-reinforced-polymer (BFRP) bars embedded in concrete in aggressive environments
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DOI：
10.1016/j.compositesb.2016.09.039
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发表时间：
2016-12-01
影响因子：
13.1
通讯作者：
Fam, Amir
中科院分区：
文献类型：
--
作者：
Hassan, Mohamed;Benmokrane, Brahim;Fam, Amir
最近，玄武岩纤维增强聚合物（BFRP）筋已成为玻璃纤维增强聚合物（GFRP）筋的一种有前途的替代品。然而，到目前为止，BFRP筋还没有被纳入设计标准和规范。这是由于对混凝土中钢筋性能的研究有限和缺乏了解，特别是当暴露于侵蚀性环境时，其粘结耐久性。本文介绍了BFRP筋在混凝土结构中的粘结耐久性研究的一些结果，以及基于短期试验结果的BFRP筋的长期粘结强度保持预测。本研究包括测试直径为12 mm的变形BFRP筋。在40 ° C、50 ° C和60 ° C的温度下暴露于碱性溶液（pH 12.9）1.5、3和6个月后，用直接拉伸载荷测试拔出样本。本文研究了碱性环境、暴露时间和高温对BFRP加固试件粘结强度的影响，以及BFRP加固试件的退化机理和破坏模式。此外，光学显微镜和扫描电子显微镜被用来研究BFRP筋的降解测试。测试结果表明，与未处理的试样相比，随着温度的升高，处理的试样的粘结强度初始增加。暴露1.5个月后，在50 ℃和60 ℃条件下处理的试样的粘结强度分别增加了25%和26%，而在40 ℃条件下处理的试样没有表现出明显的变化（轻微下降4.3%）。然而，浸泡过程中的调理标本的粘结强度恶化。与1.5个月时的对应物相比，在40 ℃下暴露6个月后，经调节的试样中出现最高粘结强度降低（16%损失），其次是在50 ℃下（7%损失）和60 ℃下（5%损失）经调节的试样。最后，长期粘结强度保持预测的BFRP筋后50年的使用寿命在干燥，潮湿和水分饱和的环境，平均年温度在5摄氏度和35摄氏度之间的范围从71%到92%。(C)2016爱思唯尔有限公司版权所有
Recently, basalt-fiber-reinforced-polymer (BFRP) bars have emerged as a promising alternative to glass-fiber-reinforced-polymer (GFRP) bars. So far, however, BFRP bars have not been incorporated into design standards and specifications. This is due to limited studies and lack of knowledge on the performance of the bars in concrete, in particular, their bond durability when exposed to aggressive environments. This paper presents some results of an extensive research program investigating the bond durability behaviors of BFRP bars in concrete structures and the long-term bond-strength-retention predications of the BFRP bars on the basis of short-term tests results. This research included testing deformed BFRP bars measuring 12 mm in diameter. Pullout specimens were tested with direct tensile loading after being exposed to an alkaline solution (pH 12.9) for 1.5, 3, and 6 months at temperatures of 40 degrees C, 50 degrees C, and 60 degrees C. This paper investigated the effects of alkaline environment, exposure periods, and elevated temperatures on bond strength as well as the degradation mechanism and mode of failure of the BFRP-reinforced specimens. In addition, optical microscopy and scanning electronic microscopy were used to investigate the degradation of BFRP bars tested. The test results indicate an initial increase in the bond strength of the conditioned specimens as the temperature increased compared to their unconditioned specimens. After 1.5 months of exposure, the specimens conditioned at 50 degrees C and 60 degrees C, respectively, had bond-strength increases of 25% and 26%, while the specimens conditioned at 40 degrees C exhibited no noticeable changes (a minor decrease of 4.3%). Nevertheless, the bond strength of the conditioned specimens deteriorated during immersion. The highest bond strength reductions occurred in the conditioned specimens after 6 months of exposure at 40 degrees C (a 16% loss), followed by specimens conditioned at 50 degrees C (7% loss) and 60 degrees C (5% loss) compared to their counterparts at 1.5 months. Lastly, the long-term bond-strength-retention predications of the BFRP bars after 50 years of service life in dry, moist, and moisture-saturated environments with mean annual temperatures between 5 degrees C and 35 degrees C ranged from 71% to 92%. (C) 2016 Elsevier Ltd. All rights reserved.