Beads-slag mortar, which uses electric arc furnace oxidizing slag (hereafter, slag) and expanded polystyrene beads as aggregates, can function as a broadband electromagnetic wave absorber by applying vibration before hardening. In this study, the effects of the aggregate volume ratio of beads-slag mortar and the particle size of the slag on aggregate distribution across the cross-section and electromagnetic wave absorption performance were investigated. It was found that reducing the aggregate volume ratio and the particle size of slag promotes the aggregate separation throughout the entire thickness, making it easier to achieve a broadband electromagnetic wave absorber.
