Application of microwave waveguide techniques for investigating the effect of concrete dielectric and reflection properties during curing

Abstract

This study deals with the measurement of dielectric constant, the magnitude of reflection coefficient, and compressive strength for G30, G40, G50, and G60 concrete mix after 0, 3, 7, 14, 21, and 28 days curing. The open-ended coaxial probe of 4.8 cm, WR510, and WR340 waveguide models operating over a frequency range of 85 MHz to 1.8 GHz, 1.45–2.2 GHz, and 2.17–3.3 GHz, respectively, are applied. Fifteen concrete cube samples 150 × 150 × 150 mm size were casted for each mix. The experimental result shows that the dielectric constant and magnitude of the reflection coefficient decrease gradually until 21 days, then increase at 28 days age of concrete. Correlated the concrete dielectric constant with design compressive strength. The results corroborate that microwave techniques correlate well for evaluating the strength of concrete. The strength characterization is suitable with related material composition, necessary experimental setup, and environmental conditions applied in this study. Furthermore, curing conditions, effects must be accounted; it is valuable in establishing a correlation between conventional properties and microwave properties of concrete.