Dynamic microstructural evolution of hardened cement paste during first drying monitored by 1H NMR relaxometry

Maruyama, Isao; Ohkubo, Takahiro; Haji, Tatsuto; Kurihara, Ryo

doi:10.1016/j.cemconres.2019.04.017

Cited by 139 publications

(47 citation statements)

References 49 publications

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“…Monitoring HCPs during the first drying under various RHs using 1 H NMR relaxometry [102] indicated that both the gel pores and inter-hydrates pores coarsened while the interlayer spacing narrowed when drying at RH below 80%, although we do NOT agree with the judgement on the transformation of fine gel pores into finer interlayer pores [116]. In general, these investigations support the contraction of interlayer pores upon drying, as discussed in Section 2.2.…”

Section: Contraction Of C-s-h Gels Upon Dryingcontrasting

confidence: 56%

“…Detailed discussions on these complex interactions are beyond the scope of this article, but any changes in the balance of EDL structure for C‐S‐H colloids will change the equilibrium distance, whether it is the interlayer spacing of several nanometers between C‐S‐H sheets or coarser gel pores 78 . Consequently, the applications of capillary pressure and other attractions would bring C‐S‐H sheets closer, 74,99 possibly dominating drying shrinkage of CBMs 100–102 . Changes in the compositions of pore water, especially the concentration of hydrated cations, 103 may alter interlayer spacing of C‐S‐H gels and thereby affect drying deformation of CBMs 101,104,105 .…”

Section: Physical Roots Of Water Sensitivitymentioning

confidence: 99%

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Water sensitivity of cement‐based materials

Zhang

Wang

et al. 2021

J Am Ceram Soc

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Cement-based materials are the most widely used construction materials on the planet. Cementbased materials play a fundamental role in modern civilization and will for the foreseeable future.Although great efforts have been devoted to discovering the behaviors and optimizing their performances, several long-standing controversies persist for the fundamental water-related properties of cement-based materials, which hinder theoretical researches and mislead technological developments. Inspired by the decreasing water permeability of clay-bearing rocks, the term "water sensitivity" in geophysics is borrowed and proposed for cement-based materials. The lamellar structure of negatively charged nanoparticles is responsible for swelling in clay-based reservoir rocks. Amorphous calcium silicate hydrate gels in cement-based materials have similar microstructural characteristics. They probably swell upon wetting and contract upon drying, making the pore structure of cement-based materials dependent on water content. More importantly, several unexplained behaviors of cement-based materials can be rationalized using water sensitivity.Thorough exploration of both the micro-structural characteristics and performances validate the use of water sensitivity for cement-based materials. Because water participates in or regulates almost all physical and chemical processes of cement-based materials, water sensitivity can be a part of the interpretations of almost all of their properties and performances.

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Section: Contraction Of C-s-h Gels Upon Dryingcontrasting

confidence: 56%

Section: Physical Roots Of Water Sensitivitymentioning

confidence: 99%

Water sensitivity of cement‐based materials

Zhang

Wang

et al. 2021

J Am Ceram Soc

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“…Therefore, in general, the evaporable water content in the concrete of a reactor building is considered to exist in either gel pores or interlayer spaces. Recent studies (Valori et al 2010;Maruyama et al 2019) have elucidated that both gel pores and interlayer spaces are confined by C-S-H sheets, and that the gel pores may be transformed into interlayer spaces in accordance with the drying process. From this point of view, the evaporable water is generally confined by C-S-H sheets and water molecules within this structure are approximately 1.0 nm (a distance of approximately four water molecules) from the surface.…”

Section: Discussionmentioning

confidence: 99%

“…HCP may contain different forms of water with different restrictions, including chemically bound water (CBW) generated by the reaction of water with cement constituents [e.g., H 2 O + CaO Ca(OH) 2 ], interlayer water that resides between calcium-silicate-hydrates (C-S-H) sheets, and adsorbed water on the C-S-H gel (Powers 1960;Feldman and Sereda 1968;Feldman and Ramachandran 1971;Muller et al 2013;Maruyama et al 2019). Additionally, capillary water may exist in large pores.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Production and the Stability of Hardened Cement Paste under Gamma Irradiation

Ishikawa

Maruyama

Takizawa

et al. 2019

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Hardened cement pastes (HCP) with different water contents were irradiated with gamma rays under different temperatures and irradiation dose rates. The relationship between the quantity of hydrogen gas produced and the water content as well as the stability of HCP under gamma irradiation was evaluated. It is experimentally confirmed that hydrogen gas was mainly produced from the evaporable water. The G value of the hydrogen production assuming the radiation energy absorbed by the total water composed of chemically bound water (CBW) and evaporable water was ranging from 0.03 to 0.42. The G value of the hydrogen production for CBW was ranging from 0.03 to 0.07, which were an order of magnitude smaller than that of the bulk water (0.45). Assuming that the radiation energy on evaporable water is used for the formation of hydrogen, it is experimentally confirmed that, in case of low dose rate, the G value tended to converge to a constant value when the evaporable water exceeded a certain value, while, in case of high dose rate, the G value increased as evaporable water increased. However, the G values of all cases grew with increasing evaporable water content and exceeded the G value of the bulk water (0.45). The CBW was not susceptible to gamma irradiation. Only 2 to 3% of the CBW was estimated to be decomposed by 200 MGy of gamma irradiation.

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“…In recent years, the development of a method for measuring the state of water in hardened cement-based materials by proton NMR measurement has advanced. By this technique, the specimen can be measured non-destructively, and the state of moisture in concrete can be accessed (Muller et al 2013a(Muller et al , 2013b(Muller et al , 2015Maruyama et al 2019;Kose et al 2013). Likewise, a technique based on low temperature differential scanning calorimetry (LT-DSC) has also been used to measure the state of water in pores.…”

Section: Introductionmentioning

confidence: 99%

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

Kurumisawa

Jensen

2020

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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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Dynamic microstructural evolution of hardened cement paste during first drying monitored by 1H NMR relaxometry

Cited by 139 publications

References 49 publications

Water sensitivity of cement‐based materials

Water sensitivity of cement‐based materials

Hydrogen Production and the Stability of Hardened Cement Paste under Gamma Irradiation

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

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