SOUTH AFRICAN NATIONAL STANDARD

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1 ISBN SOUTH AFRICAN NATIONAL STANDARD Civil engineering test methods Part GR40: Determination of the California bearing ratio 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 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-GR40:2010 (edition 1). A vertical line in the margin shows where the text has been technically modified by amendment No. 1. 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 gravels, sands and soils. Annexes A and B are for information only. Introduction Penetration tests such as the California bearing ratio (CBR) test measure mainly the resistance of the soil to deformation by shearing. The CBR test is more flexible than many other penetration tests and can be carried out on nearly all materials ranging from clay to gravel. The test method was originally developed by RR Proctor in 1933 for the control of earth dam construction in California. It was further developed by the California State Highway Department for the evaluation of subgrade strengths and was adopted by the US Corps of Engineers for the design of flexible pavements. This part of SANS 3001 is based on the South African TMH1 series used over the last 50 years. It is similar to ASTM and BS test methods (see bibliography) apart from minor variations in method. Existing apparatus that conforms to the requirements of TMH1 may be used in this method until it is no longer fit for purpose. This part of SANS 3001 is used to check the quality of materials proposed for and used as subgrade and construction materials for roads. This test method is classified as Group: B, Rating: 5, Activity: GR, in accordance with the requirements of the South African Construction Education and training Authority (CETA).

3 Contents Page Acknowledgement Foreword Introduction 1 Scope Normative references Definitions Apparatus Test sample preparation Procedure Moisture content Compaction Specimen preparation Soaking and swell Bearing test Calculations Moisture content, dry density and swell Procedure for the determination of CBR Uncertainty of the test method Test report Annex A (informative) Example of the calculation procedure Annex B (informative) Test flow chart Bibliography

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5 Civil engineering test methods Part GR40: Determination of the California bearing ratio 1 Scope This part of SANS 3001 applies to gravels, sands and soils (silts and clays) and describes a method to determine the California bearing ratio (CBR) of a material compacted in a 152 mm diameter mould using three compaction efforts and penetrated using a steel piston. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. Information on currently valid national and international standards can be obtained from the SABS Standards Division. SANS 241-1, Drinking water Part 1: Microbiological, physical, aesthetic and chemical determinands. Amdt 1 SANS 241-2, Drinking water Part 2: Application of SANS Amdt 1 SANS 1649, Non-automatic self-indicating, semi-self-indicating and non-self-indicating weighing instruments with denominated verification scale intervals. SANS 3001-GR20, Civil engineering test methods Part GR20: Determination of the moisture content by oven-drying. SANS 3001-GR30, Civil engineering test methods Part GR30: Determination of the maximum dry density and optimum moisture content. SANS 3001-PR1, Civil engineering test methods Part PR1: Determination of uncertainty of measurement, repeatability, reproducibility and bias. SANS /ISO , Test sieves Technical requirements and testing Part 1: Test sieves of metal wire cloth. SANS /ISO , Test sieves Technical requirements and testing Part 2: Test sieves of perforated metal plate. 3