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The piezoelectric sensor-based electromechanical impedance (EMI) technique has been explored as a promising method to monitor the strength development and stiffness growth ofconcrete in past decades. The EMI method, however, has not been implemented in the field to evaluate the in-place strength gain of concrete structures or pavement. This study is one of the early works to apply EMI technology to test the real-time concrete strength of interstate pavement projects. To make it field-applicable, the concrete slab test was conducted to build the prediction function using a statistical approach. The electromechanical admittance was then employed to monitor the stiffness growth of concrete over time. The conventional cylinder test (ASTM C39) was performed as a reference to assess the accuracy of the EMI sensing method. It has been found that the EMI sensing methods and the related statistical index can effectively reflect the compressive strength gain of concrete slab at different ages. The prediction model was further used to estimate the compressive strength of highway concrete pavement. The results indicated that the EMI method could provide satisfactory results in predicting the in-place strength of concrete.
Keywords: compressive strength; electromechanical impedance (EMI); field implementation; piezoelectric materials.
(ProQuest: ... denotes formulae omited.)
INTRODUCTION
Concrete is the most commonly used construction material in the world. The compressive strength of concrete is a critical factor in quality control. Typically, it is determined through mechanical testing, which uses field-cured cylinders prepared according to ASTM C31. For fast-paced construction such as highway paving/patching and airport pavement projects, however, it is critical to develop a testing method that rapidly and accurately evaluates the strength development of concrete at its very early age (within 24 hours after casting). Previous literature has indicated that a piezoelectric sensor, coupled with the electromechanical impedance (EMI) technique, can be a promising method of monitoring the change of the mechanical properties of newly cast concrete and evaluating the condition of existing concrete at the laboratory scale.1-4
Based on the direct and indirect piezoelectric effect, piezoelectric materials can act both as a transducer and a receiver, capturing the property changes of host structures to which it is attached. Among the various piezoelectric materials, lead zirconate titanate (PZT) is the most commonly used piezoelectric ceramic because it is commercially available...