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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
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Long-Life PavementsConcepts and Lab Testing Pre-bid Meeting Solano 80 04-4A0104 James M. Signore Oakland, CA 9/14/2012
PresentationOverview • 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? Leads to Fatigue Cracking Repeated Bending Repeated Deformation Leads to Rutting HMA Base Subgrade
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
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 2 Mix Designs!!! * 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 3 Mix Designs!!! AggSubbase & Subgrade NTS
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 HVEEMMix 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)
SPECIMEN FABRICATIONShear & Fatigue • Caltrans LLP – AC2 “Sample Preparation Design and Testing for Long Life Hot Mix Asphalt Pavements” • AASHTO PP3-94 Rolling Wheel Compaction
SPECIMEN FABRICATIONShear & Fatigue • Beams and Cores cut from HMA Ingot (Example)
SPECIMEN FABRICATIONShear & Fatigue • Beams and Cores cut from HMA Ingot
FATIGUE BEAMS Protection of Beams in transit/shipping is essential – no bending or flexing of packaging
SPECIMEN FABRICATIONHamburg • Superpave Gyratory Compactor
SPECIMEN FABRICATIONHamburg • Hamburg Testing Fixture – cut ‘flat’ on cores
LABORATORY TESTING • SHEAR TESTING • FATIGUE TESTING • HAMBURG TESTING
SHEAR CORE – Post Test Note Shear or “Slope” of specimen
SHEAR TESTING 5% PSS Permanent Shear Strain (PSS) “Rutting” Spec Minimum to pass Cycles
FATIGUE TESTING Not to scale 50% FS (typical) Flexural Stiffness (FS) Spec Minimum to pass Cycles (millions)
HAMBURG WHEEL TRACKING (Moisture Sensitivity) Theoretical Rut “Rut Resistant” Cycles
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