High-strength Concrete Curing (Strength Gain) Monitoring Using Piezoelectric-based Wave Propagation and Electromechanical Impedance Techniques
Creators: name: Younas, Waseem
Publisher: name: Southern Cross University
Year: 2022
Subjects: Non-destructive testing (NDT) techniques
Electromechanical Impedance (EMI)
Wave Propagation (WP)
SMart AGgregates (SMAGs)
Concrete Curing Monitoring

description: The standard method for assessing the durability of concrete is through destructive compression strength testing, which involves testing concrete cylinders or cubes cast alongside the main civil structure. However, this method has some significant drawbacks, such as unreliable results and the need for highly experienced labour. Non-destructive testing (NDT) techniques, such as the Schmidt hammer, radiography, resonant frequency, and isothermal calorimeter, can be used to monitor the concrete curing process. Nonetheless, these methods have limitations and drawbacks, and there is a demand for a new non-destructive approach to assess high-strength concrete in situ. Recent advancements in piezoelectric materials have piqued the interest of scientists in developing innovative NDT techniques. The limitations of traditional destructive and NDT methods for monitoring concrete strength can be overcome by utilising piezoelectric materials. Piezoelectric-based concrete curing monitoring techniques include Electromechanical Impedance (EMI) monitoring and Wave Propagation (WP) monitoring. EMI utilizes a single piezoelectric transducer to monitor and control the host structure, where changes in the structure's vibrational activity are reflected in electrical signal characteristics. On the other hand, WP uses at least two piezoelectric transducers, with some serving as actuators and others as sensors, and detects electrical traces left by alterations to the elastic wave's path structure. These methods are beneficial in monitoring concrete curing and have been studied for normal-strength concrete, but research into using WP and EMI to monitor high-strength concrete's curing is limited. This study investigated both WP and EMI techniques using Piezoelectric-based SMart AGgregates (SMAGs) embedded in concrete prisms to acquire electrical signals. Destructive compression tests were conducted, and empirical relationships were established between compressive strength results, WP-derived P-wave velocity, compressive strength results, and relative resonance frequency. The study found that the WP method's P-wave velocity increased from 3000 m/s on day 1 to 3218 m/s on day 7, then to 3307 m/s on day 28, indicating a rise in concrete strength. The EMI method showed a resonance frequency of 35.4 kHz and 77.45 kHz after 2 hours and 1 day of curing, respectively, with a further 25 kHz increase from day 1 to 28. The research established a strong exponential relationship between WP method signals and compressive strength results (R2=0.8674) and EMI signals and measured compressive strength results (R2=0.9332). Overall, the investigation demonstrated the applicability and benefits of both EMI and WP techniques in monitoring high-strength concrete's curing and strength gain process.