Long-Life Pavements

Concepts and Lab Testing

Pre-bid Meeting Solano 80 04-4A0104 James M. Signore Oakland, CA 9/14/2012

Presentation Overview

• Long Life Pavement (LLP)  

What it is?

What are the benefits?

• Recent California Experience 

I-5 in Red Bluff and Weed

• What to Anticipate 

Specimen Preparation & Lab Testing

Long Life Pavement – What is it?

• Design Life 40+ years • Bottom-Up Design and Construction • Renewable Pavement Surface • High Rutting and Cracking Resistance • Smooth and Safe Driving Surface

Long Life Pavement – What is it?

HMA Repeated Bending

Base

Subgrade Repeated Deformation Leads to Fatigue Cracking Leads to Rutting

Long Life Pavement What are the Benefits?

• Lower Life Cycle Cost  

Better Use of Resources Low Incremental Costs for Surface Renewal

• Lower User Delay Cost 

Fewer or Shorter Work Zone Periods for Future Maintenance

Long Life Pavements in the US

Structural Section – SOLANO 80 OGFC HMA w/ 15% Max. RAP (PG 64-28PM) HMA w/ 25% RAP (PG 64-10) Geosynthetic Interlayer Leveling Course Existing Pavement

 

2 Mix Designs!!!

Project Considerations

• Materials Selection & Testing • Structural Design • Specs • Construction

Recent Projects

• Weed I-5 D2 • Red Bluff I-5 D2

Structural Section – Weed HMA w/ 15% Max. RAP (PG 64-28PM) HMA w/ 25% RAP (PG 64-16)

SAMI*

HMA w/ 25% RAP (PG 64-16) (leveling course) Existing Cracked & Seated PCC or HMA

 

NTS

* Asphalt Rubber Seal Coat 2 Mix Designs!!!

NTS

Structural Section – Red Bluff

OGFC HMA w/ 15% Max. RAP (PG 64-28PM) HMA w/ 25% RAP (PG 64-10) HMA-Rich Bottom (PG 64-10)

  

CTB-Existing Agg Subbase & Subgrade 3 Mix Designs!!!

What to Anticipate Solano 80

Mix Design based on “Mechanistic” Lab Testing

• Hveem (CT 366) • Shear Testing (T-320) • Fatigue Testing (T-321) • Hamburg WT (T-324) • Mix must meet performance

requirements in Special Provisions

Modified (Mechanistic) Mix Design Process Establish target binder content with Hveem (CT 366) Performance Testing 1.

2.

3.

Shear testing at target binder content Select design binder content based on shear test results At design binder content Fatigue Hamburg Wheel Track (HWT) ± X

M odified Mix Design Flow Chart HVEEM Mix Design for Target “OBC H ” SHEAR Testing to determine “OBC Total of 9 specimens per mix (3 x 3BC) S ” 3 specimens prepared and tested at HBC + 3 more each @ +/- X SELECT OBC based on SHEAR test results FATIGUE Testing @ OBC S Flexural Fatigue – 20C, 2 levels of strain (bending) – 6 Total (6 x 1BC) Flexural Stiffness - 20C & 30C – 6 Total (6 x 1BC) Spare beams recommended – 14 Total if possible HWTD testing @ SOBC – 1 Test, 50C, 4 cores

M odified Mix Design Materials and Time HVEEM to determine target BC SHEAR Cores are prepared first Testing performed to determine “OBC S ” Requires 3 x 3BC Cores (6 in. diameter x 2 in. tall) Cores are prepared with Rolling Wheel Compaction (RW) OBC based on SHEAR test results FATIGUE Beams prepared after OBC S determined 6 Flexural Fatigue (2 in. tall x 2.5 in. wide x 15 in. long) 6 Flexural Stiffness (2 in. tall x 2.5 in. wide x 15 in. long) Beams are prepared with Rolling Wheel Compaction (RW) Time Per Mix 3 wks 6 wks HWTD Testing Cores are 6 in. diameter x 2.5 in. tall 1 Test with 4 cores prepared with Superpave Gyratory (SGC) 1 wk

Quantity of Materials Per Mix Design Hveem Mix Design (includes CT 371) Performance Testing (includes specimen fabrication) Shear Fatigue Hamburg Caltrans Project Typical Long Life 5 gal binder ~500 lb aggregate 5 gal binder ~500 lb aggregate 10 gal binder ~ 1,200 lb aggregate (Plant Mix Equivalent)

SPECIMEN FABRICATION Shear & Fatigue



Caltrans LLP – AC2 “Sample Preparation Design and Testing for Long Life Hot Mix Asphalt Pavements”



AASHTO PP3-94 Rolling Wheel Compaction

SPECIMEN FABRICATION Shear & Fatigue

• Beams and Cores cut from HMA Ingot

(Example)

SPECIMEN FABRICATION Shear & Fatigue

• Beams and Cores cut from HMA Ingot

SPECIMEN FABRICATION Shear & Fatigue

SPECIMEN FABRICATION Shear & Fatigue

SPECIMEN FABRICATION Shear & Fatigue

FATIGUE BEAMS

FATIGUE BEAMS Protection of Beams in transit/shipping is essential – no bending or flexing of packaging

SPECIMEN FABRICATION Hamburg

• Superpave Gyratory Compactor

SPECIMEN FABRICATION Hamburg

• Hamburg Testing Fixture – cut ‘flat’ on cores

LABORATORY TESTING

• SHEAR TESTING • FATIGUE TESTING • HAMBURG TESTING

SHEAR TESTING

SHEAR TESTING

SHEAR CORE – Post Test

Note Shear or “Slope” of specimen

SHEAR TESTING

5% PSS

Cycles

Spec Minimum to pass

FATIGUE TESTING

FATIGUE TESTING

Not to scale 50% FS (typical) Spec Minimum to pass Cycles (millions)

HAMBURG WHEEL TRACKING (Moisture Sensitivity)

Rut HAMBURG WHEEL TRACKING (Moisture Sensitivity) Theoretical “Rut Resistant” Cycles

HAMBURG WHEEL TRACKING (Moisture Sensitivity)

SPECIFICATIONS

and Testing Variability

Requirement Design Parameters Test Method Sample Air Voids HMA (15% Max RAP, Long Life) HMA (25% RAP, Long Life) Permanent deformation (min. stress repetitions) AASHTO T-320 Modified 3% +/ 0.3% 360,000 360,000 Beam Stiffness (psi) At 20 ° C and 10 Hz At 30 ° C and 10 Hz AASHTO T-321 Modified 6% +/ 0.3% 415,000 to 486,000 220,000 (min) 870,000 to 1,000,000 - Fatigue (min. repetitions) At 400x10-6 in./in. strain At 200x10-6 in./in. strain Moisture Sensitivity (min. repetitions) AASHTO T-321 Modified AASHTO T-324 Modified 6% +/ 0.3% 7% +/ 1% 23,000,000 345,000,000 12,000 25,000 950,000 12,000

SPECIFICATIONS

and Testing Variability Specifications for Shear and Fatigue are statistically based The specifications are based on the lowest 5 percentile expected from testing Comparable mixes should pass this specification 95 out of 100 times Limits are set low to accommodate large testing variability present in Shear and Fatigue Testing

Stabilometer Variability

Based on these numbers, the 5 th percentile is about 80% of the average (mean)

Questions?

Acknowledgements: Rita Leahy, Professor Monismith, Caltrans Staff