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