Binder jetting of geopolymer matrices containing hydrated salts for thermal energy storage applications

This thesis presents the research conducted at the Department of Industrial Engineering (DII), University of Padua, focusing on the fabrication of highly porous fiber-reinforced composites with a geopolymer matrix, designed for thermal energy storage via hydrated salts for the 3D printing production. A topic that has recently become of greater interest to industry, particularly in the field of sustainable energy and environmental concerns. The focus of the activity was on three main subsets: the selection of a stable thermochemical hydrated salts for energy storage, the choice of a suitable material as reinforcement in the preparation of composite, and the investigation of differences in behavior between impregnated and infiltrated states of various materials. The powder mix obtained from Metakaolin and lightweight aggregates, such as Vermiculite, Poraver and Perlite. The characterization of the products obtained consisted of: boiling tests, mechanical compression and bending tests, evaluation of geometric, apparent and real density (the last two using a pycnometer), optical microscopy, analysis of the crystalline microstructure using XRD, and TGA analysis. The results obtained suggest that, considering both the stability of aluminum sulfate and its thermochemical behavior, this salt represents the most suitable choice for the intended application. Furthermore, although the test results indicate better performance for Poraver compared to Perlite, the latter can be considered a more appropriate option for construction application to be printed using a 3D printer due to its favorable open porosity-to-salt/volume ratio.