1. Bituminous Stabilized Materials Guideline Project Initiated By: Gautrans Sabita

2. The Need for Recycling Alternatives Percentage of Designs in TRH4 Catalogue for > 3 msa 10%20%30%40% 50%60% G1 base on cemented subbase > 100 mm Asphalt on cemented subbase > 400 mm Cemented Base G1 or G2 base on unbound subbase 300 to 350 mm Cemented base & subbase

3. Current Guidelines: Main Deficiencies Mix Design  Lack of a suitable curing method  Lack of a suitable Shear Strength test  Lack of criteria to assess durability & flexibility Structural Design  Very Conservative designs  Need to expand knowledge base and incorporate long term field data

4. Project Structure Mix Design Structural Design Phase 1: Inception Study Mix Design Structural Design Phase 2: Development of Methodologies Phase 3: Guideline Compilation & Review Selection Criteria Mix Design Guidelines Structural Design Issues Construction Issues Guideline Finalization & Review

5. Tasks for Phase 2 Mix Design –Adapt triaxial test and classification limits –Develop durability test and classification limits –Standardize specimen preparation, curing, compaction & testing Structural Design –Expand LTPP database –Develop and calibrate material classification method and pavement design method

6. Crushed stone CTB Natural gravel ETB Support 3691215182124 Section Age Years MESA Accommodated to Date N12-19 (1) N12-19 (2) N1-13&14 N2-16 30 25 N1-1 20 N3-4 17 19 N7-7 P23/1 13 D2388 8 N4-5X (20-25) 8 8 N4-5X (27-30) N4/1 6 MR27 17 MR 504 (1) P24/1 MR 504 (2) MR 504 (3) Same-Himo (1) Same-Himo (2) Same-Himo (3) 10 6 11 LTPP

7. 3691215182124 Section MESA Accommodated Age Years 3691215182124 90 Surfacing 200 ETB 150 Lime stabilized base N3 HVS (1) 0 N3 HVS (2) 0 N3 HVS (3) 0 N3 HVS (5) 0 N2-16 (322A2) 8 P9/3 (372A3) 0 P9/3 (373A3) 0 P9/3 (374A3A) 0 P9/3 (374A3B) 0 P9/3 (375A3) 0 P9/3 (376A3) 0 D2388 (397A4) 0 D2388 (403A4) 1 D2388 (407A4) 2 D2388 (408A4) 3 P243/1 (409A4) 0 P243/1 (410A4) 0 P243/1 (411A4) 1 N7 (415A5) 0 P243/1 (412A4) 1 N7 (416A5) 0 N12-19 (415A5) 30 Crushed stone CTB Natural gravel LTB Support HVS

8. Structural Design Method Vision: Depend on Rational Inputs:  Determined from field tests using a specific procedure  Direct linkage with specifications Clarity and Transparency  Traceable validation  Implements design fundamentals Straightforward Implementation  Requires no specialist software  Reliable and Robust

9. Design Outputs & Expectations Cost, Effort & Experience Needed Design Method Outputs Reliability: E.g.: Is this design suitable for traffic of 3 to 8 mesa? Life Cycle: How will the pavement fail? How can it be rehabilitated? Sensitivity: What layers/parameters are most critical to prevent premature failure? Optimization: What can be done to minimize costs at reasonable risk? Prediction: How will rut depth, riding quality etc develop over time? Requires simulation

10. Development Approach CBR 7-15% > 200 mm G6 130 mm C4 200 mm BSM 1 Shear Potential Range of Traffic Accommodated Rut situation, RQ situation Cracking situation Need for rehabilitation Area = Shear Potential “Fingerprint” System Performance Indicators System Behaviour Indicator ???

11. Cumulative Traffic Failed Condition Good Condition Warning Condition Design Catalogue Structures “Fingerprint” Indicator

12. Conclusion Structural Design: –Concept finalized March 2007 –Pilot implementation & refinement Mar ’07 to Jan ‘08 Mix Design Protocols (2007) –Focus on Shear & Durability –Improved criteria and classification limits –Longer term testing and implementation of new tests…(2008+)

14. Design Methodology Concept Traffic Accommodated (mesa) 1 3 10 30 100 - 200 mm BSM on G7+ support 200 - 300 mm BSM on G6+ 150 - 200 mm BSM on 150 mm Stabilized Support 150 - 200 mm BSM on >250 mm Stabilized Support