## 5 Application of Self-Sensing Materials for
### Electromagnetic Interference Shielding  
With the ongoing digitalization of the world, electromagnetic wave propagation presents a significant challenge, posing various threats to the safety of digitalized systems equipped with electronics [263]. For instance, EMI can undermine the reliability of commu  
Figure 24: Electrically conductive concrete (ECON): (**a**) schematic illustration of heating concrete pavement; (**b**) thermal images after 1 min and 60 min [254], published by Elsevier (2018).  
nication systems utilized in traffic management. Additionally, the health of individuals can be compromised due to exposure to surrounding electromagnetic waves in transportation infrastructures, particularly in stations where wireless communication systems are prevalent. Consequently, the implementation of EMI shielding becomes crucial for transportation infrastructures to enhance the reliability of communication systems, thereby ensuring the proper functionality of electronic devices, which in turn increases safety and mitigates risks to human health.  
In this context, multifunctional cementitious composites incorporating conductive fillers, such as metal-based or carbon-based conductive fillers, can be utilized [264]. Metal-based conductive fillers predominantly reflect electromagnetic waves, whereas carbon-based conductive fillers mainly absorb them [265]. The effectiveness of EMI shielding increases with the electrical conductivity of the cementitious composite. Hence, the integration of conductive fillers into cementitious composites enhances electromagnetic shielding effectiveness by augmenting electromagnetic wave reflectivity and electromagnetic wave absorptivity.  
For instance, the electromagnetic wave absorption capacity of cementitious composites is enhanced with an increased percentage of MWCNT [266] and CF content [267]. However, it is crucial to note that optimal electromagnetic wave absorption effectiveness is achieved by increasing the concentration of conductive fillers up to the percolation threshold [268]. Furthermore, the size and surface functionalization of conductive fillers influence the electromagnetic wave absorption of cementitious composites [269]. In another study, the addition of silica fume (SF) further improved the electrical conductivity of cementitious composites incorporating MWCNTs and fly ash, leading to enhanced electromagnetic wave absorption due to improved dispersion [270].  
Moreover, incorporating other additives such as fly ash and polyvinyl alcohol (PVA) fibers into cementitious composites have been found effective in reducing microwave absorption by altering microstructures [271]. Generally, the attenuation of electromagnetic waves caused by the shielding material is depicted in Figure 25. Consequently, it can be inferred from Figure 25 that the thickness of electrically conductive cementitious composites also influences electromagnetic wave absorption performance, with thicker composites exhibiting higher electromagnetic wave absorption capacity.  
Figure 25: **(a) Attenuation mechanism of electromagnetic waves by electrically conductive cementitious composites [272], published by Elsevier (2021); **(b)** schematic representation of electrically conductive cementitious composite employed as electromagnetic shielding material [273], published by Elsevier (2013).