Bituminous Stabilized Materials Guideline

1
Bituminous Stabilized Materials Guideline

• RPF Feedback K Jenkins
• May 2006

2
Background

• South Africas 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
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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

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Mix Design

• Best tests to capture material properties
• Durability test
• Shear properties through triaxial test
• Curing

• Standardization
• Specimen preparation
• Mixing
• Compaction
• Curing
• Testing
• Interpretation

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Purpose of flexibility/fatigue tests

• Flexibility increases with increasing binder
  content

Flexibility
Strength
Cement/binder ratio
9
Strain at Break comparison
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Fatigue
Strain
11
Flexibility vs Durability
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Recent curing protocols

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

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Possible Curing Approach
Foam
Emulsion
Active filler
Inactive/no filler
Active filler
Inactive/no filler
14
Approaches to Structural Design
BEHAVIOUR
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Design Matrix
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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

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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 12) (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)

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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)

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Synthesis of observed performance
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LTPP
Age Years
MESA Accommodated to Date
Section
3
6
9
12
15
18
21
24
N12-19 (1)
30
30
N12-19 (2)
SUBBASE
N1-1314
25
N2-16
Crushed stone
25
N1-1
20
CTB
19
N7-7
Natural gravel
N3-4
17
MR27
17
ETB
P23/1
13
8
D2388
PARENT MATERIAL
N4-5X (20-25)
8
N4-5X (27-30)
8
N4/1
6
Cemented crushed stone
Same-Himo (1)
11
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
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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
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Key Trends Support Thickness

• Subbase
• Majority ETB sections have cemented subbase
• Majority foam sections have gravel subbase
• Base thickness majority 100 - 200 mm thick
• gt 3 MESA even on thin bases
• Subbase thickness majority ? 150 mm
• In TRH4, no sections for 3 to 10 MESA have
  subbases lt 200 mm. Significant savings possible?

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Key Trends Traffic accommodated

• Traffic accommodated exceeds expectations
• Emulsion example

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Key Trends Traffic accommodated

• Foam example

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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

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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

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