Enhancing Electromagnetic Wave Absorption in 3D-Printed Concrete with Superabsorbent Polymers for High Performance

The widespread application of concrete with specific functions has become indispensable in modern technology. However, the persistent issue of electromagnetic pollution poses a serious hazard to human health, electronic equipment, and military operations. Although various conventional electromagnetic absorbing materials have been incorporated, the achievable EMW-absorption performance is still restricted, with only a narrow effective absorption bandwidth. This study investigates the application of advanced 3D-printing technology to produce concrete with enhanced EMW-absorption properties with the incorporation of SAP (super-absorbent polymers). To achieve this, concrete samples with three SAP occupying the concrete volumes (0 vol.%, 20 vol.%, and 40 vol.%) and three methods (pretreatment-addition) were examined to provide an in-depth analysis of the properties and microstructures. The study reveals superior electromagnetic absorption in concrete enhanced with SAP compared to the untreated counterpart. Specifically, samples subjected to 40 vol.% Dry Treatment SAP exhibited exceptional performance, achieving 98.77% absorption at 7.53 GHz frequency with a peak reflectance of −19.12 dB, outperforming unmodified absorbing resin concrete by 25.44%. Moreover, microscopic analysis revealed irregular void distribution within the concrete, while the 3D-printing and -mixing processes led to SAP particle fractures, forming a complex 3D structure, thereby enhancing EMW-absorption performance. Ultimately, by selecting appropriate SAP pre-treatment and mixing methods based on the specific frequency range, this study provides crucial references and practical guidance for the application of EMW-absorbing concrete in military and technological contexts.