Nondestructive characterization of construction materials using ultrasonic and electromagnetic waves

本课题的主要目标是开发新的测试技术来测量矿用胶结膏体的动态特性随频率和应变水平的变化；并使用非破坏性技术来评估民用基础设施的状况。这项工作将基于精心规划和执行的实验方案，以及对机械波（超声波）和电磁波（探地雷达）传播的基本理解。正确设计抗动力激励（地震和爆破）的胶结膏体充填体对加拿大地下采矿作业的安全性、经济性和环境可持续性至关重要。然而，目前对矿用胶结膏体的动力性能还不太了解；它们的频率依赖性还没有被很好地理解。因为没有标准来测量动态特性作为频率的函数。因此，我们将改进共振柱装置，采用我们最近提出的评估膏体动态特性随频率和应变水平的函数的方法，对不同条件下的矿膏体进行动态试验。另一方面，民用基础设施的状态评估通常基于现场测量；这是侵入性的，昂贵的，在许多情况下，不可能完成。相反，超声波和探地雷达等无损检测是非侵入性的、快速的、经济的。它们可以揭示结构损伤，如破裂、脱粘和腐蚀效应，而这些是无法检测到的。在这个项目中，我们将开发新的测试程序，使用电磁和超声波的互补测量来评估沥青层覆盖的桥面；基础设施所有者迫切需要新的、可靠的技术来执行具有成本效益的维护和修复计划。这些项目的成功与否取决于基础设施状况评估的准确性。我们将首先使用探地雷达（ASTM标准）来识别关键区域，然后使用超声波测量来生成更可靠的桥面评估。

The main objectives of this proposal are to develop new testing techniques to measure dynamic properties of cemented mine pastes as function of frequency and strain level; and to use non-destructive techniques to assess the condition of civil infrastructure. This work will be based on carefully planned and executed experimental programs and a fundamental understanding of the propagation of mechanical waves (ultrasound) and electromagnetic waves (ground penetrating radar, GPR). The proper design of cemented paste backfills against dynamic excitations (earthquakes and blasting) is critical for the safety and the economical and environmental sustainability of underground mining operations in Canada. However, the dynamic properties of cemented mine paste are not well known; and their frequency dependency is not well understood. Because there is no standard to measure dynamic properties as function of frequency. Thus, we will modify the resonant column device to perform dynamic tests on mine pastes under different conditions using our recently proposed method for the evaluation of dynamic properties as function of frequency and strain level. On the other hand, the condition assessment of civil infrastructure is typically based on in-situ measurements; which are intrusive, expensive and, in many cases, impossible to complete. Conversely, nondestructive tests such as ultrasonic and GPR surveys are non-intrusive, fast, and economical. They can reveal structural damage - such as fracturing, debonding, and corrosion effects - that cannot otherwise be detected. In this project, we will develop new testing procedures for the evaluation of bridge decks overlain by an asphalt layer using complementary measurements from electromagnetic and ultrasonic waves; Infrastructure owners urgently need new and reliable techniques to perform cost-effective maintenance and rehabilitation programs. The success of these programs hinges on the accuracy of the condition assessment of the infrastructure. We will first use GPR (ASTM standard) to identify critical areas and, then use ultrasonic measurements to generate a more reliable assessment of bridge decks.