Development and implementation of concrete sensor with MWCNT for health monitoring of beams

Abstract The study focuses on developing self-sensing concrete sensors using Multi-Walled Carbon Nanotubes (MWCNTs) as conductive fillers. Concrete containing an appropriate amount of MWCNT exhibited efficient strain-sensing behaviour. The mix with 0.5% MWCNT and a maximum aggregate size of 6 mm was identified as the most effective composition for strain sensing. Durability tests were conducted to assess the suitability of the self-sensing concrete, developed with MWCNTs, for long-term use and structural integrity. The strain in self-sensing concrete is quantified through the Fractional Change in Resistance (FCR) between the embedded electrodes. A concrete sensor of size 25 mm × 25 mm × 200 mm, with electrodes placed at one-third of its length, demonstrated the most pronounced strain-sensitive FCR for flexural strain. A relationship between flexural strain and FCR is proposed for the developed concrete sensor. Flexural tests on reinforced concrete beams confirmed the sensor’s accuracy for precise strain measurement. The sensor was used for damage detection in beams with predefined damage, shown by changes in flexural rigidity ( EI ). A Genetic Algorithm (GA)-based procedure, using strain measurements at sensor locations, was first validated on beams with known EI under noisy data. When applied to beams equipped with the concrete sensors, the procedure accurately identified both the location and extent of damage. The developed concrete sensors eliminate the need for traditional electronic strain sensors. Compared to typical strain gauges, they offer better durability, ease of integration, and the capability for continuous real-time strain monitoring, thereby contributing to a sustainable solution for structural health monitoring.