Some recent developments in the determination of the Atterberg Limits

Paul J. Vardanega, Stuart K. Haigh

Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)

4 Citations (Scopus)
432 Downloads (Pure)

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 US 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.
Original languageEnglish
Title of host publicationAdvances in Transportation Geotechnics and Materials for Sustainable Infrastructure
Subtitle of host publicationGeoHubei 2014 (GSP250)
EditorsRifat Bulut, Sung-Chi Hsu
PublisherASCE
Pages48-55
Number of pages8
Edition250 GSP
ISBN (Print)9780784478509
DOIs
Publication statusPublished - Jul 2014
EventGeo-Hubei 2014 International Conference on Sustainable Infrastructure: Advances in Transportation Geotechnics and Materials for Sustainable Infrastructure - Yichang, Hubei, United Kingdom
Duration: 20 Jul 201422 Jul 2014

Conference

ConferenceGeo-Hubei 2014 International Conference on Sustainable Infrastructure: Advances in Transportation Geotechnics and Materials for Sustainable Infrastructure
CountryUnited Kingdom
CityYichang, Hubei
Period20/07/1422/07/14

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