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June 2014
Pavement design and construction technique using high strength stone interlocked cemented aggregate low fines matrix.
Gerhard van Blerk
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Introduction:“More for Less”
• Global financial constraints and a steep increase in bitumen prices
• RCA’s are seeking alternative construction techniques (Hi-Lab)
• Embrace the origin of road construction (John Loudon McAdam, 1820) through modern pavement construction techniques
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Macadam Pavement Design: “Back to Basics”
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Design Intent:High degree of aggregate interlock
Maximize stone packing, forcing “full” stone on stone interlock through a controlled process of:
• grading (percentage of large aggregate fraction)
• aggregate quality (crushing resistance)• small amount of cement (3%)• construction technique
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Material Selection and Properties: Aggregate Grading
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Hi-Lab40 AP40 RCC
0.075 1.18 4.75 9.50 19.0 37.5 63.0
SIEVE SIZE (mm)
% P
ASSI
NG
Hi-Lab40 vs AP40 vs RCC Grading Envelope
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Hi-Lab Construction Technique: Aggregate Placing
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Hi-Lab Construction Technique: Placing and Grading
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Hi-Lab Construction Technique: Cement Spreading
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Hi-Lab Construction Technique: Subbase Stabilization (mixing process)
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Hi-Lab Construction Technique: Base Stabilization (mixing process)
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Material Selection and Properties: Aggregate Grading
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Hi-Lab Construction Technique: Compaction and Final Surface
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Hi-Lab Construction Technique: Compaction and Final Surface
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Hi-Lab Construction Technique: Engineering Properties (Strength)
• Indirect Tensile Strength (ITS)
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Hi-Lab Construction Technique: Engineering Properties (Strength)
• Beam Fatigue Tensile Strain
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Hi-Lab Construction Technique: Engineering Properties (Strength)
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Hi-Lab Construction Technique: Engineering Properties (Strength)
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Hi-Lab Construction Technique: Engineering Properties (Strength)
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Hi-Lab Construction Technique: Observed Performance
Benkelman Beam Deflections
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0.25
0.5
0.75
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1.25
1.5
1.75
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Tatuanui(SectionA)
Tatuanui(SectionB)
Tatuanui(SectionC)
Te Rapa(Section A)
Te Rapa(Section B)
Taupiri Orini
Project Name
Ymax
(Ave
rage
Val
ue)
Selected Sand Layer Hi-Lab65 (Subbase Layer) Hi-Lab40 (Base Layer)
Back-calculated Stiffness (MPa)
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1000
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4000
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6000
Selected Sand Layer Hi-Lab65 (Subbase Layer) Hi-Lab40 (Base Layer) Selected Sand Layer Hi-Lab65 + Hi-Lab40 (LayersCombined)
Project Name
Med
ian
Stiff
ness
(MPa
)
Tatuanui Te Rapa Orini
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2020
Case Studies: Cost Saving
• Substantial cost savings without sacrificing performance.
• Pavement construction cost savings between 30% to 40%.
• Base layer construction cost savings between 100% to 400% e.g. SAC ($100/m^2) – Hi-Lab ($25/m^2).
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Conclusion/Summary:
• Realizing the proven performance associated with the Macadam design theory through modern stabilization equipment.
• Observed engineering properties are very promising.
• Case studies shows this technique to be a viable alternative to more costly options.
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