High-temperature electric induction constructing conductive UHPC: Effect of curing regime on stability of conductive network and mechanical properties

The resistivity of ultra-high-performance concrete (UHPC) can be effectively reduced by the dielectric breakdown phenomenon arising from the high-temperature electric induction, endowing UHPC with potential multifunctional applications. However, the instability in the resistivity of conductive UHPC is presented owing to the short duration of the electric field. In this study, the influence of electrical field duration on the stable formation of conductive networks in UHPC was explored. It turned out that the resistivity of UHPC with 2-h electric field duration after dielectric breakdown can be maintained at a steady low level (decreased from 66 kΩ·cm to 403.56 Ω·cm compared to that of steam-cured UHPC), and it also exhibited a superior compressive strength (137.9 MPa) comparable to that with 3-day steam curing (135.1 MPa), while its energy consumption was accounted for only 11 % required for steam curing. XRD and TG analysis proved the enhanced effect of the electric field on the hydration degree of UHPC, accompanied by the emergence of tobermorite and aragonite products. Moreover, the MIP experiment indicated that the pore structures of UHPC were gradually refined with the electric field duration. This work had opened up a new path for constructing an effective conductive network and rapidly enhancing the electrical and mechanical properties of UHPC.