<sup>29</sup>Si Magic‐Angle‐Spinning Nuclear Magnetic Resonance Study of Hydrated Cement Paste and Mortar

Al‐Dulaijan, Salah U.; Parry-Jones, Gwilym; Al-Tayyib, A.J.; Al-Mana, A.I.

doi:10.1111/j.1151-2916.1990.tb06582.x

Cited by 34 publications

(12 citation statements)

References 7 publications

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“…It also supported more hydration as the Q 0 peak belonged to the C 3 S and C 2 S. The intensity of the Q 1 peak decreased and the intensity of the Q 2 peak increased, resulting in an increase in the value of MCL. Through this, the activation of a cement hydration reaction could be seen as making the average length of the silicate chain longer [42][43][44].…”

Section: Cement Hydration Under Low Water Amount and High Temperaturementioning

confidence: 99%

Heat-Induced Acceleration of Pozzolanic Reaction Under Restrained Conditions and Consequent Structural Modification

Lee

Jeong²,

Kang

et al. 2020

Materials

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This study investigated the heat-induced acceleration of cement hydration and pozzolanic reaction focusing on mechanical performance and structural modification at the meso- and micro-scale. The pozzolanic reaction was implemented by substituting 20 wt.% of cement with silica fume, considered the typical dosage of silica fume in ultra-high performance concrete. By actively consuming a limited amount of water and outer-formed portlandite on the unreacted cement grains, it was confirmed that high-temperature curing greatly enhances the pozzolanic reaction when compared with cement hydration under the same environment. The rate of strength development from the dual reactions of cement hydration and pozzolanic reaction was increased. After the high-temperature curing, further strength development was negligible because of the limited space availability and preconsumption of water under a low water-to-cement environment. Since the pozzolanic reaction does not directly require the anhydrous cement, the reaction can be more easily accelerated under restrained conditions because it does not heavily rely on the diffusion of the limited amount of water. Therefore, it significantly increases the mean chain length of the C–S–H, the size of C–S–H globules with a higher surface fractal dimension. This finding will be helpful in understanding the complicated hydration mechanism of high-strength concrete or ultra-high performance concrete, which has a very low water-to-cement ratio.

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Section: Cement Hydration Under Low Water Amount and High Temperaturementioning

confidence: 99%

Heat-Induced Acceleration of Pozzolanic Reaction Under Restrained Conditions and Consequent Structural Modification

Lee

Jeong²,

Kang

et al. 2020

Materials

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“…Most studies on the effect of temperature analyze its impact on the mechanical properties of cement. 14,15 Other studies explore its effect on C-S-H gel composition based on the Ca/Si ratios observed in TEM/EDX or SEM/EDX analyses of cement paste or mortar. 16,17 Very few studies have addressed the degree of polymerization deduced from the Q 2 / Q 1 ratio indirectly obtained with 29 Si MAS NMR.…”

Section: Introductionmentioning

confidence: 99%

Effect of Temperature on C₃S and C₃S + Nanosilica Hydration and C–S–H Structure

et al. 2012

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This study aimed to monitor the effect of temperature and the addition of nanosilica on the nanostructure of the C–S–H gel forming during tricalcium silicate (C3S) hydration. Two types of paste were prepared from a synthesized T1 C3S. The first consisted of a blend of deionized water and C3S at a water/solid ratio of 0.425. In the second, a 90 wt% C3S + 10 wt% of nanosilica blend was mixed with water at a water/solid ratio of 0.7. The pastes were stored in closed containers at 100% RH and 25°C, 40°C, or 65°C. The hydration reaction was detained after 1, 14, 28, or 62 d with acetone, and then pastes were studied by 29Si magic angle spinning nuclear magnetic resonance (29Si MAS NMR).The main conclusion was that adding nSA expedites C3S hydration at any age or temperature and modifies the structure of the C–S–H gel formed, two types of C–S–H gel appear. At 25°C and 40°C, more orderly, longer chain gels are initially (1 d) obtained as a result of the pozzolanic reaction between nSA and portlandite (CH) (C–S–HII gel formation). Subsequently, ongoing C3S hydration and the concomitant flow of dimers shorten the mean chain length in the gel.

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“…In QXRD, the cement hydration degree is calculated based on the low-content crystal phases, so accuracy is limited in these circumstances [ 2 ]. In MAS NMR, overlapping of the peaks of calcium silicate hydrate gel (C-S-H) and SCMs causes deconvolution problems; furthermore, the ferrum in cement and FA leads to line broadening, which generally hinders the use of MAS NMR [ 32 , 33 ]. The application of the non-evaporable water method depends on assumptions about a specific water content bonded by the cement clinker, which is thought to be about 0.23.…”

Section: Methodsmentioning

confidence: 99%

Gel/Space Ratio Evolution in Ternary Composite System Consisting of Portland Cement, Silica Fume, and Fly Ash

Yao

2017

Materials

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In cement-based pastes, the relationship between the complex phase assemblage and mechanical properties is usually described by the “gel/space ratio” descriptor. The gel/space ratio is defined as the volume ratio of the gel to the available space in the composite system, and it has been widely studied in the cement unary system. This work determines the gel/space ratio in the cement-silica fume-fly ash ternary system (C-SF-FA system) by measuring the reaction degrees of the cement, SF, and FA. The effects that the supplementary cementitious material (SCM) replacements exert on the evolution of the gel/space ratio are discussed both theoretically and practically. The relationship between the gel/space ratio and compressive strength is then explored, and the relationship disparities for different mix proportions are analyzed in detail. The results demonstrate that the SCM replacements promote the gel/space ratio evolution only when the SCM reaction degree is higher than a certain value, which is calculated and defined as the critical reaction degree (CRD). The effects of the SCM replacements can be predicted based on the CRD, and the theological predictions agree with the test results quite well. At low gel/space ratios, disparities in the relationship between the gel/space ratio and the compressive strength are caused by porosity, which has also been studied in cement unary systems. The ratio of cement-produced gel to SCM-produced gel (GC to GSCM ratio) is introduced for use in analyzing high gel/space ratios, in which it plays a major role in creating relationship disparities.

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²⁹Si Magic‐Angle‐Spinning Nuclear Magnetic Resonance Study of Hydrated Cement Paste and Mortar

Cited by 34 publications

References 7 publications

Heat-Induced Acceleration of Pozzolanic Reaction Under Restrained Conditions and Consequent Structural Modification

Heat-Induced Acceleration of Pozzolanic Reaction Under Restrained Conditions and Consequent Structural Modification

Effect of Temperature on C₃S and C₃S + Nanosilica Hydration and C–S–H Structure

Gel/Space Ratio Evolution in Ternary Composite System Consisting of Portland Cement, Silica Fume, and Fly Ash

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29Si Magic‐Angle‐Spinning Nuclear Magnetic Resonance Study of Hydrated Cement Paste and Mortar

Cited by 34 publications

References 7 publications

Heat-Induced Acceleration of Pozzolanic Reaction Under Restrained Conditions and Consequent Structural Modification

Heat-Induced Acceleration of Pozzolanic Reaction Under Restrained Conditions and Consequent Structural Modification

Effect of Temperature on C3S and C3S + Nanosilica Hydration and C–S–H Structure

Gel/Space Ratio Evolution in Ternary Composite System Consisting of Portland Cement, Silica Fume, and Fly Ash

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Product

Resources

About

²⁹Si Magic‐Angle‐Spinning Nuclear Magnetic Resonance Study of Hydrated Cement Paste and Mortar

Effect of Temperature on C₃S and C₃S + Nanosilica Hydration and C–S–H Structure