SOUTH AFRICAN NATIONAL STANDARD

Transcription

1 ISBN SOUTH AFRICAN NATIONAL STANDARD Civil engineering test methods Part GR10: Determination of the one-point liquid limit, plastic limit, plasticity index and linear shrinkage Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001 Tel: Fax: SABS

2 Table of changes Change No. Date Scope Amdt Amended to update the introduction. Amdt Amended to update referenced standards. Acknowledgement The SABS Standards Division wishes to acknowledge the valuable assistance of the Committee of Transport Officials (COTO), and the South African National Roads Agency Limited (SANRAL). Foreword This South African standard was approved by National Committee SABS SC 59E, Construction standards Pavement materials testing, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This document was published in March This document supersedes SANS 3001-GR10:2011 (edition 1.1). A vertical line in the margin shows where the text has been technically modified by amendment No. 2. SANS 3001 consists of various parts under the general title Civil engineering test methods. Parts GR of the SANS 3001 series contain methods for testing gravel, sand and soil. Annex A forms an integral part of this document. Annex B is for information only.

3 Introduction The liquid limit, plastic limit and linear shrinkage are often collectively referred to as the Atterberg Limits. The test method is normally carried out on material passing the 425 μm sieve, and when required, also on material passing the 75 μm sieve. To avoid confusion the results from the test on material passing the 75 μm sieve should be clearly identified. The linear shrinkage test is carried out on either the material passing the 425 μm sieve or the material passing the 75 μm sieve, depending on the requirement. For materials where a plasticity index greater than 20 is expected the flow curve liquid limit test method given in SANS 3001-GR12 is recommended instead of the one-point method given in this part of SANS 3001 or the two-point test method given in SANS 3001-GR11. The test methods for liquid limit and plastic limit are similar to the ASTM and BS test methods (see bibliography), except that the amounts of material tested vary and the ASTM and BS test methods incorporate the extraction of the material from the field sample to form the test sample. The BS plasticity index gives a value approximately four units higher than the ASTM and this test method. The ASTM shrinkage test method measures volume change only, while the BS test method measures both volume change and linear shrinkage. The results of this test are used a) for primary material classification, b) to determine compliance of the plasticity index and linear shrinkage with applicable specifications, c) to indicate the presence of clays of high swell potential, and d) for the development of relationships concerning the performance of wearing course gravels. Apparatus dimensions that are critical to the outcome of the method or procedure are given with a tolerance. All other dimensions are nominal and should be considered fit for purpose. Existing apparatus that complies with the requirements of TMH1 may be used in this part of SANS 3001 until the apparatus is no longer fit for purpose. Amdt 1 This part of SANS 3001 is classified as Group: A, Rating: 5, Activity: GR, in accordance with the requirements of the South African Construction Education and Training Authority (CETA). 1

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5 Contents Page Acknowledgement Foreword Introduction Scope Normative references Definitions Apparatus Equipment and sample preparation Procedure Liquid limit Linear shrinkage Plastic limit Calculations Liquid limit Plastic limit Linear shrinkage Plasticity index Uncertainty of the test method Test report Annex A (normative) Resilience test Annex B (informative) Test flow chart Bibliography