Ettringite, a Novel Piezoelectric Source Crystal for Energy Harvesting Materials

The research objective of this Materials Engineering and Processing Collaborative Research project is to quantitatively and unambiguously verify ettringite as a piezoelectric mineral. As hypothesized, if ettringite is the piezoelectric source in calcium sulfoaluminate (CSA) cement; this discovery will enable the functionalization of calcium sulfoaluminate cement as a potential material for energy harvesting in civil engineering structures. The project will build on established multidisciplinary relationships between academic departments and centers and international collaborators that create an exceptional educational environment where students work on scientifically challenging problems with substantial potential for innovation. The overarching objective of this project is to functionalize calcium sulfoaluminate cements for energy harvesting and as a smart-sensing construction material. The aims of the research are (i) to develop the science base needed for utilization of ettringite as a piezoelectric mineral, (ii) identify, isolate and evaluate potential piezoelectric influences within the CSA mortar matrix, and (iii) the development of engineering approaches that allow efficient assessment for ettringite-based energy harvesting piezoelectric components for civil structures. Key elements of the strategy include (i) determine the piezoelectric constants of the mineral ettringite, (ii) expand the view on other potential sources of piezoelectric voltage within the hydrated CSA cement matrix; such as crystal morphology or alignment, and (iii) fabrication and piezoelectric testing of large-scale concrete elements optimized for energy harvesting. If successful, the discovery and characterization of ettringite as a piezoelectric crystal phase in cement will create new knowledge on energy harvesting from calcium sulfoaluminate cement materials. The data on material properties and piezoelectric potential of ettringite-rich cementitious structural elements will not only enable the functionalization of construction materials as energy harvesting components but also will lay a solid foundation for future piezoelectric cementitious design.