Preparation aragonite whisker-rich materials by wet carbonation of cement: Towards yielding micro-fiber reinforced cement and sequestrating CO2

In this study, an innovative wet carbonation process was developed to prepare aragonite whisker-rich materials (AWM) from cement and simulated flue gas, which subsequently served as micro-fiber additions to cement. The parameters including temperature, duration and MgCl2 concentration governing the aragonite formation were investigated, and the formation mechanism was explored. The results showed that needle-like aragonite whisker with a single crystal length of 10–30 μm and diameter of 0.5–2 μm could be synthesized rapidly when the cement suspension containing 0.05 M/L MgCl2 was carbonated at 80 °C. The formation of aragonite was favored in a suspension with a high concentration of Ca2+ and a minimum Mg2+/Ca2+ molar ratio >0.12. Additionally, amorphous phases including alumina-silica gel and silica gel were also detected. By mixing the AWM with cement, a new type of micro-fiber reinforced cement was developed, which showed significant mechanical performance improvement and embodied CO2 content (25.3 %).