Start Date

2016 12:00 AM

Description

Ultrasonic wave based methods have been proposed for monitoring the hardening process of concrete since 1990s. However, this technology is mainly limited to laboratory studies, due to limitations of test setups and lack of consistent relationship between ultrasonic measurements and engineering parameters used in practice. In this study, the authors present an ultrasonic guided wave method that uses guided waves in a steel rebar to monitor hardening of surrounding cement paste and mortar. The longitudinal L(0,1) mode guided wave in rebar is excited by an EMAT sensor and received by a piezo ceramic P-wave ultrasonic transducer. Continuous measurements during cement hydration were used to monitor the longitudinal wave attenuation resulted from leakage from the rebar to the surrounding cement paste/mortar. Shear wave velocities in cement materials were also monitored at the same time. Experiments were performed on cement paste and mortar samples. Experimental results demonstrated a strong linear relationship between the guided wave leakage attenuation and shear wave velocity for all tested samples. Both ultrasonic parameters increase with the age of cement materials, and show good correlation with the penetration resistance parameter used in practice.

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Monitoring Hardening of Cement Materials Using Ultrasonic Shear and Guided Waves

Ultrasonic wave based methods have been proposed for monitoring the hardening process of concrete since 1990s. However, this technology is mainly limited to laboratory studies, due to limitations of test setups and lack of consistent relationship between ultrasonic measurements and engineering parameters used in practice. In this study, the authors present an ultrasonic guided wave method that uses guided waves in a steel rebar to monitor hardening of surrounding cement paste and mortar. The longitudinal L(0,1) mode guided wave in rebar is excited by an EMAT sensor and received by a piezo ceramic P-wave ultrasonic transducer. Continuous measurements during cement hydration were used to monitor the longitudinal wave attenuation resulted from leakage from the rebar to the surrounding cement paste/mortar. Shear wave velocities in cement materials were also monitored at the same time. Experiments were performed on cement paste and mortar samples. Experimental results demonstrated a strong linear relationship between the guided wave leakage attenuation and shear wave velocity for all tested samples. Both ultrasonic parameters increase with the age of cement materials, and show good correlation with the penetration resistance parameter used in practice.