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Characterization and deterioration detection of Portland cement concrete using ultrasonic waves.

机译：超声波对波特兰水泥混凝土的表征和劣化检测。

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摘要

An experimental study was conducted to characterize Portland cement concrete (PCC), to detect deterioration induced by freeze/thaw and alkali-silica reaction, and to detect chloride presence in PCC using ultrasonic waves. The experimental program was initiated to investigate the effect of water to cement (w/c) ratio, aggregate type, and air entrainment on measured ultrasonic wave velocity and signal energy. Three w/c ratios (0.35, 0.45, and 0.55) were evaluated. Two aggregate types, quartzite and limestone, were included in the PCC mixes separately. Mixes were prepared as non-air entrained and air entrained. Thus, a total of twelve batches were prepared to evaluate PCC using ultrasonic waves at two frequencies, 54 and 340 kHz.; The experimental program to investigate freeze/thaw (FT) damage included the effect of curing time, w/c ratio, and aggregate type. The effect of curing time was investigated by exposing PCC specimens cured for 3 and 7 days to FT. Two w/c ratios were considered, 0.45 and 0.55. The effect of aggregate on detecting FT damage was investigated using two types of crushed stone aggregate, quartzite and limestone. Alkali-silica reaction (ASR) damage was investigated using two w/c ratios, 0.35 and 0.45. Embedded composite strain gages were used to monitor the ASR deleterious deterioration. High alkali cement and active silica aggregate were used to produce ASR.; Chloride contamination of PCC was accomplished using two methods: in the first method, chloride solutions were used in preparing PCC mixes. Three chloride concentrations were used: 1.19, 2.37, and 4.75 kg/m{dollar}sp3{dollar} of PCC. Ultrasonic measurements were taken over curing time. Powdered PCC samples were collected at 28 days of moist curing to measure the exact chloride content. The second method involved immersing PCC specimens in 6% (by weight) chloride solution. Ultrasonic measurements and powdered PCC samples were taken every two months.; The least significant difference (LSD) statistical test was used to compare the effect of different PCC properties and deterioration on measured ultrasonic velocity and signal energy. The study showed that signal energy is more sensitive than the apparent ultrasonic wave velocity to characterize PCC and to detect deterioration. Aggregate type was found to have a significant influence on ultrasonic waves propagating in PCC. Two modes of waves appear to propagate in PCC using direct and indirect methods. The direct method appears to produce non-dispersive wave mode while the indirect method appears to produce dispersive wave mode. Apparent ultrasonic wave velocity was found to increase with curing time. The effect of w/c ratio and air entrainment on signal energy was significant. Both the apparent ultrasonic wave velocity and signal energy were able to detect FT damage in PCC. The signal energy was sensitive to ASR deterioration while apparent ultrasonic wave velocity was unable to detect any ASR damage. Chloride content, on the other hand, was undetected by apparent ultrasonic wave velocity, and by signal energy analysis.
机译：进行了一项实验研究，以表征波特兰水泥混凝土（PCC），检测由冻结/融化和碱硅石反应引起的劣化以及使用超声波检测PCC中氯化物的存在。启动该实验程序以研究水灰比（w / c），骨料类型和空气夹带对测量的超声波速度和信号能量的影响。评估了三个w / c比（0.35、0.45和0.55）。 PCC混合物中分别包含两种骨料类型，石英岩和石灰石。将混合物制备为非空气夹带和空气夹带。因此，总共准备了十二个批次，以使用两个频率54和340 kHz的超声波评估PCC。研究冷冻/融化（FT）损坏的实验程序包括固化时间，w / c比和骨料类型的影响。通过将固化3天和7天的PCC样品暴露于FT中，研究了固化时间的影响。考虑了两个w / c比，分别为0.45和0.55。使用两种碎石骨料，石英岩和石灰石，研究了骨料对检测FT损伤的影响。使用两个w / c比0.35和0.45研究了碱-二氧化硅反应（ASR）的损害。嵌入式复合应变计用于监测ASR有害劣化。高碱性水泥和活性二氧化硅骨料用于生产ASR。 PCC的氯化物污染使用两种方法完成：在第一种方法中，氯化物溶液用于制备PCC混合物。使用了三种氯化物浓度：PCC分别为1.19、2.37和4.75 kg / m {dol}} sp3 {dol}。在固化时间内进行超声波测量。在湿固化28天后收集粉末状PCC样品，以测量确切的氯化物含量。第二种方法涉及将PCC标本浸入6％（按重量计）的氯化物溶液中。每两个月进行一次超声波测量和粉状PCC样品。最小显着差异（LSD）统计测试用于比较不同PCC特性和劣化对测得的超声速度和信号能量的影响。研究表明，信号能量比表观超声波速度更敏感，可以表征PCC和检测劣化。发现骨料类型对PCC中传播的超声波有重要影响。波的两种模式似乎是使用直接和间接方法在PCC中传播的。直接方法似乎产生非色散波模，而间接方法似乎产生色散波模。发现表观超声波速度随固化时间增加。 w / c比和空气夹带对信号能量的影响是显着的。表观超声波速度和信号能量均能够检测PCC中的FT损伤。信号能量对ASR劣化敏感，而表观超声波速度无法检测到任何ASR损坏。另一方面，通过表观超声波速度和信号能量分析未检测到氯化物含量。

著录项

  • 作者

    Al-Akhras, Nabil M.;

  • 作者单位

    Virginia Polytechnic Institute and State University.;

  • 授予单位 Virginia Polytechnic Institute and State University.;
  • 学科 Engineering Civil.
  • 学位 Ph.D.
  • 年度 1995
  • 页码 187 p.
  • 总页数 187
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 建筑科学;
  • 关键词

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