Pavement

Cover of Effect of Moisture Content and Laboratory Preparation Conditions on the Permanent Deformation of Unbound Granular Materials
Effect of Moisture Content and Laboratory Preparation Conditions on the Permanent Deformation of Unbound Granular Materials
  • Publication no: AP-T287-15
  • ISBN: 978-1-925294-03-3
  • Published: 30 January 2015

This report documents research to validate the wheel-tracking approach as a complementary means of evaluating the rutting performance of granular bases. Firstly, the influence of the moisture content on the laboratory wheel-tracking performances is assessed on four typical crushed rock materials that were previously tested under accelerated loading conditions. The second parts presents an evaluation of the effect of dry-back on both the performance under repeated load triaxial tests and aggregate particle orientation.

Results from this project work show an improved analysis of wheel-tracking data, based on both deformation and rut depth measurement, thereby offering encouraging results for assessing the moisture sensitivity of crushed rock material to rutting.

The data collected under repeated load triaxial conditions confirmed that at the same test moisture content, the specimen prepared at the optimum moisture content and dried-back exhibited higher resilient modulus and lower permanent deformation compared to the specimen compacted at the same moisture content without dry-back.

The particle orientation analysis undertaken demonstrated that specimens compacted in the wheel-tracker are closer to field conditions. However, the moisture content at compaction seems to have a significant effect on the void network. The material’s voids are more distributed for specimens compacted at the material optimum moisture content compared to a compacted specimen with 30% less water.

This information will help to consolidate the development of a new wheel?tracking test method for unbound granular materials, which can be validated against pavement performance during the continuing project.

  • Summary
  • Contents
  • 1. Introduction
    • 1.1. Project Background
    • 1.2. Report Outline
  • 2. Wheel-tracking Tests for Unbound Granular Materials
    • 2.1. Background
    • 2.2. Summary of the Testing Procedure
      • 2.2.1. Preparation Sequence
      • 2.2.2. Sealing Membrane
    • 2.3. Improved Wheel-tracking Tests Analysis
      • 2.3.1. Pavement Modes of Failure vs Laboratory Performance Testing
      • 2.3.2. Raw Profile Data
      • 2.3.3. Deformation Calculations
      • 2.3.4. Rut Depth Calculations
      • 2.3.5. Deformation and Rutting Rates
      • 2.3.6. Summary of the Laboratory Performance Data
    • 2.4. Evaluation of the Testing Conditions
      • 2.4.1. Terminology
      • 2.4.2. Material Dry Density Measurement
      • 2.4.3. Material Moisture Content Assessment
    • 2.5. Testing Program
    • 2.6. Evaluation of the Actual Test Dry Density
      • 2.6.1. Dry Density Results from Sand Replacement Testing
      • 2.6.2. Comparison between Average and Wheel-tracker Dry Density
    • 2.7. Preparation Moisture Content Data
    • 2.8. Adopted Wheel-tracking Testing Conditions
  • 3. Wheel-tracking Laboratory Test Results
    • 3.1. Sensitivity to Moisture Content
      • 3.1.1. Data Used
      • 3.1.2. Test Results
      • 3.1.3. Effect of Moisture on the Wheel-tracking Performance of the Tested Materials
      • 3.1.4. Comparison of the Deformation Properties of the Materials
    • 3.2. Sensitivity to the Dry Density
      • 3.2.1. Rhyolite Material (Mat. 1670)
      • 3.2.2. Hornfels Material (Mat. 1671)
      • 3.2.3. Limestone Material (Mat. 1672)
      • 3.2.4. Effect of Material Dry Density on the Wheel-tracking Performance of the Tested Materials
    • 3.3. Conclusions of the Sensitivity Analysis on Wheel-tracker Testing
  • 4. Effect of Preparation Conditions on the RLT Test Results
    • 4.1. Methodology
    • 4.2. Materials Used in this Investigation
    • 4.3. RLT Test Procedures
      • 4.3.1. Samples and Preparation
      • 4.3.2. RLT Apparatus and Setting
    • 4.4. RLT Results
      • 4.4.1. Quality of the Test and Analysing the Data
      • 4.4.2. Influence of Compaction Moisture Conditions and Dry-back
      • 4.4.3. Comparing Materials – Performance Ranking of the Materials
    • 4.5. After-testing Investigation
    • 4.6. Small-scale Wheel-tracking Test Results
      • 4.6.1. Small-scale Wheel-tracker and Permanent Deformation Tests
      • 4.6.2. Small-scale Wheel-tracking and Permanent Deformation Results
  • 5. Effect of Moisture Content at Compaction on Particle Orientation
    • 5.1. Introduction
    • 5.2. Test Program and Specimens
    • 5.3. Analysis Process using iPas Software
      • 5.3.1. Objective
      • 5.3.2. First Analysis and Data Analysis
    • 5.4. Results
  • 6. Conclusions
    • 6.1. Wheel-tracker Testing on Granular Bases
    • 6.2. Cylindrical Specimen Tested Under RLT Conditions
    • 6.3. Effect of the Moisture Content on Particle Orientation
    • 6.4. Laboratory vs Field Compaction
  • References
  • Appendix A Grading Curves for Re-used materials
  • Appendix B Wheel-tracking Tests Preparation Parameters
  • B.1 Wheel-tracker Test Preparation Conditions
  • B.2 Compaction Moisture Content
  • B.3 After-tracking Moisture Content
  • B.3.1 Moisture Content from the Top 100 mm of the Specimen
  • B.3.2 Moisture Content from the Bottom 100 mm of the Specimen
  • Appendix C Determination of the Wheel-tracker Preparation Conditions
  • C.1 Moisture Preparation Conditions
  • C.1.1 Difference between Compaction and Wheel-tracking Moisture Content
  • C.1.2 Estimation of the Appropriate Compaction Moisture Content
  • C.2 Determination of the Compaction Preparation Conditions
  • Appendix D Wheel-Tracker Tests Results
  • D.1 Details of the Data
  • D.2 Mat. 1670 – Slab 1885
  • D.2.1 Processed Surface Profile Data
  • D.2.2 Deformation and Maximal Rut Depth
  • D.3 Mat. 1670 – Slab 1913
  • D.3.1 Processed Surface Profile Data
  • D.3.2 Deformation and Maximal Rut Depth
  • D.4 Mat. 1670 – Slab 2268
  • D.4.1 Processed Surface Profile Data
  • D.4.2 Deformation and Maximal Rut Depth
  • D.5 Mat. 1670 – Slab 2350
  • D.5.1 Processed Surface Profile Data
  • D.5.2 Deformation and Maximal Rut Depth
  • D.6 Mat. 1670 – Slab 2314
  • D.6.1 Processed Surface Profile Data
  • D.6.2 Deformation and Maximal Rut Depth
  • D.7 Mat. 1671 – Slab 1867
  • D.7.1 Processed Surface Profile Data
  • D.7.2 Deformation and Maximal Rut Depth
  • D.8 Mat. 1671 – Slab 1878
  • D.8.1 Processed Surface Profile Data
  • D.8.2 Deformation and Maximal Rut Depth
  • D.9 Mat. 1671 – Slab 1906
  • D.9.1 Processed Surface Profile Data
  • D.9.2 Deformation and Maximal Rut Depth
  • D.10 Mat. 1671 – Slab 2264
  • D.10.1 Processed Surface Profile Data
  • D.10.2 Deformation and Maximal Rut Depth
  • D.11 Mat. 1671 – Slab 2288
  • D.11.1 Processed Surface Profile Data
  • D.11.2 Deformation and Maximal Rut Depth
  • D.12 Mat. 1671 – Slab 2352
  • D.12.1 Processed Surface Profile Data
  • D.12.2 Deformation and Maximal Rut Depth
  • D.13 Mat. 1671 – Slab 2323
  • D.13.1 Processed Surface Profile Data
  • D.13.2 Deformation and Maximal Rut Depth
  • D.14 Mat. 1672 – Slab 1882
  • D.14.1 Processed Surface Profile Data
  • D.14.2 Deformation and Maximal Rut Depth
  • D.15 Mat. 1672 – Slab 1900
  • D.15.1 Processed Surface Profile Data
  • D.15.2 Deformation and Maximal Rut Depth
  • D.16 Mat. 1672 – Slab 2276
  • D.16.1 Processed Surface Profile Data
  • D.16.2 Deformation and Maximal Rut Depth
  • D.17 Mat. 1672 – Slab 2324
  • D.17.1 Processed Surface Profile Data
  • D.17.2 Deformation and Maximal Rut Depth
  • D.18 Mat. 1585 – Slab 1895
  • D.18.1 Processed Surface Profile Data
  • D.18.2 Deformation and Maximal Rut Depth
  • D.19 Mat. 1585 – Slab 2292
  • D.19.1 Processed Surface Profile Data
  • D.19.2 Deformation and Maximal Rut Depth
  • D.20 Mat. 1585 – Slab 2380
  • D.20.1 Processed Surface Profile Data
  • D.20.2 Deformation and Maximal Rut Depth
  • Appendix E Properties of the Materials Used for RLT Testing
  • E.1 Particle Size Distribution
  • E.2 Compaction properties
  • Appendix F Particle Orientation Data
  • F.1 RLT 1 OMC
  • F.1.1 RLT 2 OMC
  • F.2 RLT 3 Target Moisture Content
  • F.3 RLT 4 Target Moisture Content
  • F.4 Wheel-tracker 1 OMC
  • F.5 Wheel-tracker 2_1 OMC
  • F.6 Wheel-tracker 2_2 OMC
  • F.7 Wheel-tracker Target Moisture Content 3_1
  • F.8 Wheel-tracker Target Moisture Content 3_2
  • F.9 Wheel-tracker Target Moisture Content 4_1
  • F.10 Wheel-tracker Target Moisture Content 4_2
  • F.11 ALF