Materials

Alkali-activated materials are low-CO₂ alternatives to ordinary Portland cement-based concretes. These systems use aluminosilicate-rich earth materials (calcined clays such as metakaolin) or industry by-products (ground granulated blast furnace slag and/or coal-derived fly ash) as the main constituents and do not contain any OPC powder in mix designs. By alkali-activating the aluminosilicate and calcium precursors using hydroxide, silicate and/or carbonate-based activators, the resulting systems possess similar mechanical performance to OPC-based systems at a much reduced CO₂ cost to the environment.

Current research in the group is focused on understanding the durability of these materials, specifically the chemical mechanisms controlling long-term degradation in certain aggressive environments (e.g., sulfates, CO₂). Furthermore, short-term durability issues, such as drying-induced microcracking, are being investigated from a fundamental chemistry/physics viewpoint, with potential mitigation avenues being explored in the lab.

Carbonate Materials

Carbon sequestration is an area of research to address the increasing amounts of CO₂ being released into the atmosphere. One aspect of this technology involves injecting CO₂ into depleted geological formations so that the CO₂ molecules react with existing phases to form stable mineral compounds. Other technologies include sequestering CO₂ above ground, such as via minerals carbonation. Therefore, understanding materials containing carbonate phases (various forms of CO₃) is of relevance for carbon storage, including cementitious materials that come in contact with CO₂ during the sequestration stage. SCG is investigating the disordered carbonate phases that can develop in alkali-activated materials when exposed to elevated CO₂ levels, and has shown that the development of ‘stable’ amorphous carbonates is linked with a lower extent of binder (cement) degradation.