Journal Article

COsub.2 Diffusion and Carbonation in OPC/γ-2CaO·SiOsub.2 Composite

Song, Myong-Shin, Kang, Seung-Min, Lee, Woong-Geol, Moon, Kwang-Kyun

2023

Overview

Gamma dicalcium silicate (γ-2CaO∙SiO[sub.2], abbreviated as γ-C[sub.2]S) is considered a potential candidate as a construction material owing to its high carbonation reactivity and consequent CO[sub.2] absorption. This study investigates the diffusion of CO[sub.2], a physical process, into hardened cement paste and the resulting carbonation, a chemical process. CO[sub.2] diffuses from a region of high concentration to one of a lower concentration, which is the inner core of the hardened cement. This study aimed to examine whether the diffusion of CO[sub.2] into the ordinary Portland cement (OPC)/γ-C[sub.2]S composite paste followed the conventional laws of diffusion. We also studied the diffusion of CaCO[sub.3] to determine if carbonation products were formed in the pores and examined the capture of CO[sub.2]. The paste specimens were prepared and subjected to CO[sub.2] in the carbonation chambers for varying periods. The results showed that the CaCO[sub.3] deposited in the pores affected the rate of diffusion of CO[sub.2] in the mortars and pastes, resulting in the densification of such bodies and a decreased rate of diffusion, leading to the shutdown of diffusion. The diffusion of CO[sub.2] in hardened cement pastes made from OPC and γ-C[sub.2]S follows Fick’s second law, wherein there is a change in the concentration of CO[sub.2] diffusing at a particular distance with time.

• Publisher: MDPI AG
• Subject: Lime