RESOURCES

Abstract
Abstract Ceramics with controlled porosity are used as bio-scaffolds, insulators, electrodes and lightweight materials. While their high surface area and low weight are attractive functionalities, such porous ceramics often suffer from poor mechanical properties and need energy-intensive, high-temperature sintering for manufacturing. The present work reports a low-temperature approach for the manufacturing of mechanically efficient porous ceramics. The process relies on the 3D printing of inks loaded with ceramic hollow spheres, which are biocemented by the precipitation of calcium carbonate induced by ureolytic bacteria. Electron microscopy, thermogravimetric analysis and mechanical tests are performed to study the kinetics of the biocementation process and its effect on the calcification and mechanical properties of extruded and printed samples. Hierarchical porous ceramics with a grid-like architecture and filament sizes in the order of one millimeter are effectively biocemented at ambient temperature after 2 days of calcification. The calcified structures display higher mechanical efficiency than previously reported monoliths of comparable porosity, thus demonstrating the potential of 3D printing and bacteria-driven biocementation for the low-temperature fabrication of hierarchical porous ceramics.