Change in pore structure and composition of hardened cement paste during the process of dissolution

Haga, Kazuko; Shibata, Masahito; Hironaga, Michihiko; Tanaka, Satoru; Nagasaki, Shinya

doi:10.1016/j.cemconres.2004.06.001

Cited by 74 publications

(33 citation statements)

References 5 publications

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“…In the early stage of the hydration of C3S and C2S, Ca 2+ was preferentially released into the water. As a result of this continuous release, CH crystal formation and growth occurred predominantly on the outer layer of the CSH phase 12,22) . Like calcium carbonate, the CH phase precipitates also contributed to the sealing ability of MTA.…”

Section: Discussionmentioning

confidence: 99%

“…We further speculated that the prominent presence of carbon implied the formation of calcium carbonate via the reaction of calcium hydroxide with carbon dioxide in the air 22) . The alkaline pH of MTA is an advantageous environment (pH>12) for the formation of calcium carbonate phase 22) . Calcium carbonate is poorly soluble in water and its formation -hence the precipitates formed on MTA-could contribute to the sealing ability of MTA.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, Thus, Ca is the major element that leaches out from set MTA and interacts with the external environment to form crystalline precipitates [14][15][16][17][18] . This was because MTA powder was devoid of carbon 4,9,10) , and the carbon element present in the precipitates should be supplied from the external fluid environment 22) . We further speculated that the prominent presence of carbon implied the formation of calcium carbonate via the reaction of calcium hydroxide with carbon dioxide in the air 22) .…”

Section: Discussionmentioning

confidence: 99%

“…This was because MTA powder was devoid of carbon 4,9,10) , and the carbon element present in the precipitates should be supplied from the external fluid environment 22) . We further speculated that the prominent presence of carbon implied the formation of calcium carbonate via the reaction of calcium hydroxide with carbon dioxide in the air 22) . The alkaline pH of MTA is an advantageous environment (pH>12) for the formation of calcium carbonate phase 22) .…”

Section: Discussionmentioning

confidence: 99%

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Morphological and chemical analysis of different precipitates on mineral trioxide aggregate immersed in different fluids

2010

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The purpose of this study was to analyze the ultrastructures and chemical compositions of precipitates formed on mineral trioxide aggregate (MTA; White ProRoot MTA) immersed in distilled water (DW) or phosphate buffered saline (PBS), based on the attribution that MTA's bioactivity and sealing ability are influenced by its interaction with the external fluid environment. After 1 and 14 days of immersion, precipitates formed on MTA disks were analyzed using wavelength-dispersive X-ray spectroscopy electron probe microanalyzer with image observation function (SEM-EPMA; EPMA1601, Shimadzu, Kyoto, Japan), and Fourier transform-infrared (FT-IR) spectroscopy. On DW specimens, cubic-like crystals containing Ca, O, and C (17, 66, and 17 at% respectively) were produced. State analysis of calcium kβ spectrum also revealed calcium hydroxide. On PBS specimens, acicular-spherical and lath-like crystals with Ca/P molar ratios of 1.42 and 1.58 respectively were produced. In conclusion, the precipitates formed on DW specimens were identified as calcium carbonate and calcium hydroxide primarily, whereas the precipitates on PBS specimens were inferred to be amorphous calcium phosphate.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Morphological and chemical analysis of different precipitates on mineral trioxide aggregate immersed in different fluids

2010

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“…This is because of the increased risk of the failure of the concrete. It is said that a hydrated cement system undergoes a dissolution of the hydration product due to continuous contact with water flow, followed by a reduction in structural performance (Carde & Francois, 1997;Delegrave, Gerand, & Marchand, 1997;Haga, Shibata, Hironaga, Tanaka, & Nagasaki, 2005). In fact, the stability of the multilayer system employed in radioactive waste disposal facilities is predicted through analysis, but the accuracy of the simulation is hardly acceptable.…”

Section: Introductionmentioning

confidence: 99%

Nondestructive Integrated CT-XRD Method for Research on Hydrated Cement System

Sugiyama¹,

Hitomi²,

Kajiwara³

2014

Proceedings of the 4th International Conference on the Durability of Concrete Structures

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A nondestructive integrated CT-XRD method has been developed and used to study hydrated cement system. In this research, a beam line (BL) at the third-generation synchrotron radiation facility, SPring-8, in Japan, was used. First, X-ray computed tomography (CT) was employed to obtain three-dimensional (3D) images and select a region of interest (ROI) in a given plane section of the hardened cement paste. Then, X-ray diffraction analysis (XRD) was conducted on the specified region. These operations were implemented in situ without the removal of specimen from the stage inside the BL. The hardened cement paste was precracked and then leached by continuous water flow through the specimen, and the integrated CT-XRD method was conducted before and after the leaching test. In this way, the change in the hydrated cement system was characterized over time using the same specimen. CT observation provides the location of cracks and air voids as well as high and low density substances present in the hydrated cement system. ROI is arbitrarily determined at a set of coordinates at which one likes to evaluate the change in the cement system using XRD. This newly developed technique enables the evaluation of the presence of calcium hydroxide (portlandite) over time and space.

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Change in pore structure and composition of hardened cement paste during the process of dissolution

Cited by 74 publications

References 5 publications

Morphological and chemical analysis of different precipitates on mineral trioxide aggregate immersed in different fluids

Morphological and chemical analysis of different precipitates on mineral trioxide aggregate immersed in different fluids

Nondestructive Integrated CT-XRD Method for Research on Hydrated Cement System

Leaching of Cementitious Materials by Pure Water and Strong Acids (HCl and HNO3)

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