Effect of aggregate size and inclusion of polypropylene and steel fibers on explosive spalling and pore pressure in ultra-high-performance concrete (UHPC) at elevated temperature
Effect of aggregate size and inclusion of polypropylene and steel fibers on explosive spalling and pore pressure in ultra-high-performance concrete (UHPC) at elevated temperature
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DOI：
10.1016/j.cemconcomp.2019.02.016
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发表时间：
2019-05-01
影响因子：
10.5
通讯作者：
Tan, Kang Hai
中科院分区：
文献类型：
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作者：
Li, Ye;Pimienta, Pierre;Tan, Kang Hai
本文研究了聚丙烯纤维、钢纤维和骨料粒径对超高性能混凝土高温下剥落行为和孔压增长的影响。孔隙压力和温度的同时测量在不同深度的UHPC标本下，单面加热，加热速率为2摄氏度/分钟。压缩，拉伸和渗透性试验进行分析剥落行为。PP纤维的加入完全防止了剥落，并且它们在增加渗透性方面比钢纤维和更大的骨料有效得多。PP纤维与钢纤维、PP纤维与大骨料的组合使用在增加渗透性方面表现出较强的协同效应。渗透率越高，样品中测得的最大孔隙压力越低。从温度历史中观察到两个平台，分别是由于液态水的蒸发（在试样内115和125摄氏度之间）和水蒸气的释放（从180摄氏度开始）。第二个平台被确定为PP纤维的功能温度。剥落试样的最大孔隙压力远低于其抗拉强度，这可能意味着水压力的贡献，在该地区的水分堵塞剥落。
This paper investigates the individual and combined effects of polypropylene (PP) fibers, steel fibers, and aggregate size on spalling behavior and pore pressure build-up of ultra-high-performance concrete (UHPC) exposed to elevated temperature. Simultaneous measurements of pore pressure and temperature were conducted at different depths in UHPC specimens under one-sided heating with a heating rate of 2 degrees C/min. Compressive, tensile, and permeability tests were performed to analyze spalling behavior. Addition of PP fibers fully prevented spalling and they are much more effective in increasing permeability than steel fibers and larger aggregates. The combined use of PP and steel fibers, and PP fibers and larger aggregates showed strong synergistic effect on increasing permeability. The higher the permeability, the lower was the maximum pore pressure measured in the samples. Two plateaus were observed from the temperature history due to vaporization of liquid water (between 115 and 125 degrees C inside the specimens) and release of water vapor (starting from 180 degrees C), respectively. The second plateau was identified as the functional temperature of PP fibers. Maximum pore pressures in spalled specimens were much lower than their tensile strengths, which could imply the contribution of hydraulic pressure in the region of moisture clog on spalling.