Wisconsin Rides On Us. NACE Conference April 23, 2018

Transcription

1 Wisconsin Rides On Us NACE Conference April 23, 2018

2 Our Association Wisconsin Asphalt Pavement Association Established in 1948 Statewide, non-profit representing the interests of the asphalt paving industry in Wisconsin including: Asphalt Design Construction Maintenance Specifications Costs Marketing Policy (local, state, and federal levels)

3 Our Industry Wisconsin Asphalt Businesses (WAPA Members) Asphalt Pavement Producers 75 facilities 3,600 employees Aggregate Resource Provider (Pits & Quarries) 275 locations Distributed throughout the state Associate Members Liquid suppliers, maintenance contractors, equipment manufacturers, engineering consultants, testing facilities, etc.

4 Benefits of Asphalt 75% of roads in Wisconsin are surfaced with asphalt Cost-effective Safety Smoothness Noise Speed of Construction Sustainability

5 By the Numbers Wisconsin roadway miles by network type: *includes overlays

6 Increasing Durability and Pavement Performance

7 What we ve heard.. Why are our pavements turning grey so quickly? Our pavements don t seem to last as long as they used to. How come our pavements crack so quickly? Is the DOT or industry going to anything to improve this? We don t have enough money to fix what we need to fix!

8 Recognized the need to increase durability Since the inception of Superpave mixtures, Wisconsin has seen a decrease in total percent binder of its mixes Efforts have been made to get more asphalt into the mixtures-the VMA requirement was increased by 0.5% for LT & MT surface mixtures in 2015

9 Air Void Regression

10 When do we start? Beginning in 2016 the DOT and industry collaboratively determined that the best way to increase the amount of total percent binder in the mixtures was by using a mathematical air void regression equation Via ASP 6 it was used for all mixes (excluding SMA) in 2017 In 2018 it is now a Standard Specification

11 Why air void regression? Wisconsin is confident with the dense graded aggregate structure they currently utilize We wanted virgin asphalt binder to be added, not recycled binder This was a quick, scientific, calculated way to positively improve the mix right away without redesigning hundreds of mixes

12 Air void regression 101 All asphaltic mix designs will remain at 4.0% Looking at the mix design, the AC needed to achieve 3.0% air voids is determined Values are 3.0% for: Gmm Gmb Va VMA Original Optimum %AC = ~ 5.7 Regressed Optimum %AC = ~ 6.1

13 Air void regression benefits Addition of virgin asphalt binder (approx %) Increased durability, increased asphalt film thickness Increased in place density/decreased permeability Improved workability

14 Table Minimum Required Density [1] PERCENT OF TARGET MAXIMUM DENSITY LOCATION LAYER MIXTURE TYPE LT AND MT HT SMA [5] TRAFFIC LANES [2] LOWER 93.0 [3] 93.0 [4] UPPER SIDE ROADS, CROSSOVERS, TURN LANES, & RAMPS LOWER 93.0 [3] 93.0 [4] UPPER SHOULDERS & APPURTENANCES LOWER UPPER [1] The table values are for average lot density. If any individual density test result falls more than 3.0 percent below the minimum required target maximum density, the engineer may investigate the acceptability of that material. [2] Includes parking lanes as determined by the engineer. [3] Minimum reduced by 2.0 percent for a lower layer constructed directly on crushed aggregate or recycled base courses. [4] Minimum reduced by 1.0 percent for a lower layer constructed directly on crushed aggregate or recycled base courses. [5] The minimum required densities for SMA mixtures are determined according to CMM 8-15.

15 Why change the density requirements? A 1% decrease of in-place air voids was estimated to improve the fatigue performance of asphalt pavements, to improve the rutting resistance, and to extend the service life by conservatively 10%. NCAT Report (2016)

16 Percent Within Limits (PWL)

17 Benefits of PWL Better tracking of mixture specifics More discerning than other quality measures Statistical measure of quality Encourages Uniformity Controls both the average level and variability of the product in a statistically efficient way Variability is a predictor of performance

18 Va Control Chart - High Variability QC Warning Band Warning Band JMF Limits JMF Limits QV Va Control Chart - Low Variability QC Warning Band Warning Band JMF Limits JMF Limits QV

19 Comparison Current QMP 4 point running average Volumetrics: HMA lot sizes are variable (600, 900, 1200, 1500, etc ) Densities: Nuclear Gauges are not correlated to specific mix PWL Statistically based (Individual tests) QV tests become more statistically meaningful Volumetrics: HMA lot size = 3750 ton Sublot size = 750 ton Densities: Sublot sizes will not change Nuclear gauges correlated to each mix per layer using cores Test strip prior to main production for mix and densities

20 PWL Density

21 PWL Mixture Gmb or Gmm Chart

22 PWL Air Void calculated using Gmm & Gmb values

23 When will it be used? Pilot projects in 2016 Goal was 1/Region (SW, NE, & NC) Pilot projects in 2017 Goal was 2/Region (19-NE did 10) Continuing pilot projects 2018 Minor Adjustments may be needed before full implementation Round 1: projects with > 12,000 tons per mix type Round 2: evaluate how to incorporate smaller tonnage projects

24 Tack Coat

25 Tack Coat Specification application rates increased in 2016 Obtain engineer s approval for application rate (0.050 to gallons per square yard after dilution) Contractor must show that as-placed material has 50% or more residual asphalt content 2017 research and potential pilot projects Department is encouraging revision of materials and methods to reduce tracking and maintain bond Utilize best practices

26 HMA Performance Testing WisDOT is currently conducting testing for: Hamburg Wheel (Moisture Sensitivity & Rutting Potential) Disk-shaped Compact Tension (Low Temperature Cracking) Semi-Circular Bend with I-FIT (Fatigue Cracking) Ignition Oven (AC Content)

27 Summary

28 Asphalt Pavement Design Guide Last updated in 2001 Specification updates Assist users in the following: Design Materials Construction Rehabilitation Product usage

29 WAPA Resources 11,000 visitors annually WAPA Newsletters Published bi-monthly More than 2,500 contacts Industry Insider Updates from Members offered twice a year

30 Contacts WAPA Brandon Strand Deb Schwerman