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Volume 30 (1990 - 199･･･
- Issue 4 Pages 211-
- Issue 3 Pages 165-
- Issue 2 Pages 91-
- Issue 1 Pages 1-
Volume 30, Issue 2
Displaying 1-9 of 9 articles from this issue
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Formation of Jarosite on Corroded Portland CementKazue TAZAKI, Tadahiro MORI, Tsuguhiro NONAKA, Shuji NODA1990 Volume 30 Issue 2 Pages 91-100
Published: August 10, 1990
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSConcrete sewer pipe was heavily corroded by sulfate which was produced by sulfur oxidizing bacteria in the Ohmuta region of Japan. The corroded materials were studied mineralogically to gain a better understanding of the corrosion mechanism. The formation of jarosite KFe3 (SO4) 2 (OH) 6, as a result of reaction between sulfate and hydration products of portland cement, were found in the most corroded part of concrete sewer pipe. The sulfate-generated corrosion is grouped into several zones on the base of differences in the mineral formation of secondary products:
Zone A & B; Jarosite formation zone, Zone C; Fe-rich zone,
Zone D; gypsum formation zone, Zone E; Fe-rich zone,
Zone F; Cracking zone, Zone G; Fresh concrete zone.
Zones A-E in the corroded parts include expansion, loss strength and stiffness and disintegration, whereas Zones E and F show cracking and brown rim stained with iron oxides. In Zone G, ettringite crystals are formed under conditions of high pH. Since hydrated cements containing considerable amount of large ettringite crystals show high strength but no expansion.
In order to evaluate the relative effects of corrosion of concrete, the rates of K-feldspar dissolution have been analized by EDAX-step scanning. The dissolution process of K-feldspar was observed that Al and K contents were rapidly decreased near rim, within 2μm region, whereas Fe content was increased.
The results of these analyses indicate that the effect of K component from K-feldspar dissolution is important factor to form jarosite at pH of 3.5-4.0. The dissolution mechanism of K-feldspar and the addition of Fe component are changed significantly due to the corrosion of concretes.View full abstractDownload PDF (13432K) -
Keinosuke NAGASAWA, Hikaru MORISHIMA1990 Volume 30 Issue 2 Pages 101-108
Published: August 10, 1990
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSWeathered biotite in Cretaceous hornblende-biotite granodiorite from Ono-Niimachi, Fukushima Prefecture, Northeast Japan was examined by X-ray diffraction and EPMA. Specimens 1 and 2 taken from the upper part of thick weathering profile consist of interstratification of biotite and Al-rich dioctahedral vermiculite. EPMA shows that these two specimens are composed of stacking of thin layers which each have different proportion of the components. Kaolinite is found along the cleavage plane of original biotite or partly replacing it. These two specimens are characterized by Al enrichment during lateritic weathering.
Specimens 3, 4 and 5 were taken from the lower part of weathering profile where fresh granodiorite remains as corestones. Specimen 5 from a corestone is fresh biotite with minor amount of K-vermiculite. Specimen 4 from weakly weathered granodiorite consists of biotite and K-vermiculite. Specimen 3 from saprolite is interstratification of biotite, K-vermiculite and trioctahedral vermiculite and also shows layered structure.View full abstractDownload PDF (3227K) -
Masakazu HORIO, Eiji WATANABE, Kenzi SUZUKI1990 Volume 30 Issue 2 Pages 109-114
Published: August 10, 1990
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSMotoyama-, Hara-, and Iga-kibushi clays were subjected to fractional extraction by using NaOH and Na4P2O7 to characterize the humic substance involved in the clay. Cation exchange capacity (CEC) was also measured for the untreated and H2O2-treated clays. Followings were verified:
1) The humic substance involved in Motoyama-and Hara-kibushi was mainly composed of a humin-type, which was hardly extracted with NaOH and Na4P2O7, while the humic substance was extracted readily from Iga-kibushi.
2) The humic substance extracted was considered to be bound with clay via Al-ions.
3) While CEC was larger for untreated clay than for H2O2-treated one in an alkali region, there was not much difference in CEC between both treatments in the neutral and acidic regions except Iga-kibushi.
The contribution of the humic substance to the negative charge of the clay surface was discussed on the basis of the CEC mesured.View full abstractDownload PDF (641K) -
Atsushi SATO1990 Volume 30 Issue 2 Pages 115-125
Published: August 10, 1990
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSIn heavy clay soil of the Hachiro-gate polder reclaimed in 1966, very coarse blocky or prismatic structures are observed in the Bg horizons. The shape, size, degree of the development of the structures and their arrangement in the horizons are depending on the drainage conditions.
The process of soil-structure formation, and changes in the chemical, clay mineralogical, and physical properties of the soil during the process are introduced in this article. Futhermore, I point out the subjects of the soil consolidation at the upper parts in the horizons and water pollution in the Hachiro-gata Residual Lake.View full abstractDownload PDF (5215K) -
Takashi WATANABE1990 Volume 30 Issue 2 Pages 126-130
Published: August 10, 1990
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSFour interesting topics in the clay mineralogy are discussed. They are; 1. fine structure of clay minerals, 2. the structure of water molecules in the interlayer, 3. the “particle” of clay mineral, and 4. the interstratified minerals.
With regard to the point 1, the location of the layer charge caused by the chemical substitution is discussed. The problem on the water molecules is selected in 2 and the theme whether the ice structure is correct or not is discussed.
In 3, the “fundamental particle” proposed by Nadeau (1985) is discussed.
In 4, the structure, crystal chemistry and mechanism of I/S mixed layer are summarized, and the theme to be discussed was pointed out.View full abstractDownload PDF (2653K) -
Hiromoto NAKAZAWA1990 Volume 30 Issue 2 Pages 131-136
Published: August 10, 1990
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSCompared with common inorganic materials, the smectite group of clay minerals have many unusual physical and chemical properties. Precise characterization on the minerals has, however, been hindered by the luck of large single crystals, and our current understanding and use of these materials are limited in the form of polycrystalline aggregates of under-micronmeter size particles. Because X-ray and electron diffraction methods, the common tool for structure analysis, enhance the periodic nature of subject, the local and random structure is difficult to see particularly. Some characteristics emphasized in a small particles are described for the cases of multiple-twin-domain particle of gold and the clean (111) surface of silicon single crystal. Similar futures may be present in smectite of the same order of size. A single crystal of smectite may, therefore, be a key for finer understanding and use. The current state of the studies focusing on synthesis of high-crystalline smectine is also described.View full abstractDownload PDF (2863K) -
Shin-Ichiro WADA1990 Volume 30 Issue 2 Pages 137-142
Published: August 10, 1990
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSThree open reseach problems are briefly reviewed, solutionsto which problems are indispensable for understanding properties of clay mineral/aqueous electrolyte systems.
The first problem is to elucidate the distribution pattarn of excessive negative charge generated by isomorphous substitution in tetrahedral and octahesral sheets of layer silicate minerals. This problem is closely related to predicting swelling properties of smectite and vermiculite from a given chemical composition.
The second one is to quantify surface hydroxyl groups of metal oxides and hydroxides which are responsible for development of negative and positive surface charge. Without the knowledge on the number of the reactive hydroxyl groups, verification of chemical models describing ion adsorption, e. g., surface complexation models, is difficult.
The third one is the determination of the structure of surface complexes formed at oxide/ aqueous electrolyte interfaces. Despite the success of widely accepted surface complexation models, the structure of the surface complexes adopted in them are only hypothetical, the presence of which has not been proven on a physico-chemical basis.View full abstractDownload PDF (739K) -
Yoshiaki FUKUSHIMA1990 Volume 30 Issue 2 Pages 143-147
Published: August 10, 1990
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSPolymerization reaction of εA-caprolactam initiated at an interlayer spacing of smectite and the structure of the obtained intercalated compounds were reviewed. Characteristics of clay minerals as a host for intercalation or inclusion; functions of interlayer cations, swelling behaviour, layer charge distribution, two dimentional character of silicate layers, and reactions at crystal edges of layers, were discussed.View full abstractDownload PDF (4674K) -
Fascinating Swellable CrystalsKazuo URABE1990 Volume 30 Issue 2 Pages 148-156
Published: August 10, 1990
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSTo understand the relationship between the function, including catalysis, and the structure of clay is of central importance in all clay-bearing phenomena. Employing synthetic clays makes it possible to clarify the principal structural factors determining the catalytic efficiency of acidic clays. Based on three structural factors, or particle size, cation exchange capacity and position of isomorphous substitution, successful and novel attempts to develop the catalytic functions of synthetic clays willbe presented.View full abstractDownload PDF (1067K)
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