Mechanisms of carbonation hydration hardening in Portland cements

Zając, Maciej; Irbe, Linda; Bullerjahn, Frank; Hilbig, H.; Haha, Mohsen Ben

doi:10.1016/j.cemconres.2021.106687

Cited by 125 publications

(50 citation statements)

References 76 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

Section: Introductionmentioning

confidence: 99%

“…In view of the foregoing statement, previous work focused more on the variation of the mineral phases inside the concrete after the addition of CCP, which also ignores the workability of the samples that were more related with concrete pumpability in practice. 32 Meanwhile, there is a lack of conceptual models to explain the role of CCP in the hydration behaviours of CCP-OPC system lacks. Hence, the primary objective of this study is to investigate the capacity of CO 2 capture of hydrated cement paste and the mechanical performance of samples were associated with their workability.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

et al. 2022

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Such an observation is consistent with the current state of knowledge that the addition of a Ca-rich auxiliary activator is beneficial for the formation of the main binding gel phase of C-A-S-H in the binders [ 31 , 32 ]. Additionally, the initial reaction between Na 2 CO 3 and Ca(OH) 2 results in the CaCO 3 precipitation in the aqueous phase, and thus, the presence of additional surfaces probably improves the nucleation and growth of the C-A-S-H gel phase [ 36 ]. It should be noted that the 28 days compressive strength (26.1 MPa) of C0 was lower than the strengths of binders modified with auxiliary activators.…”

Section: Resultsmentioning

confidence: 99%

Properties and Microstructure of Na2CO3-Activated Binders Modified with Ca(OH)2 and Mg(OH)2

Xie

Liu

2022

Materials

View full text Add to dashboard Cite

Delayed strength development and long setting times are the main disadvantageous properties of Na2CO3-activated slag cements. In this work, combined auxiliary activators of Ca(OH)2 and Mg(OH)2 were incorporated in one-part Na2CO3-activated slag binders to accelerate the kinetics of alkali activation. The properties and microstructure evolution were investigated to clarify the reaction mechanism. The results showed that the additions of auxiliary activators promoted the hardening of the pastes within 2 h. The 28 days compressive strengths were in the range of 39.5–45.5 MPa, rendering the binders practical cementitious materials in general construction applications. Ca(OH)2 was more effective than Mg(OH)2 in accelerating the kinetics of alkali activation. The dissolution of Ca(OH)2 released more OH− and Ca2+ ions in the aqueous phase to increase alkalinity in the aqueous phase and promote the formation of the main binding gel phase of calcium-aluminosilicate hydrate (C-A-S-H). An increase in the Ca(OH)2/Mg(OH)2 ratios increased autogenous shrinkage and decreased drying shrinkage of the binders. The formation of a compact pore structure restricted the water evaporation from the binders during the drying procedure.

show abstract

“…Among them, carbonation is a common chemical process that can take place in concrete exposed to the atmosphere and CO 2 -rich fluids and may impair the structural durability and serviceability of concrete structures due to carbonation-induced corrosion damage at the structural level [1,2]. Therefore, the investigation of the carbonation mechanism and its effect on cement material properties is relevant for an accurate service life assessment and is directly related to the crack resistance of concrete and material failure of cements, which was intensively studied in recent years [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Synergistic Effects between Carbonation and Cracks in the Hardened Cement Paste

et al. 2022

View full text Add to dashboard Cite

This paper investigates the synergistic interaction between carbonation and microcracks in hardened cement pastes. Ordinary Portland cement pastes with three different water/cement ratios of 0.4, 0.5 and 0.6, hydrated for 28 days with crack apertures ranging from 10 to 150 μm were subjected to accelerated carbonation in a climate chamber that controls the targeted relative humidity (65 and 75%), CO2 concentration (0.3 vol.% and 1 vol.%) and temperature (20 ℃). Mercury intrusion porosimetry, N2-adsorption and thermogravimetry analysis were used to quantify the carbonation-induced changes in pore size distribution, porosity and phase assemblages. Additionally, the changes in crack apertures were followed during carbonation. The results indicated that cracks within the investigated range facilitate the carbonation along the crack surface due to a faster gas diffusion process. The cracks with apertures below 50 μm increase the carbonation depth at least by a factor of two for all studied w/c and environmental conditions. We observed a constant increase in crack openings during carbonation and its linear relationship with the amount of precipitated calcium carbonate. Due to depletion of CH and decalcification of C-S-H close to the sample surface, the crack aperture increase becomes limited. Therefore, the crack apertures do not increase further after the material around the crack is carbonated. It was also found that the densification of the carbonated cement matrix coexists with large capillary pores (>50 nm) or cracks, especially for the low w/c samples. The shift in pore size distribution from about 100 nm towards smaller pores (4.5–50 nm) and a decrease in gel pore fractions after 28 days of carbonation also indicate a simultaneous calcium carbonate precipitation in meso/capillary pores and decalcification of C-S-H at the nanoscale.

show abstract

Mechanisms of carbonation hydration hardening in Portland cements

Cited by 125 publications

References 76 publications

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

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

Properties and Microstructure of Na2CO3-Activated Binders Modified with Ca(OH)2 and Mg(OH)2

Synergistic Effects between Carbonation and Cracks in the Hardened Cement Paste

Contact Info

Product

Resources

About

Mechanisms of carbonation hydration hardening in Portland cements

Cited by 125 publications

References 76 publications

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

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

Properties and Microstructure of Na2CO3-Activated Binders Modified with Ca(OH)2 and Mg(OH)2

Synergistic Effects between Carbonation and Cracks in the Hardened Cement Paste

Contact Info

Product

Resources

About

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

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