Synergetic effect of waste tire rubber and mil scale on electromagnetic wave attenuation properties of new generation mortar

Abstract In this study, the behaviors of cement based building materials containing a certain amount of crumb rubbers (CR) and mill scales as additives were explored. For this purpose, five different CR content by volume of the natural fine aggregate mortars and different mill scale (MS) doped rubberized mortars were prepared. The CR and MS used in the study were obtained from waste tires and rolling mill facility which are desirable due to economic and environmental reasons. EM behaviors of the samples were explored in the frequency range of 3–12GHz for the first time in the related literature. Flexural and compressive strength tests are then carried out. The crystallinity and morphology of the mortars were also investigated with X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). The increment of rubber content in the mortar reduced the reflection characteristic due to lower reverse polarizability of the structure with incident wave, related with the dielectric properties of rubber and decreased the reflection response of the mortar due to reduced polarization of the samples with increased dielectricity for incident wave. The dielectric constants of mortar including mill scale has higher values due to better polarizability of the small conductive parts in mill scale. The existence of conductive parts increases the electron mobility and polarizability of the structure. Besides, the higher ratio of rubber with the same mill scale percentage (15%) in mortar also slightly enhanced the dielectricity of the samples. The higher dielectric constant with respect to the free space gives opportunities to be used in shielding devices. The replacing crumb rubber with fine aggregate resulted in a decrease in both compressive and flexural strength.