Nondestructive characterization of construction materials using ultrasonic and electromagnetic waves

本提案的主要目标是开发新的测试技术，以测量水泥矿浆的动态特性，作为频率和应变水平的函数;并使用非破坏性技术评估民用基础设施的状况。这项工作将基于精心计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。在加拿大，水泥浆回填土的正确设计对动态激励（地震和爆破）的安全性以及地下采矿作业的经济和环境可持续性至关重要。然而，水泥矿膏体的动态特性并不为人所知，其频率依赖性也没有得到很好的理解。因为没有标准来测量作为频率函数的动态特性。因此，我们将修改共振柱设备进行动态测试，在不同的条件下，使用我们最近提出的方法，作为频率和应变水平的函数的动态性能的评价矿膏。另一方面，民用基础设施的状况评估通常基于现场测量;这是侵入性的，昂贵的，并且在许多情况下不可能完成。相反，非破坏性测试，如超声波和GPR测量是非侵入性的，快速的，经济的。它们可以揭示结构损伤--如断裂、脱粘和腐蚀效应--这些是无法通过其他方式检测到的。在该项目中，我们将开发新的测试程序，使用电磁波和超声波的互补测量来评估沥青层覆盖的桥面;基础设施业主迫切需要新的可靠技术来执行具有成本效益的维护和修复计划。这些计划的成功取决于基础设施状况评估的准确性。我们将首先使用GPR（ASTM标准）来识别关键区域，然后使用超声波测量来对桥面进行更可靠的评估。

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.