Monitoring the size evolution of capillary pores in cement paste during the early hydration via diffusion in internal gradients

Pop, Alexandru; Ardelean, I.

doi:10.1016/j.cemconres.2015.07.004

Cited by 27 publications

(17 citation statements)

References 40 publications

(70 reference statements)

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“…According to another study [ 24 ], the pores type and size depend, mainly, on the raw material calcium content because this contributes to the formation of the porous phases such as calcium alumino-silicate hydrate (C-A-S-H) and sodium alumino-silicate hydrate (N-A-S-H). Also, it was found that the total porosity and pore size distribution are the most important factors affecting the compressive strength of geopolymers [ 25 , 26 ].…”

Section: Introductionmentioning

confidence: 99%

“…Note, however, that the proportionality between the pore size and relaxation time is valid only if one neglects the bulk relaxation rate of the confined molecules. Moreover, in the case of porous media with magnetic impurities, it is necessary to reduce diffusion effects on transverse relaxation measurements [ 26 , 27 ]. A valuable approach to reduce diffusion effects on transverse relaxation measurements is to implement the well-known Carr Purcell Meiboom Gill (CPMG) technique [ 30 ] in combination with a lowfield NMR instrument.…”

Section: Introductionmentioning

confidence: 99%

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Revealing the Influence of Microparticles on Geopolymers’ Synthesis and Porosity

et al. 2020

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Geopolymers are zeolites like structures based on hydrated aluminosilicates units of SiO4 and AlO4. These units, known as poly(sialate), poly(sialate)-siloxo or poly(sialate)-disiloxo are chemically balanced by the group I cations of K+, Li+, or Na+. Simultaneously, the chemical reaction of formation, known as geopolymerization, governs the orientation of the unit, generating mesoporous structures. Multiple methods can be used for pore structure and porosity characterization. Among them, nuclear magnetic resonance (NMR) relaxometry allows the detection of the porous structure in a completely nonperturbative manner. NMR relaxometry may be used to monitor the relaxation of protons belonging to the liquid molecules confined inside the porous structure and, thus, to get access to the pore size distribution. This monitoring can take place even during the polymerization process. The present study implements transverse relaxation measurements to monitor the influence introduced by the curing time on the residual liquid phase of geopolymers prepared with two different types of reinforcing particles. According to our results, the obtained geopolymers contain three types of pores formed by the arrangement of the OH− and Si groups (Si-OH), Si-O-Si groups, Si-O-Al groups, and Si-O rings. After 48 days, the samples cured for 8 h show a high percentage of all three types of pores, however, by increasing the curing time and the percentage of reinforcing particle, the percent of pores decrease, especially, the gel pores.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Revealing the Influence of Microparticles on Geopolymers’ Synthesis and Porosity

et al. 2020

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“…These factor are important because it plays an important role in hydration process and significantly influence the characteristics time. Porosity and pore size of the produced cement based materials also important for hydration process because it influences the final strength and durability of the concrete [19].…”

Section: Cement Hydrationmentioning

confidence: 99%

Potential Mixture of POFA and SCBA as Cement Replacement in Concrete – A Review

et al. 2017

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Concrete is an important material used in all kind of building construction and ordinary Portland cement (OPC) is one of an important element in the production of concrete. However, the production of cement causes a problem because of high CO 2 emission to atmosphere. The manufacture of 1 tonnes of cement would produce approximately released 1 tonnes of CO 2. So, the need to search another material that can replace a cement with same properties and environmental friendly are crucial. The suitable material to replace cement has to be a pozzolanic materials. This is because pozzolanic materials has cementitious properties and high silica content. Palm oil fuel ash (POFA) and sugarcane bagasse ash (SCBA) are the material that suitable to replace cement because of high silica content. The use of POFA and SCBA in concrete has been studied by many researcher and it has been proved to improve the mechanical strength of the concrete either in normal concrete, high strength concrete or lightweight concrete. This paper would discuss the overview of the previous study on the cement replacement by POFA and SCBA and the potential of the both materials to be mix together to improve its properties. The chemical element which will be the focus point is SiO 4 , MgO, CaO and SO 3 , while the physical and mechanical properties such as workability, specific gravity, compressive strength and tensile strength will also be reviewed.

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“…The imaging modality of this method can also be performed [24]. Lastly, the diffusion measurements of water in cement is another option for studying cement hydration, especially in the early stages of hydration [25]. The other applications of NMR in civil engineering can be found in moisture content measurements [26], detection of water depth profiles in concrete or wood materials [27], and determination of porosity and pore size distribution in soils [28].…”

Section: Introductionmentioning

confidence: 99%

Sequential Diffusion Spectra as a Tool for Studying Time-Dependent Translational Molecular Dynamics: A Cement Hydration Study

Serša

2019

Molecules

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The translational molecular dynamics in porous materials are affected by the presence of the porous structure that presents an obstacle for diffusing molecules in longer time scales, but not as much in shorter time scales. The characteristic time scales have equivalent frequency ranges of molecular dynamics, where longer time scales correspond to lower frequencies while the shorter time scales correspond to higher frequencies of molecular dynamics. In this study, a novel method for direct measurement of diffusion at a given frequency of translational molecular dynamics is exploited to measure the diffusion spectra, i.e., distribution of diffusion in a wide range of frequencies. This method utilizes NMR modulated gradient spin-echo (MGSE) pulse sequence to measure the signal attenuation during the train of spin-echoes formed in the presence of a constant gradient. From attenuation, the diffusion coefficient at the frequency equal to the inverse double inter-echo time is calculated. The method was employed to study the white cement hydration process by the sequential acquisition of the diffusion spectra. The measured spectra were also analyzed by the diffusion spectra model to obtain the time-dependence of the best-fit model parameters. The presented method can also be applied to study other similar systems with the time evolution of porous structure.

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Monitoring the size evolution of capillary pores in cement paste during the early hydration via diffusion in internal gradients

Cited by 27 publications

References 40 publications

Revealing the Influence of Microparticles on Geopolymers’ Synthesis and Porosity

Revealing the Influence of Microparticles on Geopolymers’ Synthesis and Porosity

Potential Mixture of POFA and SCBA as Cement Replacement in Concrete – A Review

Sequential Diffusion Spectra as a Tool for Studying Time-Dependent Translational Molecular Dynamics: A Cement Hydration Study

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