Assessment of Non-Destructive Testing Technologies for QC/QA of Asphalt Mixtures

TR-653

PI: Jeramy Ashlock (ISU)PhD Research Assistant: Shibin Lin

Co-PIs: R. Christopher Williams (ISU), Hosin (David) Lee (UI)TAC: Scott Schram, Jeff Schmitt, Jason Omundson

Department of Civil, Construction, and Environmental Engineering

IOWA STATE UNIVERSITY

Project Goals

1. Assess accuracy, suitability of several NDE technologies for QC/QA of asphalt pavement

2. Perform preliminary study on QC/QA and subsequent health monitoring of asphalt pavements using embedded MEMS sensors

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OutlineI. Equipment and Methods

1) PaveTracker: Dielectric constant → Density2) GeoGauge: Mechanical impedance, force/deflection → Stiffness3) Surface wave test: Seismic wave speed → G=ρVs

2 , E=2(1+ν)GDispersion properties → Layer thickness & modulus

(if inversion analysis performed)

4) MEMS Sensor → moisture & temperatureII. Paving project test locationsIII. Results

1) Field: density, stiffness, wave speed (modulus)2) Lab: density, dynamic modulus3) Correlations

IV. Conclusions3/32

GeoGauge(Humboldt)

Equipment

PaveTracker(Troxler)

Custom-built surface wave testing equipment (Lin & Ashlock)

MASW

MSOR

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Surface Wave Test Methods

Multichannel Analysis of Surface Waves (MASW)

Multichannel Simulation with One Receiver(MSOR)

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Data acquisition and analysis system programmed in MATLAB

SWM Data Acquisition/Analysis Program

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MEMS Sensor

MEMS-based, RFID wireless, passive (battery-less), moisture & temperature sensor from Phase IV Engineering.

Installed on one paving project to test survivability & readability through asphalt for QC/QA and long-term performance monitoring.

Currently working with Phase IV on wireless MEMS strain sensors for concrete, asphalt.

Photo: Simon LaFlamme, ISU

http://www.phaseivengr.com/

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Field Tests: Pavetracker, Geogauge, SWM, Cores

MSOR

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Lab Tests: Density by SSD and Corelok

MSOR

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Lab Tests: Dynamic Modulus by IDT

MSOR

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Paving project test locations

1. Boone: Central Iowa Expo project (HMA and WMA)

2. Story/Hamilton: US 69 S. of Co. Rd. E-18 to S. jct. IA 175 (HMA)

3. Fayette: IA 93 from Sumner to IA 150 (FDR, CIP, OL)

4. Dallas: US 169 fr. Raccoon Mill Race to N. Raccoon River (HMA)

5. Johnson: US 6 fr. S. jct. IA 1 to Lakeside Dr. (HMA, WMA w/RAP)

6. Stanhope: IA 17 (MEMS sensor)

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Field Tests and Cores

Project Location # Tests

Boone Central Iowa Expo (HMA, WMA)

Base 35

Surface 16

US 69 (HMA) Surface 9

I 93 (FDR, CIP, OL) Surface 2, 2, 2

US 169 (HMA) Surface 6

US 6 (HMA, WMA w/RAP) Surface 6, 4

Total: 82

SWM

PaveTracker GeoGauge

Core

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Results: SWM wave speedSWM testing of base Core HB1-1 in Boone

HOT COLD (ambient)

•Rayleigh wave velocities increase significantly as asphalt pavement cools 13/32

Results: Average in situ modulus E

0.0E+00

5.0E+03

1.0E+04

1.5E+04

2.0E+04

Aver

age

E (M

Pa)

•Modulus decreases as traffic volume decreases. 14/32

Results: Indirect tension (IDT) modulus E (Master curve)

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Correction of Field Modulus to Reference Temperature

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Correction of Field Modulus to Reference Temperature

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Results: Corrected IDT modulus

•Modulus decreases as traffic volume decreases.•HMA has slightly higher modulus than WMA.•After correcting field moduli to common reference temperature: excellent agreement with rank of master curves 18/32

Results: GeoGauge stiffness

•Stiffness increases as temperature decreases.

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Results: GeoGauge stiffness

0

10

20

30

40

50

60

70

80

US 6-HMA US 6-WMA IA 93-OL US 69-HMA Boone-HMAsurface

Boone-WMAsurface

IA 93-CIP IA 93-FDR

Stiff

ness

(MN

/m)

0102030405060708090

100

Stiff

ness

(MN

/m)

HOT

COLD &AMBIENT

•GeoGauge HOT stiffness is more consistent with traffic volume. 20/32

Results: PaveTracker density19 HMA and 16 WMA base cores (4”) from Boone

•Hot = 1 to 3 hours after paving, Cold = next day (same locations)•Increase in scatter and slight decrease in avg. density overnight 21/32

Results: Correlation of PT and CoreLok densities

•Low correlation between field PT and lab Corelok density22/32

Results: Comparison of PT and CoreLok average densities

1800

2000

2200

2400

2600

2800Av

erag

e ho

t den

sity

(kg/

m3)

180020002200240026002800

Aver

age

dens

ity (k

g/m

3)PT

CoreLok

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Results: Correlation of Vs and PT/CL densities

•SWM velocity correlates poorly with PT density, well with CoreLok density24/32

In situ modulus from SWM Vs and PT density

•PT density is adequate for using with SWM Vs for NDE of in situ modulus 25/32

Results: Correlation of SWM modulus and GG stiffness

•SWM modulus correlates reasonably with HOT GeoGaugestiffness, but not with cold GG stiffness 26/32

Results: Correlation of GG stiffness and PT/CL densities

•Hot GG stiffness better than cold, but poor correlations

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Quick NDT Quality Control Procedure

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NDT Quality Assurance Procedure

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Mod

ulus

Frequency

T1

T2

T3

TF

In-situmodulusCorrectedmodulus

In-situ modulus ETF

Corrected modulus

Reduced frequency, fr

Emax

Proposed QA rating system

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Proposed quality ratings based on SWM modulus ratios.

EC21/Emax (%) >80% 60−80% 40−60% 20−40% <20% Quality rating Very high High Moderate Low Very low

QC/QA assessment for six pavement test sections in this study.

Project/ Pavement

Type

QC QA EC21QC

(MPa) EC21QC / Emax

(%) Quality rating EC21QA

(MPa) EC21QA / Emax

(%) Quality rating

US 6 HMA 20,684 94.5% Very high 19,546 89.3% Very high US 6 WMA 19,079 99.6% Very high 18,585 97.0% Very high Boone HMA 13,164 49.3% Moderate 15,021 56.2% Moderate Boone WMA 14,641 74.9% High 14,015 71.7% High

US 69 6,278 34.9% Low 6,272 34.9% Low IA 93 OL 6,210 30.2% Low 6,079 29.6% Low

Preliminary Study on Embedded MEMS-based Sensors for QC/QA

•One sensor configuration survived paving and was successfully read through 2” of ACC•Wireless, battery-less, RFID•Currently working with Phase IV on strain gauges

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Conclusions and Recommendations1. PT density had low correlation with laboratory density.2. In situ density not very sensitive to temperature variation, whereas SWM shear-

wave velocity is very sensitive to temperature.3. GeoGauge stiffness measured on hot asphalt mixtures several hours after

paving has good correlation with in situ dynamic modulus and laboratory density, is recommended for QC.

4. Accurate and objective QC/QA procedure developed, based on dynamic modulus from measured shear-wave velocity and density by efficient and economical NDT methods (SWM and electromagnetic density gauges).

5. For implementation of the QA procedure: recommended to develop master-curve database of as-built pavements using IDT dynamic modulus tests.

6. Periodic SWM+PT and/or GG tests recommended for health monitoring (compare to benchmark tests on given pavement).

7. Further development of strain gauges in collaboration with Phase IV Engineering is recommended for MEMS-based QA and health monitoring.

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Questions and comments?

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What do surface waves look like?

(from Braile, 2004)

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Surface wave tests on pavements vs. soils• Make use of dispersive nature of Rayleigh waves, by

which different frequency components of a disturbance travel at different phase velocities

Lower frequencies involve motion at greater depths, so they measure velocity & modulus of deeper layers.

Phas

e Ve

loci

ty

Frequency

Dispersion curve Layer thickness and stiffness

1. Soil stiffness (modulus) generally increases with depth, so velocity increases as frequency decreases: “Normally dispersive”

2. Pavement stiffness decreases with depth, so velocity increases as frequency increases: “Inversely dispersive”

Soil

Pavement

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4. Profiles after inversion3. Inversion: mimizingmisfit between theoretical & experimental curves by optimization methods

2. Modeling: calculate theoretical dispersion curves for assumed soil profiles

1. Testing

Frequency

Phas

e Ve

loci

ty

Experimentaldispersion curve

Frequency

Phas

e Ve

loci

ty

h1, VS1

h2, VS2

h3, VS3

Tim

e

Receiver

Frequency

Phas

e Ve

loci

ty

Theoreticaldispersion curve (Matrix methods)

h1, VS1

:hn, VSn

Surface wave testing & analysis procedure

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