Solvation Methods for Expandable Layers

Novich, Bruce E.; Martin, R. Torrence

doi:10.1346/ccmn.1983.0310311

Cited by 26 publications

(9 citation statements)

References 6 publications

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“…Orientation of the clay was achieved by the suction method on a ceramic plate. Expansion tests were performed by solvation with ethylene glycol and glycerol vapour at 60 and 90°C, respectively (Novich and Martin 1983). Specimens saturated with K were heated at 110 and 550°C.…”

Section: Soil Analysesmentioning

confidence: 99%

Micromorphology of surface crusts in the Knersvlakte, South Africa

2009

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Soils in the Knersvlakte are particularly prone to crusting and have lower inherent infiltrability than other soils across western southern Africa. Micromorphological techniques were used to examine the structure and porosity of soil crusts in the Knersvlakte to ascertain why crusting is so intense in this region. Quantile regression using boundary lines was employed to examine the relationships between infiltrability and soil properties for all samples (n = 67). This analysis showed that infiltrability is potentially maximal at low waterdispersible 'clay plus silt' content and low silt content (r 2 = 0.72 and 0.64; respectively, n = 67) ( Figure 2). The strength of crusts, pH, EC, clay mineralogy, and water-dispersible clay, silt and 'clay plus silt' content were compared, and a pore analysis using optical microscopy was undertaken on images of six soil thin sections (n = 6) (circular and parallel polarizers). Pore analysis was further undertaken on five horizontal slices of equal dimensions taken through each soil thin section. The porosity samples with low infiltrability (< 100 mm·hr -1 , n = 4) had greater crust strength, lower porosity (both total and in the least porous slice) and greater water-dispersible 'clay plus silt' and silt content than the porosity samples with high infiltrability (> 100 mm·hr -1 , n = 2). The porosity samples with low infiltrability showed a trend of lower pH and greater water dispersible clay percentage. Porosity varied within the porosity samples due to the presence of dense clay/silt bands (< 0.5 mm in width) with relatively few air vesicles. The porosity samples with horizontal slices of low porosity (but large numbers of air vesicles) had low infiltrability, while those without slices of low porosity (and relatively few air vesicles) had high infiltrability. We conclude that the intense crusting and resultant low infiltrability of soils in the Knersvlakte appears to be related to the formation of thin, dense clay/silt bands in the pedoderm.

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Section: Soil Analysesmentioning

confidence: 99%

Micromorphology of surface crusts in the Knersvlakte, South Africa

2009

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“…suction-through method (Gibbs, 1965). Expansion tests were performed by solvation with ethylene glycol (vapour at 60 ~ for 24 h; Novich & Martin, 1983), and intercalation with hydrazine (in vacuo for two days; Range etal., 1969). Potassium-saturated samples were heated at 500~ for 4 h. Semi-quantitative estimates were based on peak heights for non-clay mineral composition (Brime, 1985) and on peak areas for the clay fraction (Biscaye, 1965).…”

Section: Methodsmentioning

confidence: 99%

Parent Material and Pedogenic Processes in South Africa

Bühmann

1994

Clay miner.

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ABSTRACT:The soils over about half of South Africa are developed from sedimentary rocks of the Karoo Supergroup. Some units within the Karoo strata display variations in their mineralogical composition which correlate with fluctuations in the environment of deposition and with palaeotemperature. The former trends are reflected in the ratio of kaolinite to 2:1 layer-silicates, range from kaolinite-dominated to kaolinite-free, and are particularly evident in rocks of the Vryheid Formation, Geothermal history is preserved in various stages of smectite illitization ranging from R = 0 structures with 25% illite to 100% illite.

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“…The clay fractions were mounted on ceramic tiles by the suctionthrough method and analysed. Expansion tests were performed by solvation with ethylene glycol and glycerol (vapour at 60°C and 90°C, respectively, for 24 h; Novich & Martin, 1983). K-saturated samples were heated at 300°C and 550°C, and Li-saturated clays at 280°C (Greene-Kelly test), for 4 hours.…”

Section: Methodsmentioning

confidence: 99%

Pedogenic differences between two adjacent basalt-derived soil profiles 2. Mineralogical characteristics

Bühmann

Paterson

Kirsten

1994

South African Journal of Plant and Soil

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The mineralogical composition of a black vertisol (Arcadia form) and a red alfisol (Shortlands form) profile, derived from Jurassic basalt and situated 35 m apart, has been determined by means of X-ray diffraction analysis. The non-clay fractions of the least-weathered zones (C2) contained plagioclase (labradorite) and pyroxene (both orh and mkl) as dominant components, with labradorite slightly more prevalent in the Shortlands saprolite. The C 1 horizon of the Arcadia pedon was devoid of mafic minerals and composed of quartz and calcite, while the equivalent horizon of the Shortlands profile still contained pyroxene and feldspar, although in smaller proportions and associated with quartz. In both solums, quartz was dominant. Hematite accounted for slightly more than half of the secondary iron phases throughout the two solums. Smectite constituted the primary alteration product in both profiles. In the Arcadia soil, smectite remained the dominant phyllosilicate phase. In the Short lands profile, however, smectite was progressively transformed into kaolinite with an increasing degree of weathering and constituted about half of the clay fraction in the top horizon. The transformation of smectite to kaolinite proceeded predominantly via the dissolution-precipitation pathway. The swelling behaviour of smectite after the application of the Greene-Kelly test indicated that layer charge arose predominantly from tetrahedral substitutions in all samples. Dodecylamine intercalation and K-saturation pointed to high interlayer charge densities, characteristic of high charge smectite or low charge vermiculite. Within the Arcadia pedon, changes in chemical composition of the clay fractions were not reflected in the clay suite. In the Shortlands profile, the magnitude of trends in clay mineral composition was only partially reflected in its chemistry.Die mineralogiese samestelling van 'n swart vertisol (Arcadiavorm) en 'n rooi alfisol (Shortlandsvorm), wat ontstaan het op 'n jurassiese basalt en wat 35 m uitmekaar gelee is, is met behulp van X-straal diffraksie bepaal. Die nie-klei fraksies van die minste verweerde sones (C2) het as dominante komponente plagioklaas (Labradoriet) en piroksene (be ide orh en mkl) bevat, met Labradoriet effens minder algemeen in die Shortlands saproliet. Die C1 horison van die Arcadia pedon bevat geen mafiese minerale nie en is saamgestel uit kwarts en kalsiet, terwyl die ekwivalente horison van die Shortlands steeds piroksene en veldspate bevat het, alhoewel in kleiner hoeveelhede en geassosieer met kwarts. Kwarts was dominant in beide gevalle. Hematiet het effens minder as die helfte van die sekondere ystermineraleuitgemaak. Smektiet was die primere verweringsproduk in beide profiele. In die Arcadia profiel was smektiet die dominante filosilikaat. In die Shortlands profiel het smektiet egter progressief verander na kaoliniet met 'n toename in die graad van verwering en was ongeveer die helfte van die kleifraksie in die boonste horison. Die verandering van smektiet na kaoliniet het hoofsaaklik pl...

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Solvation Methods for Expandable Layers

Cited by 26 publications

References 6 publications

Micromorphology of surface crusts in the Knersvlakte, South Africa

Micromorphology of surface crusts in the Knersvlakte, South Africa

Parent Material and Pedogenic Processes in South Africa

Pedogenic differences between two adjacent basalt-derived soil profiles 2. Mineralogical characteristics

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