Research Progress of Electromagnetic Wave Absorbing Building Materials

With the popularization of wireless communication and electronic equipment, electromagnetic wave pollution in building space is becoming more and more serious, threatening human health and equipment safety. Traditional electromagnetic shielding has the problem of secondary pollution of reflection, so the development of efficient electromagnetic absorption building materials has become a research hotspot. This paper systematically reviews the research progress of cement-based absorbing materials, which are divided into two categories: filling type and structural type. In terms of filling materials, the microwave absorbing properties of carbon-based dielectric loss materials (such as multi-walled carbon nanotubes, graphene), magnetic materials (such as metal materials, ferrite) and their composite systems in cement matrix are analyzed emphatically. It is pointed out that the composite absorbing agent can achieve wider frequency band and stronger absorption. In terms of structural materials, the optimization effects of porous structure, multi-layer gradient structure and metamaterial structure (such as periodic array and pyramid shape) on impedance matching and loss ability are discussed. It is found that geometric design can significantly expand the effective absorption bandwidth and reduce the reflection loss. Studies have shown that the absorbing target of 'light, strong, thin and wide' can be achieved by synergistically regulating the type, content and structural design of the absorbing agent. Future research should focus on the development of multi-scale composite absorbers, structural optimization of smart metamaterials, and performance verification in actual building scenarios.