Microwave absorption performance is increasingly needed in cement composites, while multiband or broadband absorption properties are challenging to realize. This study provides a simple and reproducible metastructure for cement composites based on carbon nanotube periodic gratings, exhibiting averaged −15.5 dB reflectivity and 14.2 GHz effective bandwidth in 1–18 GHz. Theoretical requirements for the perfect absorption are analyzed, and the absorption performance and mechanism of the metastructure are studied. Furthermore, three factors affecting absorption performance are investigated, including the gratings periodicity, filling fraction, and the thickness of the cement dielectric. The metastructure with 24 mm periodicity gratings demonstrates multiband absorption performance, showing five peaks lower than −20 dB. The metastructure with 14/24 filling fraction gratings exhibits the reflectivity peak of −38.7 dB and bandwidth for −15 dB of 13.0 GHz, demonstrating broadband nearly perfect absorption performance. In addition, the metastructure with a thinner cement dielectric layer performs better absorbing properties. This study not only proposes an effective method for cement composites to achieve broadband absorption, but also provides cement composites and fireproof materials as novel candidates for the dielectric of metamaterial absorbers, which promotes the application of microwave absorbers to practical construction engineering.

水泥复合材料对微波吸收性能的要求越来越高，而多波段或宽带吸收性能难以实现。本研究为基于碳纳米管周期性光栅的水泥复合材料提供了一种简单且可重复的元结构，表现出平均 -15.5 dB 反射率和 14.2 GHz有效带宽在 1-18 GHz。分析了完美吸收的理论要求，研究了超微结构的吸收性能和机理。此外，研究了影响吸收性能的三个因素，包括光栅周期性、填充率和水泥电介质的厚度。具有 24 mm 周期性光栅的元结构展示了多波段吸收性能，显示出五个低于 -20 dB 的峰值。具有 14/24 填充分数光栅的超结构表现出 -38.7 dB 的反射率峰值和 13.0 GHz 的 -15 dB 带宽，展示了宽带近乎完美的吸收性能。此外，具有更薄的水泥介电层具有更好的吸收性能。本研究不仅提出了水泥复合材料实现宽带吸收的有效方法，而且提供了水泥复合材料和防火材料作为超材料吸收体电介质的新型候选材料，促进了微波吸收体在实际建筑工程中的应用。