Influences of CO₂‐cured cement powders on hydration of cement paste

Abstract

Carbonated cement pastes (CCP) can be used as stable carbon storage. In this work, CCP were systematically investigated as supplementary cementitious materials (SCMs)-like components used in ordinary Portland cement (OPC) paste. The fully hydrated cement pastes were pulverized into powders and then exposed to different CO 2 pressure conditions (i.e., 1.0, 2.0 and 2.5 MPa) for 24 h. These CCP powders were then mixed with OPC to form a new binder. Various fresh, hardened and microstructural properties of CCP powders and the mixtures were investigated. Initial results show that the CO 2 sequestration level of CCP increased with the growth of CO 2 pressure, and albeit a pozzolanic reaction occurred inside the mixture, the relatively higher water demand due to the use of 30% replacement of CCP led to the inferior workability and compressive strength than the control group. Finally, a conceptual model relating to the CCP-OPC paste was proposed, facilitating the comprehension of the hydration behaviours of CCP-OPC paste.

Understanding the role of seeds in reactive magnesia cement (RMC) formulations

“…Absorption bands at 1105 and 876 cm −1 can also be assigned to CO 3 2− symmetric stretch (ν1 mode) and CO 3 2− bending (ν2 mode), 45 respectively. The broad bands at 1430–1480 cm −1 can be ascribed to CO 3 2− (ν3 mode) 45–47 . Therefore, the presence of various CO 3 2− bands confirmed the formation of nesquehonite, hydromagnesite, and dypingite, as mentioned before, 48,49 which is in line with the XRD analysis.…”

“…The broad bands at 1430-1480 cm −1 can be ascribed to CO 3 2− (ν3 mode). [45][46][47] Therefore, the presence of various CO 3 2− bands confirmed the formation of nesquehonite, hydromagnesite, and dypingite, as mentioned before, 48,49 which is in line with the XRD analysis. Meanwhile, after 28 days of CO 2 curing, seeded groups showed a broader band with greater intensities between 1428 and 1490 cm −1 than that of C0 (∼1442-1479 cm −1 ) in terms of CO 3 2− bands, indicating the greater carbonate contents within seeded groups.…”

CO2 Mineralization Methods in Cement and Concrete Industry

“…The carbonated cement paste can be used as an SCM to produce a composite cement [196][197][198][199]. The pozzolanic activity of the alumina-silica gel results in the formation of a phase assemblage which is similar to those found in composite cements containing siliceous fly ash and limestone.…”

Unveiling the Carbon Footprint Reduction Potential of Cementitious Composites: CO2 Sequestration in a Lime-Clay Binder Incorporating Medium-Grade Clay

“…The theoretical CO 2 capture capacity calculated using Steinour's formula (Table 2) confirms that the significantly higher CaO content in the OPC-containing sample greatly contributed to the increased CO 2 capture capacity. 33 The interlayer water molecules within ettringites disappear at 100 °C, while calcium silicate hydrate (C−S−H) phases experience a wide range of water loss from 50 to 600 °C. Consequently, the weight loss between 50 and 100 °C was Notably, the noncarbonated mixes depicted a higher loss within this range, signifying the C-A−S-H decalcification due to carbonation, as observed from FTIR analysis.…”