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  • Nondestructive Pavement Nondestructive Pavement Thickness Measurement Thickness Measurement

    Jagan Gudimettla, P. E.Jagan Gudimettla, P. E. FHWA Mobile Concrete LaboratoryFHWA Mobile Concrete Laboratory

    Presenter Presentation Notes Good Morning

  • Presentation OutlinePresentation Outline

    

    Introduction / BackgroundIntroduction / Background 

    MCL Experience with MIT Scan T2MCL Experience with MIT Scan T2

    

    Current Work with MIT Scan T2 TargetsCurrent Work with MIT Scan T2 Targets 

    Cost ComparisonCost Comparison

    

    SummarySummary

    Presenter Presentation Notes My presentation is on a new piece of equipment called MIT Scan T2. It is used to determine thickness of pavements thoguhtt non distructive means. This is the outline of my preesntation.

  • MIT ScanMIT Scan--T2T2

  • MIT ScanMIT Scan--T2T2

  • Introduction / BackgroundIntroduction / Background

    

    Operating Principle Operating Principle 

    How to use MIT Scan T2How to use MIT Scan T2

    

    Memory ManagementMemory Management 

    Charging and Operating TimeCharging and Operating Time

    

    Maximum Depth MeasurementMaximum Depth Measurement 

    LimitationsLimitations

    Presenter Presentation Notes Operating Principle: The MIT-SCAN-T2 generates magnetic fields to assist in determining the thickness of the asphalt or concrete layer. The device excites “answering fields” generated from eddy currents, which have been induced inside an aluminum or a zinc-plated steel target as a reaction to a pulsed magnetic field. This measuring method is based on the principle of electro-magnetic tomography. Crucial innovations are the application of a sensor field and the analysis of the spatiotemporal answering signal.

    How to Measure Thickness: Two Modes Memory Management: Data Transfer to PC Charging and Operating Time: Battery Charge: AC or DC, 1.5 hrs of charging, Operating time > 8 hrs or 1000 measurements. Where it cannot be used: Cannot use for CRCP or where reinforcement is present or electromagnetic fields

    Maximum Measured Depth: 50cms

    Other Items: Distance between two targets – 0.5m, Weight – 6 pounds

  • MIT ScanMIT Scan--T2T2

  • MIT ScanMIT Scan--T2T2

  • AccuracyAccuracy 

    Specified: Specified: ++ 0.5% of the measured depth 0.5% of the measured depth + 3/64 in (1 mm)+ 3/64 in (1 mm)

    

    Translates to 0.1 in (less than 3 mm) for Translates to 0.1 in (less than 3 mm) for 13 in pavement13 in pavement

    Metal TargetsMetal Targets 

    Size and Shape requirementSize and Shape requirement

    

    Metal TypeMetal Type 

    CostCost

  • Metal Target DiscsMetal Target Discs

  • Metal Target DiscsMetal Target Discs

    Target ID Maximum Depth, in

    AL RO 12 7.0 in

    AL RO 30 13.8 in

    ST RO 07 4.7 in

    ST RO 12 7.0 in

    ST RO 30 13.8 in

  • MCL Field Visit to Washington StateMCL Field Visit to Washington State

  • MCL Field Visit to Washington StateMCL Field Visit to Washington State

  • MCL Field Visit to Washington StateMCL Field Visit to Washington State

    Core Difference (in)

    Difference (mm)

    1 0.062 0.062 1.6

    2 0.0820.082 2.1

    3 0.0430.043 1.1

    4 0.047 0.047 1.2

    5 0.165 0.165 4.2

    6 0.0270.027 0.7

  • MCL Field Visit to ArizonaMCL Field Visit to Arizona MIT T2 Results AZ DOT Cores

    Test # Thickness, in Test # Thickness, in

    1 15.1 1 15.32

    2 15.0 2 15.11

    3 15.8 3 14.98

    4 15.7 4 15.8

    5 15.5 5 15.72

    Average 15.42 6 15.28 7 15.42

    8 15.63

    9 15.07

    10 15.39

    Average 15.37

  • FHWA Work with TargetsFHWA Work with Targets

    

    Measuring MechanismMeasuring Mechanism

  • Effect of NailsEffect of Nails

    No nails 3 Nails Halfway 3 NailsAll the way

    Difference, in 0.003 0.011 0.011

    1 Nail 2 Nails 3 Nails 4 Nails

    Difference, in 0.007 0.007 0.007 0.023

  • Target OptionsTarget Options

    

    ShapesShapes 

    Thickness Thickness

    

    OrientationOrientation

  • Typical Thickness SpecificationTypical Thickness Specification

    Lot – 2000 sq.yd – 1 core from each lot

    → one core every 1500 ft

    → 4 cores / lane mile

  • Typical Thickness SpecificationsTypical Thickness Specifications Payment Schedule

    Thickness Index Range English (Metric) Percent Payment

    0.00 or more (0.00 or more) 103

    -0.01 to -0.05 (-0.01 to -1.27) 102

    --0.06 to 0.06 to --0.10 (0.10 (--1.28 to 1.28 to --2.54)2.54) 101101

    -0.11 to -0.15 (-2.55 to -3.81) 100

    --0.16 to 0.16 to --0.20 (0.20 (--3.82 to 3.82 to --5.08)5.08) 9999

    -0.21 to -0.25 (-5.09 to -6.35) 98

  • Estimate for Coring/Depth CheckEstimate for Coring/Depth Check

    

    Contractor / DOT CostsContractor / DOT Costs →→

    TruckTruck →→

    Core drillCore drill →→

    Drill bitsDrill bits →→

    Staff time for the drillingStaff time for the drilling →→

    Staff time to deliver coresStaff time to deliver cores →→

    Staff time for patchingStaff time for patching

    

    DOT CostsDOT Costs →→

    Staff time to determine and mark core locationsStaff time to determine and mark core locations →→

    Staff to observe the drilling and take possession Staff to observe the drilling and take possession of the coresof the cores

    →→

    Staff time to make and record the measurementStaff time to make and record the measurement →→

    Staff time for the independent assuranceStaff time for the independent assurance

    $ 90 - 110 / Core

  • Estimate for using MIT Scan T2Estimate for using MIT Scan T2

    

    Contractor CostsContractor Costs →→

    Staff time for taking MIT Scan T2 Staff time for taking MIT Scan T2 measurementsmeasurements

    

    DOT CostsDOT Costs →→

    Staff time for placing TargetsStaff time for placing Targets →→

    Staff to observe taking MIT Scan T2 Staff to observe taking MIT Scan T2 measurementsmeasurements

    →→

    Staff time for the independent assuranceStaff time for the independent assurance

    →→

    Verification Core Verification Core –– 1 Core for every 10 Targets1 Core for every 10 Targets →→

    Target Cost Target Cost -- $2 $2

    -- 10 10 MinutesMinutes

    -- 10 10 MinutesMinutes

    -- 10 10 MinutesMinutes

  • Cost ComparisonCost Comparison

    

    Assume $30/hr laborAssume $30/hr labor labor $15labor $15 Target $2Target $2 Core $10Core $10 Total Total $27$27

    

    Per lane mile 4 cores requiredPer lane mile 4 cores required

    SavingsSavings

    $73 / location $73 / location OR OR

    $292 / lane mile$292 / lane mile

  • SummarySummary

    

    Easy to UseEasy to Use 

    NonNon--DestructiveDestructive

    

    ExpedientExpedient 

    Cost EffectiveCost Effective

  • ContactsContacts

    

    Interested in MIT Scan T2 Interested in MIT Scan T2 

    Contact either:Contact either: –– CPTP ProgramCPTP Program 

    Sam Tyson (202) 366 1326Sam Tyson (202) 366 1326 

    Shiraz Tayabji (410) 997 9020Shiraz Tayabji (410) 997 9020

    –– Mobile Concrete LaboratoryMobile Concrete Laboratory 

    Gary Crawford (202) 366Gary Crawford (202) 366--12861286 

    Jim Grove (202) 366Jim Grove (202) 366--66066606 

    Jagan Gudimettla (202) 366Jagan Gudimettla (202) 366--13351335

  • Questions ???Questions ???

  • �Nondestructive Pavement Thickness Measurement ��Jagan Gudimettla, P. E.� FHWA Mobile Concrete Laboratory� Presentation Outline MIT Scan-T2 MIT Scan-T2 Introduction / Background MIT Scan-T2 MIT Scan-T2 Slide Number 8 Metal Target Discs Metal Target Discs MCL Field Visit to Washington State MCL Field Visit to Washington State MCL Field Visit to Washington State MCL Field Visit to Arizona FHWA Work with Targets Effect of Nails Target Options Typical Thickness Specification Typical Thickness Specifications Estimate for Coring/Depth Check Estimate for using MIT Scan T2 Cost Comparison Summary Slide Number 24 Questions ??? Slide Number 26

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