3D-Printed Smart Reinforced Beam for Strain Monitoring

The automation of concrete constructions through 3D printing has garnered considerable attention in civil engineering due to significant advantages over conventional methods. Nevertheless, the widespread adoption of this technology faces substantial challenges stemming from inherent uncertainties associated with the additive manufacturing process. A solution is to functionalize the 3D printed components with self-sensing capabilities to monitor performance during construction and operation and thus assess quality in real-time. Here, we study the local functionalization of 3D printed components through a hybrid 3D printing process. To do so, we build on prior work in self-sensing cementitious composites by integrating graphite powder and carbon microfbers as conductive fllers into cement-based mixtures to generate substantial piezoresistive capabilities. The technology is demonstrated on a 3D printed reinforced concrete beam. The smart beam is fabricated using a self-sensing composite at the bottom, followed by a continuous transition to a traditional cementitious mix. The printed self-sensing layers serve as strain-responsive interfaces capable of mapping strain field evolution by continuously monitoring changes in electrical resistance. A series of quasi-static and dynamic tests were performed to characterize the strain-sensing performance of the developed composite specimens. Results demonstrate the successful integration of self-sensing cementitious materials into the 3DP fabrication process, highlighting their potential for real-time monitoring of construction quality, detection of load-path alterations, and early identification of structural defects.