Overview. Disadvantages. Pavement Life. Pavement Preservation Treatments. Asphalt Technology Course SEAUPG ANNUAL MEETING NOVEMBER 15, 2012

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1 Overview Determine Benefits Make Project Selection Evaluate Materials and Mix Design (Pooled Fund) Monitor Performance Present Conclusions 2012 SEAUPG Annual Meeting Hilton Head Island, SC November 15, Benefits Provides low life cycle cost (Thin lifts ¾ 1 in) Uses a surplus aggregate Provides useful tool for pavement preservation No curing time No loose stone Excellent smoothness Reduces noise Practically impermeable Good workability Reduced chance of segregation High asphalt content Disadvantages Can be offset by use of fine fractionated RAP Still economical due to thin lift Low friction resistance at high speeds Greater potential for rutting 3 4 Pavement Preservation Treatments Pavement Life Location Traffic Underlying Pavement Ohio Performance, yrs. High/Low Asphalt 16 Low Composite 11 High Composite 7 North Carolina Concrete 6 10 Illinois Low Asphalt 7 10 New York Asphalt 5 8 Indiana Low Asphalt 9 11 Georgia Low Asphalt NAPA Survey 6

2 Preservation Treatment Life Annual Cost of Preservation Treatment Treatment Expected Life Range Thin Surface Chip Seal Slurry Seal Microsurface NAPA Survey 7 8 Project Selection Avoid Projects Needing Structural Rehab Visual Survey Type of distress Extent of distress Severity of distress Structural analysis Functional analysis 9 10 Avoid Projects Needing Structural Rehab May Be Useful Application For Raveling Cracking 11 12

3 May Be Useful Application For Materials and Mix Design NCAT Report Laboratory Refinement and Field Validation of 4.75 mm Superpave Designed Asphalt Mixtures Smoothness Friction? Randy C. West Michael A. Heitzman Grant Julian Michael Rausch NCAT Report Background Based on 2002 NCAT Report for Southeastern Superpave Center Pooled Fund Study Results used to recommend adoption by AASHTO Established gradation range controlled on 1.18 and mm sieves 1.18 mm 30 54% passing mm 6 12% passing Design Va 4.0% Minimum VMA 16% Recommended refinement/validation 15 AASHTO Specifications for 4.75mm NMAS Study Refinements Needed Materials 2 aggregate types; 3 gradations Volumetrics Minimum VMA Maximum VMA NCAT Report Work Plan Phase 1 Refine Mix Design Procedure Phase 2 Field validation of revised procedure Phase 3 Monitor performance for 3 years % G N ini Aggregate properties FAA Dust: Binder ratio V a criteria Use of Modified Binders 17 18

4 Refine Mix Design Procedure Optimum Asphalt Content 13 aggregate blends from various states V a 4 & 6% N d 50 & 75 4 plant produced mixes (MS, MD, MI, GA) Performance Tests Rutting MVT Moisture Susceptibility AASHTO T 283 Permeability ASTM PS 121 ( FM5 565) Cracking Resistance FE ANOVA for P be VMA Source DF Seq SS F Stat P N d V a Agg. Source Error Total R 2 = R 2 (adj) = Effect of Design V a on VMA Effect of FAA on VMA 23 24

5 Effect of FAA on %G N i Rutting MVT TSR Tensile Strengths Effect of Natural Sand on TSR Fracture Energy 29 30

6 Design ESAL (Millions) AASHTO Specification Nd Min. FAA Depth from Surface < 100 mm > 100 mm Min. SE Min. VMA (%) VFA (%) Ni < < to < < to < < 89.0 Sieve Size Min. Max. Va = 4.0% 12.5 mm 100 D:B Ratio = 0.9 to mm mm mm mm 6 12 Recommended Changes to Spec Gradation Change % passing 1.18 mm to 30 55% Change % passing mm to 6 13% SE Keep the same (Limit sand to 15% if FAA < 45) D:B Ratio Minimum 1.0 (1.5 if > 30 million ESAL) FAA If > 3 million ESALs, use 45 min. for all depths Ni Keep the same Va Use % Range VMA and VFA Use Vbe < 3.0 million ESAL 12 to 15% > 3.0 million ESAL 11.5 to 13.5% Proposed Revised Specification Field Validation Design ESAL (Millions) Nd Min. FAA Min. SE Min. Vbe (%) Max. Vbe (%) Ni D:B Ratio < < to < < to < < Sieve Size Min. Max. Va = 4.0 to 6.0% 12.5 mm mm mm mm mm 6 13 Four States Alabama, Missouri, Tennessee, Minnesota Traffic Level < 0.3 million to about 15 million ESALs Field Summary Field TSR Results Gradation 1.18 mm sieve about 5% finer than design mm sieve VMA Increased during production (Range ) VFA Exceeded spec limits D:B Increased during production (Range ) Recommend 1.0 to 2.0 for all traffic levels 35 36

7 Conclusions of Pooled Fund Study Mix design results largely controlled by aggregate properties > 3 stockpiles to control gradation Use 50 gyrations for low traffic; 75 gyrations for all other levels V a range of % needed to reduce AC for high VMA mixtures Replace VMA and VFA with V be range D:b Ratio > 1.5 improved rutting resistance Limit natural sand to < 15% 4.75 mm mixes are practically impermeable Test Track Cycle IDT (Pa) N7-1: PG S9-1: PG S10-1: WMA Foam PG S11-1: WMA Add. PG S12-1: TLA PG Test Track Cycle Rutting 2012 Pavement Preservation Sections Lee Road 159 N7-1: PG S9-1: PG S10-1: WMA Foam PG S11-1: WMA Add. PG S12-1: TLA PG Conclusions Almost always most cost effective of PP treatments Improves ride quality Reduces distresses (not for structural use) Reduces noise Provides longer life than other PP treatments Expected performance > 10 years on asphalt 6 10 years on PCC 41