Low CO2 cement to prevent thaumasite formation

This project investigates the use of cement blends containing calcined clay and limestone for marine infrastructures with the aim of reducing CO2 emissions associated with marine construction. The investigated cement blends offer environmental benefits but concerns about their durability in harsh environments like cold, sulfate-rich seawater have not been answered yet. Previous studies indicate that cement containing limestone forms thaumasite when exposed to sulfate containing solutions, which could also apply to seawater. Thaumasite is not stable above 20 degrees and this durability concern is therefore only relevant for concrete exposed to cold temperatures, such as the temperatures we experience in Denmark. The formation of thaumasite can cause damage to the surface of concrete, which can eventually expose the reinforcement and lead to shortened service lives for constructions in the marine environment.

This project investigates the formation of thaumasite and how it can be prevented in calcined clay and limestone formulations. The project uses a combination of laboratory experiments, thermodynamic modeling, and field exposure.