Electrical properties of ultra-high-performance concrete with various reinforcing fibers

Abstract

Understanding the electrical properties of ultra-high-performance concrete (UHPC) is of paramount importance in the realm of smart concrete as it unlocks the potential for creating advanced, intelligent, and resilient infrastructure systems. This study focused on systematically assessing the electrical behaviors of UHPC with two commonly-used reinforcing conductive fillers, i.e. carbon fibers (CFs) and steel fibers (SFs). The effects of fiber type, fiber length, fiber content, and curing age on the alternating current (AC) resistivities and AC electrochemical impedance spectroscopy (AC-EIS) spectra of fiber-reinforced UHPC were investigated, and the equivalent circuit models of fiber-reinforced UHPC were established. Experimental results showed that the AC resistivities of UHPC with CFs and with SFs both exhibited a faster growth rate during the 14–28 d of curing, but subsequently decelerated after the completion of hydration, and stabilized at 90–120 d. Compared with the control sample, the addition of both CFs and SFs resulted in a reduction of the electrical resistivity of UHPC, with a more pronounced decrease observed with higher fiber content. In particular, the addition of SFs demonstrated a more significant reduction in UHPC’s AC resistivity in relative to CFs, with the addition of 4 vol.% copper-plated end-hook SFs remarkably lowering the resistivity by up to 87.5%. Furthermore, the introduction of different types of fibers caused remarkably different AC-EIS topologies of UHPC. The proposed equivalent circuit models reveal that compared to the control sample, the introduction of fibers can provide the fiber-fiber conductive paths and fiber-wrapped hydration products (Q F R F) within UHPC matrix. The role of UHPC matrix (Q 1 (R 1 W 1) in the conductive path of SFs-reinforced UHPC is weakened compared to that of CFs-reinforced UHPC as reflected by the differences in the impedance values of Nyquist plots.

The pioneer of intelligent and sustainable construction in tunnel shotcrete applications: a comprehensive experimental and numerical study on a self-sensing and self-heating green cement-based composite

“…The convergence of nanotechnology and concrete science has given rise to a groundbreaking era in construction materials, where self-sensing and self-heating capabilities are seamlessly embedded into the electrical conductive concrete matrix [5,[33][34][35]. Self-sensing concrete involves the incorporation of conductive fillers such as carbon nanomaterials (CNMs) and microfibres including steel and carbon fibres, forming a conductive network that can detect variations in strain, stress, or other structural parameters within the concrete [1,13,[36][37][38][39]. This real-time monitoring capability offers unprecedented insights into the structural health of the material, enabling early detection of potential issues and facilitating timely maintenance interventions [40][41][42][43][44][45].…”

Influence of cement and water content on the multifaceted capabilities of a self-sensing cement-based geocomposite: a comprehensive analysis

“…Implementing real-time monitoring of these inherent damages during the initial stages can effectively curtail their progression, extend the service life of structures, reduce maintenance expenses, and avert the abrupt failure of these constructions [4,12,13]. This continuous damage detection and monitoring process and the assessment of the condition of engineering infrastructures is often referred to as structural health monitoring (SHM) [14][15][16]. SHM relies heavily on measurement principles to collect data on factors such as structural deformation, vibration, temperature, and corrosion, among others [15,17].…”