US: CO2-sequestering alternative cement developer CarbonCure and the Massachusetts Institute of Technology Masic Lab have published a study establishing a new chemomechanical framework for CO2 mineralisation in cement. The study found that early-age CO2 injection fundamentally reroutes cement hydration by introducing a transient reactive silica gel phase. This phase templates a more homogeneous calcium-silicate-hydrate (CSH) microstructure and increases 24-hour compressive strength compared to reference samples.
The study concluded that mechanical gains in CO2-activated systems are not solely attributable to the pore-filling effect of nanocarbonates, but are ‘significantly’ driven by alteration of the hydration sequence. As such, the researchers advised that the optimisation CO2 utilisation technologies should focus on controlling the kinetics of silica gel generation and consumption as well as the degree of carbonate formation.