Bitumen Stabilisation

Technical Guideline:  Bitumen Stabilised Materials

This Technical Guideline is now available in hardcopy or Electronic version, to download a soft/Electronic version copy (4Mb) at no cost please click here.
Should you wish to obtain a hardcopy, please refer to the Products & Publications section of this website.

Pavement Number (PN) Based Design

Click here to access the system

The PN-based design method is a simple, robust and reliable approach to determining the structural capacity of a planned pavement structure. The method uses a five layer pavement system to determine an overall indicator of the long term load spreading capacity of the combined pavement layers. This indicator is called the Pavement Number (PN) and is determined by multiplying the Effective Long Term Stiffness (ELTS) of each layer with the layer thickness. These products are then added for all layers above the subgrade, and scaled to provide a number from zero to roughly 70, which is directly correlated with structural capacity.

The PN-based method was developed and calibrated using more than 20 pavement structures which had either been subjected to actual long term trafficking, or to controlled accelerated testing using the GDPTRW Heavy Vehicle Simulator (HVS) machine.

To become familiar with the PN based pavement design method, we recommend the following approach: Read the Background Information and Help Related Inputs section of this website to ensure you understand the basic concepts underlying this approach.  If you require additional background information, download the project documentation (Background Reports and Documentation).  To use the PN-based design approach, click on the PN Design Tab at the top of the page. A simple input table is provided, with a link to more technical details. When you click on the Submit button, a report will be shown which you can copy and paste as needed.

Laboratory Tests

• Method 1. Dilution test for bitumen emulsion
• Method 2. Determining Foam Characteristics of Bitumen
• Method 7. Simple Triaxial Test Procedure
• Method 7. MIST Conditioning and Test Procedure
• Method 8(1). Determine MDD and OMC using Vibr Hammer
• Method 8(2). Vibratory Compaction Procedure
• Method 8(3). Refusal Density Protocols for Site Compaction Specs
• Method 9. Prep of cores for testing
• Method 10. Prep of field specimens

Materials Classification Method

In a rehabilitation design situation, the processing of available materials condition data (such as backcalculated stiffness, CBR and grading) to determine the most appropriate materials class is often difficult and fraught with inconsistency. This applies especially to situations where various sources of information (often involving small sample sizes) have to be used to drive design decisions.

To assist designers in the process of interpreting materials test data, a consistent and rational manner has been developed. The method is easy to use, but does require designers to properly process available test data before applying the materials classification method. Guidelines for doing this are provided on the Materials Classification input page.

As with the PN-based design method, we strongly recommend that you first read the information on this website before you start using the method. To apply the materials classification method, click on the click on the link below this paragraph. Follow the steps that are outlined to generate a Materials Classification Report. The report summarizes your available test data, and shows how this information is used to determine the most likely Design Equivalent Materials Class.

Click here to access this system

Background Reports and Documentation

• TG2 Report Mix Design Phase II
  • Appendix - B Task 2: Development of a Simple Triaxial Test
  • Appendix - C Task 3:  Correlation of BSM Stiffness Part I
  • Appendix - E Task 5:  Advanced Classification System for Cold Mixes Based on Repeated Load Permanent Deformation Triaxial Test, Part 1
  • Appendix - F Task 6: Advanced Classification System: Part II Temp Freq Adv Class TGX
  • Appendix - G Task 7: Curing Protocol: Improvement
  • Appendix - H Task 8: Curing Protocol: Validation
  • Appendix - I Task 9: Moisture Sensitivity: Part I (Improvement)
  • Appendix - J Task 10: Moisture Sensitivity: Part II (Validation)
  • Appendix - K Task 11: Durability: Ageing of bituminous binder
  • Appendix - L Task 12: Laboratory Compaction
  • Drawings for triaxial equipment
• Summary of LTTP Emulsion and Foamed Bitumen Treated Sections
• A Method for Consistent Classification of Materials for Pavement Rehabilitation Design
• A Knowledge Based Structural Design Method for Pavements Incorporating Bituminous Stabilized Materials

We Need Feedback!

Although the PN-based design and materials classification methods are fairly complete, the methods still need to be refined before they can be included in the new guidelines for the design and use of bitumen stabilized materials. To a large extent, this refinement consists of improved calibration of rules and constants used in the methods. Also, we need feedback from practitioners to make the method more robust, user-friendly and reliable. We thus encourage you to provide us with constructive, specific feedback that can be used to improve the methods to benefit all pavement design practitioners in southern Africa. Click here to provide feedback.