The increasing complexity of modern infrastructure demands materials that are not only strong and durable but also capable of providing real-time feedback on structural performance. This has led to the development of intelligent cementitious composites that combine structural and sensing functions. Strain-Hardening Cementitious Composites (SHCC) have emerged as promising candidates due to their high ductility, controlled cracking behavior, and potential for functional integration. Implementing such materials in demountable interface elements could enable reusable, self-monitoring structural systems.

This research experimentally investigates the integration of self-sensing technology into demountable SHCC connections. The material used combined polyvinyl alcohol (PVA) fibers for ductility and crack control with carbon fibers (CF) as conductive fillers to enable piezoresistive behavior. The piezoresistive effect, where mechanical stress causes a change in electrical resistance, allows strain to be measured through electrical signals. Based on previous interlocking connection studies, several geometries were designed and fabricated using 3D-printed Acrylonitrile Butadiene Styrene (ABS) molds, later cast with SHCC using silicone rubber molds to capture precise details.

Two main experimental programs were conducted. The first involved cyclic tensile tests to examine the relationship between mechanical strain and electrical resistance. Resistance changes were recorded using a four-probe setup, while strain was monitored through Linear Variable Differential Transformers (LVDTs) and the testing machine. The second program involved monotonic tensile tests to evaluate mechanical strength, strain capacity, and failure modes, with additional monitoring using Digital Image Correlation (DIC) to verify strain measurements and observe crack development.

Results showed that the SHCC specimens exhibited stable strain-hardening behavior and distributed microcracking, ensuring ductility. A consistent and repeatable relationship between cyclic loading and fractional change in resistance (FCR) confirmed effective piezoresistive response. Calculated gauge factors indicated adequate sensitivity for structural monitoring applications. The geometry of the interface and electrode configuration significantly influenced both mechanical and electrical behavior, highlighting the need for careful optimization. Polarization effects were also identified and addressed to ensure accurate readings.

Overall, the study demonstrates that SHCC with PVA and carbon fibers can function as both structural and sensing elements. Their use in demountable connections supports the development of intelligent, sustainable, and reusable infrastructure. Future work should focus on long-term durability, optimization of geometry and mixture design, and scalability toward practical applications, paving the way for smart, adaptive cementitious systems in modern construction.