Exploration of novel additives to portland cement binder systems

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On an annual basis the combined cement and oil exploration/production industries account for almost one quarter of Canada's total green house gas emissions. Both industries are actively identifying and implementing changes to help reduce their carbon footprint. Carbon Upcycling Technologies (CUT) is an important part of that effort, exploring new opportunities for concrete additives that could have a major impact in terms of increased durability and carbon sequestration. CUT has developed a process for the production of carboxylated graphine oxide (GO) nano-sheets by capturing waste carbon dioxide from cement kilns and upstream petroleum flaring/incinerating/venting operations. GO nano-sheets represent an exciting new technology for concrete, with reported improvements in compressive and tensile strength. The high surface area of these particles provide abundant nucleation sites for the growth of the calcium-silicate-hydrate phases that bind aggregates together in concrete. At the same time, GO nano-sheets can adsorb water and other organic admixtures, and may interfere with fresh concrete workability. This research program will investigate GO nano-sheet interactions with commonly used concrete admixtures, specifically air-entraining and water-reducing agents, and identify strategies to overcome any adsorption-related incompatibilities. CUT is also exploring a two-part metal-oxide and potassium phosphate (K-phosphate) based additive that has been demonstrated to enhance the compressive strength of concrete, but may also improve the corrosion resistance of embedded steel. The research program will investigate corrosion-related durability aspects of both the GO nano-sheet and K-phosphate additives in terms of chloride permeability/diffusion and accelerated corrosion testing.