Early Age Carbonation Heat and Products of Tricalcium Silicate Paste Subject to Carbon Dioxide Curing

• Published in: Materials Vol. 11; no. 5; p. 730
• Main Authors: Li, Zhen, He, Zhen, Shao, Yixin
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 04.05.2018; MDPI
• Subjects: Calcite; Calcium carbonate; Calcium silicate hydrate; Calcium silicates; Carbon dioxide; Carbonation; Compressive strength; Curing; Electron microscopes; Energy transmission; Heat transmission; Hydration; NMR; Nuclear magnetic resonance; Retrofitting; Silicon dioxide; Tricalcium silicate; X-ray diffraction; carbonation heat; CO2 uptake; 29Si MAS NMR; carbonation curing; TEM-EDS
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma11050730

This paper presents a study on the carbonation reaction heat and products of tricalcium silicate (C3S) paste exposed to carbon dioxide (CO2) for rapid curing. Reaction heat was measured using a retrofitted micro-calorimeter. The highest heat flow of a C3S paste subject to carbonation curing was 200 times higher than that by hydration, and the cumulative heat released by carbonation was three times higher. The compressive strength of a C3S paste carbonated for 2 h and 24 h was 27.5 MPa and 62.9 MPa, respectively. The 24-h carbonation strength had exceeded the hydration strength at 28 days. The CO2 uptake of a C3S paste carbonated for 2 h and 24 h was 17% and 26%, respectively. The X-ray diffraction (XRD), transmission electron microscope coupled with energy dispersive spectrometer (TEM-EDS), and 29Si magic angle spinning–nuclear magnetic resonance (29Si MAS-NMR) results showed that the products of a carbonated C3S paste were amorphous silica (SiO2) and calcite crystal. There was no trace of calcium silicate hydrate (C–S–H) or other polymorphs of calcium carbonate (CaCO3) detected.