Development of robotic sprayable self-sensing cementitious material for smart structural health monitoring

Abstract

Self-sensing cementitious materials are critical to smart structural health monitoring with the piezoresistivity as an indicator for internal stress and cracks in the structure, which have been frequently utilized as functional coatings in engineering practices. To facilitate the automatic deployment of self-sensing cementitious materials, the compatibility with robotic spraying has been systematically investigated in this study. Pre- and post-spraying evaluations have been conducted for the mixtures with carbon fibers at different dosages, including rheology, tackiness, compressive strengths, and electromechanical responses. On this basis, the addition of 0.4 vol.% carbon fiber was confirmed as the optimal dosage with both competent spraying performance and self-sensing function in the corresponding mixture. Furthermore, the porosity characteristics and fiber agglomeration of the designed mixtures were quantitatively assessed by micro computed tomography (micro-CT), which suggested their relationship to the mechanical and self-sensing properties. Apart from the structural application potential of the developed self-sensing mixture, this study also provides detailed guidance for the optimization of other value-added robotic sprayable cementitious materials.