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Some recent developments in the determination of the atterberg limits

Vardanega, PJ and Haigh, SK (2014) Some recent developments in the determination of the atterberg limits. Geotechnical Special Publication. pp. 48-55. ISSN 0895-0563

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Abstract

The Atterberg Limits are the most common tests specified by practicing geotechnical and pavement engineers the world over. They are used to classify soils using the framework pioneered by Terzaghi and Casagrande during their work with the U.S. Public Roads Bureau in the 1920s and 1930s and are also correlated with many fundamental soil parameters used in design and construction projects. In the 21st century the Atterberg Limits remain a key component of the testing armory of practicing geotechnical engineers, as they can be obtained easily for the large numbers of samples that are needed on major construction projects and allow for rapid assessments of key soil parameters. Their fundamental definitions are worthy of review; the thread-rolling test for plastic limit has remained largely unchanged since Atterberg first described it in 1911, but the definition and measurement of liquid limit varies across the globe. The fundamental mechanics of the Casagrande Cup liquid limit have been the subject of recent study showing clearly that liquid limit determined in this way relates to a fixed value of specific soil strength (i.e. strength per unit density) as opposed to a fixed strength value when liquid limit is measured by the fall-cone method. These findings explain the deviation between liquid limits measured by the two methods for high plasticity soils without the need to invoke different strength regimes. The brittle failure mechanism in the thread-rolling test has also been recently re-examined. It is proposed that the brittle failure observed in the plastic limit test is caused by either air entry or cavitation in the clay and plastic limit and does not correspond to a fixed strength. The Atterberg Limits are used to compute liquidity index which is widely related to clay strength variation, this is critical for many areas of construction (especially when rapid assessments of strength are required). The Russian code for the design of piled foundations, for example, uses liquidity index values to assess shaft friction. Recent research outcomes at the University of Cambridge have challenged certain assumptions pertaining to widely used correlations between liquidity index and undrained strength. © ASCE 2014.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div D > Geotechnical and Environmental
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:05
Last Modified: 22 Oct 2020 04:50
DOI: 10.1061/9780784478509.007