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Learn how Washington State is enhancing asphalt pavement durability by increasing asphalt amount and density requirements. Explore VMA specifications, compaction incentives, and asphalt binder changes.
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INCREASING PAVEMENT LIFE Kurt Williams, State Materials Engineer Washington State Department of Transportation April 16, 2019 Roger Millar, Secretary of Transportation Keith Metcalf, Deputy Secretary of Transportation
Washington State Highways 18,500 Lane Miles
Washington State Highways Statewide Lane Miles Concrete 2,250 12% 18,500 Lane Miles Asphalt 9,383 51% Chip Seal 6,865 37%
Washington State Highways Statewide Lane Miles Concrete 2,250 12% 18,500 Lane Miles Asphalt 9,383 51% Chip Seal 6,865 37% Vehicle Miles Traveled Concrete 28% Asphalt 66% Chip Seal 6%
HMA Pavement Life Eastern Washington Average 11.5 years Western Washington Average 16.2 years
Hot Mix Asphalt Pavement Life - Years Between Resurfacing Western Washington
Hot Mix Asphalt Pavement Life - Years Between Resurfacing Western Washington
Hot Mix Asphalt Pavement Life - Years Between Resurfacing Western Washington
Two Areas of Focus:1) Increasing the amount of asphalt2) Increasing the Density requirement
1) Increasing the amount of asphalt • Implemented field testing for Voids in Mineral Aggregate (VMA) • HMA mix design process and performance testing • Not all HMA mixes placed required additional asphalt
VOIDS IN MINERAL AGGREGATE (VMA) AIR VOIDS (VMA) VOIDS IN MINERAL AGGREGATE ASPHALT AGGREGATE AGGREGATE
VMA SPECIFICATION • 2018 VMA Field Tolerance -1.5%
VMA SPECIFICATION • 2018 • 2019 VMA Field Tolerance -1.5% VMA Field Tolerance -1.0%
VMA SPECIFICATION • 2018 • 2019 • 2020 VMA Field Tolerance -1.5% VMA Field Tolerance TBD VMA Field Tolerance -1.0%
1/2 Inch HMA Asphalt Content Percent Asphalt Content Average Percent Asphalt Content Year
3/8 Inch HMA Asphalt Content Percent Asphalt Content Average Percent Asphalt Content Year 2018 Data is from Jan thru Sept 2018
FHWA Increased HMA Density Research Phase II 2018 Study 2016 Study
COMPACTION SPECIFICATION INCENTIVE Above 91.5% Pay Factor 0.8 DISINCENTIVE Below 91% Pay Factor 0.4 • 2018
COMPACTION SPECIFICATION INCENTIVE Above 91.5% Pay Factor 0.8 DISINCENTIVE Below 91% Pay Factor 0.4 INCENTIVE Above 92% Pay Factor 1.0 DISINCENTIVE Below 91.5% Pay Factor 0.6 • 2018 • 2019
COMPACTION SPECIFICATION INCENTIVE Above 91.5% Pay Factor 0.8 DISINCENTIVE Below 91% Pay Factor 0.4 INCENTIVE Above 92% Pay Factor 1.0 DISINCENTIVE Below 91.5% Pay Factor 0.6 INCENTIVE Above 92% Pay Factor TBD DISINCENTIVE Below 92% Pay Factor TBD • 2018 • 2019 • 2020
2010 - 2018 HMA Average Percent Density AverageCompaction All Mix Designs 93.7
2018 COMPACTION SUBLOTSCompared to 2016 and 2020 Forecast 93.4%
2018 COMPACTION SUBLOTSCompared to 2016 and 2020 Forecast 93.4% 93.7%
2018 COMPACTION SUBLOTSCompared to 2016 and 2020 Forecast 93.4% 93.7%
HMA Bonus and DeductionCompaction Dollars Tons of HMA Tons HMA Placed Year
HMA Bonus and DeductionCompaction Bonus Paid Dollars Tons of HMA Tons HMA Placed Year
HMA Bonus and DeductionCompaction Bonus Paid Dollars Tons of HMA Tons HMA Placed Deduction Year
Average HMA Cost per Ton vs. Average Asphalt Binder Price Average Cost of HMA per Ton 3/8 Inch HMA Cost Per Ton
Average HMA Cost per Ton vs. Average Asphalt Binder Price Average Cost of HMA per Ton 3/8 Inch HMA Cost Per Ton ½ Inch HMA Cost Per Ton
Average HMA Cost per Ton vs. Average Asphalt Binder Price Average Cost of HMA per Ton Average Cost of Asphalt Binder per Ton 3/8 Inch HMA Cost Per Ton ½ Inch HMA Cost Per Ton Average Cost of Asphalt Binder per Ton October 2018 Cost
2018 Standard SpecificationsAsphalt Binder Changes 2017 and Prior Years: AASHTO M 320 Grading System PG64-22 PG70-22 PG64-28 PG70-28 PG76-28 2018 Implemented: AASHTO M 332 *MSCR Grading System PG58S-22 PG58H-22 PG58V-22 PG64S-28 PG64H-28 PG64V-28 *MSCR: Multiple Stress Creep Recovery
2010 - 2018 Asphalt Binders Meeting Specifications Percent Asphalt Binders Meeting Specifications Percent Passing Asphalt Binders Tests Year
2018 Asphalt Binder Meeting Specification 99.1% 97.2% Percent Asphalt Binders Meeting Specifications MSCR 2018 Year
2018 VMA TestingPercent Meeting Specification 99.1% 97.2% 90.7% 89.8% Percent Meeting Specifications 47 Projects 35 Projects Year
2017 – 3/8 Inch HMA VMA TestingProduction Data Percent Voids in Mineral Aggregate (VMA) Lower Specification Limit: 15 Pre 2018 Spec 3/8”
2018 – 3/8 Inch HMA VMA TestingProduction Data 14 Contracts 22 Contracts Percent Voids in Mineral Aggregate (VMA) Lower Specification Limit: 15 Lower Tolerance Limit: 13.5 Pre 2018 Spec 3/8” 2018 Spec 3/8”
2018 – 3/8 Inch HMA VMA TestingProduction Data 2019 Lower Tolerance Limit: 14.0 Percent Voids in Mineral Aggregate (VMA) Lower Specification Limit: 15 Lower Tolerance Limit: 13.5 Pre 2018 Spec 3/8” 2018 Spec 3/8”
2017 – ½ Inch HMA VMA TestingProduction Data HMA Class 1/2 Inch VMA Production Data Percent Voids in Mineral Aggregate (VMA) Lower Specification Limit: 14 Pre 2018 Spec 1/2”
2018 - ½ Inch HMA VMA TestingProduction Data 36 Contracts 16 Contracts Percent Voids in Mineral Aggregate (VMA) Lower Tolerance Limit: 12.5 Lower Specification Limit: 14 Pre 2018 Spec 1/2” 2018 Spec 1/2”
2018 - ½ Inch HMA VMA TestingProduction Data 2019 Lower Tolerance Limit: 13.0 Percent Voids in Mineral Aggregate (VMA) Lower Tolerance Limit: 12.5 Lower Specification Limit: 14 Pre 2018 Spec 1/2” 2018 Spec 1/2”
HMA Bonus and DeductionMixture Dollars Tons of HMA Tons HMA Placed Year
HMA Bonus and DeductionMixture Bonus Paid Dollars Tons of HMA Tons HMA Placed Year
HMA Bonus and DeductionMixture Bonus Paid Dollars Tons of HMA Tons HMA Placed Deduction Year