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Journal Articles

Pore distribution of water-saturated compacted clay using NMR relaxometry and freezing temperature depression; Effects of density and salt concentration

Okubo, Takahiro*; Ibaraki, Moe*; Tachi, Yukio; Iwadate, Yasuhiko*

Applied Clay Science, 123, p.148 - 155, 2016/04

 Times Cited Count:19 Percentile:73.19(Chemistry, Physical)

The pore distribution of water-saturated compacted clay (Na-montmorillonite at 0.8 and 1.4 g/cm$$^{3}$$ saturated by three salt concentrations) was evaluated using $$^{1}$$H NMR relaxometry and freezing point depression. The populations of interlayer water with four hydrated state and non-interlayer water were calculated from the assumed thresholds. The sample with lower density exhibits higher population of non-interlayer water up to 55%. Low-temperature $$^{1}$$H NMR experiments in view of freezing point depression indicated that mesopore water in approximately 4 nm space observed in the calorimetric study was considered as non-interlayer water and the threshold temperature. The result showed that population of non-interlayer water by expected from freezing point depression agreed with $$^{1}$$H NMR relaxometry within 10%. Correlation experiments between longitudinal ($$T_{1}$$) and transverse relation times ($$T_{2}$$) at -10$$^{circ}$$C suggested that high-mobility bulk-like water molecules existed at a clay density of 1.4 g/cm$$^{3}$$.

Oral presentation

Pore distribution of saturated compacted montmorillonite using NMR relaxometry; Effect of salt concentration

Okubo, Takahiro*; Ibaraki, Moe*; Tachi, Yukio; Iwadate, Yasuhiko*

no journal, , 

1H NMR relaxometry was applied for investigation of pore structure in compacted saturated montmorillonite with different salt concentration. The samples compacted to dry densities of 0.8 and 1.2 g/cm$$^{3}$$ were saturated with pure water, 0.05, 0.10, 0.50, and 1.0 M NaCl solutions. Population of water in different hydrated layer corresponding to 1-, 2-, and 3 hydrated layer was estimated from longitudinal relaxation distributions. The population of water in 1-, 2-, and 3 hydrated layers changed as a function of NaCl concentration. The threshold to discriminate between inter- and intra-layer water is 3 hydrated layer, which is questionable from existence of 4 hydrated layer revealed by modelling of X-ray profile. The amount of water in 1- and intra-layer were negligible small for all conditions at dry density of 1.2 g/cm$$^{3}$$. On the other hand, water in 2-hydrated layer was decreased instead of increment of water in 3-hydrated layer.

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