Bituminous Stabilized Materials Guideline: Inception Study

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Bituminous Stabilized Materials Guideline
Inception Study

• Project Funded By
• Gautrans
• Sabita

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Background

• ETB Materials Two guidelines exist
• Sabita Manual 14 (1993)
• Sabita Manual 21 (1999)
• Foamed Bitumen Materials
• TG2 Interim Guideline

• Guidelines widely used, but there is a need to
• Modernize
• Improve
• Create a single, combined guideline

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Main Deficiencies Mix Design

• Lack of a suitable Curing Method
• More appropriate tests to assess
• Flexibility
• Shear Strength
• Durability

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Main Deficiencies Structural Design

• Conservative structural designs (catalogue and
  design charts)
• Questions about 2-Phase modelling
• Need to incorporate curing effects
• Limited database used for development
• Lack of validation using long term field data

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Project Structure
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Inception Study ObjectivesMix Design

• Identify Durability Test and gather curing data
• Investigate Triaxial Testing protocols
• Investigate Strain-at-Break
• Plan and re-direct further activities

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Inception Study ObjectivesStructural Design

• Gather available performance data (LTPP HVS)
• Analyze and identify trends (if any!)
• Assess key deficiencies in available information
• Plan and re-direct further activities

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Progress to Date Structural Design

• 126 Roads appeared on radar
• 104 Emulsion Treated Base
• 22 Foamed Bitumen
• Only some roads suitable to study
• Duplication amongst reported projects
• Many roads recently constructed
• Some very low traffic and/or no data
• Urban legend

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Some Best Candidate Projects

• N12-19 (1974)
• N2-16 (1982)
• N3-4 (1988)
• N4-5X (1997)
• N4-1 (1997)
• MR27 (1988)
• N1-1 (1984)
• N1-13 14 (1980)
• P504 (1995)
• Same-Himo Project (1992, LTPP study)
• N7-7 (1987)
• P24-1 (1999)
• 20 Promising projects in total

• HVS Tests
• N3-4, Mooi River
• N2-16, East London
• P9-3 Petrus Steyn
• P243-1 Vereeniging
• N7, near CT
• N12-19 (current)

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Classification Approach
For each project, assess and classify

• ETB/Foam source material
• ETB/Foam stability flexibility properties
• Support Layer quality and class
• Subgrade quality and class
• Maximum deflection range before/after
  construction
• Standard axle range accommodated in field or HVS

Vision

• Develop a design approach that relies on
  measurable, non-ambiguous parameters
• Ensure transparent, straightforward validation of
  recommended designs