Clay Science
Online ISSN : 2186-3555
Print ISSN : 0009-8574
ISSN-L : 0009-8574
Volume 14, Issue 4
Displaying 1-12 of 12 articles from this issue
  • Article type: Cover
    2010 Volume 14 Issue 4 Pages Cover1-
    Published: 2010
    Released on J-STAGE: June 22, 2017
    JOURNAL FREE ACCESS
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  • Article type: Appendix
    2010 Volume 14 Issue 4 Pages App1-
    Published: 2010
    Released on J-STAGE: June 22, 2017
    JOURNAL FREE ACCESS
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  • Article type: Appendix
    2010 Volume 14 Issue 4 Pages App2-
    Published: 2010
    Released on J-STAGE: June 22, 2017
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  • Article type: Appendix
    2010 Volume 14 Issue 4 Pages App3-
    Published: 2010
    Released on J-STAGE: June 22, 2017
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  • Article type: Appendix
    2010 Volume 14 Issue 4 Pages App4-
    Published: 2010
    Released on J-STAGE: June 22, 2017
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  • AYE AYE THAN, KAZUYUKI SHOJI, SHIN-ICHIRO WADA
    Article type: Article
    2010 Volume 14 Issue 4 Pages 141-146
    Published: 2010
    Released on J-STAGE: June 22, 2017
    JOURNAL FREE ACCESS
    We improved the method for determination of carbonate in soils and clays (Wada (1997) Soil Sci. Plant Nutr., 43, 45-50). A sample was placed in a flexible gas-tight plastic bag attached with stopcock and heat-sealed. The carbonate in the sample was decomposed by addition of HCl and the generated CO_2 was diluted by injecting a known amount of air followed by determination of the CO_2 concentration of the gas in the bag. The carbonate content of the sample was calculated by summing the amount of gaseous and dissolved CO_2, the latter of which was estimated with the aid of Henry's law. A series of test using standard carbonate minerals showed a 20min of digestion was sufficient for complete dissolution. The improved method was applied to some clays and soil samples. Some Japanese soils from greenhouses contained about 0.08 to 0.35mol kg^<-1> of carbonate, while their soil pH values were significantly lower than those expected from carbonate equilibrium.
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  • KENJI TAMURA, KAZUYA MORIMOTO, TAKATSUGU USHIROUCHI, HIROHISA YAMADA, ...
    Article type: Article
    2010 Volume 14 Issue 4 Pages 147-153
    Published: 2010
    Released on J-STAGE: June 22, 2017
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    Ion-exchange treatment of natural vermiculite (VER) with dodecylammonium (DDA) ions and subsequent preparation of a polyamide 6 (PA6) based nanocomposite was conducted to investigate the potential suitability of VER for use in polymer nanocomposites. In order to investigate the ion-exchange behavior, ground VER powder and DDA were treated at 60℃ for 12h, in which time the intercalation reaction was completed. DDA intercalation was rapid and complete for VER even in dilute DDA solution (0.5 mass%) at a low suspension VER concentration of 1 mass%. The VER-PA6 nanocomposite was formed via exfoliation of a DDA modified VER (DDAVER) layer. DDAVER was melt-kneaded with PA6 in a twin-screw extruder at 260℃. The morphology of the nanocomposite was characterized using X-ray diffraction and transmission electron microscopy. Measurements of the mechanical properties and methanol permeability were also carried out. The DDAVER-PA6 nanocomposite exhibits a high degree of VER exfoliation and the rigidity and gas barrier properties also appear to reflect the nanocomposite morphology. Addition of a small amount of DDAVER with 3 mass% silicate was sufficient to improve the rigidity, heat resistance and barrier properties of the nanocomposite.
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  • JUN KAMEDA, ATSUSHI OKAMOTO, TAKASHI MIKOUCHI, RYUJI KITAGAWA, TOSHIHI ...
    Article type: Article
    2010 Volume 14 Issue 4 Pages 155-161
    Published: 2010
    Released on J-STAGE: June 22, 2017
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    To understand the origin of its unique morphology, the structure of vermiform chlorite has been investigated. Two chlorite specimens (magnesian chamosite) were analyzed: vermicular aggregates in quartz-feldspar veins in a pelitic schist, and those grown on a quartz single-crystal surface. Both specimens show very similar textures; they are composed of pseudohexagonal chlorite plates of several tens μm in lateral size and several hundreds nm in packet thickness, stacked to form long vermicular aggregates up to several hundreds μm. Chemical analyses indicated that the two specimens have similar compositions with ^<IV>Al 1.2〜1.3 per 4.0 sites and Fe/(Mg+Fe) ratio of 〜0.55. XRD and EBSD indicate IIbb semi-random stacking. HRTEM shows that the stacking is considerably disordered in terms both of the layer orientation and direction of the interlayer displacement. The vermicular morphology of chlorite is probably originated from a relatively faster spiral growth along the stacking in hydrothermal fluid.
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  • MASASHI NAKANO, KATSUYUKI KAWAMURA
    Article type: Article
    2010 Volume 14 Issue 4 Pages 163-171
    Published: 2010
    Released on J-STAGE: June 22, 2017
    JOURNAL FREE ACCESS
    Net microbial decomposition of calcium silicate hydrate (C-S-H) that results in the biodegradation of concrete has been analyzed theoretically on the basis of the conservation principle of Gibbs free energy in the microorganism-concrete systems. Microorganisms have been considered to be adhered to concrete surface by forming micro-colonies and bio-films. The growth and decay of microorganisms were expressed using Monod-based equation. It was predicted that the mean density of microorganisms in bio-films reached 6.7×10^<-6>g/cm^3. The bio-film thickness reached 19.5μm. The net microbial decomposition depth of C-S-H in concrete was about 7 to 10μm/year and did not exceed 40μm/year at most, provided that microorganisms of 4×10^<-9> and 4×10^<-8>g/cm^3 adhered to concrete surface.
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  • Article type: Appendix
    2010 Volume 14 Issue 4 Pages App5-
    Published: 2010
    Released on J-STAGE: June 22, 2017
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  • Article type: Cover
    2010 Volume 14 Issue 4 Pages Cover2-
    Published: 2010
    Released on J-STAGE: June 22, 2017
    JOURNAL FREE ACCESS
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  • Article type: Cover
    2010 Volume 14 Issue 4 Pages Cover3-
    Published: 2010
    Released on J-STAGE: June 22, 2017
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