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Bituminous Stabilized Materials Guideline

As South Africa's road network ages and crushed stone quarrying becomes increasingly difficult, the need for new rehabilitation strategies is evident. This guideline aims to modernize the use of foam and emulsion as sustainable solutions in road construction, ensuring that they are placed on equal footing to crushed stone materials. Through a systematic approach involving field data and innovative design methods, this guideline seeks to improve mix and structural design, ultimately enhancing the longevity and performance of South African roads.

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Bituminous Stabilized Materials Guideline

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  1. Bituminous Stabilized Materials Guideline RPF Feedback : K Jenkins May 2006

  2. Background • South Africa’s road network is ageing • Many designs use crushed stone • But, difficult to open new quarries • Increasingly inappropriate solution • Need to rehabilitate with available materials • Use of foam and emulsion are appropriate solutions for many cases

  3. Guidelines • Emulsion materials • Sabita Manual 14 (1993) • Sabita Manual 21 (1999) • Foamed bitumen materials • TG2 Interim Guideline (2002) • Guidelines widely used, but need to • Modernize • Improve • Place foam and emulsion on equal footing • Create a single, combined guideline

  4. Current Project • Initiated and funded by Gautrans and SABITA • Update and produce a new, combined guideline document • Objectives • Improved mix and structural design • Use of real field data and HVS data to develop design method • Construction guidelines

  5. Project Structure Phase 1: Inception Study Structural Design (F Long) Mix Design (K Jenkins) Phase 2: Development of Design Guidelines Structural Design (F Jooste) Mix Design (K Jenkins) Selection Criteria Phase 3: Guideline Compilation & Review Mix Design Guidelines Structural Design Issues Construction Issues Guideline Finalization & Review

  6. Inception Study Results • Investigated aspects of mix design that need development, and planned these development activities • Proposed a structural design method • Investigated the type and quality of data from field pavements that can be used to develop design method

  7. Mix Design • Best tests to capture material properties • Durability test • Shear properties through triaxial test • Curing • Standardization • Specimen preparation • Mixing • Compaction • Curing • Testing • Interpretation

  8. Purpose of flexibility/fatigue tests • Flexibility increases with increasing binder content Flexibility Strength Cement/binder ratio

  9. Strain at Break comparison

  10. Fatigue Strain

  11. Flexibility vs Durability

  12. Recent curing protocols • 24 hours in mould and 72 hours at 40°C (unsealed)  Six months in road (Loudons, 1994) • 24 hours in mould and 72 hours at 40°C (sealed)  Six months in road (TG2, 2003) • 24 hrs at ambient (unsealed) + 48 hours at 40°C (sealed) + several hours cooling at ambient (unsealed)  Medium cure (Wirtgen, 2004) • 24 hours at ambient (unsealed) and 48 hours at 40°C (sealed)  Medium cure (Houston, 2004) • 20 hours at 30°C (unsealed) and 2x24 hours at 40°C & change bag (sealed)  Med cure (Univ Stell, 2004)

  13. Possible Curing Approach Foam Emulsion Active filler Inactive/no filler Active filler Inactive/no filler

  14. PERFORMANCE INFORMATION FWD Test Pits Emod1 Visuals Class B Nf DCP Class B Emod2 Field Performance LAB 3-10 Mesa Options Class A Long Term Field Performance Elastic Theory Emod3 RSD MDD Approaches to Structural Design BEHAVIOUR

  15. Traffic Class: 0 to 1 MESA 10 to 30 MESA 1 to 3 MESA 3 to 10 MESA       000 BS-B 000 BS-A  000 BS-C 000 BS-A 000 BS-B 000 BS-A 000 BS-B Subgrade Class A  000 SC-C 000 SC-B 000 SC-C 000 SC-C 000 SC-B 000 SC-B 000 SC-B        000 BS-A 000 BS-A 000 BS-A 000 BS-B 000 BS-A 000 BS-B 000 BS-B  Subgrade Class B 000 SC-A 000 SC-B 000 SC-B 000 SC-B 00 SC-B 00 SC-A 00 SC-A     000 BS-B  000 BS-B 000 BS-B 000 BS-A 000 BS-A 000 BS-A   000 SC-C 000 SC-B 000 SC-B 000 SC-A 000 SC-C 000 SC-C  000 BS-B   000 BS-A 000 BS-A Subgrade Class C Not Recommended Without Special Subgrade Preparation or Addition of Selected Layers 000 SC-B 000 SC-B 000 SC-A Legend and Notes:  = Structural Capacity validated through LTPP data (see Appendix A for Details)  = Structural Capacity validated through HVS testing (see Chapter 5 for Details) 000 BS-X Denotes 000 mm of Bitumen Stabilized Material, Class X = Structural Capacity estimated by interpolating between LTPP data and HVS testing 000 SC-X Denotes 000 mm of Class X support material Design Matrix

  16. Key Aspects of the Method • Focus on materials investigation • Some results to come from mix design • Specific guidelines for materials classification • Directly linked to observed field performance • Limited intermediary analysis steps • Yes / no system, limited scope to manipulate or misinterpret • Suitable for all levels of practitioners

  17. Emulsion (13) N1 Section 1 (Kraaifontein) N1 Sections 13 and 14 (Springfontein and Trompsburg) N2 Section 16 (Kwelera, East London) N3 Section 4 (near Mooi River) N4 Section 1 (Scientia to Pienaars River) N4 Section 5X (2 sections) (Wonderfontein to Crossroads) N7 Section 7 (near Kammieskroon) N12 Section 19 (Exp 1&2) (near Daveyton) MR27 (near Stellenbosch) P23/1 (Kroonstad to Steynsrus) D2388 (Cullinan) LTPP Sections Foamed bitumen (7) • P24/1 (near Vereeniging) • MR504 (A, B, C) (near Shongweni) • Same-Himo (1, 2, 3) (Tanzania)

  18. HVS Sections • N3 near Pietermaritzburg (4 ETB) • N2-16 near East London (1 ETB) • P9/3 near Heilbron (6 ETB) • D2388 near Cullinan (4 ETB) • P243/1 near Vereeniging (2 ETB,2 FTB) • N7 (TR11/1) near Cape Town (2 FTB) • N12-19 near Daveyton (1 ETB)

  19. Synthesis of observed performance

  20. LTPP Age Years MESA Accommodated to Date Section 3 6 9 12 15 18 21 24 30 N12-19 (1) 30 N12-19 (2) SUBBASE N1-13&14 25 N2-16 Crushed stone 25 N1-1 20 CTB N7-7 19 Natural gravel N3-4 17 MR27 17 ETB 13 P23/1 8 D2388 PARENT MATERIAL N4-5X (20-25) 8 N4-5X (27-30) 8 6 N4/1 Cemented crushed stone 11 Same-Himo (1) 11 Same-Himo (2) Recycled BTB Same-Himo (3) 11 10 MR 504 (1) 10 MR 504 (2) Crushed stone 10 MR 504 (3) P24/1 6 Natural gravel

  21. HVS MESA Accommodated Age Years Section 3 6 9 12 15 18 21 24 3 6 9 12 15 18 21 24 90 Surfacing 200 ETB 150 Lime stabilized base 150 Lime stabilized base N3 HVS (1) 0 N3 HVS (2) 0 SUBBASE N3 HVS (3) 0 N3 HVS (5) 0 Crushed stone N2-16 (322A2) 8 P9/3 (372A3) 0 CTB P9/3 (373A3) 0 Natural gravel P9/3 (374A3A) 0 P9/3 (374A3B) 0 LTB P9/3 (375A3) 0 PARENT MATERIAL P9/3 (376A3) 0 D2388 (397A4) 0 D2388 (403A4) 1 D2388 (407A4) Cemented crushed stone / natural gravel 2 D2388 (408A4) 3 P243/1 (409A4) 0 P243/1 (410A4) 0 Recycled BTB P243/1 (411A4) 1 P243/1 (412A4) 1 Crushed stone N7 (415A5) 0 N7 (416A5) 0 N12-19 (415A5) Natural gravel 30

  22. Key Trends: Support & Thickness • Subbase • Majority ETB sections have cemented subbase • Majority foam sections have gravel subbase • Base thickness: majority 100 - 200 mm thick • > 3 MESA even on thin bases • Subbase thickness: majority  150 mm • In TRH4, no sections for 3 to 10 MESA have subbases < 200 mm. Significant savings possible?

  23. Section N1 Section 13 & 14 TRH4 Traffic (MESA) 10 - 13 10 - 30 Pavement Structure 50 mm Surfacing 38 mm Surfacing 150 mm G1 160 mm ETB 150 mm ETB 250 mm C3 Key Trends: Traffic accommodated • Traffic accommodated exceeds expectations • Emulsion example:

  24. Section MR 504 (1) TG2 TG2 Traffic (MESA) 0.9 - 1.8 0.1 – 0.3 1 - 3 Seal 30 AC Pavement Structure 125 mm FB2 125 mm FB2 Slurry 125 mm FTB 150 mm G6 200 mm C4 150 mm G6 Key Trends: Traffic accommodated • Foam example:

  25. Tasks for Next Phase • Mix Design • Develop triaxial test and classification limits • Includes standardizing testing protocols • Develop durability test and classification limits • Standardize specimen preparation, particularly curing and compaction • Structural Design • Expand LTPP database • Develop and calibrate material classification method and design matrix

  26. Where are we now? • Submitted proposals for Phase 2 • Final approval pending • Thereafter we will be forging ahead with further investigation (test methods and protocols) and materials classification

  27. We hope to find a good marriage between cold materials and performance… Thank you

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