Measuring Dielectric Properties of Portland Cement Concrete: New Methods

摘要

Electrical characterization of Portland cement concrete (PCC) is necessary for reliable operation of electromagnetic nondestructive evaluation (NDE) techniques. Examples of such techniques include ground penetration radar (GPR). To better understand the dielectric properties of PCC, a study was conducted to evaluate PCC complex permittivity and magnetic permeability over a wide band of frequencies (100 KHz-10 GHz) usign both time domain and frequency domain techniques. To achieve this, three measuring devices were designed and built: a parallel plate capacitor, a coaxial line fixture and a TEM horn antenna. The parallel plate capacitor covers the low radio frequencies (RF) characterization (0.1 40 MHz). The coaxial setup covers the frequency spectrum of 100-1000 MHz while the antenna covers the microwave frequencies (1-10 GHz). The PCC specimen under test assumes different geometry for different setups: a prism for capacitor setup, a cylinder for the coaxial setup, and a rectangular slab for the antenna setup. This paper presents the design of the three setups.