Bituminous Stabilized Materials Guideline RPF Feedback : K Jenkins May 2006

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

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

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

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

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

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

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

Strain at Break comparison

Fatigue Strain

Flexibility vs Durability

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)

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

Approaches to Structural Design MDD RSD LAB DCP Visuals Test Pits FWD INFORMATION BEHAVIOURPERFORMANCE NfNf Emod1 Emod2 Emod3 Class B Class A Field Performance 3-10 Mesa Options Elastic TheoryLong Term Field Performance

Design Matrix

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

LTPP Sections 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) Foamed bitumen (7) P24/1 (near Vereeniging) MR504 (A, B, C) (near Shongweni) Same-Himo (1, 2, 3) (Tanzania)

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)

Synthesis of observed performance

Crushed stone CTB Natural gravel ETB Cemented crushed stone Recycled BTB Crushed stone Natural gravel SUBBASE PARENT MATERIAL Section Age Years MESA Accommodated to Date N12-19 (1) N12-19 (2) N1-13&14 N N N N7-7 P23/1 13 D 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) LTPP

Section MESA Accommodated Age Years 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 Cemented crushed stone / natural gravel Recycled BTB Crushed stone Natural gravel SUBBASE PARENT MATERIAL HVS

Key Trends: Support & Thickness Subbase –Majority ETB sections have cemented subbase –Majority foam sections have gravel subbase Base thickness: majority 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?

Key Trends: Traffic accommodated Traffic accommodated exceeds expectations Emulsion example: N1 Section 13 & mm Surfacing 160 mm ETB 150 mm ETB TRH mm Surfacing 150 mm G1 250 mm C3 Section Traffic (MESA) Pavement Structure

Key Trends: Traffic accommodated Foam example: Section Traffic (MESA) Pavement Structure MR 504 (1) Slurry 125 mm FTB 150 mm G6 TG2 0.1 – 0.3 Seal 125 mm FB2 150 mm G6 TG AC 125 mm FB2 200 mm C4

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

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

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