Guidelines on the selection and use of road construction ...

1 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).

2 Process. Transport Research Laboratory Guidelines on the selection and Use of construction Materials CONTENTS. PREFACE. 1 INTRODUCTION ..1-1. General Background ..1-1. Purpose of the Document ..1-1. Document Strategy ..1-2. Scope of the Document ..1-3. 2 THE GEOLOGICAL Principal Rock Groups ..2-1. General Groups ..2-1. Igneous Rocks ..2-1. Sedimentary Rocks ..2-2. Metamorphic Weathering ..2-3. Processes ..2-3. Transported Materials ..2-4. In Situ Materials ..2-4. Structure ..2-5. General ..2-5. Folds ..2-5. Texture ..2-6. Fabric ..2-6. Classification and Characterisation of Materials Sources ..2-6. General Hard Rock Sources ..2-6. Weak Rock Transported Soils ..2-7. Residual Soils and Duricrusts ..2-8. 3 THE ACQUISITION AND UTILISATION OF ROAD construction MATERIALS. INFORMATION ..3-1. General Data Acquisition Programming.

3 3-2. Information Programme Existing Information Scope and Objectives ..3-3. Maps as Information Sources ..3-4. Aerial photographs ..3-4. Satellite imagery ..3-5. Climatic Data ..3-6. Geotechnical and construction Materials Desk Study Assesment ..3-6. Exploration Phase ..3-7. Scope ..3-7. Required Outcomes from an Exploration Exploration Data Resource Investigation ..3-9. Scope of Resource Investigation Procedures for Resource Investigation Phase ..3-9. Required Outputs from Resource Investigation Investigation Phase Data Assessment ..3-10. Reserve Transport Research Laboratory Guidelines on the selection and Use of construction Materials Scope ..3-10. Required Outputs from Reserve Definition Phase ..3-10. Final Information Special Investigations ..3-11. construction Record 4 EXTRACTION AND PROCESSING ..4-1.

4 Material Extraction ..4-1. General ..4-1. Hard Rock Weak Rock Quarrying ..4-4. Borrow-Pitting ..4-4. General ..4-5. Sizing and Screening ..4-6. Quality Environmental General Impacts ..4-8. Mitigation of Impacts and Restoration ..4-8. 5 MATERIAL selection ..5-1. selection and Assessment Criteria ..5-1. Common In Situ Imported Capping Filter-Drainage Unbound Granular Pavement Materials ..5-2. Bitumen Bound Granular Pavement and Surfacing selection and Assessment Procedures ..5-4. General Road Environment and Geotechnical Impacts ..5-4. Earthwork Embankment In Situ Unbound Granular Pavement Aggregate ..5-5. Options for Material Common In Situ Unbound Granular Pavement Aggregate ..5-7. 6 ENGINEERING MATERIALS Materials Testing General Principles ..6-1. Test Identification and selection Application of Testing Standards.

5 6-2. Programme Test Programme General ..6-3. Testing The Laboratory Data Management ..6-5. Laboratory Physical Condition General ..6-5. Moisture ..6-5. Atterberg Transport Research Laboratory Guidelines on the selection and Use of construction Materials Particle Size and Shape ..6-7. Density ..6-8. Derived Indices ..6-9. Laboratory Simulation Tests ..6-9. General ..6-9. Volume Density CBR Relationships ..6-11. Soil and Rock Material Strength ..6-12. Aggregate Strength and Surfacing Aggregate Chemical Testing ..6-14. Petrographic General ..6-15. Optical Microscopy ..6-15. Scanning electron microscopy (SEM) ..6-15. X-ray diffraction (XRD) ..6-16. Methylene Blue In situ tests ..6-16. CBR Testing ..6-16. Density Testing ..6-17. Suction Measurement ..6-17. 7 SAMPLING AND STATISTICS ..7-1. Statistics ..7-2. General.

6 7-2. Means and Variation ..7-2. Normal Sample size ..7-3. Repeatability and Reproducibility ..7-3. Student's t Regression 8 STABILISATION OF NATURAL MATERIALS FOR ROAD BUILDING ..8-1. Mechanical Stabilisation ..8-1. Bitumen Chemical General ..8-2. Portland Cement as a Stabiliser ..8-3. Lime as a Stabiliser ..8-3. Chemical Stabilisers ..8-5. Secondary Stabilising Agents ..8-5. Application of Chemical Stabilisation ..8-6. Strength of Stabilised Materials ..8-6. Soil Cement ..8-6. Cement Bound Granular Material (CBM) ..8-7. Lean Concrete ..8-7. Strength Requirements for Pavement Layers ..8-7. Two-Stage Testing for Chemical Stabilisation ..8-8. ICL and ICC Testing ..8-8. Strength Testing ..8-8. Preparation of specimens..8-9. Durability Tests ..8-9. selection of Chemical Stabilisation Method ..8-10. Transport Research Laboratory Guidelines on the selection and Use of construction Materials selection of Stabilisation Type.

7 8-10. selection of cement selection of lime content..8-11. construction Carbonation ..8-12. construction Control of Shrinkage/Reflection Quality Control ..8-15. 9 REFERENCES ..9-1. Transport Research Laboratory Guidelines on the selection and Use of construction Materials 1 INTRODUCTION. General Background The frequently distinct engineering behaviour of naturally occurring construction materials within sub- tropical and tropical regions, as compared with those in temperate zones, has been identified as a key factor in determining the long-term engineering success or failure of road projects in developing countries (Millard ,1990). The engineering behaviour of near surface sub-tropical and tropical soils and rocks is a function of the impact of their interaction with the road environment and the weathering processes.

8 Both the tropical weathering process and key aspects of the road environment (eg climate) are radically different from those in temperate regions, where the great majority of the research and development of materials standards, specifications and construction procedures have originated. In the tropics and sub-tropics roads will tend to have non-standard responses to the impacts of environment and traffic that will not be picked up unless the approach to investigation and assessment of construction materials is specifically tailored to that environment. There is also a greater need to view the application of specifications and construction practices in terms of a whole road unit, including earthworks and drainage, rather than in terms of individual pavement layers. It follows that there has been a need to derive and implement design and construction procedures specifically for the tropical and sub-tropical regions.

9 Overseas Road Note 31 (ORN 31), which is now widely used in developing countries, provides such guidance on the structural design of sealed roads within tropical regions and defines the construction material requirements in terms of standard properties. ORN. 31 does not seek, however, to provide details relevant to the selection , testing and appropriate use of these materials. Neither does it present information on alternative or non-standard approaches to material assessment and the conflicts that may arise out of employing inappropriate test procedures. The report comes at a time of change. Roads departments and related Ministries are, by necessity, becoming more commercial with the establishment of road agencies etc. Also there are moves to unify standards and procedures in Europe, which inevitably will impact on specifications and standards used in the developing world that are based on British or other existing European national standards.

10 The report also comes at time of heightened environmental awareness both in terms of protection against adverse impacts and in the more effective husbanding of non-renewable natural construction materials that are in some areas are becoming increasingly difficult to identify. It is now increasingly viewed as vitally important to use materials appropriate to their role in the road, that is, to ensure that they are neither sub- standard nor wastefully above the standards demanded by their engineering The above comments serve to highlight the need for identification, selection , processing and construction procedures that can be allied to relevant materials standards and specifications to ensure that appropriate construction materials sources are utilised to maximum long-term advantage. Purpose of the Document This document comprises the technical report on research undertaken under a TRL Knowledge and Research (KaR) contract (R6989) with DFID to produce Guidelines on the selection and use of construction materials in developing countries.