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 The Perpetual Pavement requires that the structure be designed and constructed from the bottom-up and that it have a combination of thickness and HMA characteristics which preclude fatigue cracking and durability problems. The renewable pavement surface must be designed to resist rutting and tailored for specific applications. In the end, the Perpetual Pavement will provide a uniform, smooth and safe driving surface, and it will avoid the huge expense associated with reconstruction. 3

Long Life Pavement – What is it? Leads to Fatigue Cracking HMA Repeated Bending Base The two most devastating forms of distress in flexible pavements are bottom-up fatigue cracking and rutting. These usually occur in relatively thin HMA pavements. Fatigue cracking occurs when repeated applied wheel loads (mouse click) cause bending in the HMA layer (mouse click) and a crack forms (mouse click). It’s similar to bending a coat hanger back and forth until it breaks. If the pavement structure is weak, then repeated deformation in the pavement will occur (mouse click) and rutting will eventually appear in the wheel paths of the road (mouse click). Subgrade Repeated Deformation Leads to Rutting 4

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 Existing Pavement  2 Mix Designs!!! Leveling Course

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) 2 Mix Designs!!! HMA w/ 25% RAP (PG 64-16) SAMI* HMA w/ 25% RAP (PG 64-16) (leveling course) Existing Cracked & Seated PCC or HMA * Asphalt Rubber Seal Coat 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!!! NTS

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

Modified Mix Design Flow Chart HVEEM Mix Design for Target “OBCH” SHEAR Testing to determine “OBCS” 3 specimens prepared and tested at HBC + 3 more each @ +/- X Total of 9 specimens per mix (3 x 3BC) If Fail Testing SELECT OBC based on SHEAR test results FATIGUE Testing @ OBCS 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

Modified Mix Design Materials and Time Time Per Mix 3 wks 6 wks 1 wk HVEEM to determine target BC SHEAR Cores are prepared first Testing performed to determine “OBCS” 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 OBCS 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) HWTD Testing Cores are 6 in. diameter x 2.5 in. tall 1 Test with 4 cores prepared with Superpave Gyratory (SGC)

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

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

Note Shear or “Slope” of specimen SHEAR CORE – Post Test Note Shear or “Slope” of specimen

Permanent Shear Strain (PSS) “Rutting” SHEAR TESTING 5% PSS Permanent Shear Strain (PSS) “Rutting” Spec Minimum to pass Cycles

FATIGUE TESTING

Flexural Stiffness (FS) FATIGUE TESTING Not to scale 50% FS (typical) Flexural Stiffness (FS) Spec Minimum to pass Cycles (millions)

HAMBURG WHEEL TRACKING (Moisture Sensitivity)

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

HAMBURG WHEEL TRACKING (Moisture Sensitivity)

SPECIFICATIONS and Testing Variability   Design Parameters Test Method Sample Air Voids Requirement 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 Beam Stiffness (psi) At 20° C and 10 Hz At 30° C and 10 Hz AASHTO T-321 6% +/- 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 AASHTO T-321 23,000,000 345,000,000 25,000 950,000 Moisture Sensitivity (min. repetitions) T-324 7% +/- 1% 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 5th percentile is about 80% of the average (mean)

Questions? Acknowledgements: Rita Leahy, Professor Monismith, Caltrans Staff