Discussion: Fall-cone penetration and water content relationships of clays

Brown, Philip J.; Downing, Michael Christopher

doi:10.1680/geot.2001.51.9.819

Cited by 6 publications

(3 citation statements)

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“…The reliability of the PL result relies heavily upon the expertise of the operator performing the test. This method has been described by Belviso et al (1985) as 'a rather crude procedure', and has long been criticised by others, such as Houlsby (1982), Whyte (1982) and Brown & Downing (2001). The drawbacks of the test are well documented, and include its highly subjective nature, its over-reliance on operator judgement, and variations in the amount of pressure applied during rolling, the speed of the rolling technique used, and the geometry of the thread.…”

Section: Determination Of Consistency Limitsmentioning

confidence: 99%

A new method of measuring plastic limit of fine materials

Sivakumar¹,

Glynn²,

Cairns³

et al. 2009

Géotechnique

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Index properties such as the liquid limit and plastic limit are widely used to evaluate certain geotechnical parameters of fine-grained soils. Measurement of the liquid limit is a mechanical process, and the possibility of errors occurring during measurement is not significant. However, this is not the case for plastic limit testing, despite the fact that the current method of measurement is embraced by many standards around the world. The method in question relies on a fairly crude procedure known widely as the ‘thread rolling' test, though it has been the subject of much criticism in recent years. It is essential that a new, more reliable method of measuring the plastic limit is developed using a mechanical process that is both consistent and easily reproducible. The work reported in this paper concerns the development of a new device to measure the plastic limit, based on the existing falling cone apparatus. The force required for the test is equivalent to the application of a 54 N fast-static load acting on the existing cone used in liquid limit measurements. The test is complete when the relevant water content of the soil specimen allows the cone to achieve a penetration of 20 mm. The new technique was used to measure the plastic limit of 16 different clays from around the world. The plastic limit measured using the new method identified reasonably well the water content at which the soil phase changes from the plastic to the semi-solid state. Further evaluation was undertaken by conducting plastic limit tests using the new method on selected samples and comparing the results with values reported by local site investigation laboratories. Again, reasonable agreement was found.

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Section: Determination Of Consistency Limitsmentioning

confidence: 99%

A new method of measuring plastic limit of fine materials

Sivakumar¹,

Glynn²,

Cairns³

et al. 2009

Géotechnique

View full text Add to dashboard Cite

show abstract

“…Based on Schofield & Wroth (1968) and Wroth & Wood (1978) the strength gain factor R MW has been assumed as 100 by many researchers, but the authors' Figs 3 and 4 show this assumption to be false. A wide variation of R MW has been found by several other authors (Karlsson, 1961;Whyte, 1982;Wood, 1983;Wijeyakulasuriya, 1990;Brown & Downing, 2001;Nagaraj et al, 2012;Vardanega & Haigh, 2014).…”

Section: Contribution By G E Barnesmentioning

confidence: 51%

“…Koumoto & Houlsby (2001) showed that, theoretically, K could vary from about 1 for a rough cone to 2·0 for a smooth cone and, experimentally, between 0·85 and 1·2. Brown & Huxley (1996) and Brown & Downing (2001) found that, although Hansbo's expression with K % 0·8 applies to water contents near the liquid limit, at lower liquidity indices much lower cone factors were appropriate.…”

Section: Contribution By G E Barnesmentioning

confidence: 99%