PROJECT REPORT  
                        
                        
                        
                        
                        
                       Guidelines on the selection and use of road 
                       construction materials 
                        
                        
                        
                       by Transport Research Laboratory 
                        
                        
                                                    
                       Subsector:                  Transport 
                                                    
                       Theme:                      T2 
                                                    
                       Project Title:              Guidelines on the selection and use of road construction materials 
                                                    
                       Project Reference:          R6898 
                                                                                                                                     
                                                                         APPROVALS                                                   
                                                                                                                                     
                       Project Manager                                   Quality reviewed                                            
                                                                                                                                     
                                                                                                                                     
                        
                        
                        
                        
                        
                        
                        
                        
                        
                        
                       This report prepared for the Infrastructure and Urban Development Division (IUDD) of the 
                       Department For International Development (DFID) Knowledge and Research program must not 
                       be referred to in any publication without the permission of DFID. The views expressed are 
                       those of the author(s) and not necessarily those of DFID. 
                        
                        
                       TRL is committed to optimising energy efficiency, reducing waste and promoting recycling and 
                       re-use. In support of these environmental goals, this report has been printed on recycled paper, 
                       comprising 100% post-consumer waste, manufactured using a TCF (totally chlorine free) 
                       process. 
                                                                               
                                                                               
                        
                      Transport Research Laboratory    Guidelines on the Selection and Use of Construction Materials 
                       
                                                                  CONTENTS 
                       
                       PREFACE 
                      1 INTRODUCTION.....................................................................................................................1-1 
                         1.1 General Background..........................................................................................................1-1 
                         1.2    Purpose of the Document..................................................................................................1-1 
                         1.3 Document Strategy............................................................................................................1-2 
                         1.4    Scope of the Document.....................................................................................................1-3 
                      2      THE GEOLOGICAL BACKGROUND....................................................................................2-1 
                         2.1 Introduction.........................................................................................................................2-1 
                         2.2 Principal Rock Groups.......................................................................................................2-1 
                             2.2.1 General Groups..........................................................................................................2-1 
                             2.2.2 Igneous Rocks............................................................................................................2-1 
                             2.2.3 Sedimentary Rocks....................................................................................................2-2 
                             2.2.4 Metamorphic Rocks....................................................................................................2-2 
                         2.3 Weathering.........................................................................................................................2-3 
                             2.3.1 Processes...................................................................................................................2-3 
                             2.3.2 Transported Materials ................................................................................................2-4 
                             2.3.3 In Situ Materials..........................................................................................................2-4 
                         2.4 Structure.............................................................................................................................2-5 
                             2.4.1 General.......................................................................................................................2-5 
                             2.4.2 Folds...........................................................................................................................2-5 
                             2.4.3 Discontinuities.............................................................................................................2-6 
                             2.4.4 Texture........................................................................................................................2-6 
                             2.4.5 Fabric..........................................................................................................................2-6 
                         2.5    Classification and Characterisation of Materials Sources ................................................2-6 
                             2.5.1 General Classification.................................................................................................2-6 
                             2.5.2   Hard Rock Sources....................................................................................................2-6 
                             2.5.3   Weak Rock Sources...................................................................................................2-7 
                             2.5.4 Transported Soils .......................................................................................................2-7 
                             2.5.5   Residual Soils and Duricrusts....................................................................................2-8 
                      3      THE ACQUISITION AND UTILISATION OF ROAD CONSTRUCTION MATERIALS 
                      INFORMATION.................................................................................................................................3-1 
                         3.1 Introduction.........................................................................................................................3-1 
                         3.2 General Objectives.............................................................................................................3-1 
                         3.3    Data Acquisition Programming..........................................................................................3-2 
                             3.3.1 Information Groups.....................................................................................................3-2 
                             3.3.2 Programme Planning..................................................................................................3-2 
                         3.4 Existing Information Acquisition.........................................................................................3-3 
                             3.4.1 Scope and Objectives ................................................................................................3-3 
                             3.4.2 Maps as Information Sources....................................................................................3-4 
                             3.4.3 Aerial photographs .....................................................................................................3-4 
                             3.4.4 Satellite imagery.........................................................................................................3-5 
                             3.4.5 Climatic Data ..............................................................................................................3-6 
                             3.4.6   Geotechnical and Construction Materials Data.........................................................3-6 
                             3.4.7 Desk Study Assesment..............................................................................................3-6 
                         3.5 Exploration Phase..............................................................................................................3-7 
                             3.5.1 Scope..........................................................................................................................3-7 
                             3.5.2 Procedures..................................................................................................................3-8 
                             3.5.3   Required Outcomes from an Exploration Phase.......................................................3-8 
                             3.5.4 Exploration Data Assessment....................................................................................3-8 
                         3.6 Resource Investigation ......................................................................................................3-9 
                             3.6.1   Scope of Resource Investigation Phase....................................................................3-9 
                             3.6.2   Procedures for Resource Investigation Phase..........................................................3-9 
                             3.6.3   Required Outputs from Resource Investigation Phase.............................................3-9 
                             3.6.4 Investigation Phase Data Assessment....................................................................3-10 
                         3.7 Reserve Definition............................................................................................................3-10 
                       
                      Transport Research Laboratory    Guidelines on the Selection and Use of Construction Materials 
                       
                             3.7.1 Scope........................................................................................................................3-10 
                             3.7.2 Procedures................................................................................................................3-10 
                             3.7.3   Required Outputs from Reserve Definition Phase..................................................3-10 
                             3.7.4 Final Information Assessment..................................................................................3-11 
                         3.8 Special Investigations......................................................................................................3-11 
                         3.9    Construction Record Keeping..........................................................................................3-11 
                      4 EXTRACTION AND PROCESSING......................................................................................4-1 
                         4.1 Introduction.........................................................................................................................4-1 
                         4.2 Material Extraction .............................................................................................................4-1 
                             4.2.1 General.......................................................................................................................4-1 
                             4.2.2   Hard Rock Quarrying..................................................................................................4-2 
                             4.2.3   Weak Rock Quarrying................................................................................................4-4 
                             4.2.4 Borrow-Pitting.............................................................................................................4-4 
                         4.3 Processing..........................................................................................................................4-5 
                             4.3.1 General.......................................................................................................................4-5 
                             4.3.2 Crushing......................................................................................................................4-5 
                             4.3.3 Sizing and Screening .................................................................................................4-6 
                         4.4 Quality Control....................................................................................................................4-7 
                         4.5 Environmental Issues.........................................................................................................4-8 
                             4.5.1 General Impacts.........................................................................................................4-8 
                             4.5.2   Mitigation of Impacts and Restoration .......................................................................4-8 
                      5 MATERIAL SELECTION........................................................................................................5-1 
                         5.1 Introduction.........................................................................................................................5-1 
                         5.2    Selection and Assessment Criteria ...................................................................................5-1 
                             5.2.1 Common Fill................................................................................................................5-1 
                             5.2.2 In Situ Sub-Grade.......................................................................................................5-2 
                             5.2.3 Imported Capping Layer.............................................................................................5-2 
                             5.2.4 Filter-Drainage Material..............................................................................................5-2 
                             5.2.5   Unbound Granular Pavement Materials....................................................................5-2 
                             5.2.6   Bitumen Bound Granular Pavement and Surfacing Aggregate................................5-3 
                         5.3    Selection and Assessment  Procedures...........................................................................5-4 
                             5.3.1 General Frameworks..................................................................................................5-4 
                         5.4    Road Environment and Geotechnical Impacts .................................................................5-4 
                             5.4.1 Earthwork Embankment Materials.............................................................................5-4 
                             5.4.2 In Situ Sub-Grade.......................................................................................................5-5 
                             5.4.3   Unbound Granular Pavement Aggregate..................................................................5-5 
                         5.5    Options for Material Utilisation...........................................................................................5-5 
                             5.5.1 Common Fill................................................................................................................5-5 
                             5.5.2 In Situ Sub-Grade.......................................................................................................5-6 
                             5.5.3   Unbound Granular Pavement Aggregate..................................................................5-7 
                      6      ENGINEERING MATERIALS TESTING................................................................................6-1 
                         6.1 Introduction.........................................................................................................................6-1 
                         6.2    Materials Testing Programmes..........................................................................................6-1 
                             6.2.1 General Principles......................................................................................................6-1 
                             6.2.2   Test Identification and Selection Guidelines..............................................................6-1 
                             6.2.3   Application of Testing Standards...............................................................................6-2 
                             6.2.4 Programme Planning..................................................................................................6-3 
                         6.3    Test Programme Management..........................................................................................6-3 
                             6.3.1 General.......................................................................................................................6-3 
                             6.3.2 Testing Equipment......................................................................................................6-4 
                             6.3.3 The Laboratory Environment......................................................................................6-4 
                             6.3.4 Personnel....................................................................................................................6-5 
                             6.3.5 Data Management......................................................................................................6-5 
                         6.4    Laboratory  Physical Condition Tests................................................................................6-5 
                             6.4.1 General.......................................................................................................................6-5 
                             6.4.2 Moisture......................................................................................................................6-5 
                             6.4.3 Atterberg Limits...........................................................................................................6-6 
                       
                      Transport Research Laboratory    Guidelines on the Selection and Use of Construction Materials 
                       
                             6.4.4   Particle Size and Shape.............................................................................................6-7 
                             6.4.5 Density........................................................................................................................6-8 
                             6.4.6 Derived Indices...........................................................................................................6-9 
                         6.5 Laboratory Simulation Tests..............................................................................................6-9 
                             6.5.1 General.......................................................................................................................6-9 
                             6.5.2 Volume Change..........................................................................................................6-9 
                             6.5.3 Compaction...............................................................................................................6-10 
                             6.5.4 Density –CBR Relationships....................................................................................6-11 
                             6.5.5   Soil and Rock Material Strength ..............................................................................6-12 
                             6.5.6   Aggregate Strength and Durability...........................................................................6-13 
                             6.5.7 Surfacing Aggregate Tests.......................................................................................6-14 
                         6.6 Chemical Testing.............................................................................................................6-14 
                         6.7 Petrographic Evaluation...................................................................................................6-15 
                             6.7.1 General.....................................................................................................................6-15 
                             6.7.2 Optical Microscopy...................................................................................................6-15 
                             6.7.3   Scanning electron microscopy (SEM) .....................................................................6-15 
                             6.7.4 X-ray diffraction (XRD).............................................................................................6-16 
                             6.7.5 Methylene Blue Testing............................................................................................6-16 
                         6.8 In situ tests .......................................................................................................................6-16 
                             6.8.1 CBR Testing.............................................................................................................6-16 
                             6.8.2 Density Testing.........................................................................................................6-17 
                             6.8.3 Suction Measurement..............................................................................................6-17 
                      7 SAMPLING AND STATISTICS..............................................................................................7-1 
                         7.1 Introduction.........................................................................................................................7-1 
                         7.2 Sampling.............................................................................................................................7-1 
                         7.3 Statistics.............................................................................................................................7-2 
                             7.3.1 General.......................................................................................................................7-2 
                             7.3.2   Means and Variation ..................................................................................................7-2 
                             7.3.3 Normal distribution......................................................................................................7-2 
                         7.4 Sample size........................................................................................................................7-3 
                         7.5    Repeatability and Reproducibility......................................................................................7-3 
                         7.6 Student’s t test....................................................................................................................7-4 
                         7.7 Regression Analysis...........................................................................................................7-4 
                      8      STABILISATION OF NATURAL MATERIALS FOR ROAD BUILDING.............................8-1 
                         8.1 Introduction.........................................................................................................................8-1 
                         8.2 Mechanical Stabilisation....................................................................................................8-1 
                             8.2.1 Compaction.................................................................................................................8-1 
                         8.3 Bitumen Stabilisation..........................................................................................................8-2 
                         8.4 Chemical Stabilisation........................................................................................................8-2 
                             8.4.1 General.......................................................................................................................8-2 
                             8.4.2   Portland Cement as a Stabiliser ................................................................................8-3 
                             8.4.3   Lime as a Stabiliser....................................................................................................8-3 
                             8.4.4 Chemical Stabilisers...................................................................................................8-5 
                             8.4.5   Secondary Stabilising Agents....................................................................................8-5 
                         8.5    Application of Chemical Stabilisation ................................................................................8-6 
                             8.5.1   Strength of Stabilised Materials .................................................................................8-6 
                             8.5.2 Soil Cement................................................................................................................8-6 
                             8.5.3   Cement Bound Granular Material (CBM)..................................................................8-7 
                             8.5.4 Lean Concrete............................................................................................................8-7 
                             8.5.5   Strength Requirements for Pavement Layers...........................................................8-7 
                             8.5.6 Two-Stage Stabilisation..............................................................................................8-7 
                         8.6    Testing for Chemical Stabilisation.....................................................................................8-8 
                             8.6.1 ICL and ICC Testing...................................................................................................8-8 
                             8.6.2 Strength Testing.........................................................................................................8-8 
                             8.6.3 Preparation of specimens. .........................................................................................8-9 
                             8.6.4 Durability Tests...........................................................................................................8-9 
                         8.7    Selection of Chemical Stabilisation Method....................................................................8-10