Roadroid 1st international Workshop 13-14.2014, Bangkok, Thailand

Ground Penetrating Radar (GPR)Using GPR in Infrastructure Condition Analysis

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Introduction

Markku KnuutiMSc Civil Engineer

Helsinki, Finland

✤ Experience: Papua New-Guinea, Azerbaijan,

Bulgaria, Kazakhstan, Russia, Pakistan,

Malaysia, Iran, Estonia, Latvia, Finland, Sweden

and Austria

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GPR - General

✤ Non-destructive method for efficient

pavement surveys.

✤ Only method to collect continuous data of

layer thickness

✤ Fast method to localise any anomalies in

the road structure such as bad drainage

✤ Measurement can be done in traffic speed

✤ Interpretation of the data is the biggest

work and needs experienced experts to

analyse the data. ¾ of total work time

goes to this work.

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Theoretical

Background

✤ Based on Electromagnetic impulses

and its travel time in the different

materials

✤ Each material has its typical Er-value

✤ Er-value for pavement typically 6-7

✤ Er-value for gravel is 8-9

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Survey Unit

✤ Air Couple High Frequency + Low

Frequency Antennas

✤ GPR Control Unit

✤ GPS and Encoder

✤ Video-logging

✤ Roadroid for IRI and Inventories

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Network Level

Surveys

✤ Thickness of bitumen bound layers (needed in HDM-4)✤ Thickness of unbound base layer (needed in HDM-4)✤ Structural sections (cement stabilization sections)✤ Special Structures (Culverts)

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Project Level

Surveys

Layer thicknesses

FWD deflection

Emod-values

(back calculation)

SCI / BCI /Emod

Design

BC Results:

Red line – target levelOrange line – starting level

Blue line – after design

Targeted rehabilitation design - 20-30% savings in the costs!

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Basic Design:

50mm new pavement only

Before

After

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Targeted

Design with FWD and GPR

After

Before

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Quality Control

✤ Design thickness vs. results from the GPR

Pavement

Unbound Base

Sub-base

Filter layer (sand)

Pavement

Unbound Base

Sub-base

Filter layer (sand)

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Quality Control

✤ Air void content of a new pavement

✤ Pavement Thickness

✤ Moisture in the structure

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Road Condition

Monitoring

✤ Er-values indicates

the pavement

condition

✤ Higher values

indicates pavement

distresses

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Road Condition

Monitoring

✤ Poor condition

pavement has high

Er-values

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More

InformationMarkku Knuuti

FinnOC

markku.knuuti@finnoc.fi

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