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 materialsSabita Manual 14 (1993)Sabita Manual 21 (1999)
• Foamed bitumen materialsTG2 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
Fle
xib
ility
Str
en
gth
Strain at Break comparison
0500
10001500
20002500
30003500
0 0
1.8 3 3 3
1.8
1.8 5 0
1.8
1.5
1.5
2.2
5
2.2
5 3 3
3.6
3.6
3.6
2.4
BC (%)
Str
ain
at b
reak (m
icro
str
ain
)
CSIR Results
Stell Results
Fatigue
1000
10000
100000
1000000
10000000
100000000
1000000000
10 100 1000
Ferricrete (EBT)
Ferricrete (FBT)
Lime-RAP (FBT)
Lime-RAP (EBT)
Sand mix (EBT)
Eff
ecti
ve f
atig
ue li
fe, N
f
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 BEHAVIOUR PERFORMANCE
Nf
Emod1
Emod2
Emod3
Class B
Class B
Class A
Field Performance
3-10 Mesa Options
Elastic TheoryLong Term Field Performance
Traffic Class:
Subgrade Class A
Subgrade Class B
Subgrade Class C
0 to 1 MESA 1 to 3 MESA 3 to 10 MESA 10 to 30 MESA
000 BS-B
00 SC-B
000 BS-B
000 SC-B
000 BS-B
000 SC-C
000 BS-A
000 SC-B
000 BS-A
000 SC-C
000 BS-A
000 SC-B
000 BS-B
00 SC-A
000 BS-A
000 SC-B
000 BS-C
000 SC-C
000 BS-A
000 SC-B
000 BS-B
000 SC-C
000 BS-A
000 SC-B
000 BS-B
000 SC-A
000 BS-A
000 SC-B
Not Recommended Without Special Subgrade Preparation or Addition of
Selected Layers
000 BS-B
00 SC-A
000 BS-B
000 SC-B
000 BS-A
000 SC-C
000 BS-A
000 SC-B
000 BS-B
000 SC-C
000 BS-A
000 SC-B
000 BS-A
000 SC-B
000 BS-A
000 SC-A
000 BS-B
000 SC-A
Legend and Notes:
000 BS-X Denotes 000 mm of Bitumen Stabilized Material, Class X
000 SC-X Denotes 000 mm of Class X support material
= Structural Capacity validated through LTPP data (see Appendix A for Details)
= Structural Capacity validated through HVS testing (see Chapter 5 for Details)
= Structural Capacity estimated by interpolating between LTPP data and HVS testing
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 SectionsEmulsion (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
3 6 9 12 15 18 21 24Section Age
YearsMESA Accommodated to Date
N12-19 (1)
N12-19 (2)
N1-13&14
N2-16
30
30
25
25
N1-1 20
N3-4 17
19N7-7
P23/1 13
D2388 8
N4-5X (20-25) 8
8N4-5X (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
10
10
11
11
11
LTPP
3 6 9 12 15 18 21 24Section MESA Accommodated Age
Years3 6 9 12 15 18 21 2490 Surfacing200 ETB150 Lime stabilized base150 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 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?
Key Trends: Traffic accommodated
• Traffic accommodated exceeds expectations
• Emulsion example:
N1 Section 13 & 14
10 - 1338 mm Surfacing
160 mm ETB
150 mm ETB
TRH4
10 - 3050 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)
0.9 - 1.8
Slurry
125 mm FTB
150 mm G6
TG2
0.1 – 0.3
Seal
125 mm FB2
150 mm G6
TG2
1 - 3
30 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
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