TROXLER 3451 User Manual

Manual of Operation and Instruction

Model 3451

Enhanced

RoadReader™ Plus

Surface Moisture-Density Gauge

NOTE

The Model 3451 Enhanced RoadReader Plus is equipped with a
global positioning system (GPS) receiver. If the gauge is moved
a long distance between uses, the GPS system must be allowed
to initialize. In some instances, initialization may take as long as
30 to 45 minutes from the time the gauge is powered on with the
GPS enabled. Note also that the gauge must be positioned such
that the GPS receiver can receive signals from the GPS
satellites (see page 1–5 for more information). If the GPS does
not initialize within 45 minutes, contact your Troxler
representative.

Troxler Electronic Laboratories, Inc.

3008 Cornwallis Rd.  P.O. Box 12057

Research Triangle Park, NC 27709 U.S.A.

Phone: 1.877.TROXLER

Outside the USA: +1.919.549.8661

Fax: [phone]

www.troxlerlabs.com

Troxler gauges are protected by U.S. and foreign patents

Copyright  2004 – 2009

Troxler Electronic Laboratories, Inc.

All Rights Reserved

No part of this manual may be reproduced or transmitted in any
form or by any means, electronic or mechanical, including
photocopying, recording, or information storage and retrieval
systems, for any purpose without the express written permission of
Troxler Electronic Laboratories, Inc.

Bluetooth is a registered trademark of the Bluetooth Special Interest

Group (SIG).

Federal Express is a registered trademark of the Federal Express

Corporation.

Intermec is a registered trademark of Intermec Technologies Corp.
Magnalube-G is a registered trademark of Carleton-Stuart

Corporation.

Microsoft, Windows, Windows XP, Excel, and ActiveSync are

registered trademarks of Microsoft Corporation.

Pentium is a registered trademark of Intel Corporation.
RoadReader is a trademark of Troxler Electronic Laboratories, Inc.
WD-40 is a registered trademark of the WD-40 Company.

PN 110399
July 2009
Edition 3.1

ii

TROXLER SERVICE CENTERS

Troxler Corporate Headquarters

3008 Cornwallis Road

P.O. Box 12057

Research Triangle Park, NC 27709

Phone: 1.877.TROXLER (1.877.876.9537)

Outside the U.S.A.: +1.919.549.8661

Fax: [phone]

Web: www.troxlerlabs.com

Technical Support

Phone: 1.877.TROXLER (1.877.876.9537)

E-mail: [e-mail]

Florida Service Center

2376 Forsyth Road
Orlando, FL 32807
Fax: [phone]

Texas Service Center

2016 East Randol Mill Road

Arlington, TX 76011

Fax: [phone]

Illinois Service Center

1430 Brook Drive

Downers Grove, IL 60515

Fax: [phone]

Northern California Service Center

11300 Sanders Drive, Suite 7
Rancho Cordova, CA 95742

Fax: [phone]

Troxler European Subsidiary

Troxler Electronics GmbH

Gilchinger Strasse 33

D.82239 Alling nr. Munich, Germany

Phone: ++49.8141.71063

Fax: ++49.8141.80731

E-mail: [e-mail]

To locate an independent, Troxler-authorized service
partner near you, call 1.877.TROXLER
(1.877.876.9537).

Suite 406

NOTE

Model 3451 iii

HOW TO USE THIS MANUAL

Congratulations on the purchase of the Troxler Model 3451
Enhanced RoadReader Plus. Troxler continues the proven

technology of its 3400 Series surface moisture-density gauges with
the Troxler Model 3451 Enhanced RoadReader Plus.

The Model 3451 Manual of Operation and Instruction contains
information on safely using this gauge. Also included in this manual
are safety warnings, gauge setup, troubleshooting, and general
maintenance.

iv

CONVENTIONS USED IN THIS MANUAL

Throughout this manual, symbols and special formatting are used to
reveal the purpose of the text as follows:

WARNING

Indicates conditions or procedures that, if not followed
correctly, may cause personal injury.

CAUTION

Indicates conditions or procedures that, if not followed
correctly, may cause equipment damage.

NOTE

Indicates important information that must be read to
ensure proper operation.

Button Angle brackets and a different typestyle indicate a

button or character (number or letter) to press on
the handheld personal digital assistant (PDA) or on
the keyboard of a personal computer (PC) when
using the Data Manager software provided with the
gauge. For example, “Press Start” means to press
the button labeled Start.

Display A different typestyle is used in text to indicate

information or messages displayed on the PDA or
computer.

 Diamonds indicate a list of things needed (such as

equipment) or things to know.

 Check marks indicate the performance of an action.

With lists of check marks, follow the instructions in
the order of the check marks.

 Triangles indicate that more than one option is

available. Carefully select the option that applies.

Model 3451 v

NOTES

vi

TABLE OF CONTENTS

CHAPTER 1. INTRODUCTION TO THE MODEL 3451

Introduction................................................................................... 1–2

Global Positioning System Accuracy ........................................... 1–5

Gauge Parts and Accessories........................................................1–8

Unpacking and Inspection .......................................................... 1–11

CHAPTER 2. THEORY OF OPERATION

Density..........................................................................................2–2

Moisture........................................................................................ 2–3

Thin Layer .................................................................................... 2–5

Calibration .................................................................................... 2–6

CHAPTER 3. GETTING STARTED

Model 3451 Illustration ................................................................ 3–3

Source Rod Positions.................................................................... 3–5

Before Using the Gauge and PDA................................................ 3–6

Turning the Gauge and PDA On................................................... 3–8

Troxler Menu.............................................................................. 3–10

RoadReader Plus Main Menu..................................................... 3–16

Project Files................................................................................ 3–19

Status........................................................................................... 3–24

CHAPTER 4. USING THE GAUGE

Taking a Standard Count .............................................................. 4–2

Preparing a Test Site..................................................................... 4–7

Taking Measurements................................................................. 4–10

CHAPTER 5. SETUP AND TARGET MENUS

Gauge Setup Menu ....................................................................... 5–2

Target.......................................................................................... 5–14

Model 3451 vii

TABLE OF CONTENTS (Continued)

CHAPTER 6. ADJUSTING MEASUREMENTS

Calibration Offset..........................................................................6–2

Special Calibration......................................................................6–14

CHAPTER 7. USING DATA MANAGER

Introduction...................................................................................7–3

System Requirements....................................................................7–4

Starting the Data Manager Program..............................................7–5

Manage Project Data .....................................................................7–6

View Project Configuration.........................................................7–11

Recover Projects..........................................................................7–19

APPENDIX A. RADIATION THEORY AND SAFETY

Radiation Theory..........................................................................A–2

Radiation Safety...........................................................................A–5

Regulatory Requirements...........................................................A–14

Gauge Use Precautions...............................................................A–17

3451 Radiation Profile................................................................A–18

APPENDIX B. 3451 SPECIFICATIONS

Measurement Specifications.........................................................B–2

Radiological Specifications..........................................................B–5

Electrical Specifications............................................................... B–6

Mechanical Specifications............................................................ B–7

APPENDIX C. TROUBLESHOOTING AND SERVICE

Diagnostics Menu ......................................................................... C–2

Troubleshooting............................................................................C–9

Batteries...................................................................................... C–24

Replacing Fuse...........................................................................C–26

Mechanical Maintenance............................................................ C–27

Replacement Parts...................................................................... C–29

Returning the Gauge for Service................................................ C–32

viii

TABLE OF CONTENTS (Continued)

APPENDIX D. TRANSPORTATION AND SHIPPING

U.S. Shipping Requirements........................................................ D–2

Canadian Shipping Requirements................................................ D–5

APPENDIX E. STANDARD COUNT LOG

APPENDIX F. UNIT CONVERSION

Measurement Units.......................................................................F–2

Radiological Units ........................................................................ F–2

APPENDIX G. SPECIAL EUROPEAN CONSIDERATIONS

Declaration of Conformity........................................................... G–2

Safety Warnings........................................................................... G–3

INDEX

WARRANTY

Model 3451 ix

LIST OF FIGURES

Figure

1–1 Model 3451 Parts and Accessories............................1–9

2–1 Effect of Moisture on Depth of Measurement...........2–4

3–1 Model 3451 Illustration .............................................3–3

3–2 Back Panel Details.....................................................3–4

3–3 Source Rod Positions.................................................3–5

3–4 Troxler Menu...........................................................3–10

3–5 Notes Screen............................................................3–10

3–6 Calculator.................................................................3–11

3–7 Intermec Launcher Display......................................3–12

3–8 Windows Desktop....................................................3–12

3–9 Return to Troxler Menu...........................................3–13

3–10 Battery Status Display .............................................3–17

3–11 RoadReader Plus Software Main Menu...................3–18

3–12 Project Menu............................................................3–20

3–13 New Project Setup Wizard, Page 1..........................3–20

3–14 Project File Selector.................................................3–22

3–15 Project Data Display................................................3–22

3–16 Project Erase Prompt ...............................................3–23

3–17 Gauge Tools Menu...................................................3–24

3–18 Gauge Status Menu..................................................3–24

3–19 View Status Display.................................................3–25

3–20 View Constants Display...........................................3–25

3–21 Source Decay Menu.................................................3–27

3–22 GPS Location Display.............................................3–28

4–1 Standard Menu...........................................................4–2

4–2 Standard Count Position ............................................4–3

4–3 Standard Count Results..............................................4–5

4–4 View Standard Screen................................................4–6

4–5 Drill Rod Assembly...................................................4–8

4–6 Marking the Test Area...............................................4–8

4–7 Entering Project Notes.............................................4–12

4–8 Count Results, Soil Mode........................................4–13

4–9 Count Results, Asphalt Mode..................................4–16

4–10 Gauge Positioned Around a Core Site.....................4–18

Title Page

x

LIST OF FIGURES (Continued)

Figure

4–11 Gauge Positioned Over Designated Test Site..........4–19

4–12 Individual Count Results, Thin Layer Mode........... 4–20

4–13 Averaged Count Results, Thin Layer Mode............ 4–20

5–1 Change Settings Menu ..............................................5–2

5–2 Gauge Setup Menu....................................................5–2

5–3 View Setup Display................................................... 5–3

5–4 Set Units Menu.......................................................... 5–4

5–5 Mode Change Display...............................................5–6

5–6 Count Time Menu..................................................... 5–7

5–7 Enter Code Menu ...................................................... 5–8

5–8 Enter Customer Name Menu.....................................5–8

5–9 Change User Code Menu .......................................... 5–9

5–10 Depth Indicator Menu............................................. 5–10

5–11 Leak Test Menu.......................................................5–11

5–12 Leak Test Interval Menu......................................... 5–12

5–13 Leak Test Date Menu..............................................5–13

5–14 Target Menus ..........................................................5–15

5–15 Proctor Value Menu................................................ 5–15

5–16 Input Proctor Value Display.................................... 5–16

5–17 Proctor File Selector................................................ 5–17

6–1 Offset Menu .............................................................. 6–3

6–2 Wet Density Offset Select......................................... 6–4

6–3 Input Wet Density Offset .......................................... 6–4

6–4 Moisture Offset Select............................................... 6–5

6–5 Input True Percent Moisture .....................................6–7

6–6 Enter Moisture Offset File Name.............................. 6–7

6–7 Input Moisture Value from Gauge............................ 6–8

6–8 Input True Moisture .................................................. 6–8

6–9 Offset File Selector ................................................... 6–9

6–10 Moisture Offset Erase Prompt.................................6–11

6–11 Trench Offset Select................................................6–12

6–12 New Trench Offset Confirmation ........................... 6–13

6–13 Soil Special Calibration Menu................................ 6–15

6–14 Gauge Positioned Over Designated Test Site..........6–16

6–15 Input True Density ..................................................6–17

Title Page

Model 3451 xi

LIST OF FIGURES (Continued)

Figure

6–16 Enter File Name.......................................................6–17

6–17 Special File Selector................................................6–18

6–18 Special Calibration Erase Prompt............................6–18

6–19 Enter Rod Position...................................................6–19

6–20 Taking Measurements Around a Core Site..............6–20

6–21 Thin Lift Special Calibration Menu.........................6–21

6–22 Input Top Layer Thickness......................................6–22

6–23 Input True Density...................................................6–24

6–24 Thin Layer Special Calibration Results...................6–24

6–25 Enter File Name.......................................................6–24

6–26 Thin Lift File Selector..............................................6–25

6–27 Thin Lift Special Calibration Erase Prompt.............6–25

6–28 Input Number of Averages ......................................6–27

7–1 Data Manager Main Menu.........................................7–5

7–2 Manage a Project Menu.............................................7–6

7–3 Connect PDA to PC Prompt ......................................7–8

7–4 View a Project Display..............................................7–8

7–5 Project Data Spreadsheet .........................................7–10

7–6 Print Active Project Menu .......................................7–11

7–7 Gauge Constants Display.........................................7–13

7–8 Project Setup Display...............................................7–14

7–9 Standard Counts Display .........................................7–14

7–10 Project Status Display..............................................7–16

7–11 Source Decay Display..............................................7–16

7–12 Stat Test Display......................................................7–18

7–13 Drift Test Display....................................................7–18

7–14 Recover Project Menu.............................................7–19

7–15 Connect Gauge to PC Prompt..................................7–20

A–1 Diagram of an Atom.................................................A–2

A–2 Effect of Distance on Exposure ................................A–7

A–3 Cleaning the Sliding and Fixed Blocks...................A–12

A–4 Model 3451 Gauge and Transport Case..................A–18

Title Page

xii

LIST OF FIGURES (Continued)

Figure

C–1 Diagnostics Menu......................................................C–3

C–2 Stat Test Menu ..........................................................C–3

C–3 View Stat Co unts.......................................................C–4

C–4 Stat Test Results........................................................C–4

C–5 Review Stat Test .......................................................C–4

C–6 Drift Test Menu.........................................................C–6

C–7 View Drift Counts.....................................................C–7

C–8 Drift Test Results ......................................................C–7

C–9 Review Drift Test......................................................C–7

C–10 Replacing NiMH Battery Pack or Fuse...................C–25

D–1 Type A Package Testing Results.............................. D–4

Title Page

Model 3451 xiii

LIST OF TABLES

Title Page

Table

1–1 GPS Position Accuracy..............................................1–7

A–1 Radiation Profile for Model 3451 Gauge................A–19

xiv

ATTENTION 3451 GAUGE OWNER

This unit contains functions that require an ACCESS CODE.
This code must be entered before these functions may be used.

The ACCESS CODE for this gauge is:

4012

This page should be removed if the access code is not to be
distributed to other parties or users of this gauge.

Model 3451 xv

NOTES

xvi

CHAPTER 1

INTRODUCTION TO THE MODEL 3451

This chapter provides a brief overview of the Troxler Model 3451
Enhanced RoadReader Plus, as well as an explanation of the
global positioning system (GPS). This chapter also includes a list of
the gauge parts and accessories, and instructions for unpacking and
inspecting the gauge.

CONTENTS

Introduction................................................................................... 1–2

Global Positioning System Accuracy ........................................... 1–5

Gauge Parts and Accessories........................................................ 1–8

Unpacking and Inspection .......................................................... 1–11

1. INTRODUCTION

Model 3451 1–1

INTRODUCTION

Troxler’s Model 3451 Enhanced RoadReader Plus combines the
impressive features of the Model 3450 RoadReader Plus with
advanced global positioning system (GPS) and wireless
technologies to provide unparalleled performance, flexibility, ease
of use, and operator safety.

Like the 3450 gauge, the Model 3451 incorporates the proven
capabilities of Troxler’s 3400 (moisture/density) and 4640 (thin­layer density) gauges in a single unit that can perform thin-layer,
backscatter, direct transmission, and moisture measurements. In
addition to the features found in the 3450 gauge:

 The Model 3451 is controlled using a handheld personal digital

assistant (PDA), which allows the operator to stand away from

the gauge while operating it via Bluetooth wireless
communications.

 An onboard GPS receiver enables the Model 3451 to store

precise GPS coordinates, along with the standard date and time
stamp, for each measurement.

 The Data Manager PDA to PC Model 3451 for Windows XP

software included with the gauge enables the operator to collect
project data from the PDA or gauge on a personal computer
(PC), print project configuration information, and recover data
from the gauge in case of an emergency (such as the loss of the
PDA).

With the Model 3451, the operator can quickly and precisely
measure the moisture content and density of construction materials.
The gauge’s features include:

 Three measurement modes (soil, asphalt, and thin layer) for

precise compaction control readings in most construction
materials:

Soil Mode: For moisture/density determinations in soil, soil-

stone materials in layers of 4 inches or greater.

Asphalt Mode: For density determinations in asphalt or

hardened concrete layers of 4 inches or greater.

Thin Layer Mode: For density determinations in asphalt layers

of less than 4 inches.

1–2

 Calibration offsets (wet density, moisture, and trench) and

special calibrations (soil and thin layer) to expand measurement
possibilities, and to enhance gauge readings on materials that
may fall outside the range of factory calibration.

 Over 30 functions to facilitate all phases of testing compaction

on construction materials.

 To preserve battery life, the gauge shuts down automatically

after five hours of inactivity.

The Model 3451 meets or exceeds all applicable American Society
of Testing and Materials (ASTM) standards (or corresponding
equivalent), including:

 ASTM D-2950: Standard Test Method for Density of

Bituminous Concrete in Place by Nuclear Method.

 ASTM D-6938: Standard Test Methods for In-Place Density

and Water Content of Soil and Soil-Aggregate by Nuclear
Methods (Shallow Depth)

NOTE

As of November 2006, ASTM D-6938 replaced ASTM
D-2922: Standard Test Methods for Density of Soil and
Soil-Aggregate in Place by Nuclear Methods (Shallow
Depth) and ASTM D-3017: Standard Test Method for
Water Content of Soil and Rock in Place by Nuclear
Methods (Shallow Depth).

Any licensing issues discussed in this manual are for the United
States. To purchase a Model 3451 in Canada, owners must obtain a
radioisotope license from the Canadian Nuclear Safety Commission
(CNSC). The owner should obtain copies of the AECB Regulations
and the Transportation of Dangerous Goods Act and Regulations
(TDG). For other countries, please consult your local regulatory
agency.

1. INTRODUCTION

Model 3451 1–3

Owners are encouraged to require study of this manual before
allowing anyone to use the gauge. A potential hazard does exist if
improperly used. Appendices A and D, which cover radiological
safety, should be required reading for all users and potential users.

If these appendices are not completely understood, users should
seek assistance from Troxler, an appointed Troxler
representative, or others designated within the user's
organization.

Additional radiation safety information is available by attending a
Troxler Nuclear Gauge Training Course.

Before operating the Model 3451 gauge, users in European
countries must refer to Appendix G for special considerations,
additional safety warnings, and the Declaration of Conformity.

Since changes are made to local, state, and federal regulations on a
continuing basis, the owner/operator must maintain awareness of
current requirements. The responsibility for compliance ultimately
falls on the owner. An owner in the United States may also wish to
purchase and subscribe to Titles 10 and 49 of the Code of Federal
Regulations (CFR) in addition to applicable local/state regulations.

1–4

GLOBAL POSITIONING SYSTEM ACCURACY

As described earlier, the Model 3451 is equipped with a global
positioning system (GPS) receiver that provides accurate

information on the location (latitude and longitude) of the gauge.
This information is stored with each gauge measurement. The GPS
receiver used in the Model 3451 has Wide Area Augmentation
System (WAAS) capabilities, which provides accuracy to within 3 m
(10 ft). However, the accuracy is dependent upon the user’s location
and other factors as described below.

The global positioning system (GPS) is a satellite-based navigation
system that consists of 24 satellites and a network of ground stations
that monitor and control those satellites. The satellites orbit the earth
at an altitude of approximately 11,000 miles, and constantly
transmit signal information back to earth. A GPS receiver uses this
information to determine its location.

To determine its latitude and longitude, a GPS receiver must receive
the signals from at least three satellites.

On average, the receiver used in the Model 3451 gauge is accurate
to with 15 m (approximately 50 ft) when receiving GPS data alone.
However, the WAAS capabilities can increase the accuracy to
within 3 m (10 ft), as shown in Table 1–1.

The accuracy of GPS information can be affected by a number of
atmospheric forces and other conditions. The Wide Area
Augmentation System (WAAS) corrects for these factors by placing
GPS receivers at 25 known, precisely surveyed locations, called
reference stations, across the United States. The reference stations
determined a measured distance to each satellite using the signals
received from the satellites. For each satellite, the stations compare
the measured distance to the actual range (as calculated from its
known position) to determine a differential correction for each
satellite

1. INTRODUCTION

Model 3451 1–5

Two master stations, located on either coast, collect data from the
reference stations to create a GPS correction message. This message
is then broadcast through two geostationary satellites that are in a
fixed position over the equator. The GPS receiver applies the
correction factors contained in the correction message to increase
the accuracy of its measurements.

Note that the signals from the WAAS satellites may not be available
to gauge users in locations where trees, mountains, and other large
objects obstruct the view of the horizon. On other occasions, the
GPS receiver may not be able to access the signals from the three
satellites required to determine a position. As noted earlier, the
gauge stores location information with the results of each
measurement. The measurement display also denotes the quality of
the location fix as follows:

 If WAAS information is available during a gauge measurement,

the fix quality for that measurement will be denoted as DGPS
fix.

 If a GPS location is determined, but the WAAS information is

unavailable, the fix quality will be denoted as GPS fix.

 If the GPS receiver cannot determine a location, the latitude and

longitude will be denoted as 0.

NOTE

The Wide Area Augmentation System (WAAS) is
currently functional only in the United States.

NOTE

If the gauge is moved a long distance between uses, the
GPS system must be allowed to initialize. In some
instances, initialization may take as long as 30 to 45
minutes from the time the gauge is powered on with the
GPS enabled. Note also that the gauge must be
positioned such that the GPS receiver can receive signals
from the GPS satellites as described above. If the GPS
does not initialize within 45 minutes, contact your
Troxler representative.

1–6

Table 1–1. GPS Position Accuracy

Quality of
GPS Data

1. INTRODUCTION

Accuracy Fix Quality

GPS reading
with WAAS

GPS reading
without WAAS

No GPS reading N/A

Within 3 m
(10 ft)

Within 15 m
(50 ft)

DGPS fix

GPS fix
Latitude and longitude

displayed as 0.

Model 3451 1–7

GAUGE PARTS AND ACCESSORIES

Figure 1–1 shows the gauge and its accessories.

1. The Gauge is the portable instrument containing electronic

modules, a cordless serial adapter with Bluetooth wireless
technology, a rechargeable battery pack, detectors, and the
radioactive sources.

2. The Intermec

provides the operator interface with the gauge. Included with
the PDA are a stylus, a rechargeable battery pack, a serial cable,
a dc adapter used to charge the PDA from an automobile
cigarette lighter, a universal ac adapter and ac power cord used
to charge the PDA from an ac outlet, a Quick Start Guide, and a
Pocket PC Companion CD containing Microsoft ActiveSync
software.

3. The Transport Case for the Model 3451 is a Type A package.

Always use a Type A package to ship the Model 3451.

4. The Reference Standard Block provides a measurement

standard for standard counts. It is also used during stability and
drift tests.

5. The Scraper Plate/Drill Rod Guide is used to prepare the test

site and to guide the drill rod when preparing the source rod
hole for direct transmission measurements.

6. The Drill Rod is used to drill holes for direct transmission

measurements. Do not use the gauge source rod to drill holes.

7. The Extraction Tool provides leverage to remove the drill rod

from soil materials.

8. The Model 3451 Manual of Operation and Instruction details

how to use the gauge. Both the manual and the Transportation
Guide discuss radiation safety and gauge shipping concerns.

9. The AC Charger and DC Adapter are used to charge the gauge

batteries. The ac charger accepts 110 (220 and European
optional) V ac, 50/60 Hz and supplies 12 V dc. The dc adapter
allows recharging from an automobile cigarette lighter.

10. The Data Manager PDA to PC Model 3451 for Windows XP

software includes tools for retrieving and managing project data
from the PDA or gauge. This software is provided on CD-ROM
(not shown).



700 Series Color Mobile Computer, or PDA,

1–8

1. INTRODUCTION

MODEL 3451 GAUGE

TRANSPORT CASE

PN 110422.3451

REFERENCE STANDARD BLOCK

PN 107830

DRILL ROD

PN 100421

EXTRACTION TOOL

PN 103680.1000

SERIAL CABLE,

PN 110708

(GAUGE TO PC)

SCRAPER PLATE/
DRILL ROD GUIDE

PN 107795

Note: Images not to scale.

Figure 1–1. Model 3451 Parts and Accessories

Model 3451 1–9

AC CHARGER

PN 110403

(FOR GAUGE)

INTERMEC 700 SERIES

MOBILE COMPUTER (PDA)

PN 110687

DC (AUTO) ADAPTER

UNIVERSAL AC ADAPTER

PN 104156

(FOR GAUGE)

PN 110691

&

AC POWER CORD

PN 110690
(FOR PDA)

DC (AUTO) ADAPTER

PN 110692
(FOR PDA)

SERIAL CABLE ASSEMBLY

PN 110693

(PDA to PC)

Note: Images not to scale.

Figure 1–1. Model 3451 Parts and Accessories (Continued)

1–10

UNPACKING AND INSPECTION

Troxler recommends that the operator wear a dosimeter while
working with the gauge. Upon receipt of the gauge from the factory,
perform a complete inspection and inventory. If the shipping case
and/or any other part or accessory appears damaged, notify the
carrier and your Troxler Representative immediately.

Check the shipping cases for the items listed on page 1–8. In
addition, the shipping cases should contain the Gauge Warranty and
a Source Certificate.

For shipping to another location or back to the factory, save the
boxes and any packing material. For shipping instructions and
regulations, please see Appendix D.

NOTE

Charge the 3451 batteries for 2.5 hours prior to initial
use. Install the PDA battery pack and charge the PDA as
directed in the Quick Start Guide provided with the unit.

NOTE

If the PDA battery pack is completely discharged when
the gauge and accessories are unpacked, charge the PDA
for 4 hours before use. Refer to the Quick Start Guide
provided with the unit for instructions on installing and
charging the battery pack.

Lift the gauge from the transport case and inspect the outside
surface for damage. Check the lock on the source rod handle and
make sure the keys fit. Remove the lock, release the trigger, and
check the source rod operation. It should move up and down with
little effort. Return the gauge to the transport case.

1. INTRODUCTION

Model 3451 1–11

NOTES

1–12

CHAPTER 2

THEORY OF OPERATION

This chapter provides a brief description of the theory of operation
of the Troxler Model 3451 Enhanced RoadReader Plus. The direct
transmission and backscatter modes of operation are illustrated,
along with an explanation of the cesium-137 source,
americium-241:beryllium source, and detector geometry.

CONTENTS

Density.......................................................................................... 2–2

Moisture........................................................................................ 2–3

Thin Layer .................................................................................... 2–5

Calibration .................................................................................... 2–6

Offsets .................................................................................... 2–6

2. THEORY OF OPERATION

Model 3451 2–1

DENSITY

The Troxler Model 3451 Enhanced RoadReader Plus uses two
modes of operation: direct transmission mode (with the source rod
extended into the material to be measured) and backscatter mode
(with the source rod in the backscatter position). Source rod
positions are described in Chapter 3.

Direct transmission mode is used on materials with layers four
inches thick or more. This mode is most commonly used on soils,
but can also be used to measure asphalt and concrete. In the direct
transmission position, the source rod extends through the base of the
gauge into a pre-drilled hole to a desired depth. Photons from the
cesium-137 (Cs-137) source in the source rod pass through the test
material. While passing through the test material, the photons
collide with electrons and lose energy. A high material density
increases the probability of these photon collisions. This decreases
the number of photons that reach the Geiger-Mueller (G-M)
detectors in the base of the gauge. Thus, the number of photons
reaching the detectors is inversely related to the density of the
material: the higher the density of the material, the fewer the
photons that reach the detectors. Using the gauge calibration, the
gauge software converts the G-M detector counts to a density value.

Backscatter mode is used on concrete, asphalt, and soil layers
approximately four inches thick. In the backscatter position, the
source rod is lowered to the first notch below the SAFE (shielded)
position. This places the source and the detectors in the same plane.
Shielding between the source and detectors greatly reduces the
number of photons reaching the detectors in a direct path from the
source. Thus, the photons from the Cs-137 source must travel into
the test material and scatter (or reflect) at least once to reach the
G-M detectors. The detectors in the gauge base count these scattered
photons. For thin layer readings, the gauge uses two sets of G-M
detectors. Refer to the Thin Layer section on page 2–5.

2–2