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Modification and validation of piezoelectric ring actuator technique to monitor setting and hardening of cement-based materials.

机译：压电环致动器技术的修改和验证，以监测水泥基材料的凝固和硬化。

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摘要

A period of cement hydration is one of critical in the life span of concrete structures. One of the reasons of collapse of concrete structural elements during and after construction is the error in determining the concrete characteristics at early age. Recently, non-destructive test emerged as a popular way to evaluate the properties of cement-based materials. This test offers continuous measurements of concrete properties as well as ability to monitor any changes in the current state of structural materials. In the existing research, some of these methods fail to capture well properties of the materials in the plastics stage.;A new piezoelectric pulse testing device (Piezoelectric Ring Actuators Technique), (P-RAT) was initially developed at the University of Sherbrook as a non-destructive test (NDT) for soil. This technique is considered a completely new, versatile, advanced and accurate. The development of the new technique (P-RAT) was done on two main bases: the first was the development of piezoelectric ring actuators set-up and the second is the development of the interpretation method. The setup ' is composed of two main units; emitter and receiver, and is capable of measuring shear and compression wave velocities in specimens. With this technique, many problems of pulse tests, which make interpretation of results difficult and ambiguous, were solved in soil. The P-RAT overcomes wave reflections at boundaries (end-caps and sides), sample disturbance, weak shear coupling between soil and device (interaction) as well as the fixation problems, low resonant frequency and limited input voltage of the existing device.;The previous method is exploited forward to measure the hydration properties of cement-based material. To apply this test method, it is necessary to determine how the evolution of shear wave velocity can be related and sensitive to the hydration of cement-based materials. Validation of the P-RAT with four conventional test setups that can be used to monitor early setting and hydration of cement-based materials is carried out. These tests include penetration resistance to monitor initial and final setting respectively, calorimetric to monitor heat of hydration, electrical conductivity to monitor change in continuity of the pore structure and compressive strength at 24 hours.;The phase one of this investigation included trial tests to investigate the possibility of employing the original setup used for soil (P-RAT ) to determine setting and hardening properties of cement-based material. Based on the results of the preliminary test, two modifications were conducted to the previous test device to fit with cement based material and to obtain adequate resonant frequency for cement-based materials. These modifications are the design of the container and changing the dimensions of the rings. The resultant version of P-RAT after the modification was referred to be as P-RAT2.;Calibration of the P-RAT2 with water specimen was undertaken using the compression wave velocity and resulted in 99.33% accuracy. One paste mixture was tested three times to determine the experimental error of the P-RAT2. The repeatability carried out on the P-ART2 proved the ability of this setup to capture accurate results of the shear wave velocity. This relative error is limited to 9 %.;A number of series of validation was performed on cement paste and mortar mixtures proportioned with various water cement ratios (w/cm) as well as chemical admixtures. The w/cm ratio ranged between (0.35 and 0.50). The investigated chemical admixtures comprise of high-range water-reducing agent, viscosity-modifying agent, set-accelerating agent, and set-retarding agent. The presented validations examine the ability of a P-RAT2 to monitor the hydration of the cement-based materials. The hydration is characterized by setting time, heat of hydration, electrical conductivity, and compressive strength at 24 hours. The results obtained using the P-RAT2 was correlated to those obtained using the conventional tests and strength measurement.;The results enable to validate the ability of P-RAT2 to accurately detect variations in the hydration of cement-based materials. In addition, the initial and final time of setting can be determined from the derivation of velocity vs. time curve. The results show that conductivity, resistivity, has a bilinear relationship to shear wave velocity. The compressive strength at 24 hours was correlated to both the shear wave velocity and shear modulus obtained using the P-RAT2. Furthermore, analytical model was derived to estimate the w/cm in mortar mixture by measuring the shear wave velocity (Vs) and the corresponding time (t).;Keywords: cement-based materials, hydration, non-destructive test, piezoelectric ring actuator technique, and shear wave velocity,
机译：水泥水合期是混凝土结构寿命的关键之一。混凝土结构元件在施工期间和施工后倒塌的原因之一是早期确定混凝土特性时的错误。近来，非破坏性测试成为评估水泥基材料性能的一种流行方法。该测试提供对混凝土性能的连续测量，以及监视结构材料当前状态的任何变化的能力。在现有的研究中，其中一些方法未能在塑料阶段捕获材料的良好性能。； Sherbrook大学最初开发了一种新的压电脉冲测试装置（压电环致动器技术）（P-RAT），对土壤的无损检测（NDT）。这项技术被认为是一种全新，通用，先进和准确的技术。新技术（P-RAT）的开发基于两个主要基础：第一是压电环形致动器装置的开发，第二是解释方法的开发。设置“由两个主要单元组成；发射器和接收器，并且能够测量样品中的剪切波和压缩波速度。通过这种技术，解决了土壤中脉冲测试的许多问题，这些问题使结果的解释变得困难而又模棱两可。 P-RAT克服了边界（端盖和侧面）的波反射，样品干扰，土壤与设备之间的弱剪切耦合（相互作用）以及固定问题，低谐振频率和现有设备的有限输入电压等问题。先前的方法被向前开发以测量水泥基材料的水合性能。要应用此测试方法，必须确定剪切波速度的演变如何与水泥基材料的水合作用相关并敏感。使用四种常规测试设置对P-RAT进行验证，这些设置可用于监测水泥基材料的早期凝固和水合作用。这些测试包括分别用于监测初始和最终设置的抗渗透性，用于监测水合热的量热法，用于监测孔结构连续性变化和24小时抗压强度的电导率;该研究的第一阶段包括试验性试验以研究可以使用用于土壤的原始设置（P-RAT）来确定水泥基材料的凝固和硬化特性。根据初步测试的结果，对先前的测试设备进行了两次修改，以适合水泥基材料，并为水泥基材料获得足够的谐振频率。这些修改是容器的设计和更改环的尺寸。修改后所得的P-RAT版本称为P-RAT2 。；使用压缩波速度对水样进行P-RAT2校准，结果精度为99.33％。测试一种糊剂混合物三遍，以确定P-RAT2的实验误差。在P-ART2上进行的可重复性证明了该设置具有捕获剪切波速度的准确结果的能力。此相对误差限制为9％。;对与各种水灰比（w / cm）和化学外加剂成比例的水泥浆和砂浆混合物进行了一系列验证。 w / cm比在（0.35和0.50）之间。所研究的化学混合物由高范围减水剂，粘度调节剂，促凝剂和缓凝剂组成。提出的验证检查了P-RAT2监测水泥基材料水化的能力。水合的特征在于设定时间，水合热，电导率和24小时的抗压强度。使用P-RAT2获得的结果与使用常规测试和强度测量获得的结果相关。该结果能够验证P-RAT2准确检测水泥基材料水化变化的能力。此外，可以根据速度与时间的关系曲线确定设定的初始时间和最终时间。结果表明，电导率，电阻率与剪切波速度呈双线性关系。 24小时的抗压强度与使用P-RAT2获得的剪切波速度和剪切模量相关。此外，通过分析剪切波速度（Vs）和相应的时间（t），推导了分析模型，以估计砂浆混合物中的w / cm。关键词：水泥基材料，水化，无损试验，压电环致动器技术和剪切波速度，

著录项

  • 作者

    Soliman, Nancy Ahmed.;

  • 作者单位

    Universite de Sherbrooke (Canada).;

  • 授予单位 Universite de Sherbrooke (Canada).;
  • 学科 Engineering Civil.;Engineering Mechanical.;Engineering Materials Science.
  • 学位 M.Sc.A.
  • 年度 2010
  • 页码 126 p.
  • 总页数 126
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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