Electromechanical Response of Smart Ultra-High-performance Concrete under Uniaxial Load: Experimental Investigation and Electric Field Analysis

This study explores the electromechanical response of smart ultra-high-performance concrete (S-UHPC) under uniaxial tension and compression using both attached and embedded electrodes with direct current. Within the linear elastic region, the response of S-UHPC was influenced by the type of electrode due to the deformation of the silver paste used in the attached electrodes. Furthermore, although the electromechanical response of S-UHPC beyond the linear elastic region showed minimal variation between different electrode types, their self-sensing capabilities were significantly affected by the choice of electrode. Under uniaxial tension, the electrical resistivity of S-UHPC decreased marginally up to the limit of proportionality and then more substantially beyond it, primarily owing to the formation of matrix cracks. This reduction in electrical resistivity associated with crack formation was corroborated through electrical field analysis performed using COMSOL MultiphysicsⓇ. A key finding was that the decrease in electrical resistivity (from 0.1788 to 0.0286 kΩ·cm, -84.0 %) in the tensile strain-hardening region could be attributed to an increase in electrical current density within steel fibers; specifically, the current density increased from 0.2417 to 0.7047 A/mm2 as the number of matrix cracks increased from zero to seven.