Accelerated carbonation progress in cementitious materials and its microstructure

Abstract:

The carbonation phenomenon of cement-based materials is considered critically important for future developments in the cement industry, particularly from a durability perspective, as the field moves toward reducing the clinker ratio to lower CO₂ emissions. In countries like Japan, where lowering the clinker ratio is industrially challenging, carbonation is also regarded as a valuable means of CO₂ uptake, contributing to the sequestration of CO₂ within concrete structures.
In this presentation, we investigate the mechanisms governing accelerated carbonation tests, which are commonly used as a proxy for natural carbonation. Specifically, we conduct accelerated carbonation at 5% CO₂ concentration on cement pastes with different Ca/Si ratios in their C–S–H phases, aiming to elucidate how the progression of the carbonation front is rate-limited under various conditions.
The second part of the presentation focuses on a commonly used characterization method for cementitious materials—thermogravimetric analysis (TGA). We address the observation that CO₂ is released from carbonated cement pastes at unexpectedly low temperatures during heating. While this low-temperature decomposition region (below 600°C) has traditionally been attributed to the breakdown of vaterite, aragonite, or amorphous calcium carbonate, we demonstrate that it may in fact result from different underlying phenomena.

Short bio:

Dr. Ippei Maruyama is a professor at the University of Tokyo. He is a visiting professor of the Museum at Nagoya University and of the Research Center for Green X-tech at Tohoku University. He earned his B.Eng. in 1998, M.Eng. in 2000, and Dr.Eng. in 2003 from the University of Tokyo. Before he joined the University of Tokyo, he was an assistant professor at Hiroshima University (2003-2005), associate professor (2005-2016), and professor (2016-2022) at Nagoya University.
He is the chair of the International Committee on Irradiated Concrete, the editor-in-chief of the Journal of Advanced Concrete Technology, and an associate editor of Materials and Structures. He is leading several national projects relating to the aging management of concrete structures in nuclear power plants, the Fukushima Daiichi decommissioning process, the calcium carbonate circulation system for construction, and the standardization of quantification methods for mineralized CO2 using cementitious materials.
His current research topics include atomic-scale studies of the colloidal nature of C-S-H, design of concrete structures, wood materials, radiation physics and chemistry for concrete, multi-scale modeling of concrete and concrete structures, and application of calcite concretion.