Carbon uptake potential and reactivity of synthetic calcium magnesium aluminosilicate glasses

In order to achieve zero-carbon concrete, high replacement levels of cement by SCMs as well as carbon capture and utilization (CCU) methods need to be exploited as much as possible. Enforced carbonation of calcium aluminosilicate glasses has the ability to shed light on the complex carbon uptake behavior in supplementary cementitious materials (SCMs). In addition to the carbon uptake, the process could lead to an increase in reactivity is SCMs through the formation of limestone and a calcium-poor Si-Al-gel. In this study, we use synthesized calcium aluminosilicate glasses with a range of compositions and investigated their carbon uptake potential and the effect of enforced carbonation on their reactivity. For this, various compositions of synthesized glass powders (the compositions of the glass powders cover a range of Ca/Si and Al/Si ratios) were carbonated using different methods ranging from moist carbonation to wet carbonation to autoclaving. The effectiveness of the processes was evaluated by comparing the carbonated and uncarbonated glass powders using thermogravimetric analysis and several other methods. The reactivity of the powders before and after carbonation is investigated by applying the modified R3 test. Results showed that CO2 uptake in calcium aluminosilicate glasses was negligible. This is an interesting finding as SCMs are commonly studied for CO2 uptake, and our results show up to 25% CO2 uptake in SCMs. The reasons that the synthetic glasses do not show uptake are being investigated. It is possible that minor impurities drive the uptake, or that crystalline and amorphous phases show very different uptake behaviors. The results will provide a better insight into the type of materials that are most promising in terms of CO2 uptake and pozzolanic reactivity to be applied as SCMs after a CCU treatment. These findings that have important implications in the emergence of SCMs contributing to zero-carbon concrete in the future.     «

In order to achieve zero-carbon concrete, high replacement levels of cement by SCMs as well as carbon capture and utilization (CCU) methods need to be exploited as much as possible. Enforced carbonation of calcium aluminosilicate glasses has the ability to shed light on the complex carbon uptake behavior in supplementary cementitious materials (SCMs). In addition to the carbon uptake, the process could lead to an increase in reactivity is SCMs through the formation of limestone and a calcium-poo...     »