Mechanical and piezoresistive behaviour of 3D printed self-sensing one-way concrete slab

Self-sensing concrete is a smart concrete that can sense the stress, strain and to predict the cracking in concrete members. This study utilizes an extrusion-based 3D machine to print self-sensing reinforced one-way concrete slabs to compare with casted counterparts. Activated carbon powder and carbon fibres were used in the mix to act as functional fillers for the self-sensing concrete, improve the fibre alignment and to enhance the fibre-matrix bond of the 3D printed sample. Mechanical experiments (compressive and four-point flexural strength), electrical resistivity as well as piezoresistive response are conducted to understand the cracking behaviour. The carbon composites also enhance the mechanical strength of the concrete mix, reaching 56.02 MPa of compression strength in the parallel print direction and 355.55 Ω.cm of resistivity. Furthermore, the piezoresistive response of the prisms was also investigated, the perpendicularly printed 3D specimens provided the best response, exhibiting a strong fit with the predictive equation. This study presents a novel approach to fabricating self-sensing concrete slabs using 3D printing, enhancing their potential for real-time structural health monitoring.