Temperature Dependency of Short-Term Length-Change and Desorption Isotherms of Matured Hardened Cement

Maruyama, Isao; Rymeš, Jiří

doi:10.3151/jact.17.188

Cited by 17 publications

(8 citation statements)

References 43 publications

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“…This discrepancy appears to be inappropriate. However, several reports have shown that the C-S-H packing density, interlayer spacing, and the microstructures change with temperature (Gallucci et al 2013;Bahafid et al 2017;Gajewicz-Jaromin et al 2019;Maruyama and Rymeš 2019). According to these studies, the interlayer spacing for specimens at 10°C is 35% larger than that at 60°C, and samples at 60°C were associated with increased pore size (capillary and interhydrate pores).…”

Section: Resultsmentioning

confidence: 97%

Water Uptake in OPC and FAC Mortars under Different Temperature Conditions

Kiran

Samouh

Matsuda

et al. 2021

ACT

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This experimental and numerical study aims to evaluate the penetration depth of contaminated water in the concrete structures involved in the Fukushima Daiichi nuclear powerplant. The influence of the mortar mixture on water absorption was investigated by varying the composition: mortars containing aggregates from river sand and crushed limestone sand were compared, and 15% of the cement in the mixture was substituted with fly ash. The effect of temperature in nuclear conditions is also significant; therefore, water uptake at temperatures of 20 and 60°C was considered. Finally, pre-drying conditions were studied by drying the sample at two different conditions: at 105°C and at 40% RH (relative humidity) and 20°C. Water uptake was monitored using x-ray computed radiography in combination with mass measurements. In all cases, anomalous sorption, or a nonlinear relationship between penetration depth and the square root of exposure time was observed, with the sorption curves showing bimodal behavior. The aggregate type had no significant effect on the water uptake results. However, the samples containing fly ash clearly had lower water uptake rates, which can be explained by the differences in the calcium silicate hydrate (C-S-H) structures. With increasing temperature, the penetration was slightly accelerated at the beginning of the experiment, with the rate of penetration then decreasing rapidly. The densification of C-S-H at higher temperatures could contribute to this phenomenon. Microstructural rearrangements can also explain why the highest uptake rates occurred for samples that were exposed to severe drying conditions (105°C). The experimental results were consistent when the microstructural rearrangement was considered, further confirming these conclusions.

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Section: Resultsmentioning

confidence: 97%

Water Uptake in OPC and FAC Mortars under Different Temperature Conditions

Kiran

Samouh

Matsuda

et al. 2021

ACT

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“…In the context of nuclear power plants, capturing the temperature dependency of this dynamic microstructure (related data has been reported by Maruyama and Rymeš (2019)) is critical for a more accurate estimation of the moisture transport, such as in a recent trial by Li and Xu (2019). To the authors' knowledge, no similar data for mid-range periods have been reported thus far.…”

Section: Introductionmentioning

confidence: 87%

“…Water movement in cement-based materials is dominated by the smallest pores with the smallest diffusivity and any variation in its microstructure will have important impacts on the apparent global transport coefficient. Under saturation conditions, the distribution of the pore sizes changes with the collapse of pores with time and many attempts to quantify this have been presented in previous studies (Gajewicz et al 2016;Zhou et al 2017Zhou et al , 2018Holthausen and Raupach 2018;Maruyama and Rymeš 2019).…”

Section: Introductionmentioning

confidence: 99%

Temperature-Dependent Water Redistribution from Large Pores to Fine Pores after Water Uptake in Hardened Cement Paste

Kiran

Samouh

Igarashi

et al. 2020

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During sorption, the microstructural evolutions of two different cement pastes (with water-to-cement ratios of 0.40 and 0.55) are studied via proton-nuclear-magnetic-resonance relaxometry. The water uptake test is performed for samples dried at 105°C under three different temperatures of 20°C, 40°C, and 60°C for the first twenty-six days of sorption. It is observed that the water went first to the larger pores before migrating to the finest ones. This behavior is accelerated with increasing temperature. The rate of water exchange between fine and large pores is estimated and found to increase with temperature for both studied mixtures. The activation energy corresponding to this water movement is calculated and found to be higher for the lowest water-to-cement ratio, owing its finer microstructure. Finally, the activation energy related to the local water transport in re-distribution from large pores to fine pores is calculated and found to be inferior to the experimental results, which can be explained by the dynamic microstructure not being considered in the classical theories. Recently, based on the proton nuclear magnetic resonance ( 1 H-NMR) relaxometry technique, the dynamic

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“…It is suggested that the irreversible shrinkage starts to form around 80% RH, but there is no direct experimental evidence. Temperature also has a strong influence on the shrinkage strain in this region (Maruyama and Rymeš 2019).…”

Section: Introductionmentioning

confidence: 93%

The Relative Humidity Range for the Development of Irreversible Shrinkage in Hardened Cement Paste

Maruyama

Kishi²,

Aili

2021

ACT

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For better understanding of irreversible shrinkage, nine hardened cement paste (hcp) samples with three different cement types and three different water to cement ratio were prepared. Four different relative humidity conditioning histories containing the first desorption, re-humidification and the second desorption are investigated for all the specimens to obtain the length change and water sorption isotherms. The irreversible shrinkage strain was developed when the specimen was dried up to less than 80% relative humidity (RH), while other previous experiments in literatures showed that the shrinkage strain between 40% RH and 11% RH is reversible. It is concluded that the irreversible shrinkage strain is developed between 80% RH and 40% RH, which is also supported by the change in water vapor BET surface area of hardened cement paste after long-term drying.

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Temperature Dependency of Short-Term Length-Change and Desorption Isotherms of Matured Hardened Cement

Cited by 17 publications

References 43 publications

Water Uptake in OPC and FAC Mortars under Different Temperature Conditions

Water Uptake in OPC and FAC Mortars under Different Temperature Conditions

Temperature-Dependent Water Redistribution from Large Pores to Fine Pores after Water Uptake in Hardened Cement Paste

The Relative Humidity Range for the Development of Irreversible Shrinkage in Hardened Cement Paste

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