Increasing efficiency of carbon dioxide sequestration through high temperature carbonation of cement-based materials

Too high moisture content prevents CO2 from penetrating into the inner part of samples, compromising CO2 diffusion and overall carbonation effect.

“It is believed that too high moisture content prevents CO 2 from penetrating into the inner part of samples [31,87,91,94,95], therefore compromising CO 2 diffusion and overall carbonation effect.”

Rising temperature accelerates diffusion of CO2 and leaching of calcium ions yet reduces solubility of CO2 and calcium ions in liquid.

“This is because rising temperature accelerates the diffusion of CO 2 and the leaching of calcium ions [48,91] yet reduces the solubility of CO 2 and calcium ions in liquid.”

For carbonation at elevated temperature, high water content may benefit carbonation.

“However, for the carbonation at elevated temperature, high water content may benefit carbonation [91].”

Small RCA tend to have a high mass percentage of old mortars containing high calcium composition available for carbonation, and small RCA have a larger specific surface area in contact with CO2 compared to large particles.

“This is attributed to (i) small RCA tend to have a high mass percentage of old mortars containing high calcium composition available for carbonation [54,79,86] and (ii) small RCA have a larger specific surface area (in contact with CO 2 ) compared to RCA with large particles [91].”

In [91], highest CO2 sequestration appeared at approximately 80°C, while a much higher temperature over 80°C up to 300°C reduced final CO2 uptake.

“The measured experimental results in [91] showed that the highest CO 2 sequestration appeared at approximately 80 • C, while a much higher temperature over 80 • C (up to 300 • C) reduced the final CO 2 uptake.”