Investigation of the Relationship Between Impact Resonance Test Results and Air Void Contents of Shear Gyratory Compacted Specimens

The objective of this study was to investigate the relationships between impact resonance test (IRT) results and the air void content of shear gyratory compactor (SGC) specimens, for quality control purposes. Hence, a total of 12 specimens were prepared with a SGC and submitted to IRT at ambient temperature (around 23 °C) and −20 °C. The IRT setup was designed to experimentally determine the fundamental resonance frequency of the longitudinal mode of vibrations. The research findings indicate that it is not possible to determine this resonance frequency at ambient temperature because of the specimen geometry combined with the high damping of the material. At a temperature of −20 °C, two resonance frequencies corresponding to the fundamental resonance frequencies of the longitudinal and transverse modes were observed nearby, which is a consequence of the specimens’ geometry. The proximity of the two detected resonance frequencies is a source of uncertainty for the identification of the one corresponding to the longitudinal mode. Considering these findings, much care is needed when using SGC specimens for evaluating longitudinal resonance frequencies at both temperatures.