THE PROBLEM #WorldofAsphalt Photo: Rosenberger 1 2/8/2019 I71 in - PDF document

2/8/2019 Best Practices for Construction of Longitudinal Joints Wayne Jones, P.E. Senior Regional Engineer Asphalt Institute THE PROBLEM #WorldofAsphalt Photo: Rosenberger 1

2/8/2019 I‐71 in Cincinnati, OH Photo: Grass Photo: Rosenberger • Note condition of the rest of the mat • Also sealed each side of patch Photo: Rosenberger 2

2/8/2019 Micro‐surfacing 15” wide over LJ I‐64 in IL for 25 miles, Aug’14 Photos: Buncher An Agency and Industry Concern Longevity matters, it impacts:  DOT Program Costs  HMA Industry’s Livelihood o LCCA o Alternate Bid Competitiveness  Travelling Public o “…Stay Out” The Problem New construction in Oklahoma ‐ not yet opened to traffic. Permeable at the Longitudinal Joint #WorldofAsphalt 3

2/8/2019 Clarification of Terms • Density: weight per volume (i.e. 140 pcf) • Percent Relative Compaction: Comparison of a measured density to a reference density − i.e. in place density of 94% Theoretical Maximum Density • All industries have jargon − Shorthand to simplify communications • When speaker and slides refer to density, it is jargon for percent relative compaction − i.e. 94% density really means 94% TMD Typical Nuclear Density Profile Texas Transportations Institute Study In this case, In this case, “density” actually “density” actually means “density!” means “density!” Unconfined Middle of Mat Hot Side Lowest Highest In‐between Value Value Value Joint vs. Mat Density (Representative of Other Studies) 95 94 93 93.6 93.5 93.1 93.1 92 91 90 Joint Density 90.5 89 89.7 Mat Density 88 87.8 88.1 87 86 85 84 Wearing Surface Binder Course 1 2 3 4 12.5mm 19.0mm 2006‐2007, with 6” cores taken over joint 4

2/8/2019 The Problem Permeability: can be catastrophic! Permeable Below 92% Density DENSITY VS. PERMEABILITY 12.5 mm WEARING COURSE 98.0% Density (% Gmm) 96.0% LONGITUDINAL JOINTS 94.0% MAT 92.0% 90.0% 88.0% 86.0% 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 -5 / sec) Coefficient of Permeability (K) (cm x 10 Dean Maurer, P.E. Oklahoma DOT Research on 25.0 mm Superpave Mix Permeability Permeability vs. Density Mix # 1 900 Mix # 1 (coarsest possible) 800 Permeability - cm/s x 10-5 Mix # 2 700 600 Mix # 3 500 Mix # 4 400 300 Mix # 5 200 Mix # 6 100 Mix # 6 0 (finest possible) 91 92 93 94 95 96 97 98 Density - % of Gmm Gierhart ‐ 2004 5

2/8/2019 What typically affects longitudinal joint density and/or creates longitudinal joint problems? • the way the specifications are written • the way the asphalt is placed • the way the asphalt is compacted #WorldofAsphalt SPECIFICATIONS #WorldofAsphalt “If you can’t measure it, you can’t manage it.” Peter Drucker 6

2/8/2019 Various Approaches No • High Agency Risk INCREASING INNOVATION LJ Spec • No Incentive for Quality INCREASING RISK • One size fits All Method • Agency assumes some Risk Spec • No Incentive for Innovation • Requires On‐site Oversight by Agency • Allows Innovation for Contractor • Balances Risk, Includes Incentives & Density Disincentives Spec • May have Triggers (i.e. Sealing/Overbanding • Not Appropriate for Small Jobs Tiered Approach to Spec (i.e. Include Small Quantity Spec) • For small jobs where limited density measurements are attainable, contractor follows method spec or Tiered submits compaction plan Approach • On larger Jobs where a statistically based sample size is attainable, the Contractor follows a density specification with incentives and disincentives Joint Performance vs. Joint Density (as % of Mat) Methods for Evaluating Longitudinal Joint Quality in Asphalt Pavements ‐ S. Williams, et al. Univ. of Arkansas Good Joint Performance when 97% of the Mat Fair Joint Performance when 93 to 97% of the Mat Poor Joint Performance when < 93% of the Mat Longitudinal Asphalt Pavement Joint Construction…Performance ‐ D. Morian, et al. Quality Engineering Solutions, NV Significantly better joint performance (12 yrs.) when; 98% of the Mat versus lesser joint performance (8 yrs.) when 95% of the Mat Assuming mat density is 94% of G mm , then: ‐ 98% of the mat density is 92% G mm (8% P a ), = Good Performance ‐ 95% of the mat density is 89% G mm (11% P a ), = Fair Performance ‐ 93% of the mat density is 87% G mm (13% P a ), = Poor Performance 7

2/8/2019 Proposed Acceptance Criteria for an LJ Density Spec Six‐inch Cores located either directly over visible joint for butt joint, or middle of wedge for wedge joint. This gives a 50/50 split, in order to average the G mm of both lots. Intended for Intended for highway work ‐ highway work ‐ • > 92% of G mm : maximum bonus may be too may be too difficult to meet on difficult to meet on parking lot, city, parking lot, city, • Between 92% and 90% of G mm : county projects county projects 100% pay, pro‐rated bonus, need to “overband” or where there is where there is “surface seal” joint limited room for limited room for full paving / full paving / • < 90% of G mm : reduced payment, overband or compaction train compaction train surface seal joint Defining Different Types of Longitudinal Joints Butt (Vertical) Joint Milled or Cutback Joint Notched Wedge Joint Frequently Done in “Overbanding” the L.J. AK and PA “Surface sealing” covered later in Section 5, Other Options 8

2/8/2019 Quality Control and Acceptance of Joint Density Density Gauge 6‐inch Core Pennsylvania Story on Longitudinal Joint Density Article in NAPA’s magazine, Asphalt Pavement , Sept/Oct 2012 http://www.nxtbook.com/nxtbooks/naylor/NAPS0512 • Increasing density was viewed as key • 2007 ‐ began measuring joint density • 2008 ‐ method spec. of best practices • 2008 and 2009 ‐ continued gathering data on joints • 2010 ‐ New joint density specification. Transition year with no bonuses or penalties. • 2011‐2014 – bonuses and penalties on joint density Pennsylvania DOT Joint Density Spec Highlights • Both type of LJs allowed (butt or notch wedge) • Joint Lot = 12,500’. Core every 2,500’. 5 cores per lot. • Core location For Butt: directly over visible joint o For Notch Wedge: middle of wedge o • Percent Within Limits (PWL) • Incentive starts at 80% PWL • Disincentive at <50% PWL • Lower Specification Limit 2010‐2013: 89% TMD o 2014: 90% TMD o • Corrective action for < 88% TMD 9

2/8/2019 In‐place Density Summary, Reported by PA DOT PA: How Did it Work? Year # Lots Avg. Roadway Avg. Joint Density, Density, %TMD %TMD 2007 18 93.9 87.8 begin measuring at Jt. 2008 43 94.1 88.9 method spec 2009 29 94.1 89.2 method spec 2010 No data, transition to PWL spec PWL, LSL 89% 2011 137 94.1 91.0 PWL, LSL 89% 2012 162 94.0 91.6 PWL, LSL 89% 2013 167 93.9 91.4 2014 316 94.1 92.3 PWL, LSL 90% 2015 493 92.6 PWL, LSL 90% PA: Annual Statewide Totals on How Did the Longitudinal Joint Spec Affect Pay? Incentives/Disincentives for Joint Density Incentive Disincentive Year Payments Payments 2011 $268K $99K 2012 $489K $63K 2013 $588K $25K 2014 $1,002K $127K Key Steps in Implementing New LJ Spec • Multi‐year plan (versus all at once) • Agency and industry work together • Training (best practices, possible alternatives) • Establish baseline of existing joint densities (randomly selecting projects to test) • Make incremental changes (trying different techniques, products, or specs.) • Evaluation Plan: measure densities to compare to baseline, monitor performance, etc. 10

2/8/2019 Key Steps in Implementing New LJ Spec (continued) • If requiring a minimal density for first time, take incremental steps: • First year require “report only” (calculate any bonus/penalty without adding/subtracting dollars) • Second year can start bonuses and penalties • Gradually increase density requirement to reach 90%, or possibly higher as it can be shown to be accomplished on regular basis • Evaluate progress, comparing densities to baseline DESIGN #WorldofAsphalt Poor planning – joint in wheelpath Danny Gierhart photo 11

2/8/2019 Offset joints between layers by at least 6‐inches; surface joint should be near centerline (not in wheelpath) Avoid Placing the Joint Where Striping Will Go DELDOT Which Can Eventually Result In This DELDOT 12

2/8/2019 Final Lift Joint Layout Plan DELDOT DELDOT PLACEMENT #WorldofAsphalt We Know Unsupported Edge Will Have Lower Density Sufficient Material Proper Overlap for Roll‐Down Cold (unconfined) side Hot (confined) side Low Density Area 13

2/8/2019 The Best Longitudinal Joint: Echelon Paving New Jersey Rolled Hot Echelon Paving Longitudinal Joint Joint passes between the quarters But, the need to maintain traffic limits the opportunities to pave in echelon Consequently, most longitudinal joints are built with a cold joint. 14