Accelerated carbonation of alkali-activated blended blast furnace slag and wood fly ash: Carbon capture kinetics, chemical and mechanical evolutions

The influence of fly ash/slag ratio, alkaline activator silica modulus (Ms), and curing method have been evaluated on the carbonation of biomass fly ash and blast furnace slag blends. In addition to quantifying the CO2 sequestration capacity, the influence of carbonation on the chemical and mechanical properties of materials was explored to assess their durability. Results show that higher fly ash contents lead to higher CO2 diffusion, while slag limits carbonation to the surface of specimens. A higher fly ash content induces higher carbonation at Ms= 0 (as high as 0.36 mmol/g), while the most significant adsorption at a high slag content is obtained at Ms= 1.32 (as high as 0.33 mmol/g). Carbon capture and storage values as high as the pressure decay chamber recorded 0.36 mmol/g, while TGA shows the adsorption capacity of the binder as high as 3.69 mmol/g. Mechanical strength variation is proved to be a function of Ca/Si and is evaluated accordingly.