PSI - Issue 83

Samia M. Mohamed et al. / Procedia Structural Integrity 83 (2026) 63–71

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self-sensing composites (Wang and Aslani, 2023). These results highlight the critical role of interlayer bonding quality and conductive network continuity in determining the sensing reliability of printed materials. 3.3. Dispersion and Percolation Challenges of Conductive Fillers The sensing performance of cementitious composites is strongly dependent on the formation of a continuous conductive network within the matrix. In most self-sensing systems, this network is formed when the conductive filler content approaches the percolation threshold , where electrical conductivity increases dramatically due to the formation of interconnected conductive pathways. However, maintaining uniform dispersion of conductive fillers within the cement matrix remains a significant challenge. Several studies have shown that carbon-based fillers such as carbon fibers, carbon nanotubes, and graphene derivatives can significantly reduce electrical resistivity and improve sensing sensitivity. For example, You et al. reported that incorporating multi-walled carbon nanotubes into UHPFRC systems reduced electrical resistivity from 2.6 × 10 ⁵Ω ·cm to approximately 393 Ω ·cm , while also enabling crack-related self sensing behavior (You et al., 2017). Similarly, Dogra et al. demonstrated that hybrid graphene-based systems containing rGO and CB could achieve fractional changes in resistance of up to 400 %, indicating extremely high sensing sensitivity (Dogra et al., 2025). However, nanoscale fillers frequently agglomerate and have poor dispersion in the highly alkaline cement matrix, resulting in unstable electrical signals and impaired mechanical performance. As a result, enhancing dispersion techniques and optimizing filler dosage remain important research targets. 3.4. Limited Structural-Scale Validation Although numerous studies have demonstrated promising sensing performance at the material level , structural-scale validation remains relatively limited. Most investigations have been conducted on small laboratory specimens such as cubes, prisms, or small printed elements. Only a few studies have explored the integration of self-sensing cementitious composites into full-scale structural components. For example, Atkinson and Aslani investigated 3D-printed self sensing column shells and reported that while printed specimens exhibited compressive strengths of approximately 56 MPa , sensing reliability could deteriorate once structural cracking occurred (Atkinson and Aslani, 2023). Similarly, embedded self-sensing nodes fabricated by 3D printing have been proposed as a strategy for monitoring structural behavior during loading (Liu et al., 2025). These studies demonstrate the feasibility of integrating sensing functionality into structural components, but they also highlight the need for further research on long-term durability, signal stability, and environmental effects under real service conditions. 3.5. Future Research Directions Future research should focus on developing integrated material design approaches that simultaneously address the competing requirements of printability, mechanical performance, and sensing functionality. Hybrid conductive systems combining micro-scale fibers and nano-scale fillers appear particularly promising, as they can enhance electrical conductivity while maintaining acceptable mechanical properties. Another promising direction is the use of data-driven material design and machine-learning techniques to optimize conductive networks in printable cementitious composites. For example, Nandurkar et al. proposed a multi-scale deep learning framework for optimizing 3D-printed self-sensing cementitious composites containing hybrid nano-carbon fillers, reporting improvements of 25–35 % in electrical conductivity and 40–50 % in interlayer conductivity (Nandurkar et al., 2025). Finally, future studies should investigate the long-term durability and environmental stability of these materials under realistic service conditions, including cyclic loading, moisture variations, and temperature fluctuations. Addressing these challenges will be essential for enabling the practical deployment of smart, self-monitoring cementitious infrastructure fabricated through additive manufacturing .