3D printed smart repairs for civil infrastructure

This paper outlines the development of 3D printed smart materials for civil infrastructure repair and monitoring. The materials employed in this project are metakaolin-based geopolymers, characterized as "smart" due to their ability to simultaneously sense and repair steel and concrete structures. As metakaolin geopolymers attain comparable mechanical properties to ordinary Portland cement and favourable adhesive characteristics, they can be used to restore the structural integrity of degraded concrete elements. Geopolymers furthermore exhibit a pronounced electrical conductivity due to the presence of free ions in their matrix. Geopolymers can therefore be used to detect variations in strain and temperature through changes in electrical impedance. In essence, these are repair materials that also enable constant monitoring. In this project, smart materials are being extruded with the assistance of a 3D printer, and will ultimately be robotically applied. The extrusion of smart cement patches via a 3D printer allows greater versatility of design and improved geometrical repeatability. Patch shape and size can be easily adjusted according to the requirements of each given circumstance, while robotics will allow printing in areas with hazards or limited access. In this paper, we will present our latest progress in printing and characterising the mechanical and electronic properties of geopolymer patches, and discuss how raw sensor data can be interpreted into measures of structural health. We will also outline the challenges in the system’s design, and describe the future work required to scale the technology up to real industrial applications.

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