Frequency spectrum analysis of lightweight foamed concrete using microwave dielectric measurement technique

Abstract

The dielectric characterization of concrete is a significant parameter to study the microwave signal transmission for the building materials. In this paper, a microwave measurement system has been developed using open ended coaxial sensor and vector network analyzer for frequency spectrum analysis of lightweight foamed concrete. The measurement setup is validated prior to make sure the system is working properly. The results of dielectric constant and loss factor of different densities lightweight concrete samples are measured and analyzed from 150 kHz to 8 GHz. From the analysis, the lightweight foamed concrete is a frequency spectrum friendly building material. In addition, the relationship between the dielectric constant and density of the lightweight foamed concrete is found to be interrelated. The empirical modeling of some selected frequencies has been formed. The models are useful for the future application on determining the dielectric constant and characteristic of lightweight concrete samples.

Determination of density and compressive strength of lightweight foamed concrete using frequency domain approach

“…The increase in the LFC density causes the dielectric constant to increase as shown in Figure 3(A). The results show that the LFC dielectric constant ranges from 1 to 3 as reported in Reference 12. These values are much lower than reported in Reference 24 for conventional concrete.…”

“…It has been further extended to the foamed concrete measurement using frequency domain method recently. 12 Due to the highly cellularised microstructure in the LFC, the conventional testing method is insufficient to characterize the key material attributes of foamed concrete, particularly for low-density foam. 13 However, the current understanding of foam concrete mechanical property remains limited, and there is no working analytical model.…”

“…The advantages of utilizing the electrical method provide a nondestructive approach and in situ measurement to characterize the concrete have been proposed using effective conductivity at the microwave frequency 10 and DC resistivity 11 correlated with compressive strength. It has been further extended to the foamed concrete measurement using frequency domain method recently 12 . Due to the highly cellularised microstructure in the LFC, the conventional testing method is insufficient to characterize the key material attributes of foamed concrete, particularly for low‐density foam 13 .…”