SHRP2 R R06C T Tec echno nology to o Enh nhanc ance Q e Qual ualit ity C Cont ntrol on n Asphalt Pa Pavements: : Paver er Mount unted ed T Ther ermal al Pr Profil iler er Hosted by: FHWA/AASHTO January 31, 2018
R06C Technologies to Enhance QC on Asphalt Pavements Moderator: Presenters: • Kate Kurgan; • Stephen Cooper, FHWA AASHTO • Harold Von Quintus, P.E., ARA • Bill Stone, P.E., Missouri, DOT • Peter Moulton, Pike Industries • Ed Dalrymple, Chemung Contracting Presentation will be available for viewing on the AASHTO SHRP2 website: http://shrp2.transportation.org/Pages/R06C_RapidT echnologiestoEnhanceQualityControl.aspx 2
R06C Technologies to Enhance QC on Asphalt Pavements The Challenge: Develop solutions to measure and quantify non-uniformity of asphalt mixture at construction Increased use of night paving makes inspection more difficult Localized non-uniform areas fail prematurely. Random testing seldom catches problem 3
R06C Technologies to Enhance QC on Asphalt Pavements Thermal Profile during Density uniformity Placement: Pave-IR after Compaction: Rolling Density Meter 4
Agenda • Thermal Profiler Technology • Equipment and Data Acquisition • Field Demonstration Projects • Application and Benefits • Industry Perspectives and Views • Questions and Answers 5
Webinar Objectives • Describe use of the Paver Mounted Thermal Profiler Technology. • Identify equipment and understand the installation and use of equipment & software. • Discuss results/findings from the field demonstration projects. • List contractor’s and agency’s opinions and/or perspective of the Thermal Profiler as a QC or QA tool. 6
Part 1: What is it and why use it?
Thermal Profiler Technology Infrared Thermography Defined: The mapping of temperature contours (equal temperature) over the surface of a material. Contours are used to evaluate materials by measurement of their surface temperature and its variation. 8
Thermal Profiler Technology Mat Temperature Measurements: • IR sensors, IR-Bar ; first device for continuous readings. • Pave-IR Scanner ; second generation device for continuous readings. 9
Thermal Profiler Technology How is the thermal profile measured? • Sensor—detects infrared radiation emitted from the mat. • Scans the mat 6 to 10 ft. behind the screed. • Creates thermal profile of the mat surface. 10
Thermal Profiler Technology Why is it important? • Aggregate segregation in mat = temperature differentials • Non-uniform temperatures = non-uniform densities 11
Thermal Profiler Technology • Lower mat temperatures in localized areas results in lower mat density (reduced compaction) and reduces the service life or increases maintenance. 12
Thermal Profiler Technology Cold spots; areas with increased potential for: • Fatigue cracks • Raveling • Pot holes Cold Spot 13
Thermal Profiler Technology Thermal streaks with increased potential for longitudinal cracking and raveling. Loss of service life or increase in maintenance costs. Research and Development 14
Thermal Profiler Technology Segregation – A difficult issue to resolve, when it is difficult to identify or confirm. 15
Part 2: Equipment Installation & Use and Data Acquisition
Equipment and Its Installation Equipment • Mast Base • Mast Extension • Mast Arm • IR Scanner • DMI • GPS Unit • Wiring • Connection bolts & materials 17
Equipment and Its Installation IR mast base and extension attached to paver. Mounted to a Steel Plate Attached to Work Platform Mounted Directly to Screed 18
Equipment and Its Installation • IR Scanner attached to paver; scans mat behind screed in one direction. • GPS attached to the mast arm. 19
Equipment and Its Installation DMI placed on wheel hub to measure distance during paving operation. 20
Equipment and Its Installation IR scan screen used to see/monitor mat temperatures in real time; attached to the mast post or extension. 21
Data Processing and Reports Raw Temperature Profile; all data collected and retained in the data file. 22
Data Processing and Reports Summary of Raw Data for One Lot Avg. Temp. = 285 ºF Not mat temperatures 23
Data Processing and Reports Data Processing—eliminate invalid temperature measurements, 3 steps: 1. Eliminate measurement locations within 2 feet of the mat’s edge. 24
Data Processing and Reports Data Processing—eliminate invalid temperature measurements, 3 steps: 2. Eliminate temperature readings < 170 ºF and > 400 ºF. 3. Eliminate data with paver stops greater than 60 seconds. Data eliminated between locations: – 2 feet behind measurement location of stop – 8 feet in front of measurement location of stop 25
Data Processing and Reports 90000 Summary of Processed Data 80000 for one day of paving 70000 60000 Raw IR data: T avg. = 296.2 ºF Frequency 50000 Processed data: T avg. = 305 ºF 40000 30000 20000 10000 0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 Temperature Bins (degree F) 26
Data Processing and Reports Temperature Differential Criteria, each 150 foot segment: ∆ = − T T T 98 . 5 1 . 0 • ∆T < 25 ºF Minor temperature difference • 25 ºF < ∆T < 50 ºF Moderate temperature difference • ∆T > 50 ºF Severe temperature difference 27
Data Processing and Reports Review results in real time. 28
Data Processing and Reports Locations without thermal Report; Tex 244-F segregation. Thermal profile summary. 29
Part 3: Field Demonstration Projects; Summary & Findings
Field Demonstration Projects AK WA VT ME MT ND OR MN NH WI MA NY ID SD RI WY MI PA CT NE IA NV OH NJ IL IN DE UT WV CO MD KS MO VA CA KY DC NC Northern TN EFL Mariana OK AZ AR Islands / NM SC Guam GA MS AL American TX Soma LA HI V.I. FL PR 31
Field Demonstration Projects All field demonstration projects; effect of MTVs : MTV Thermal Percent Severe Temp. Project Delivery Truck Type Included Differentials Streaking Alaska Bottom-Dump 17 None Windrows EFL End Dump 83 None No Illinois End Dump 40 None No Maine End Dump 5 None Yes End Dump & Flow Missouri 25 None Yes Boys NJ End Dump 21 None Yes Virginia End Dump 5 None Yes NC End Dump 18 None Yes WV End Dump 41 None No WV End Dump 5 None Yes Above includes paver stops. 32
Field Demonstration Projects Multiple demonstration projects; effect of loading trucks: • One dump of mix in truck bed – severe temp. differential • Two dump, no stockpile – reduced temp. differential. Properly loading trucks significantly reduced the number of severe temperature differentials. 33
Field Demonstration Projects Multiple demonstration projects; effect of number of trucks: • Avg. temperature differential at start of paving project was about 30 ºF. • Avg. temperature differential after adding two trucks was about 15 ºF. Few trucks with high local traffic = more paver stops. Two more trucks = fewer paver stops & more uniform temp. 34
Field Demonstration Projects Multiple demonstration projects; effect of number of trucks : • Significant paver delay between • Reduced paver delay trucks. between successive trucks. Extensive delay with screed heater on. EFFECT: Less variability in mat density, and reduced contractor’s risk of being penalized. 35
Field Demonstration Projects Multiple demonstration projects; effect of tarps : Properly installed and maintained tarps significantly reduced the temperature differentials by about 40 percent. 36
Field Demonstration Projects Multiple demonstration projects; effect of loading trucks : Trucks with improperly Trucks with properly installed tarps. installed tarps. Temperature differences between trucks. 37
Part 4: Application and Use
Application & Use Perspective as a QA Tool: • Continuous readings to evaluate mat uniformity through temperature uniformity. • Uniform temperatures imply uniform densities, which usually mean lower maintenance. 39
Application & Use Impact on Contractor’s compaction operation: After recognizing the effect of temperature sensitive zone; VA DOT demonstration project. 40
Application & Use Role of IR in Quality Assurance Programs: 1. Contractor QC plan – Monitor production/placement operations to minimize temperature differentials of mat. – Minimize risk of being penalized. – Forensic tool to trouble shoot low or non-uniform mat densities. 2. Agency acceptance plan – Reduce future distress and maintenance costs. – Dispute resolution. 41
Application & Use IR role in QC plan, answering specific questions: • What changes need to be made, if any? – Paver delays and speed. – Paver maintenance; augers, kick-back flights, slat conveyor, etc. – Number & loading of trucks – Tarps – Etc. • When to make those changes? 42
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