Use of fall cones to determine Atterberg limits: a review

Clays Clay Miner, 1955

Correns and Lippmann have extended the work carried out in England on swelling chlorites by some investigations on Keuper clays.

Applied Clay Science, 2004

Among some few others tests, the evaluation of the Atterberg limits is a very basic soil mechanical test allowing a first insight into the chemical reactivity of clays. Basically, the liquid limit and the plasticity index are highly and mainly influenced by the ability of clay minerals to interact with liquids. In this contribution, a correlation between the Atterberg limits and clay mineralogy is proposed. This correlation increases the understanding between clay mineralogists and engineers in soil mechanics; additionally a wealth of information in clay mineralogy literature is now available to predict the mechanical behaviour of clays via index tests.

Clays and Clay Minerals, 2007

As the water content is increased, the consistence of a fine-grained soil changes from a semi-solid state to a plastic state and finally to a liquid state. The plastic limit (PL) is the soil water content where the consistence is transformed from a semi-solid state to a plastic state. The liquid limit (LL) is the soil water content where the consistence is transformed from a plastic state to a liquid state. The plastic limit and liquid limit are often collectively referred to as the Atterberg (or consistency) Limits. Although the liquid and plastic limits are easily determined quantities, fundamental interpretations of the limits and quantitative relationships between their values and compositional factors are more complex. Previous studies examined artificially-prepared soil samples that contained monomineralic clays and a non-clay substance (quartz sand). These studies have shown that in soils without expandable clays the PL and LL water contents were mostly related to surface area and clay content.

Journal of Environmental Quality, 1995

Of the determinative methods used to study clay minerals, chemical analysis is the oldest and most established. Before the development of the earliest instrumental techniques, such as X-ray diffraction and thermal methods, the identification of clay-mineral phases was accomplished by chemical analysis, supplemented where possible by optical data and physical characteristics such as specific gravity, colour, hardness, etc. However, fine-grained materials cannot be characterized reliably using these methods alone, and misidentifications were common. With the routine application of infrared spectroscopy and electron microscopy, in addition to X-ray diffraction and thermal analysis, instrumental techniques are now unquestionably superior to chemical analysis for clay-mineral identification and a clay is often described and identified without recourse to chemical analysis. Nevertheless, for complete characterization, a chemical analysis is still essential, as this is the only way that a structural formula can be calculated and the distribution of cations in the structure defined directly. A full characterization should include the determination of all the major and minor elements (with the proportion of the iron present in the ferrous and ferric forms) and also the determination of the cation-exchange capacity and, if possible, the anion-exchange capacity. Classification of clay minerals has always depended heavily on chemical data, and many clay-mineral groups, such as smectites, illites and chlorites, are subdivided according to composition. The characterization of a clay mineral as 'dioctahedral' or 'trioctahedral' can be determined from a b-dimension measurement using X-ray or electron-diffraction techniques, but these terms also have a chemical connotation, indicating the valency of the cations occupying the octahedral sheets. The type and Clay Mineralogy: Spectroscopic and Chemical Determinative Methods.

Applied Clay Science, 2012

Clays and Clay Minerals, 2003

Clays of a soil sequence with five profiles in the Val Genova (northern Italy) along an elevation gradient with climate ranging from moderate to Alpine were investigated with XRD using several diagnostic treatments. Smectites developed in the surface horizons of podzolic soils either from chlorite through the removal of hydroxy interlayers or from mica, which weathers in a first step to regularly or irregularly interstratified clay minerals. Citrate treatment allowed the detection of low-charge expandable minerals in the Bhs or Bs horizons. Therefore, the reduction of the charge of 2:1 clay minerals occurred before the removal of hydroxy polymers by fulvic acids and low-weight organic acids. Due to the more intense podzolization process near the tree line, the d 060 region showed a temporal evolution of trioctahedral to dioctahedral mineral structures in the well developed Podzols. The pedogenic smectites of the E or Bhs horizons generally included one or several populations with various charges. In most cases, smectite was a heterogeneous mixture of montmorillonite and interstratified beidellite-montmorillonite. A pure beidellite phase could not be detected. The soils near the tree line, where weathering processes were most intense, had two main components: one with a charge >0.75, representing vermiculite-like minerals, and the other with a charge near 0.25, representing smectite. The charges of the beidellitic component and montmorillonite were almost equal. The higher the weathering state of the investigated soils, the lower was the layer charge of smectites.

Geotextiles and Geomembranes, 2007

In the field, particularly in landfill cover system applications, a geosynthetic clay liner may be exposed to inorganic cations such as calcium, magnesium and aluminium which can alter the performance of the GCL bentonite component especially if accompanied by drying and re-wetting as a result of seasonal changes in temperature and rainfall. To investigate the impacts of wetting and drying, the Atterberg limits of the GCL bentonite component and swelling of the GCL were determined under wet-dry cycling with calcium chloride solution used for the wetting cycles. From the quantities of calcium chloride added at each wetting stage, estimates were made of the degree of ion exchange of calcium for sodium on the clay. The authors recognise that there is a substantial literature on the effects of inorganic salts such as calcium chloride on the behaviour of bentonite. However, so far as they are aware, the results of such tests involving cation exchange have not been investigated in terms of the degree of exchange achieved.

Geoderma, 2009

Changes in the clay mineralogy of soil samples collected from the Rothamsted Classical 10 Experiments over the past ~150 years were examined. Comparisons were undertaken to assess 11 the impact of (i) different fertiliser practices on the top soil and sub soil of the Park Grass 12 Experiment and (ii) the effects of changing land-use from agriculture to woodland where soil 13 pH either remained close to pH 7 or became acid. Analyses were undertaken on the <0.2 µm 14 clay fraction and measurements included cation exchange capacity (CEC), surface area and 15 X-ray diffraction (XRD). The fine clay fraction of all the samples is composed of 16 illite/smectite (I/S), illite and kaolinite minerals. Decomposition modelling of XRD spectra 17 identified three I/S phases including (i) a high smectite I/S phase (d(00l) ~15Å), (ii) a low 18 smectite I/S phase (d(00l) ~12.5Å) and (iii) an illite phase (d(00l) ~11.2Å). The I/S phase is 19 typically made up of ~60 % of high smectite I/S, ~20 % low smectite I/S and ~20 % illite. 20 Attempts to account for changes in clay CEC and surface area with time proved to be 21 inconclusive, possibly because of the differing proportions of the three I/S phases in each 22 sample. Some temporal changes in the d(00l) spacing of I/S mineral phases from the 23 decomposed XRD spectra (>0.4 Å) are reported in both top soil (0-23 cm) and sub soil (46-69 24 cm) and are likely related to (i) changes in soil K + or NH 4 + status and/or (iii) increasing soil 25 acidity. The greatest change was found in the Park Grass Experiment (NH 4 ) 2 SO 4 plot where 26 36 37

Mining and Metallurgy Engineering Bor, 2013

This paper presents the results of interlaboratory testing the soil consistency-the Atterberg limits (liquid, plasticity and shrinkage limit). The tests were performed on representative samples of soil. The results were analyzed in two ways: numerical method-the Cochran test of precision and graphical interpretation-calculation of z value in accordance with the Standard ISO 5725-2 [1]. The followings were calculated: variance of repeatability Sr 2 , interlaboratory variance S L 2 and reproducibility variance S R 2 .The samples were distributed by the method of divisibility to all participating laboratories.

Applied Clay Science, 2010

A current semi-empirical model of conversion of smectite to illite implies that the process is associated with formation of quartz and chlorite and will not cause significant illitization in the hydrothermal period of a repository if the activation energy is of the commonly assumed magnitude and the temperature is lower than about 100°C. The model is supported by several natural analogues and hydrothermal experiments in laboratories and field tests. In all the experiments, which were conducted under open chemical conditions, the confined clay was exposed to thermal gradients for at least 1 year. Most of the tests were small-scale and of "1D-type", one being performed with strong gamma radiation, and the others with different porewater compositions. One was a Mockup experiment simulating the KBS-3V concept on 50% scale, and one a full-scale KBS-3V field experiment at 400 m depth in granitic rock. They all showed that while smectite remained the major clay mineral a number of processes changed the physical properties in bulk, the most important changes being reduction of the expandability and increase of the hydraulic conductivity of the hottest part of the buffer. The latter is concluded to have been caused by contraction of clay aggregates that became permanent by precipitation of silica and iron compounds, the cementing agents emanating from dissolved accessory minerals as well as from montmorillonite. Fe-rich montmorillonite underwent particularly important dissolution.