Speaker 1: Heongwon Suh, Hanyang University, South Korea
Title 1: Fire-Resistance Mechanisms in Low-Lime Calcium Silicate Cement as a Carbonatable Binder
This study investigates the thermal resistance mechanism of a low-lime calcium silicate cement (CSC) and ordinary Portland cement (OPC) blend paste cured in a carbonation environment. The effects of heating (200–800°C) were analyzed through compressive strength, surface cracks, and volume changes. X-ray diffraction (XRD) with Rietveld refinement and thermogravimetric analysis (TGA) provided insights into qualitative and quantitative changes in reaction products. Additionally, synchrotron X-ray nanoimaging was employed to examine the nanoscale structure of reaction products and its correlation with thermal resistance. Findings highlight the physicochemical transformations that contribute to improved fire resistance in CSC-OPC blend cement pastes.
Speaker 2: Zhenli Yang, University of Tokyo, Japan
Title 2: Impacts of ethylenediamine on crystallization and morphology of calcium carbonation.
The sequestration of CO2 into a precipitated mineral carbonate through a wet-carbonation process is a promising option for carbon capture and storage. By controlling polymorphs and properties, calcium carbonates (Cc) can be converted into value-added industrial materials. A classical way to achieve this is a two-step carbonation, including extract Ca2+ by additives such as amines, and then reaction CO2 . Here, we use an one-step, direct carbonation using ethylenediamine (EDA) at various dosages (1%, 5% and 10%) to control the Cc polymorph and crystallization process. The effects of EDA on carbonation process of hardened cement paste were investigated from two sides: the liquid phase and the solid phase.The results indicate that 5% EDA achieves the highest carbonation degree, generating the most Acc, which later transforms to vaterite. The absorption and complexation of EDA within Acc have greatly disrupts lattice structure of the formed Cc precipitates and alters its crystallization from calcite to vaterite.
This webinar is brought to you by the RILEM Youth Council (RYC) and hosted by Seongmin Cho (East Asia RYC representative).
