THE EFFECT OF WATER CEMENT RATIO AND VIBRATION TIME OF MORTAR MIXED WITH THE ELECTRIC FURNACE OXIDIZING SLAG AND STYROFOAM BEADSS ON ELECTROMAGNETIC WAVE ABSORPTION PERFORMANCE

<p>In order to prevent communication failure caused by interference between devices that use electromagnetic waves such as wireless LAN in buildings, electromagnetic wave absorbers are required on the walls and floors of buildings. In the case of a wide range of electromagnetic frequencies, a narrow-band absorber that absorbs electromagnetic waves only in a specific frequency band cannot prevent communication problems, so a broadband absorber is required.To solve this problem, a broadband electromagnetic wave absorber has been studied by using a mortar made of electric furnace oxidizing slag, which has high density and complex permittivity, and styrofoam beads, which have lower density than electric furnace oxidizing slag （hereinafter referred to as beads slag mortar） as aggregate. The beads slag mortar becomes a wide band electromagnetic wave absorber in which the electric furnace oxidizing slag and styrofoam beads are separated by vibrating when uncured, and the complex relative permittivity and complex relative permeability gradually increase from the direction of electromagnetic wave incidence to the bottom of the mortar, like a multi-layered electromagnetic wave absorber. This wide band electromagnetic wave absorber can be manufactured easily and inexpensively because it can be manufactured with the general equipment used for mortar fabrication.<br/>In this study, the area occupied by the electric furnace oxidizing slag per unit cross-sectional area of the specimen and the return loss of the specimen are measured in order to clarify the effect of water cement ratio and vibrating time of beads slag mortar on the separation of beads and electromagnetic wave absorption performance. As a result of the measurement of the area occupied by electric furnace oxidizing slag per unit cross-sectional area, it was found that the electric furnace oxidizing slag and styrofoam beads of the beads slag mortar flowed as the mortar was vibrated, and the beads slag mortar flowed more easily even with a short vibrating time as the water cement ratio increased.<br/>From the measurement of the return loss, it was found that the electromagnetic wave absorption performance of the beads slag mortar increased with the increase of the water cement ratio and the increase of the vibrating time until the two layers separated and peaked.</p>