Midwest Geotechnical Conference Indianapolis, Indiana September 22, 2015 Bob Arndorfer

 Historical Practice  Research Study/Findings  Goals/Benefits  Development and Highlights of New Specification  Pilot Projects  Issues/Modifications Necessary  Moving Forward 2

 Where we were 3 years ago  Observational Method  Compact “until there is no appreciable displacement either laterally or longitudinally, under the compaction equipment.”  Somewhat Vague  Have Been Attempts to Reduce Subjectivity – Limited Success 3

 Subjective – No Consistent Method of Acceptance  No Documentation During Construction  Non-uniform Compaction Results  Issues Raised by Paving Contractors  Other States Using More Advanced Means 4

 Department Goal - Move to Performance Specs For Material Acceptance  Qual Mgmt Program (QMP) - Contractor tests/monitor  Reduces Departmental oversight and staff time  Give contractor more control of their operations Ultimate Goal: Increase Pvmt. Performance  Based on all this – Department Decided to Have Some Research Done on This Topic 5

 Many National Studies Using Different Devices  Dynamic Cone Penetrometer (DCP)  Lightweight Deflectometer (LWD)  Intelligent Compaction  Geogauge  Nuclear Gauge  Sand Cone  Other 6

 Investigate the Effectiveness of Our Current Methods, Survey Other States, Layout Future  Titled: ‘Feasibility Analysis of Base Compaction Specification’  Completed in 2012 by University of Wisconsin- Milwaukee (PI was Professor Hani Titi)  Investigated 11 Existing, and 10 New, HMA Pavement Projects  Look at Current, and Long-term, Base Performance 7

 Projects Located in Various Geographic and Geologic Regions of the State  ME Sensitivity Analysis Using DARWin-ME  Investigate Density-based and Modulus-based Methods  Look at Cost Implications of Differing Compaction Methods 8

 Investigate Project Material Records  Investigative Methods on Existing Projects  FWD  Visual Pavement Distress Surveys  Investigative Methods on Current Projects  Lightweight Deflectometer  Dynamic Cone Penetrometer  Sand Cone  Geogauge  Lab Tests including Resilient Modulus 9

 Out of 49 States and 13 Canadian Ministries, Only 4 Use Subjective Observation Methods for Acceptance – WI Was One of Four  Over 90% of the 63 Contacted Highway Agencies Used Density-Based Methods for Quality Control of Aggregate Bases 10

 71% of Highway Agencies Follow ASTM or AASHTO Test Methods  63% Use Nuclear Density Test Measurements  44% Use Standard Proctor for Max Density - Target Density: %  27% Use Modified Proctor for Max Density - Target Density: % 11

 High Variability of WI Bases Being Placed  Field Density  Moisture  HMA Pavement Performance Was Related to Spatial Variability and Non-uniform Density of Base Course  Well Performing HMA Pavements Exhibited Low Levels of Spatial Variability and Good Uniformity in Aggregate Base Courses 12

 The Uniformity of Base Density Appears to be More Critical Than Level of Compaction  Mechanistic-Empirical (ME) Sensitivity Analysis Showed Reduced Life (Increased distress levels) in Pavements With Lower Base Modulii  Base Density Work on 63% of Projects Had No Significant Impact on Project Schedules  53% of Responding Agencies Reported Density Implementation Has No Cost Impacts on Projects . 13

 42% of Highway Agencies are Looking for New Methodologies to Replace/Complement Their Current Density-Based Specifications  Recommend Quantitative Method of Acceptance Based on Testing  Suggest Investigating Continuous Compaction Control Techniques  Recommend Transitioning to Modulus-based Testing (More research needed to fully implement this.) 14

 Better Bases Facilitate Better HMA Compaction, Resulting in Longer Pavement Life  Measurements Will Increase Consistency of Base Placement Operations and Results  Measurement Will Provide Consistent/Defined Method of Base Acceptance – Not Subjective  Reduce Long-term HMA Pavement Maintenance Costs 15

 Reduce Contractor Risk at Time of Bidding and Provide More Equity  Provide Project Documentation of Compactive Levels Achieved  Any Construction Cost Increases Will Still Result in Reduced LCCA Costs  Move WisDOT/Contractor to QMP – Allow Contractor More Control of Their Operations  Transition From Method Spec. to Performance Specification 16

 Based on Study Results – Need New Spec  Aggregate Responsibility at WisDOT - ??  WisDOT and Industry Meetings  Application Issues to Address  What Types of Projects  Define Size of Projects  Where Used on Projects  Base Compaction Methods Already Being Used for WisDOT Airport Construction 17

 Developed Two Specifications/Test Methods  Milled/Pulverized and Overlay  Base Aggregate – Different testing based on percentage of RAP/RCA (Cut-off at 20% RAP/RCA)  Contractor to Provide QMP Plan  Required Certified Testers  QC and QV Requirements Set  Dispute Resolution – Third-party Lab (Vague)  How to Address Failures – Contractor to Take Corrective Actions Until Spec is Met 18

 Target Density Limit: 95% T-180 Modified Proctor  Additional Proctor if Gradation Varies ≥ 10% on Any One Sieve  Departmental QV Testing at Frequency of 30% of Contractor QC Testing  Payment Based on Ton or SY Basis 19

 Base Aggregate  Density Testing Frequency – Every 1000 tons  Gradation and Proctor – Every 3000 tons  Payment based on Tons  Mill/Pulverize and Overlay  Density Testing Frequency – Every 3000 SY  Gradation – Every 9000 SY  Additional Proctor if AC content changes by ≥ 1.5% by visual observation  Payment based on SY 20

 WisDOT Generally Works Closely With Industry When Developing Specifications  Different Perceptions  Paving industries in favor of it  Grading industry less enthused  Aggregate producers opposed  WI Transportation Builders Association has concerns  FHWA – Supports Movement to Density  Department – Favors Measurement 21

 Difficult to Bid - Unknowns  Increased Contractor Workload  Perceived Increased Contractor Risk  Potential For Project Delays if Issues  May Require More Compactive Effort by Contractor  Subgrade (Lower Layers) May Not Have Required Density 22

 Multiple Sources May be Used - Complications  Frequency of Testing – How Much?  Consider a Density Incentive?  Concerns Over Failed Tests and Remediation  Potential Project Delays Due to Required Testing  Concern Over Timing of Base Acceptance – (Delays in acceptance or Changes due to environmental conditions.) 23

 HMA Projects Only – Pvmt. Design Process  Travel Lanes and Shoulders Only  Pay Quantity Based on Total Material (Ton/SY)  Include Payment for Compaction Water  Base Aggregate 1¼”  Quantity ≥ 30,000 tons  Subgrade Improvement or QMP Subgrade, or Both  Mill/Pulverize and Relay  Quantity ≥ 40,000 SY 24

 Final Specification Language Developed  Various Geographic and Geologic Areas  Different Contractors  Density Results Used In One of Two Ways  Project Control  For Information Only 25

 Pilot Specification Used on 11 Projects  8 Base Aggregate  3 Mill/Pulverize and Relay  Generally Went Well, Some Issues Meeting Density Requirements  At End of Construction Season - Department Met With Industry to Discuss Improvements and Implement Revisions 26

2013 Project Results 27

 95% of T180 Difficult to Consistently Achieve  Issues With Density Measurements When RAP/RCA >20%  More Definition Needed on Corrective Actions and Acceptance Methods for Material Not Meeting Density  Findings of 2013 Projects Used to Modify Spec for 2014 Pilot Projects 28

 Pilot Specification Used on 9 Projects  8 Projects Base Aggregate, 1 Project Mill  576k tons Base Agg, 41k SY Mill/Relayed HMA  Revised Specifications  Base - Require 93% T180  Base - Testing frequency increased to 1500 tons  Base - In addition to dry density, can determine target density by wet density or control strip method (>20%)  Mill/Overlay – Only use control strip for target density  Corrective Actions Clarified 29

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 Variation of QC and QV Proctor Values  Issues With Proctor Test Requirement When Gradation Changes by ≥ 10% on Any Sieve  Desire to Use Family of Curves  Timing of Density Testing and Acceptance  Need For Pre-placement Meeting  Need to Establish Dry-back Moisture Test Frequency 31

 Use QC Proctor Value for All Testing Once Verified by QV Tests (Require ≤3 pcf difference)  New Proctor Necessary When Moving Average of Four Gradation Tests Differs by ≥10% on Any Sieve  QC Can Use Family of Proctor Curves  Dry-back Moisture Content Required Every 9000 tons Base 32

 Contractor to Provide Description of Placement Methods, Staging, Equipment, Etc. in QMP  Require Pre-placement Meeting  Clarification on Retesting and Documentation of Corrected Lots 33

 Will be Standard Special Provision for 2016 Construction Season  Apply to all HMA Projects That Meet Criteria  Monitor to See if Additional Updates Necessary  Incorporate Into PCC Pavement ?  Lead to Water Bid Item on All Base Projects ?  Contractors Not Complaining Much - Improving  Contractors Realizing Importance of Water for Compaction 34

 Base Agg. Research Report Can Be Found At: pavements pavements  Questions? 35