Self-sensing performance of cementitious composites with functional fillers at macro, micro and nano scales

Self-sensing cementitious composites have attracted substantial attention as a multifunctional construction material for structural health monitoring (SHM). This study aimed to develop self-sensing cementitious composites using a combination of macro, micro and nanoscale conductive fillers, as the hybrid fillers can take advantage of different types of conductive fillers and create a synergistic effect. Magnetite aggregate (MA), carbon fibre (CF) and carbon nanotube (CNT) were combined and used as the conductive fillers for the fabrication of self-sensing cementitious composites, where the mechanical properties, electrical properties and piezoresistive performance were studied. The MA at 100 wt% achieve the optimal mechanical properties, leading to a 5% increment in compressive and a 25% increment flexural strength with a value of 37.3 and 5.7 MPa. Additionally, multiple reinforcing effects were achieved when combining different types of functional fillers, which a single filler cannot achieve. The best conductive filler combination is MA, CF and CNT hybridisation, each at 100, 0.3 and 0.05 wt%, respectively. A 17% improvement in terms of compressive strength can be observed. And the piezoresistive response can achieve a maximum fractional change in resistivity of 44.7% and demonstrates enhanced linearity, repeatability, signal to noise ratio and stability.

Automated summary

This study develops self-sensing cementitious composites using a combination of various conductive fillers, such as magnetite aggregate, carbon fiber, and carbon nanotube, to enhance their mechanical properties, electrical properties, and piezoresistive performance. The optimal conductive filler combination is found to be MA, CF, and CNT hybridization, each at specific weight percentages, leading to significant improvements in compressive strength and piezoresistive response.