Abstract
The roles of dielectric materials in adjusting the electromagnetic wave (EMW) absorption performance of an EMW absorber are as crucial as the EMW absorbents. The commonly used cement-based materials, such as mortar, are typical composites of multiple dielectric materials, such as quartz sand and air in the pores. This study investigates the EMW-absorption performances within the frequency range of 2 GHz to 18 GHz of cement paste and mortar samples with different sand-to-cement ratios (S/C), water-to-cement ratios (W/C), and thicknesses. The bow-frame method is used to measure the EMW reflection loss (RL) curves of slab-like samples. The coaxial method is used to record the electromagnetic parameters of the sample powders, which are also used to calculate the EMW RL curves. The results prove that the EMW-absorption performances of a slab-like mortar sample are monotonically related to the S/C ratio and the actual air volume, which is closely related to the thickness.