Measurements of microwave reflection properties of early-age concrete and mortar specimens

Measurement and monitoring results on reflection properties of concrete and mortar cubic specimens are presented in this paper. The results were obtained by using a sweeping microwave frequency over entire X-band (8.2 – 12.4 GHz). Dependencies of the reflection coefficient and conductance on water-to-cement ratio and effect of coarse aggregates in the specimens are demonstrated. It is shown that the decays on magnitudes of reflection coefficients of concrete and mortar specimens have different rates versus days. The causes and effects of measurement uncertainties are discussed. The expected applications of the results for the determination of physical properties of cement-based materials are also discussed.