Advanced Chemically Bonded Ceramics for Medicine and Environment

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In this work we will research the basics of micro-fibrous reinforcement of the novel bone cements, in particular the Calcium-Phosphate-Silicate Cement (CPSC) and Geo-Polymers (GP), en-route to trigger and assess self-healing processes in these materials. Our most stunning discovery in the area of bioceramic cements was their potential for self-healing in the simulated biological environment (SBF). These novel bioceramics consolidate and strengthen near- room temperature, are strain-tolerant (maintain > 80% strength at ~2% strain, with fracture toughness > 2 kJ/m2) and can repair themselves through the “smart” interaction with the micro-environment within the cracks. We consider this discovery important enough to extend its investigation to environmental ceramics, such as chemically bonded Geo-Polymers (GP). Here we will target environmental remediation including “green” cements, in the long term possibly replacing Portland cement, capture of heavy metals, or stabilization of mine tailings. Specifically, we propose research into toughening and self-healing of the two types of strain-tolerant chemically-bonded ceramics: (1) hydraulic phosphate-modified calcium-silicates (CPSC) for biomedical applications (orthopedic, dental), and (2) polymeric low-cost alkaline alumino-silicates (GP) for large-scale environmental applications. Two research themes are defined as follows: Theme 1: Basic and Applied Studies on Self-Healing of Toughened (Strain-Tolerant) Phospho-Silicate Biocements. The long-term objective is to develop process technology for the novel orthopedic/dental bio-cements alternatives superior to calcium phosphate cements. In the shorter term we will study the fundamental aspects of the recently discovered self-healing and mechanical performance of toughened CPSC; and determine the effects of materials processing and materials characteristics on drug-delivery characteristics of such strain-tolerant CPSC biocements. Theme 2: Basic and Applied Studies on Self-Healing Toughened (Strain-Tolerant) Structural Geo-Polymers. The long-term objective is development of process technology for the composite Strain-Tolerant Geo-Polymers (STGP) with self-healing characteristics, for variety of large-scale environmental and structural applications. In the shorter term we will develop processes for dispersion and bonding of short fibers within GP; study the effects of interactions between the various toughening phases and GP variants on the mechanical, thermal and chemical properties of the novel STGP; and study and develop self-healing mechanisms for STGP.