Nondestructive characterization of construction materials using ultrasonic and electromagnetic waves

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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.