CEE Ph.D. Defense Announcement: Low-CO2 Cement Synthesis and Durable Cementitious Materials for Sustainable Concrete Infrastructure

Abstract: Improving the sustainability of concrete infrastructure requires simultaneous decarbonization of cement production and extension of structural service life. Conventional Portland cement manufacturing is highly carbon-intensive due to limestone calcination and fossil-fuel combustion, while concrete structures frequently require repair and rehabilitation because of cracking and deterioration. Addressing only one stage of the lifecycle is insufficient. This dissertation advances sustainability at both the materials production stage and the structural use stage.

First, a novel electrochemical pathway is developed for synthesizing Portland cement and alkali-activated cementitious materials. Instead of relying on conventional limestone calcination, this approach utilizes electrochemically generated calcium hydroxide combined with silica- and alumina-rich sources derived from natural minerals and industrial waste streams. This method shifts cement manufacturing from a fossil-fuel-driven thermochemical process to a cleaner electrochemical route. The effects of raw material composition, oxide ratios, and thermal conditions on clinker phase formation were systematically investigated. A synthesis strategy was established that produces cement clinker phase compositions and physical properties comparable to ordinary Portland cement, while significantly reducing associated CO₂ emissions.

Second, the dissertation enhances structural durability through the development and mechanistic investigation of intrinsically self-healing cementitious materials. Crack healing behavior, healing products, and healing efficiency were examined under varying environmental exposure conditions. The study elucidates the chemical and microstructural mechanisms governing autonomous crack closure and strength recovery in ultra-ductile, high-strength cementitious systems.

Together, these contributions establish a dual-pathway framework for sustainable concrete infrastructure: reducing embodied carbon during material production while extending service life through intrinsic durability improvement. The findings connect fundamental cement chemistry with cementitious materials performance and lifecycle sustainability, establishing scalable strategies for low-carbon, durable concrete systems.