Location

Arlington, Virginia

Session Start Date

8-11-2008

Session End Date

8-16-2008

Abstract

Sand aging, a process during which the engineering properties of clean sands such as stiffness, penetration resistance and liquefaction resistance may exhibit considerable improvement over periods of only weeks to months after deposition and/or densification by different ground improvement processes, has been shown over the past 30 years to be of considerable practical importance. Numerous examples from a range of projects are presented. Chemical, physical-mechanical, and microbiological processes are examined relative to their adequacy for explaining the observed behavior. Although chemical precipitation-cementation reactions had initially been considered a primary cause, the evidence clearly favors a secondary compression-like process during which particle rearrangements and internal interparticle stress changes and redistributions among groups of particles occur, accompanied by only small volumetric compressions. Information about the rate and magnitude of property changes during aging is summarized, and it is seen that there is considerable variability, dependent on the sand type, its initial state, applied stress conditions, and the specific property being measured. Thus, while the case history information may provide useful guidance about how much property change there will be due to aging and how fast it may occur, each case should be evaluated separately by means of field measurements. Further improvement in the understanding and quantification of sand aging may be possible using rate process and discrete element analysis methods.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Sixth Conference

Publisher

Missouri University of Science and Technology

Publication Date

8-11-2008

Document Version

Final Version

Rights

© 2008 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Aug 11th, 12:00 AM Aug 16th, 12:00 AM

Aging of Sand – a Continuing Enigma?

Arlington, Virginia

Sand aging, a process during which the engineering properties of clean sands such as stiffness, penetration resistance and liquefaction resistance may exhibit considerable improvement over periods of only weeks to months after deposition and/or densification by different ground improvement processes, has been shown over the past 30 years to be of considerable practical importance. Numerous examples from a range of projects are presented. Chemical, physical-mechanical, and microbiological processes are examined relative to their adequacy for explaining the observed behavior. Although chemical precipitation-cementation reactions had initially been considered a primary cause, the evidence clearly favors a secondary compression-like process during which particle rearrangements and internal interparticle stress changes and redistributions among groups of particles occur, accompanied by only small volumetric compressions. Information about the rate and magnitude of property changes during aging is summarized, and it is seen that there is considerable variability, dependent on the sand type, its initial state, applied stress conditions, and the specific property being measured. Thus, while the case history information may provide useful guidance about how much property change there will be due to aging and how fast it may occur, each case should be evaluated separately by means of field measurements. Further improvement in the understanding and quantification of sand aging may be possible using rate process and discrete element analysis methods.