Freezing of partly saturated cementitious materials – Insight into properties of pore confined solution and microstructure

Bednarska, Dalia; Koniorczyk, Marcin

doi:10.1016/j.conbuildmat.2020.118895

Cited by 14 publications

(3 citation statements)

References 46 publications

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“…The relationship between RH and saturated pore size can be illustrated by the well-known Kelvin–Laplace equation (eq ) based on mechanical and physicochemical equilibrium, presented as follows: where γ represents the surface tension of the pore fluid, r denotes the average radius of the meniscus curvature, RH stands for internal relative humidity, R is the universal gas constant, T indicates temperature, and v ’ signifies the molar volume of water. Based on eq and with an RH of 55% (in the case of this study), nanosized pores of around 4 nm were saturated, which meant that only thin water films were present in RCPs. , Unlike the solution-precipitation process, a nanometer-thick water film on the inner or outer surfaces of RCPs would provide a low energy barrier for CO 2 dissolution. Carbonic acid or bicarbonate ion generation has been identified by molecular dynamic studies. , The 29 Si NMR result demonstrated that Q 3 was the dominant coordination for sample SGRH55–24 h, during which the CH was not depleted as shown in the XRD result, whereas C–S–H started to decalcify in water-rich carbonation only when the CH was depleted.…”

Section: Discussionmentioning

confidence: 99%

“…Based on eq 8 and with an RH of 55% (in the case of this study), nanosized pores of around 4 nm were saturated, which meant that only thin water films were present in RCPs. 21,58 Unlike the solution-precipitation process, a nanometer-thick water film on the inner or outer surfaces of RCPs would provide a low energy barrier for CO 2 dissolution. Carbonic acid or bicarbonate ion generation has been identified by molecular dynamic studies.…”

Section: Ion Concentration Evolutionmentioning

confidence: 99%

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Utilizing Waste Cement for Carbon Dioxide Sequestration and Capture: The Role of Water Content on the Growth of Calcium Carbonate

Ma,

Jiang,

Jiang

et al. 2024

ACS Sustainable Chem. Eng.

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High-alkaline waste cement possesses significant potential for effectively capturing and sequestering carbon dioxide, transforming it into calcium-rich, highly reactive, supplementary cementitious materials. Water plays a pivotal role in facilitating this reaction, yet there is a conspicuous absence of extensive research in this domain. This study elucidates the mechanisms by which water affects the growth behavior (precipitation and crystallization) of calcium carbonate (Cc) in hydrated cement paste during carbonation. The findings indicated that the presence of water dramatically affected Cc's polymorphs, morphology, and crystal properties. With an increase in water content from RH = 55% to a liquid−solid ratio of 40, the calcite grain size underwent significant enlargement from less than 200 to over 400 nm. Moreover, as the water content increased, the different Cc polymorphs evolved into mainly calcite, and the polycrystalline Cc was transformed to monocrystalline calcite. Insufficient water elevated the local pH and ion concentration, resulting in a prolonged supersaturation duration. Meanwhile, the nanosized water film restricted the Cc growth and hindered Ostwald ripening, leading to the preservation of amorphous calcium carbonate (ACC) and poor crystallization of Cc.

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Section: Discussionmentioning

confidence: 99%

Section: Ion Concentration Evolutionmentioning

confidence: 99%

Utilizing Waste Cement for Carbon Dioxide Sequestration and Capture: The Role of Water Content on the Growth of Calcium Carbonate

Ma,

Jiang,

Jiang

et al. 2024

ACS Sustainable Chem. Eng.

View full text Add to dashboard Cite

show abstract

“…Therefore, the pore size distribution cannot be calculated from the freezing process. In order to solve this problem, a measurement method using an auxiliary cycle has been proposed (Ishikiriyama et al 1995;Koniorczyk et al 2018;Bednarska and Koniorczyk 2020), but it was not adopted in this study because of its detrimental effect on the specimen.…”

Section: Freezing Processmentioning

confidence: 99%

Thermoporometry and Proton NMR Measurement on Cement Paste Equilibrated at Different Relative Humidities

Kurumisawa

Jensen

2020

ACT

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In this study, thermoporometry by differential scanning calorimetry and proton NMR measurements of hardened cement paste equilibrated under different humidity conditions were carried out, and the results of both measurements were compared. The results reveal that thermoporometry by low temperature DSC measurement cannot detect the water present in samples equilibrated at low relative humidity. On the other hand, it is possible to detect a signal at low relative humidity by proton NMR measurement. It is clarified that water strongly bound to the surface, which cannot be detected by low temperature DSC, exists at a relative humidity of 33% or less. If it is relevant to detect tightly held water, such as water present in the fine gel pores, it is recommended to apply proton NMR measurements. This paper is an extended English version of the authors' previous work [Kurumisawa, K. and Jensen, O. M., (2020). "Measurement of cement paste at different humidities by thermoporometry and proton NMR."

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Elucidating the evolution of pore structure, microstructural damage, and micromechanical response in cement pastes containing microencapsulated phase change materials under freeze-thaw conditions

Paswan,

Das

2024

Cement and Concrete Composites

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Freezing of partly saturated cementitious materials – Insight into properties of pore confined solution and microstructure

Cited by 14 publications

References 46 publications

Utilizing Waste Cement for Carbon Dioxide Sequestration and Capture: The Role of Water Content on the Growth of Calcium Carbonate

Utilizing Waste Cement for Carbon Dioxide Sequestration and Capture: The Role of Water Content on the Growth of Calcium Carbonate

Thermoporometry and Proton NMR Measurement on Cement Paste Equilibrated at Different Relative Humidities

Elucidating the evolution of pore structure, microstructural damage, and micromechanical response in cement pastes containing microencapsulated phase change materials under freeze-thaw conditions

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