NMR observation of water transfer between a cement paste and a porous medium

Fourmentin, M.; Faure, Paméla; Rodts, Stéphane; Peter, Ulrike; Lesueur, Didier; Daviller, D.; Coussot, Philippe

doi:10.1016/j.cemconres.2017.02.027

Cited by 47 publications

(9 citation statements)

References 35 publications

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“…This could be attributed to the development of a denser microstructure upon hydration. On the other hand, the increase in the w/b ratio increased the peak intensities, which is in line with Fourmentin et al 26 The additional peak (Peak 2), observed in the 10-200 ms range, is attributed to the free water in larger capillary pores. As expected, its intensity is significantly larger in the pure Portland cement with SAP than that without SAP due to the water absorbed by SAP.…”

Section: Absorption/desorption Kinetics Of Sap In Pure Portland Cement Pastesupporting

confidence: 89%

“…NMR is a versatile non-destructive technique that allows gathering quantitative and qualitative information on cement hydration, its pore structure and the state of water in porous materials. This technique, extensively described in other studies, 23,24,25,26 makes it possible to easily distinguish between the free water in the cement matrix and the water in SAP by studying the evolution of H-NMR signals associated with changes in the matrix pore structure. 24,25,27,28 Furthermore, the strong changes in the NMR relaxation time that occur as a result of the development of the matrix pore structure provide insight into the transfer of water into SAP and from SAP back into concrete.…”

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confidence: 99%

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Internal curing of blended cement pastes with ultra‐low water‐to‐cement ratio: Absorption/desorption kinetics of superabsorbent polymer

Liu

Shi

et al. 2021

J. Am. Ceram. Soc.

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Generally, the low water-to-cement or binder ratio (w/c or w/b) of high-performance concrete (HPC) and ultra-high performance concrete (UHPC) 1 results in extremely low porosity and high compressive strength. However, it impacts significantly the hydration reaction due to the lack of free water and pore spaces. Insufficient water in low w/b pastes results in autogenous shrinkage and internal stresses caused by self-desiccation, which leads to the development of earlyage cracking (micro-or macro-cracks). 2 To mitigate the above problems, additional water should be provided within the concrete, which is referred to as internal curing (IC). 3,4,5 IC, through the use of pre-wetted lightweight aggregates (LWA) or superabsorbent polymers (SAPs), enables a subsequent release of water as cement hydrates, improving thus the degree of saturation of capillary pores while maintaining high internal relative humidity (IRH) in low w/b ratio cement-based materials. Besides, IC decreases the capillary stresses, promotes the hydration reaction 6 and improves laterage strength, 6 resistance to carbonate, 7 chloride ion penetration, 8 freeze-thaw resistance, 8,9,10 and self-sealing. 11,12,13,14 Compared with LWA, SAP is usually added in a dry state during mixing. 15 Upon addition, SAP absorbs part of the mixing water and gradually empties it after setting. The absorption capacity of SAP can be measured using direct or indirect methods such as the tea-bag method, 16,17 filtration method, 17 optical microscopy, 18 hydration heat method, 19 traditional

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Section: Absorption/desorption Kinetics Of Sap In Pure Portland Cement Pastesupporting

confidence: 89%

mentioning

confidence: 99%

Internal curing of blended cement pastes with ultra‐low water‐to‐cement ratio: Absorption/desorption kinetics of superabsorbent polymer

Liu

Shi

et al. 2021

J. Am. Ceram. Soc.

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“…Moisture profiles of porous materials during heating could be studied and conclusions could be drawn on how the water escaped the sample as a function of time 32 , 33 . The profiles can be used to study drying or saturation of a mortar sample 34 , 35 , the water release from a cement paste to a porous material 36 or for autogenous healing 37 . Only a few studies utilizing NMR relaxometry for water release by SAPs towards the cementitious matrix have been done.…”

Section: Introductionmentioning

confidence: 99%

The water kinetics of superabsorbent polymers during cement hydration and internal curing visualized and studied by NMR

Snoeck

Pel

Belie

2017

Sci Rep

139

101

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SuperAbsorbent Polymers (SAPs) can be applied as an admixture in cementitious materials. As the polymers are able to swell, they will absorb part of the mixing water and can then release that water back towards the cementitious matrix for internal curing. This is interesting in terms of autogenous shrinkage mitigation as the internal relative humidity is maintained. The mechanism is theoretically described by the Powers and Brownyard model, but the kinetics and water release still remain subject of detailed investigation. This paper uses Nuclear Magnetic Resonance (NMR) to study the release of water from the superabsorbent polymers towards the cementitious matrix during cement hydration. The release of water by the SAPs is monitored as a function of time and degree of hydration. The internal humidity is also monitored in time by means of sensitive relative-humidity sensors.

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“…This conclusion is supported by MRI observations of the transfers between two solid porous media in contact [14][15]. However, it was already remarked that the water contained of a cement paste in contact with an initially dry bed packing (with larger pores) can be extracted by capillary effects so as to finally saturate the bead packing [16]. These observations were carried out by NMR (Nuclear Magnetic Resonance) on bead packing samples surrounded by paste.…”

Section: Introductionmentioning

confidence: 77%