Effect of Temperature on Ultrasonic Nonlinear Parameters of Carbonated Concrete

Abstract

In order to explore the monitoring technique of concrete carbonation in various temperatures, longitudinal ultrasonic nonlinear parameters of carbonated concrete are measured by using an embedded composite piezoelectric transducer (ECPT) and a surface-mounted transducer. The effect of temperature from −20 (Formula presented.) C to 40 (Formula presented.) C with a temperature interval of 5 (Formula presented.) C and water–cement ratio on the measurements of ultrasonic parameters for carbonated concrete is investigated. The ultrasonic transmission detection method and the second harmonic generation (SHG) technique for longitudinal waves are used in the study. Results of the experiment demonstrate that ECPT is effective in the monitoring of the changes in ultrasonic parameters of carbonated concrete. At the temperature ranging from 15 (Formula presented.) C to 40 (Formula presented.) C, the increasing temperature slightly increases the relative nonlinear parameters of carbonated concrete. It decreases significantly that the relative nonlinear parameters of carbonated concrete measured at 0 (Formula presented.) C compared with that at 10 (Formula presented.) C. The configuration in this measurement is also appropriate for the assessment of carbonated concrete during carbonation time in low-temperature environments (below 0 (Formula presented.) C). In the same carbonation time, the relative nonlinear parameters also increase slightly when the temperature is at −20 (Formula presented.) C to 0 (Formula presented.) C, but it does not change too much. Furthermore, there is a more significant variation of the nonlinear parameters in the same carbonation time for the specimens with a high water–cement ratio than that with a low one.