DEVELOPMENT OF A PROCEDURE FOR THE AUTOMATED COLLECTION OF FLEXIBLE PAVEMENT LAYER THICKNESSES AND MATERIALS:

PHASE IIA - EXECUTIVE SUMMARY REPORT

FLORIDA DOT STATE PROJECT 99700-7550

report prepared by:

EMMANUEL G. FERNANDO, PhD., P.E. Texas Transportation Institute

Texas A&M University College Station, Texas

and

KENNETH R. MASER, PhD., P.E. INFRASENSE, Incorporated Cambridge, Massachusetts

September 1993

ABSTRACT

The overall objective of this project is to develop, test, and implement a ground penetrating radar system to supply accurate pavement layer data for the pavement management activities of the Florida DOT. The project has been divided into different phases that successively demonstrate, develop, pilot test, and implement radar technology for Florida pavement conditions.

The subject of the present report is the Phase I demonstration of the potential of current GPR technology to estimate pavement layer thicknesses and classify base material type. This demonstration consisted of a sequence of research activities that included the following:

1. selection of test sites for radar thickness evaluation;

2. radar survey of test sites established;

3. blind predictions of layer thickness and base material type made solely on the basis of interpretation and analysis of raw radar data, and visual observation of surface characteristics of test sites selected by the Florida DOT;

4. collection of ground truth information to verify the radar predictions;

5. re-interpretation of radar traces to improve accuracy of thickness predictions using ground truth information; and

6. adjustment of radar predictions by calibrating to a single core.

The sites selected covered a variety of Florida pavement materials, with asphalt layers that consisted of multiple lifts. Analysis of the radar measurements made on these sites were divided into 3 different types (blind, adjusted, and calibrated) to assess the accuracy of the radar predictions against the availability of reliable, supporting information. Data collected from ground truth surveys were used to evaluate the accuracy of the radar predictions.

The findings from the study demonstrate that existing radar technology can be used with success to predict layer thicknesses and identify base material type. Implementation of this technology for these purposes on a network wide scale is feasible, and will require adaptation of current analy­sis procedures to handle Florida pavement materials. This will require evalu­ation of a variety of Florida pavements to develop guidelines for interpreting and analyzing radar data.

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DISCLAIMER

The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Federal Highway Administration or the Florida Department of Transportation. This report does not constitute a standard, specification, or regulation.

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ACKNOWLEDGEMENTS

This report presents the results of Phase I of a 3-phase study sponsored by the Florida Department of Transportation, to demonstrate, develop, pilot test and implement radar technology for estimating pavement layer thicknesses and classifying base material type. The guidance and support of the Florida DOT Project Manager, Mr. Bruce Dietrich, is gratefully acknowledged. We would also like to extend our appreciation to the District 3 Materials Office whose personnel did the coring work for the ground truth surveys conducted herein, and would like to specifically acknowledge Messrs. James Best and Troy Clark for their valuable support. The cooperation and support of the Tallahassee Maintenance Office under the direction of Mr. Mike Roddenberry is also acknowledged.

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TABLE OF CONTENTS

PAGE

ABSTRACT . ii

DISCLAIMER iii

ACKNOWLEDGEMENTS iv

EXECUTIVE SUMMARY 1

CHAPTER 1. INTRODUCTION 3

CHAPTER 2. DESCRIPTION OF RADAR SURVEYS 6

CHAPTER 3. COLLECTION OF GROUND TRUTH INFORMATION 11

CHAPTER 4. RADAR DATA ANALYSIS. . . . . . . . . . 29

CHAPTER 5. COMPARISON OF RADAR PREDICTIONS WITH GROUND TRUTH DATA 47

CHAPTER 6. ASSESSMENT OF RADAR PREDICTIONS 58

CHAPTER 7. CONCLUSIONS 62

REFERENCES

APPENDIX A - TABLES OF THICKNESS DATA FROM GROUND TRUTH SURVEYS

APPENDIX B - BLIND PREDICTIONS OF LAYER THICKNESS PROFILES OF FLORIDA TEST SITES .............. .

APPENDIX C - TABLES OF PREDICTED AND MEASURED THICKNESSES AT INDIVIDUAL CORE LOCATIONS . . . . . . . . . . .

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EXECUTIVE SUMMARY

The overall objective of this project is to develop, test, and implement a ground penetrating radar system to supply accurate pavement layer data for the pavement management activities of the Florida DOT. The project has been divided into different phases that successively demonstrate, develop, pilot test, and implement radar technology for Florida pavement conditions.

The subject of the present report is the Phase I demonstration of the potential of current GPR technology to estimate pavement layer thicknesses and classify base material type. This demonstration consisted of a sequence of research activities that included the following:

1. selection of test sites for radar thickness evaluation;

2. radar survey of test sites established;

3. blind predictions of layer thjckness and base material type made solely on the basis of interpretation and analysis of raw radar data, and visual observation of surface characteristics of test sites selected by the Florida DOT;

4. collection of ground truth information to verify the radar predictions;

5. re-interpretation of radar traces to improve accuracy of thickness predictions using ground truth information; and

6. adjustment of radar predictions by calibrating to a single core.

The sites selected covered a variety of Florida pavement materials, with asphalt layers that consisted of multiple lifts. Analysis of the radar measurements made on these sites were divided into 3 different types (blind, adjusted, and calibrated) to assess the accuracy of the radar predictions against the availability of reliable, supporting information. Results from comparisons of the radar predictions with corresponding ground truth informa­tion are summarized as follows:

1. On average, the means of the blind predictions for asphalt thickness deviated from the corresponding measured means by 0.5 inches. On 3 of the 5 sites considered for demonstration of radar's capability to predict layer thicknesses, the means of the blind predictions for asphalt thickness were within 0.1 inch or 2 percent of the corresponding measured means. The largest discrepancies were obtained in Site 4 where a sand asphalt hot mix (SAHM) layer was observed from the field survey. The reflections from this layer were highly variable due perhaps to local moisture infiltration associated with the relatively high air voids content of this material. Once this condition was recognized and correctly accounted for in the analysis, the discrepancies were reduced to within 10 percent of the measured means. This result reflects the potential improvement in prediction capability that may be obtained as knowledge and experience with Florida pavement materials are accumulated and the analysis software is adapted for these materials. It also

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indicates the potential improvement in accuracy that is possible when supporting information are available for interpreting the radar measurements. This information need not necessarily come from cores.

2. For sites where predictions of base layer thickness were made, the means of the predicted thicknesses were found, on the average, to be within 0.9 inches of the measured means. In one site (Site 6), the mean of the blind predictions was equal to the measured mean. The largest discrepancy between means (2.1 inches, or 23 percent of the measured mean) was obtained for Site 1. This discrepancy was reduced to 1 inch (11 percent of the measured mean) when the layering within the asphalt was correctly accounted for in the analysis. In all cases, the differences between predicted and measured means for base thickness were reduced to within 0.5 inches after calibration.

3. The base material was correctly classified for 4 of the 6 test sites, or for 8 of the 14 classifications that were made (1 in each of Sites 1, 2, 3, and 6; 2 in Site 4; and 8 in Site 5 which had numerous changes in pavement section over a 1.5 mile length). The presence of a concrete base was found to be indi~ated by the appearance of regularly spaced peaks in the dielectric profile of the asphalt layer, attributed to moisture infiltration through transverse cracks on the surface, and by the absence of a clear reflection from the bottom of the concrete base due to the lossy characteristic of this material. On the other hand, the presence of a sand asphalt base was found to be indicated by the variability in the reflections from the base, and by negative and positive reflections at the top and bottom of the layer respectively. These results again show the benefit of knowing certain characteristics of a given material that would leave specific signatures in the radar data which may be used for identification. The task at hand is to establish a data base of base material types and associated radar signatures which may be used to reliably discriminate between limerock, concrete, and "other" base material types.

4. In general, the section changes in Site 5 were successfully detected from the radar measurements. Only 1 section in Site 5 (Section 4) was erroneously identified as being different from the adjacent sections. This was again attributed to the presence of a SAHM base layer which was associated with highly variable reflections in the radar data. This result again shows the benefit of knowing something about a given material that may be used for radar data interpretation.

In summary, the findings from the study demonstrate that existing radar technology can be used with success to predict layer thicknesses and identify base material type. Implementation of this technology for these purposes on a network wide scale is feasible, and will require adaptation of current analy­sis procedures to handle Florida pavement materials. This will require evalu­ation of a variety of Florida pavements to develop guidelines for interpreting and analyzing radar data.

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CHAPTER 1. INTRODUCTION

Knowledge of asphaltic pavement layer thickness and properties is important in many areas of pavement management. Accurate thickness data is needed throughout the roadway network to improve pavement performance predictions, to establish structural load carrying capacities, and to develop maintenance and rehabilitation priorities. On a project level, accurate knowledge of pavement thickness is required for overlay design and to interpret the results of structural tests, such as Dynaflect and FWD. For new construction, it is important to assure that the thickness of materials being placed by the contractor is close to specification.

Layer thicknesses may be determined from historical records. However, records are often highly inaccurate or nonexistent. The only presently acceptable methods for pavement thickness measurements are through core samples and test pits. These are time consuming, destructive to the pavement system, dangerous to field employees, and intrusive to traffic.

Ground penetrating radar is a non-contact technique which has the potential for surveying pavement thickness while operating at highway speed. Until recently the radar data required qualitative interpretation and these techniques were not well established or understood. But, recent research has now automated data interpretation and allowed verification.

The present study evaluates the applicability of current ground penetrating radar (GPR) technology to estimate pavement layer thicknesses and classify base material type for the pavement management program of the Florida Department of Transportation (FDOT).

PREVIOUS RADAR APPLICATIONS

Ground penetrating radar equipment has been available for the past 15 years. The initial applications of this equipment were to geological and geotechnical investigations. In these applications, the radar data is collected by dragging an antenna along the ground surface. The resulting radar data is displayed graphically and interpreted manually by someone with expertise in radar data interpretation.

The application of radar to pavement evaluation is more recent. This capability has been suggested in a number of research experimental studies (1,2) and specifically suggested as a means for improvement of FWD backcalculations (3). In fact, an ASTM specification exists (4) for the measurement of pavement thickness with radar. In these applications r however, the radar technology used was identical to that developed for geotechnical purposes.

Recently, systematic investigations have been carried out in Texas and Kansas which compared predicted to actual thickness for a range of conditions. The radar technology used in these investigations was very different from the original geotechnical approach. The equipment used was a non-contact horn

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antenna suspended from a moving vehicle. Data interpretation was automated using software based on an electromagnetic model of the pavement layer structure that is used to obtain quantitative results for asphalt thickness from the raw radar data.

In the Texas study (5,6), results from four SHRP asphalt pavement test sites based on 50 cores showed the accuracy of the radar predictions for asphalt thickness to be within ± 5% (± 0.31 inches). When one calibration core was used per site, the accuracy was improved to ± 0.11 inches. The accuracy of the radar predictions for base thickness was within ± 1.0 inch. The nominal layer thicknesses at these sites ranged from 1 to 8 inches of asphalt and 6 to 10 inches of base. Moisture content in the base was also predicted to within 2 percent by weight, and the results also showed that the radar predictions were independent of survey speed (from 5 to 40 mph) and were repeatable.

In the Kansas study (7,8), 14 sites were selected to represent the population of pavement types present in the state. The radar results showed substantial variations in asphalt thickness within each 1000 foot test section, and, in general, higher values of asphalt thickness than were reported in available records. The radar predictions, when correlated with data from 73 ground truth cores, show an accuracy of ± 5% to ± 10%, depending upon the treatment of the data. The asphalt thicknesses encountered in this study ranged from 2.5 to 20 inches.

Other reported applications of radar include void detection underneath concrete pavements and bridge deck evaluation. In a study done for" the Houston office of the Texas DOT, radar was successfully used to detect voids underneath jointed concrete slabs, and thus locate areas where grouting was needed (9). In this study, radar measurements taken at a spot on the pavement with known moisture filled voids were used in establishing a reference with which to interpret radar measurements taken along the concrete roadway for the presence of voids.

In New Hampshire, a radar-based bridge deck evaluation system has been developed for the state DOT by INFRASENSE (10,11). The system, known as OECAR for DEck £ondition 8ssessment using Radar, was evaluated through network surveys covering 44 bridge decks. It was shown that the system can be successfully implemented on a production basis, and reliably used to measure bridge deck deterioration.

OBJECTIVES AND SCOPE

The review of radar applications presented above point to the potential of using GPR technology for estimating pavement layer thicknesses on a network-wide basis. The overall objective of this study is to provide for the systematic implementation of GPR technology, within the Florida DOT, for inventory of pavement layer thicknesses and base material types. This is evident in the approach adopted for this study, which has been divided into distinct phases covering:

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1. a demonstration of the applicability of using radar to predict layer thicknesses and classify base material type (Phase I);

2. a pre-production survey (Phase IIA), and radar system development and pilot, implementation (Phase lIB); and

3. a statewide radar survey (Phase III).

The subject of the present report is the Phase I demonstration of the potential of current GPR technology to estimate pavement layer thickness and classify base material type. This demonstration consisted of a sequence of research activities that included the following:

1. selection of test sites for radar thickness evaluation;

2. radar survey of test sites established;

3. blind predictions of layer thickness and base material type were made solely on the basis of interpretation and analysis of raw radar data, and visual observation of surface characteristics of test sites selected by the Florida DOT;

4. collection of ground truth information to verify the radar predictions;

5. re-interpretation of radar traces to improve accuracy of the thickness predictions using the ground truth data collected; and

6. adjustment of radar predictions by calibrating to a single core.

The next series of chapters document the research efforts made and the results obtained, beginning with a description, in Chapter 2, of the surveys made on the selected test sites. This is followed by separate chapters presenting, the ground truth surveys conducted (Chapter 3); the blind interpretation and analysis of the radar data (Chapter 4); the comparison of the blind predictions with ground truth information and the adjustments made to improve the agreement with the observed (Chapter 5); a summary assessment of the radar predictions (Chapter 6); and the Phase I conclusions (Chapter 7).

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CHAPTER 2. DESCRIPTION OF RADAR SURVEYS

The data analyzed in this report was collected at 6 sites selected for evaluation by the Florida DOT. Data was collected using radar equipment leased from Pulse Radar, Incorporated of Houston, Texas. Ambient temperature during data collection was in the mid-90's. The area had received daily rainfall during the month preceding the survey. However, there was no rainfall during the day of the surveyor during the preceding day.

TEST SITES SURVEYED

Originally, there were 5 test sites established by the Department for the Phase I demonstration study. The locations of these test sites are shown in Figure 1 and are identified as follows:

1. Site 1 - located on the eastbound outer lane of US 27 near the intersection with SR 59;

2. Site 2 - adjacent to Site 1 and located on the westbound outer lane of US 27 near the intersection with SR 59;

3. Site 3 - located on the westbound outer lane of US 27 near the Chaires crossing;

4. Site 4 - adjacent to Site 3 and located on the eastbound outer lane of US 27 near the Chaires crossing; and

5. Site 5 - located on the westbound outer lane of West Tennessee Street along US 90 from Appleyard to intersection with SR 263 (Capitol Circle).

During the day of measurements, a sixth site was established that represented original pavement construction. Radar data collected on this site were used in the equipment demonstration conducted the following day at the Florida DOT office in Tallahassee. This site is on the Westbound outer lane of Mahan Drive along US 90, beginning alongside a sidewalk manhole located past the intersection of Mahan Drive and West Bacon Drive, and ending just prior to the intersection of Mahan Drive with Phillips Road.

The lengths of the selected test sites are as follows:

1. Sites 1 to 4 approximately 0.3 miles;

2. Site 5 1.5 miles; and

3. Site 6 approximately 420 feet.

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Figure 1. Location of Radar Test Sites.

For all sites except Site 5, the beginning and ending locations of each site were marked with paint stripes sprayed on the shoulder together with the corresponding site number. For Site 5, the middle of the intersection of West Tennessee Street with Appleyard was designated as the start of the site, while the middle of the intersection with SR 263 (Capitol Circle) was designated as the end of the site.

Sites 1 to 4 are located in a somewhat rural area east of Tallahassee. For the purpose of locating these sites, it is noted that Sites 3 and 4 are approximately 6.4 miles east of the intersection of US 27 and US 319, and that Sites 1 and 2 are approximately 7 miles east of Sites 3 and 4.

SURVEY PROCEDURE

Radar measurements were made starting with the sites farthest east of Tallahassee. Traffic control for the measurements was provided by the Springhill Road Maintenance Office. For Site 1, a lane closure was initially set up for the eastbound outer lane. Metal plates placed on the pavement surface at the beginning and ending locations (Figure 2) provided reference markers in the radar data with which to identify radar signals taken within the site. The radar van from Pulse Radar was driven continuously along the test site, with measurements being initiated prior to the beginning of the site and terminated past the end of the site. A chaser vehicle also followed the van during the measurement process.

The above procedure proved to be efficient enough to eliminate the need for lane closure to conduct the radar measurements on the other test sites. Consequently, Sites 2, 3, 4, and 6 were surveyed using only the chaser vehicle equipped with an arrowboard to direct traffic to the passing lane of each test site. The metal plates were set down by FOOT personnel prior to the passage of the radar van, and removed after passage of the van. Measurements were made at a speed of about 10 mph, which, for the data acquisition capability of the Pulse Radar system, provided approximately one radar waveform every foot.

For Site 5, which was selected to assess the capability of current radar technology to detect changes in pavement section, no metal plates were used, and the van was driven at the normal traffic speed which ranged from 0 to 30 mph. For this site, measurements were initiated when the van was about at the middle of the intersection of Appleyard and West Tennessee Street, and terminated at about the middle of the intersection of West Tennessee with SR 263. The chaser vehicle was still used to direct traffic to the passing lane during the survey of this site.-

Radar data were collected along the centerline of the test lane at Sites 1 and 2, and along the left wheel path at the other test sites. Additionally, at the suggestion of the Florida DOT, radar measurements were made along the right wheel path of the test lanes for Sites 3 and 4. All data were collected directly to the hard disc of the 386

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Figure 2. Metal Plate Used to Identify Site Limits.

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microcomputer housed inside the Pulse Radar van. Data were subsequently copied to floppy diskettes for further analysis by INFRASENSE and TTl.

For the purposes of this analysis, two sets of calibration tests, consisting of a plate reflection, end reflection, and time calibration tests were carried out during the survey. The first set of tests was conducted after completion of the radar measurements on Site 1, to take advantage of the lane closure set up for this site. The second set of tests was conducted in a parking lot after measurements were made on all test sites.

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CHAPTER 3. COLLECTION OF GROUND TRUTH INFORMATION

In order to verify the blind radar predictions as well as to provide information for re-interpreting the radar measurements on selected test sites, field cores were taken to determine actual asphalt thicknesses, to measure actual base thicknesses from the core holes, and to identify the type of base material for each test site. The blind predictions of layer thicknesses will be presented in Chapter 4. Adjustments of these predictions were later con­ducted to improve the agreement with the measured core thicknesses. These adjustments were made based on information obtained from the cores which were useful in re-interpreting and re-analyzing the radar measurements. The steps taken to improve the accuracy of the thickness predictions are presented in Chapter 5. The present chapter is devoted to discussing the efforts made to collect information for verifying the radar predictions and documenting the pertinent data collected.

SAMPLING PLAN FOR GROUND TRUTH SURVEY

For the ground truth survey, a sampling plan was initially developed to establish the number and locations of cores at each site. This sampling plan is presented in Table 1. The choice of sample size, or number of cores to take from each site, was guided by the following considerations established in consultation with the Florida DOT Project Manager for this study:

1. the capability of current GPR technology to predict layer thicknesses will be evaluated through comparisons of the radar predictions with the ground truth data collected from Sites 1, 2, 3, 4, and 6; and

2. the capability of current GPR technology to detect changes in pavement section will be evaluated using data collected from Site 5.

The first consideration necessitated that a sufficient number of cores be taken from Sites 1, 2, 3, 4, and 6 to enable statistical inferences to be drawn concerning differences between the means of the predicted and measured layer thicknesses. However, from a practical point of view, the volume of traffic on a particular site was also considered in establishing the sample size. This was particularly important for Sites 5 and 6 where the volume of traffic was high, making it particularly necessary to minimize the length of time a site was closed to traffic due to coring operations.

The high volume of traffic on Site 5 was a factor that influenced the decision to use the site primarily for evaluating the capability of current GPR technology to detect changes in pavement section. Based on the radar data, there were 7 predicted changes in pavement section on this 1.5 mile long site, which would have required an impractically larger sample size than was proposed if statistical comparisons of means of predicted and measured layer thicknesses had to be made for the different sections comprising the site. Consequently, for Site 5, cores were generally taken to bracket changes in pavement section identified from the radar data and from the straight line

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Table 1. Proposed Coring Plan

Site Number of Wheel Core locations referenced Cores Path from start of test site

1 9 Centerline 200, 300, 390, 590, 790, 990, 1190, 1290, & 1440 ft.

2 10 Centerline 30, 130, 240, 300, 400, 580, 600, 780, 1050, 1390 ft.

3 8 Left 50, 140, 270, 420, 640, 950, 1090, & 1470 ft.

100, 300, 400, 490, 610, 690, 790, 920, 990, 1260, & 1390

4 11 Left ft. (Take concrete cores at 100, 790, and 1390 ft.)

4 9 Right 200, 300, 490, 590, 690, 890, 990, 1090, & 1290 ft.

5-1 2 Left 640, 1190 ft.

1340, 1440, & 1560 ft. (If 5-2a 3 Left base is PCC, take concrete

core at 1440 ft.)

5-2b 1 Left 1640 ft. >.

1880, 2210, 2470, 2870, & 3170 ft. (If base is PCC,

5-2c 5 Left take concrete core at 2470 ft. )

5-3 3 Left 3280, 3460, & 3610 ft.

3810, 3960, & 4160 ft. (If 5-4 3 Left base is PCC, take concrete

core at 3960 ft.)

5-5 2 Left 4260 & 4400 ft.

5-6 3 Left 4480 (at transition between 5-5 and 5-6) 4700, & 5940 ft.

6 4 Left 50, 150, 250, & 350 ft.

TOTAL 73 (73 asphalt cores plus possibly 6 concrete cores)

Cores/site 12 (12 asphalt cores per site)

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diagram provided by the Florida DOT after blind predictions of layer thick­nesses and base material type were made and reported to the Department.

For the other sites, the sample size was established such that the difference between the mean of the core thicknesses and the true universe mean for a given site would be within a certain tolerance for a given probability level. The universe mean, herein, is defined to be the mean that would be obtained if one were able to measure asphalt thicknesses at all points within a given site, a task that is not practically possible since it would require an extremely large sample size. Thus, the universe mean must generally be estimated by sampling the thicknesses at a number of locations, determining the mean of the sampled thicknesses, and establishing the interval about the sampled mean within which the universe mean may be expected to occur with a given probability. For this study, a maximum permissible deviation of 0.25 inches between the sampled mean and the universe mean was used in establishing the number of cores to take from a given site. Assuming a probability level of 95 percent, the sample sizes for Sites 1, 2, 3, 4, and 6 shown in Table 1 were determined.

For each site, the locations of cores were established so as to cover the range in asphalt and base thicknesses that were seen from the radar data. Cores were proposed to be taken along the path(s) the radar antenna tracked when the measurements were made. The only exception was Site 3 where it was proposed to take cores only at the left wheel path, even though radar measure­ments were made on both wheel paths as recommended by the Department. However, analysis of the radar data on this site showed that the layer thicknesses are very similar for both wheelpaths. Consequently, in order to minimize the num­ber of cores that need to be taken, it was proposed to take cores only at the left wheelpath of Site 3. This aspect of the sampling plan was brought to the attention of the Florida DOT Project Manager who raised no objections, and who later revealed that there was actually no difference in pavement cross sec­tions at the left and right wheel paths of Site 3. This site is actually adja­cent to Site 4 where the right wheel path is on a widened section of the test lane. The recommendation to survey both wheel paths of Sites 3 and 4 was made merely to make less obvious to the research team the site where there was an actual difference in pavement cross section at the left and right wheel paths (Site 4).

In addition to the cores, the sampling plan called for taking dry samples of base and subgrade materials at selected test pit locations in Sites 1, 2, 4, and 5. The proposed test pit locations, shown in Table 2, were established based on the radar data. For example, it was proposed to take base and subgrade samples from Site 1 at the locations shown in the table since analy­sis of the radar data indicated a higher base dielectric constant at the sec­ond test pit location, i.e., 780 feet, than at the first test pit location, i.e., 350 feet. Moisture content and dielectric measurements on base and subgrade samples were made in the materials laboratory at TTl to provide data to support or substantiate the results of the radar analysis.

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Table 2. Proposed Sampling Plan for Base & Subgrade Materials.

Site Number of Wheel Test pit locations Test Pits Path referenced from start of

test site

1 2 Centerline 350, & 780 ft.

2 2 Centerline 260, & 890 ft.

4 2 Right 710, & 1310 ft.

5-1 1 Left 600 ft.

1460 ft. (will be done if 5-2a 1 Left cores show base is not

regular concrete)

5-5 1 Left 4300 ft.

5-6 1 Left 4950 ft.

TOTAL 10

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FIELD DATA COLLECTION PROCEDURE

Each site was initially closed to traffic prior to commencing the coring activities, with traffic control being provided by the Tallahassee Maintenance Office. Core and test pit locations were then laid out with a measuring wheel, and marked on the pavement surface with spray paint. Once this was done, 6-inch diameter cores were taken from the designated core locations by wet coring. The thicknesses of individual lifts in a given core were then measured after the loose core was pulled out from the pavement. In addition, the total thickness of the asphalt concrete layer was measured from inside the hole whenever a core was broken.

Measurement of base thickness was accomplished by initially removing the base material inside a core hole using a post hole digger. Removal of the base material was facilitated by attaching the post hole digger to a power tool that rotates it. This technique helps in loosening the base material inside the core hole, and was particularly useful for removing limerock which was found to be generally stiff. Once the base material has been removed, and the subgrade exposed, the base thickness was measured from inside the hole. Measurements of core and base thicknesses were made by the coring crew from the District 3 Bituminous Section at Chipley. All measurements were recorded on appropriate forms.

At the designated test pit locations, a crew from the Tallahassee Maintenance Office used a jack hammer to remove the asphalt surface layer so that dry samples of base and subgrade materials can be obtained. Base samples were taken from the top, middle, and bottom of the base to check for significant differences in moisture content with depth in the base layer. Subgrade samples were obtained from the top of the subgrade.

Base and subgrade samples for moisture content determinations were placed inside plastic Ziploc bags. In addition, approximately 55 pounds of material from each of the base and subgrade layers were placed in separate cloth bags for laboratory measurements of dielectric constants of molded soil samples prepared at ~ifferent moisture contents.

Cores and soil samples were placed inside boxes for shipment to TTl at the end of each work day. Labels were affixed to each bag of soil sample that identified the type of sample, i.e., base or subgrade, and the location where the sample was taken, i.e, site number, wheelpath, and test pit location. In addition, for base samples on which moisture content determinations were planned, the label identified where in the base the sample was taken, i.e., top, middle, or bottom.

Cores were also placed inside 6-inch diameter PVC pipes for added protec­tion during shipping. Each pipe was 12 inches long, with a vertical cut along its length to accommodate the core, and a label for recording the appropriate information on site number, wheel path, core location, and total core thick­ness. This label was filled up prior to placing a core inside a PVC pipe.

All test pits and core holes from the ground truth survey were patched by a crew from the Tallahassee Maintenance Office.

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SUMMARY OF GROUND TRUTH DATA

Table 3 shows computed means and standard deviations of asphalt and base thicknesses measured at the different test sites. Measured layer thicknesses at the individual core locations are presented in Tables A.1 through A.7 of Appendix A. The range in measured asphalt thicknesses is shown graphically in Figure 3 for each test site. The mean of the measured thicknesses is also shown by the horizontal tick mark within each vertical line representing the range of asphalt thickness for a given site.

The widest range in asphalt thickness is seen in Site 5 where the core data reveals several changes in pavement cross section within the site. The high end of the range for asphalt thickness was measured towards the end of Section 5 of Site 5 (at a footage of 4481) where there is a localized thicken­ing in the asphalt layer that was also observed from the radar data for this site. Likewise, the widest range in base thickness is also seen in Site 5, where, as shown in Figure 4, the base layer varies from a low thickness of 5 inches to a high of 11.50 inches.

It was also observed that the cores generally consisted of different lifts, as illustrated in Figures 5 through 10. The lift thicknesses shown in the figures are the means of the corresponding individual lift thicknesses recorded by the coring crew from the District 3 Bituminous Section. The identification of the type of material in each lift is based on information from the coring log and from pavement design sheets provided by the Florida DOT after blind radar predictions have been made and reported to the Depart­ment. The thicknesses of individual lifts of cores from the various test sites are documented in Tables A.8 through A.14 of Appendix A. It is impor­tant to recognize the layering observed in the different test sites since this will usually cause overlapping of the radar signals which must be considered in the analysis.

The type of base material observed in each test site is summarized in Table 4. It is observed that, from Section 1 to Section 3 of Site 5, there are 4 different changes in base material which mirror the segmentation of the site into Sections 1, 2a, 2b, 2c, and 3. The sand asphalt hot mix (SAHM) base from Section 3 to Section 6 of Site 5 was found to be a material characterized by high air voids and low dielectric constant, as evident from Table 5 which shows laboratory measured values of air voids content, bulk specific gravity, and dielectric constant for this material. This characteristic may be useful in identifying sand asphalt hot mixes from radar measurements.

Laboratory measured values of moisture content, for soil samples taken from test pits, are presented in Table 6. The measurements indicate that the moisture content does not vary significantly with depth in the base layers of sites where samples were collected.

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Table 3. Means and Standard Deviations of Measured Layer Thicknesses at Test Sites.

Site Wheel Mean Thickness (inches) Std. Deviation (inches) Path

Asphalt Base Asphalt Base

1 Centerline 5.68 9.14 0.29 0.42

2 Centerline 6.95 8.55 0.29 0.34

3 Left 4.93 9.63 0.47 0.66

4 Left 7.15 8.48 0.42 0.23

4 Right 7.30 6.70 0.27 1.32

5-1 Left 4.08 9.35 0.04 0.21

5-2a Left 6.57 9.70 0.32 2.16

5-2b Left 8.55 5.70 - -- - --

5-2c Left 7.20 9.50 0.74 0.82

5-3 Left 5.17 5.53 0.31 0.06

5-4 Left 4.85 5.53 0.79 0.15

5-5 Left 7.17 5.40 5.58 - 0.35

5-6 Left 4.43 5.43 1.03 0.11

6 Left 3.06 11.75 0.05 1.26

17

-ex>

..-CI) Q.) .c () c: ---CI) CI) Q.) c: ~ ()

.c ~ Q.) \.....

0 0

14~------------------------------------------------~

12 ................................................................................................................................................................................................................................................................................................. .

10··················

8

6··············l······ . " ........... , ...................................................................................................... , ........................................... , ..................................................... , ............................. .

~ 4 ......................................................................................................................................................................................................................................................................................... .

I-

2

4L, Site

4R o~--~------~------~------~------~------~------~--~

5 6 1 2 3

Figure 3. Range in Measured Asphalt Thicknesses for Each Site.

14.0~--------------------------------------------~

13.0- .................................................................................................................................................................................................................................................................................. .

12.0- ................ , .................................................... , ................ , ....... , ........................................................................................... , .... .

.-CJ) (l) .c 11.0- .. · ........ · .. ·· .. ··· .. ·· .. ·· ......................................................................... , ............. , ................................................................................ .

() c .----CJ) CJ) (l) c ~ ()

...... .c 0..0

f-

10.0- ...... ··· ...... .

goOf -

(l) CJ) 8.0- .. ··· .... ·· .. ········· co co -

7.0-· .. ····· .. ··· .. ·· .. ····················· .. ············· ............................................................................................................................................................................................................................. . I--

6.0- .......................... . . ............................................................................................................................................................................................................... .

5.0~--,l--------~I------~I--------~I------~I------~~------~I-----,1 2 3 4L 4R 5 6

Site

Figure 4. Range in Measured Base Thicknesses for Each Site.

N 0

-(j) (]) .c u c .---(j) (j) (]) c ~ u .c I-~ ...J

6~--------------------------------------------------~

5· .. ·················· .. ·············· .. ·············· .. ·· ................ __ ......................................................................... .

4

3

2 ........................... .

1 ............. .

o -'--------------f

Binder

8lEE Crack relief

....................................................................

Site 1 Core Lifts

_ Type I ~ Leveling

~ Type II overbuild ~ FC-2 & Type S

Figure 5. Observed Layering in Site 1 Cores.

7.---------------------------------------------------~

6 ................... ..

....-(/) Q) 5 ............ . ..................................... H-f-+HH-I-H-I-t++t++H+H++-I++-I++++++++++-l............................................... . ...................... .

..c 0 c ---(/)

4 ...................................................................... ~~~yyyyy<.,.~~~~~~~Y<,...<A ...................................................................... .

(/) Q) c ~ 0

3 ......................................................................... YY'~vYY~~~~~~..,I<..IV<~~~oVQ ........................................................................ .

..c r-

N ~ 2 .......................................................................... J;<.A~~~~yyyyy<.,.~~~~~~VQ .......................................................................... .

........ ..J

1 ............................................................. .

O--L.-------

Site 2 Core Lifts

SAHM ~ Type II ~ Leveling

8llE Crack relief ~ Type II overbuild ~ FC-2 & Type S

Figure 6. Observed Layering in Site 2 Cores.

N N

5.0--.---------------------,

4.0 ............................................................ . ...-en ~ 3.5- ................................................. ~ ..................................................................... .

C3.0-················································ ..................... ~I~ ...................................................................... . en ~ 2.5-············ . . ................................ H-H-t--H+++-H-+--t-'i-+t++++++--1-H+t-++++++++H ...................................................................... .

~ 2.0-·················································.................. ~~ ...................................................................... . .c I-~ 1.5- .. · .. ······ .. ·· .. ··· ...... ···· .. ·· .. ··· .... ·· .....J

1.0-······ ....................................................... .

0.5-················ .. ···· .. ···························· .................. .

0.0

Site 3 Core Lifts

~ Type S ~ Leveling EEW Crack relief

~ ~ype II overbuild ~ FC-2 & Type S

Figure 7. Observed Layering in Site 3 Cores.

8.-------------------------------------------------------~

..-CJ)

7"""""",,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,~~ •• """".'"'''.'''''''' ... '''''' ...... '''''''' ... ''''''' .. '' ... ' .. '''''''

6·""", .. "",·,,,,,,,·, .. ,,,·,,,,,,,,,,,,,,,·,·,,,,,,,·,'''''''., .... '''~ "".".".,,, ...... " ... ,, ... ,, .. ,',.,","' ... '.".""''''''''' .. '" ... , Q)

..c..: () c 5 """,",." .. ","", .... ',',',.".,"", .. ,' .. """,',"""" .. ~ffi~~ftWm~~ftWffi~~ftW~""·"·' .. ' .. ·"""·" .. "''' .. ·''''·'''' """",."" .. "."""""" .---CJ) CJ) Q) 4"",,,,,,,'"'''' c ~ (,,)

..c ~

~

N :..J 2 ,,,, .. ,,,,,., .. ,,,, .. ,,, w

1

Site 4 Core Lifts (LWP)

~~~~~ Type II & SAHM ~ Leveling HW Crack relief

~ Typ~ II overbuild ~ FC-2 & Type S

Figure 8. Observed Layering in Site 4 Cores Taken Along Left Wheel path.

8~--------------------------------------------------------~

7 ~ ..................... . U) 6 Q) ..c g 5

en en Q) c ~ (.)

..c r-~ .....J

4····························

2

1 ...... .

Site 4 Core Lifts (RWP)

~~~~ Type II & SAHM ~ Leveling ~ Crack relief

~ ~ype II overbuild ~ FC-2 &.Type S

Figure 9. Observed Layering in Site 4 Cores Taken Along Right Wheel path.

3.5~------------------------------------------------~

-Cf) Q) .c () c ---Cf) Cf) Q) c ~ () 1.5

171'777 'z Z 'z Z Z Z Z 1

........................ / '7 ?? 17 '7 '777. '77 '77

I7 I7777 '7

.-.c N

~ (Jl

~ ~

1.0- ............ . . ............................................ /VV;A,vV;N.vc;.;<"NV..,.<..,vV;N.vc;.;<"NV..,.<..,vV;A,v;.;<"N.vc;.A ................................ · .. · .. · ..... .

'7 ~z.

77

17 .. "'17.A.-'V' ....... """""""....., ....... .A.-'V''"''-IV''''''''''''''''''''''"....., ....... .A.-'V''"''-IV'''''''''''''''''''''''./V''-'''I··· .. ··································

171

'7 'Z 1 7

0.5-

"'.7 ?.77T7 ~7 '7 '77777 ?? '77 '7 '7 '77777 '7/ 'Lt "'.7

'77 '7777772 '7

Site 6 Core Lifts

Figure 10. Observed Layering in Site 6 Cores.

Table 4. Base Material at Different Test Sites Identified from Ground Truth Survey.

Site Wheel Base Materi a 1 Path

1 Centerline Limerock

2 Centerline Limerock

3 Left Limerock

4 Left Portland Cement Concrete

4 Right Soil Cement

5-1 Left Limerock

5-2a Left Reddish brown sand

5-2b Left Limerock

5-2c Left Reddish brown sand

5-3 Left SAHM

5-4 Left SAHM

5-5 Left SAHM

5-6 Left SAHM

6 Left Limerock

26

Table 5. Laboratory Measured Values of Air Voids Content and Dielectric Constant for SAHM Base Material.

Site Location Air Voids Bulk Specific Dielectric (feet) Content (%) Gravity Constant

5-3 3280 13.28 2.07 2.47

5-3 3460 18.53 2.02 2.99

5-4 3810 16.10 2.03 2.93

5-4 3960 13.57 2.03 3.17

5-5 4260 15.23 2.05 2.77

5-6 4700 13.30 2.09 1.46

Mean: 15.00 2.05 2.63

Std. Deviation: 2.08 0.03 0.62

27

Table 6. Moisture Contents of Soil Samples from Test Pits.

Site Location Moisture Content (% of dry weight) (ft)

Base Subbase Subgrade

To~ Middle Bottom

1 350 9.76 9.26 11.3 - -- 8.46

1 780 9.76 10.15 10.2 --- 6.43

2 260 9.57 9.73 10.39 - -- 9.26

2 890 9.75 10.01 10.01 - -- 9.88

4R 710 --- - -- - -- 7.06 5.00

4R 1310 - -- --- - -- 6.87 4.07

5-1 600 8.28 8.66 9.08 - -- 7.43

5-2a 1460 7.77 7.65 7.72 - -- 5.75

5-5 4300 - -- --- --- - -- 7.76

5-6 4950 - -- - -- --- --- 9.26

28

CHAPTER 4. RADAR DATA ANALYSIS

Prior to presenting results from the blind interpretation and analysis of the radar data, a review of basic principles of GPR data analysis is provided in an effort to provide the reader with a basic understanding of how the technology works. This includes an example illustrating the basic procedure for analyzing raw radar waveforms.

PRINCIPLES OF GROUND PENETRATING RADAR

Ground penetrating radar operates by transmitting short pulses of electromagnetic energy into the pavement using an antenna attached to a survey vehicle (see Figure 11). These pulses are reflected back to the antenna with an arrival time and amplitude that is related to the location and nature of dielectric discontinuities in the material (air/asphalt, asphalt/base, etc). The reflected energy is captured and may be displayed on an oscilloscope to form a series of pulses that are referred to as the radar waveform. The waveform contains a record of the properties and thicknesses of the layer within the pavement. Figure 12 shows the relationship of the layer thicknesses to the radar waveforms. Figures 13 and 14 show typical pavement waveforms collected during this project.

The pavement layer thicknesses and properties may be calculated by measuring the amplitude and arrival times of the waveform peaks -corresponding to reflections from the interfaces between the layers (see Figure 12). The dielectric constant of a pavement layer relative to the previous layer may be calculated by measuring the amplitude of the waveform peaks corresponding to reflections from the interfaces between the layers. The travel time of the transmit pulse within a layer in conjunction with its dielectric constant determines the layer thickness, as follows:

Thickness = velocity x (time/2) ( 1 )

Since the measured time between peaks represents the round trip travel of the radar pulse, the thickness computation is based on time divided by 2. The radar velocity can be computed from the dielectric constant of the medium, €, using the formula:

velocity 11.8

{€ (inches/nanoseconds) (2)

29

Antenna

Figure 11. Illustration of Radar Survey Vehicle.

30

· Vo I tage

T t AC 1

Tlme(ns.) Radar

Waveform

Antenna

CJ tc-Reflected

<D rays

surface

(2) Asohal t

Q) Base

Subgrade

Pavement Cross Section

Figure 12. Model of Radar Pavement Data.

31

4SPJMLT LAVER5

:1 ........... ".' ......... '". .. ...... •• '" ,. ............... , ... I ........... ............ ",' • I • ..... '.' .................... ..

.. . . .. .. . .. .. .. . .. .. .. . .. .. · .. .. .. o .. .. .. · .. .. .. .. .. .. .. • to .. .. · . . . . . .. .. . .. .. -: .............. :................ ............. .............. .. ............ -: ............... :. .. .. .. .. .. .... ...... .. · . . : : :--~

\......-"-......... - .

----. +> OJ OJ 4-~

OJ -4ee w u . N c:

C'O +> Vl 'r-0

280.

.. . .800 ' ~-.~~.,---~ ... , : .... ~~

w w

xE0

800.

600.

400.

200.

.000

1.\ ,. , I: \ ·l(\ ~ . .: .. /":\ ... ; ........ : ....... : ....... : ........ ; ........ ; ........ : ....... :

11,'<', ' I" : l '.: : : : : : : : III ' , I ., 1. 1>--- . -' . II . II" '. . I "'''~ .... --. __ .... ~..r---.. _.,....~ ;--... ---~--- ---.... . .'

-..., I I i I I~ "\ : I ".--.. !, .... .:-•• , -.".---,- : : • -------.: ---: •• ~.. _-----'" --+ I. III I~III I, 'I :1' / l'.A\ ....... : : ' . . . _ .. -.. - .... : - : \ ,iii I' ·ll,.... ... 'J'.' . ------........ ... ..-.--------:.----.--. :. ....-... --.;....., ..• - ..•. . ---.. " (r I; I \" "'. III I' ,'1 .... r ..: : :- ---" ....... : ----'. . .... : , . .----.. :

. \ ...... 111·lt· .. ~ .. '\ . ... ·t· , ....... r ...... ·· ............................. ' .• ".-": • '" •...•.• :. . . \ .,. . " I JI:' ,. '. ~ I" 'o': .• ------ . . . . •• :"""." .-' ..... :

. \ "I I . , 1 '" '........ II' ',', . . . .---......~ -.------~-.... .. ""'7---~- ..... .----.. '" ..... ' t ~I II ~ ......... : ,I 1',:/ "--J: : :.. . ... _---.. .- : . ... ... : .... -. :

... I I'· \ 1 \ \ v:"... ~ ' ...... ~ ' .. ",",---.---''''---.: --Po- : ..... _,;. .: ___ .. \. ,I L~ I : '\~ '-. .'-.:/ (.'. '" .. ,--... . .• .-: . .---- ..... ...... _---r-.. " .. : l- ......

"II .. I Ll Il~ \ \" I: ("'!.. II,-,.!" ---....: __: : .............. : __ : '~'-\..-'-'-': I nJI'-I\, ..• ' 'I.. ".,..- ... _. . r!" I .-' .. ---...... . ····nl l ·.·'··,····.·· .. , ... ~ ... -.................. ---+ ......... ,.., ..,..'- ........... . -'I, \ ..... II . I II. 1\ .... I .. (-......... ~. - .. --• .-: : : '."" ./:........... ':' . . .. -=-~~-... ~-~,

... "II' l ... \ " \ " /,'". ....... : : .. .......----~: -----: : ---........ : : ..... - .... \ "I II II: \ \ """ \ / I" \ ~ : l .. ---.. _.·..-: : -,.-;--... - ..... _-.... '---------r ,.~ __ .---;

.... II Il--, I'.,. "\'--.1: III ... ··\1, 1 ... -:-. : .. _ ..--.. __ : : : : _ .. ----.:-- :

__ ., .... ,.'1/1: \ \ '''', \ :,' I '/.-.... \ : .. -... . .... '!'"'-" : -.....----;.-.. __ ..• :-.-----;-"'. ... ..• -..;. .. - . ...-.... - .... : · \ ..... / J';.~·'i ~ .... ",' ~.,;J IL I (' ·\I·l··-~ •.•• ....,( • ~ •....•• ! ........ : .. ,"'"",-... : ........ : ............... ,_ •...... :

, I II" I I \ , . I I \. • --. J.. .. -. --- " . -.. \ " 1III : 'I I .... , \\ / ,,/. ... ". : •• - •• ----•• :--- ----:---- ----;---••• "'-- ... ~. . •• -----: - •. ' '.;'_.-"".--... :

" .... I~,..I, I~ "'-.'" 'It··, ,'-.,r' : :..... : --: : _. : \ I I:~, \ \:,' I" ~ Il : .-.. ;..-_-.----. "'--_.' ._ . - •• ' '.. : .-- :

---'. '. "~ I . I \ '--a ......... I I "I' .... .. ___ --. : .-• ..; ... ---., /..: -----.---:-- ....... ". ..... . , ".1. . 1 ... 'i" II' I" '" . . . -. . ..... i"'.. . " I'~' I " .... rl....... I .~ •• , : ______ : • • . ...,.,.... : -.. .... :

.. \ . ,I •• \ L ~,. • • :.. •• 'Z~ I • "~ • ~ .'. • •• '-" . .."-,,,-", . • :-......... --:'"7-:--:--:-..-+....... . . . . . .: ,r'.------......:..--......') ,""- ..... . ___ • " • I l·~ ',' ( ,,'~" __ - . • .." _ •• • •• • ............. r.,. .. '"I '-' L J • I \ -.... .~, , • .~ • • • -.,.-.-........ • • "", •. ' --.. • " 11 ria I "'. ..'-. I I, .... '___ • • . '..c. ~ - :

-... \ ... /:11',,1;"\ 1,\1........... \ ..... :... ,/ .... ", \'1 .~ .. I-------'\ .......... ·· .. r ----: ..... _--.-!'-.... .._ .. ~-. ~.,;"'" '\ ,jj ...... - ..... -___.; " / I ,'1, '. . " "p' • • • -. • • • " 1'11"" \ '11/-.. It - .. '" .-~ __ • • • , ~ : ---...... • , 11'11"1 I ')1 ,I' ....- -"9'_-___ --- ""'\00....... -. ~ - •

.-.... \, ... ' I I : II ... , ...... II I \.... : .•.. ---............ : : -: -......-___ --.... : --: '''''- "'~ -.. .... -: • '. • J "I i ·t,· 11'\' . ".' . ':"I'~ . r~, . V·~· ................................................ "':"" ~ ....... :

\ ) I,'" \ , of I" ~--'----;'----' • - ~.---....'------.' ---'" \.,., III i : "11\ .... " \ . • ~l " \ ~/-... / ... : : ------:---.... -----~' .. ----.. -: .'-..-) .. ; ... --.;

" I J/ ". .....".J. ' ... ' . . . . . . \ )I t~ \ \' / ,'" : ,,;..----. :-------: : . ..--... . --.... -.. '- :

... \..~ II I: 1\ ' .. _ ... " /, ,.,.... .. , \ : ".-----. .• : -; "'!'--.-~-------:-- ............ )" .-... : .... I I Il\ l~', .... ~ : 1/ \ t~.,· ~.t--.. _ _-.;.-...... : : : __ "---', '"': .. --... :

__ ~ . \ . hit Jo J, 1 ~": . . J, ••• • ,~a;a • ,'--', .,,' '.' .----: • • , •• , • • .--.-. • • • • "'-"~';-"'. • • • .-..;-:-...... • ........... -;-:-. • • • 1.. ;. •.• 0: • • ....... -. • ... • .. ·1, ., .• ,' 11111r..\1, I. "--." ~ .. } II..... .......... ---...,.,: : : '---/: --•• ' : ... - ...... , .;..-•• , :

• tll'll\ ',', I ,... • • • • • ',--'P _ \. II IJI: III '...... ... •••• ."1 l.""'·, \ : ....-... ../. .. ----...---..-.--.:. ... ..,..---.~ "':"~-"'''-''''''':'''''.'-''''''\. .~.---.......... :

'.. .... .. ,Ir ...... \.. .... : /,. ... \ : I' ...... • • -.. ..--. • ... .... •

'\ Ill"\ (\ .••. 1/ ,,_., : : : --: : .. -'-" "j.L,..( •

... \. 'III~· ~ \ ~ .......... \.J/ / ,I·r "·'\ \. : ... ..---.... ----.. ..-:----------+---~ .---:-------.--:--/ " .. ,: .... -.... .-..... -.. : · \· .... 1 I~~( I' ~ .. "' .. ' .. "'f' .. ~,L.~..i! .....•. ;. ..•.•.. i ....... .; ... '-;-..... : ........ :. . . . .. .-W ........ :

" I I : I L', I,.:.' _ I.: j.,.----....P---. ______ . ... ____ ~--.. _-... : " "I' . I 1\ '" '. 0/ "., •••• ~. ._-"'_.r. . ! -- "'!'--...... .', .... . .... "... : I "., "~,' / ... '-r'. : . . ---' : "'".,../

" ~I·IL' .......... _... . .....--..... . . '- -' _ \ Lli : I ..... .... :/ll" \, "'" : ...... ~-... " .. ___ .. -"":".- --..----------i--~ .. ,-....... -__ _ __ ....-~ '1'. . .... --: ·.11_1 .\ ....... ,. ".r _.. --~. • ... " '. • ... 11· '.. .."..... : / •• -.:,. . ....---10 .'. .-.",

'. IJ ":J " I.. r. .-" "'~-'" _. '"1\ '(-J .: •• \ •• ".' '1' • .. •••• : .• ..:, ............ ~.-. ~ :.-: ..... ---- ••• ~ ........ ~~ ••••••••• " > •• .. . ... , , .... ' I ...... "'-~ II I·· ...... r .. - .......... .- ........... --'''~''''': . ,', .' .... l ..... ··1 •• , t .... oo.....J.,. ..... :

\ , '''.-'. ".'

1

Figure 14. Sample Radar Waveforms for Site 6, LWP. xE0

where 11.8 is the radar velocity in free space in inches/nanosecond. Combining equations (1) and (2), one obtains

Thickness (5.9 x time)

IE (inches)

where time is measured in nanoseconds.

(3)

Computation of the surface layer dielectric constant can be made by measuring the ratio of the radar reflection from the asphalt to the radar amplitude incident on the pavement. This ratio, called the "reflection coefficient", can be expressed as follows:

Reflection coef (1-2) (F, -;;:) (F, + r;;)

(4)

where the subscripts 1 and 2 refer to the successive layers. The incident amplitude on the pavement can be determined by measuring the reflection from a metal plate on the pavement surface, since the metal plate reflects 100%. This is why a metal plate reflection test is conducted as part of a radar survey. Using the data obtained rearranging equation (4), and noting that the dielectric constant of air is 1, one obtains the asphalt dielectric constant, ca ' as follows:

where A ApI

amplitude of reflection from asphalt surface amplitude of reflection from metal plate (= negative of incident amplitude)

(5)

A similar analysis can be used to compute the dielectric constant, cb' of the base material. The resulting relationship is (6):

~F - R2J2 C - C

b a F + R2 (6)

34

where:

F 4F. (1 - fa)

R2 ratio of reflected amplitude from the top of the base layer to the reflected amplitude from the top of the aspha It.

The above equations are used to compute asphalt and base layer thicknesses from the radar data. An example illustrating the application of the equations in determining layer thicknesses is given in Figure 15. Similar calculations were made on the radar data collected from the different sites. A typical result is shown in Figure 16 which shows the predicted asphalt and base thickness profiles for the left wheel path of Site 3. Additional aspects of radar data analysis are discussed in the following sections.

ANALYSIS OF ASPHALT LAYERS

In the above discussion it is assumed that there is one homogeneous layer of asphalt overlying a base material. In fact, most asphalt pavement structures are composed of several asphalt layers. These may be the result of successive pavement overlays and/or of particular pavement design specifications. As shown in Chapter 3, the FOOT pavements tested in the program had 4-5 distinct layers ranging in thickness from 0.2 to 5 inches. Most of these layers appeared to have been placed as part of the design.

In some cases, the dielectric properties of the asphalt layers are similar enough to allow the asphalt to be treated as a homogeneous layer. In other cases, including those of the Florida DOT pavements, the layer property differences are significant and must be considered in the data analysis.

When the asphalt layers are thick, i.e., greater than 2.5 inches, the analysis of the asphalt layers is relatively simple. The second layer of asphalt can simply be treated as if it were the base material, and the analysis method described above for the base can be used for the second asphalt layer. When the layers are thin, however, it is sometimes difficult to clearly distinguish one from the other in the raw data, since the reflections overlap. Distinguishing and accounting for thin layers adds to the complexity of the analysis.

INFRASENSE has implemented a procedure in its PAVLAYER software for distinguishing thin asphalt layers, and this procedure was used in the analysis of the Florida DOT data. The procedure involves the removal of early reflections to reveal the presence of secondary layers. Figure 17 illustrates the results of this procedure. Figure 17 shows the same data for Site 6 as shown in Figure 14, but with the surface reflection

35

18.8

8 .. 88

6.88

~ 4.88 . a

x 2.88

VI +J

.888 ..-0 >

-2.88 QJ en m -4.88 +J ..-0 > -6.88

-8.88

....... ',' ......... .......... ......... 'f········· 'J ....... ... ';" ... ...... ~ .......... f········· . I" ••••••••

! i I

1......TJH •. ! 2.64 i4.0 i

-~" ~"

ICMi

.~.5~5 cP .• ®ITJIIHI ~.l"!~--':""'" ...

I j 0.19 Ia\ i i 1 i ! ......... · .. 1 .. ··· .... T .. ··· .. 10· .. · r .. · .. · .. ·1 .... ··· ... 1' ........ r .. ·· .. ··1

HIHHIII:HH IIHI:IHI

Time (Nanoseconds x 2)

/. Z'/l I/~)

[

; +

J -

!'-. (, I

i rvit) fl.,)

5. 'j .a t'J fJ-. t) (2. l'l) I{

= :: 5.'18 J. I fl:: i.i ~ t·:;'· b I

1 ~ J"tt'U... .~ c~~tL ,,4- fr<-1..1-~

F = = 'fJ:;:;:;

- ~.Ob

R.2 .::

r/~/ t:b - f~

N:..;t •

, - 5 l~1

Ab/A ::: f). I'! /",S)'5

[F~RL r 5.("

F + Rz..

S; Lj Lltb

'.1 Jr:?b

- t!.H

[ - :l. C(.

·-(l...(..·v

,b-.1 (If)

/.( Ili,17

-"'.3' r il.;) 7 ::

f-O.:3/'

I 3 1/

'fJ, '"

Figure 15. Sample Radar Waveform and Thickness Calculations.

36

Base

o ~~~~~~~~~~~~~~~~~~~~~~~ o 100 200 300 400 500 600 700 800 9001000110012001300140015001800

Distance (feet)

Figure 16. Predicted Layer Thickness Profiles for Site 3, LWP.

w co

xE0 ••••••• °0 ••••••• 0.0 ••••••• ••••••• . . • , •• ...... •• 0 •••

............... t. :

': . .

4000 , ...... i' ....... :. . . . . . .. . ..... .

3000

2000

1000

.000

xE0

Figure 17. Radar Waveforms for Site 6, LWP, After Removal of First Surface (Note Appearance of Two Asphalt Layers).

removed. The result reveals a two layer asphalt structure, with an analysis that yielded a 1.3 11 surface layer over a 1.7 11 lower layer. In fact, the cores revealed a similar structure, as shown in Figure 18.

INTERPRETATION OF BASE MATERIAL TYPE

The predicted layer thicknesses, and base material type for the different sites surveyed are summarized in Table 7. For the purpose of identifying the base material, the following general categories were used: 1) limerock; 2) old concrete pavement; and 3) other base material. In all cases, the asphalt/base interface was visible in the radar data facilitating calculation of asphalt thickness. As discussed below, the base/subgrade interface was not clear in all cases.

Layer material interpretation was based on the estimated layer thickness, the dielectric constant, and its spatial variation. In general, layers detected below the surface layer, with predicted thicknesses of 3 inches o~ less, and dielectric constants of 8 or less were assumed to be asphalt layers. Thicker layers with dielectric constants greater than 8 indicate granular, stabilized, or concrete layers. The following items were considered in the effort to classify the base materials of the different test sites:

1. The ability to detect the base/subgrade interface through a thick base layer suggests a granular base, since radar transmission through such layers is fairly good.

2. The inability to detect the base/subgrade interface suggests (a) a clay or concrete layer, since transmission through these materials is generally poorer, or (b) the base and subgrade materials may be similar so that no base/subgrade interface can be detected.

3. The presence of regularly-spaced transverse cracks at the pavement surface and the appearance of strong reflections at regular spacings in the radar data suggest the presence of an old concrete pavement beneath the asphalt material.

In an effort to get more information with which to differentiate between limerock, and a base material falling into the 1I 0 ther ll category, laboratory measurements of the dielectric constants of molded limerock samples at different moisture contents were conducted at TTl. Limerock material for these tests was provided by the District Materials Engineer of District 3 who indicated that the material was typical of those used on roadways in northwest Florida. The results of these measurements are shown in Figure 19 where it is seen that the measured dielectric -constants vary from about 8 to 20 for a range of moisture contents between 6 and 14 percent. The general trend observed from the figure is an increase in the dielectric constant with increasing moisture content. In addition, analysis of radar data taken from the Florida DOT parking lot in Tallahassee (which has a limerock base) showed dielectric constants ranging from 11 to 19, which suggest field moisture contents of between 10 to 14 percent based on the laboratory results. These moisture

39

Asphalt Thickness (inches)

3.5

2.5

1.5 •

.5 a

- - Firat Layer (FC-1) - Total Asphalt Thickness

• I Second Layer (T -11) EE FC-1 Core

o T-11 Core ~ Total Core Thickness

• I· • • •• • • I I ,. • ••• I I.

• I ·0 I 0 • I I. I· I· I·. D I II • ••• . .. . . .-.. . .. . . I • ~ •• • • I .1 • I I • II.. I. I I I • ____ II. • I ... •• I I I

, ........ " 'I · I I'" , #A , .." \ r I ,t. \ _ _ ,. CD - -- "E13 .. ... .. .. ~. tf-I.l--' - , .. "

I

100 200 Distance (ft)

300 400

Figure 18. Plot of Predicted Layer Thicknesses versus Core Thicknesses, Site 6.

Table 7. Summary of Layer Thicknesses and Base Material Type Predicted Blind.

Site Distance Average Total Base Material (feet) Thickness (inches) Type

Aspha 1t Base

1 all 5.6 11. 2 1 imerock

2 all 6.9 9.1* old concrete (or other material, perhaps clay)

3 (LWP) all 4.4 10.3 limerock

3 (LWP) all 4.7 10.5 1 imerock

4 (LWP) all 6.0 - -- old concrete

4 (RWP) all 6.2 - -- other

5-1 o - 1262 4.5 - -- other

5-2a 1262 - 1618 5.0 - -- other

5-2b 1628 - 1664 7.9 - -- other

5-2c 1680 - 3206 5.6 - -- other

5-3 3226 - 3725 4.3 5.9 1 imerock

5-4 3745 - 4244 3.2 5.4 other

5-5 4213 - 4458 3.0 4.5 limerock

5-6 4631 - end 2.8 5.0 1 imerock

6 o - 420 3.3 11.8 1 imerock

* Predicted using radar data for first 500 feet of test site.

41

20.0,-----------------------

• 18. 0 ....... --.--.-... -.-.. ---......... -.. -... -... -............ -.. -.-..... --.... -.-.--.------.. . ._--_ ... - .. _ ...... __ ... _ .... _._ .. _-

-ffi 16. 0 ......... -................ -.... -.--..... -....... -......................................... -.-.-........ -.--.--.-.. -.---.-.-.. ----.--......................... --..... -.--.. -.,. 1i5 c o ~ 14 0 .......... -........................ -............................................................... -.... -... -.. -... --... -.. - ................ - .. ----.. -.-.-... -.-.-.-................... --....... -.--... . ·c t5 Q)

Q)

o 12. 0 .......... -............................ -........................... . ......................... -........................ -..... -.--............ -.............. _.-... -........... -.-........................ --........ -.. .

• 1 o. 0 ....... -........................................................................................... - ................. --.-----.... ---.--................................................ --.--............ -.-.. .

• • 8.0+-----~--~----~----~----~--~~--~----~

6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 Moisture Content (percent)

Figure 19. Measured Dielectric Constants of Molded Limerock Samples.

contents may be reasonable considering the amount of rainfall the Tallahassee area has received prior to the week of the survey.

It is realized that other base materials may have dielectric constants in the same range as those measured for limerock. However, in the absence of any other information other than what were available, and considering that limerock is used widely as a base material in Florida, it was decided to classify a base as limerock whenever the predicted dielectric constant was 8 or greater, and the material was identified to be granular based on the considerations given above. Obviously, further investigations have to be made to establish guidelines for determining whether a material is limerock, or some other granular or stabilized material. In the succeeding phases of this project, a laboratory evaluation using TTl's dielectric probe will be used to obtain dielectric properties for a range of base and subgrade materials.

DETECTION OF CHANGES IN PAVEMENT SECTION

The 1.5 mile survey of Site 5 was carried out in order to test the capability of radar to identify changes in pavement layer structure. The identification was carried out by examining the raw radar data, and by noting locations where significant changes in the radar pattern occurred. Examination of the raw radar data was carried out in two ways: (I) examination of groups of raw radar waves; and (2) examination of a colorized presentation of the radar data.

Figures 20 and 21 show examples of waveform presentations which reveal an abrupt change in pavement structure. Figure 22 shows a colorized presentation of the same change as that shown in Figure 20.

SUMMARY OF BLIND RADAR PREDICTIONS

The thickness analysis for Sites 1 to 4, and Site 6 was carried out at 4 foot longitudinal increments. More detailed analyses at 1 foot increments were carried out on Site 4 and on selected sections of Site 2 to reveal details and spatial pattern of reflection anomalies. Site 5 was analyzed at 10 foot longitudinal intervals.

The results of these analyses can be summarized in terms of the mean values and standard deviation of the thicknesses computed for each detected layer. These results are presented in Table 7. The classification of base material type into the three categories of "1 imerock" , "concrete", and "other" was based on an interpretation of the thickness and dielectric constants of the layers, and on knowledge of possible occurrences in pavement construction as noted earlier. The predicted thickness profiles for all sites are presented in Appendix B.

/

43

xE0 ....... ; ........ : ........ : ........ : ........ ; ........ : ............................ . • •• 0

800.

800 .

. 5-3

· . . . . : ........ ~ . .. . .. : · . . · . "-.

~~..-.:::~---~: : : · . . · . . 5-2 · . .

200 .

. 000

xE0 Figure 20. Waveform Presentation of Major Change in Pavement Structure.

Figure 21.

xE0

800.

600.

400.

200.

.000

. t~; . ~'~111 ~'WI

,oJ I I': I ~ I ,~_. -..'

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..... I.~ .... ~' ';\ .. :. t\ ... ~ ........ 'L'r,' •• 1:.;~--:--:'.~-_~~"'7 .. ,( ... : . .::. .. ,:,~ ..... _: -___ ...,.:...,....;-.......--....:.-.-----...--*-.-r_--..: - .. ',I, Jly . '\ '" - 't '...,. ----- ..... ----- . . . -.

\~::::::} ~ \~::::::~: ~. ~ ~ ~ - ~ : : : :

1 .

xE0 Waveform Presentation of Localized Thickening of Asphalt Layer in Site 5.

! 2455'

GROUND-PENETRATING RADAR SURVEY U.S. Highway 90, Tallahassee, Florida

FLORIDA DOT - SECT S-L - August 7, 1991

! )I't '

, " t'l I J II

I, I'

"

! 3198'

*Each TIC mark = 1" Travel Distance -+-+

Feature

SU A B T

Description Location (ft.)

Pavement Surface Asphalt Base Interface Base/Subbase Transition

4129 4129 4129 3198

Depth (in.)

o 3.5 6.2

Green Dark Blue Dark Blue

NOTE: After the Transition asphalt base and base/subbase are both positive interfaces

B

T 4129'

Figure 22. Colorized Representation of Radar Data Showing tne Chanqe from Sectior: 2

to Section 3 of Site 5.

46

CHAPTER 5. COMPARISON OF RADAR PREDICTIONS WITH GROUND TRUTH DATA

Three types of thickness calculations were made using the radar data. These were:

1. Blind: These are the results of the original data analysis, as presented in Table 7. These predictions were made without any prior knowledge of the pavement structure at each test site.

2. Adjusted: These results were obtained for sites 1, 4L, and 4R using adjusted analysis procedures based on pavement structure information provided by the cores.

3. Calibrated: These are the results generated by calibrating the data for each site by the results of the first core taken from each site.

The purpose of these three calculations was to assess the accuracy of the radar data vs. the need for supporting information. The "adjusted" data represents the improvement in the results which could be achieved by knowing more about the pavement conditions encountered in this study. In essence, the adjustment represents how the interpretation of the radar data might have been done differently had supporting information, such as on layering of the asphalt, been available, or there was prior radar experience with the pavement section encountered. This knowledge would accumulate with experience and could be applied to future analyses. The "calibrated" data represents the accuracy which could be achieved if cores were regularly collected in conjunction with the radar survey.

The data from these three types of analyses has been compared with the core data in two ways: (1) through comparisons of the average layer thickness using radar vs. the average layer thickness using cores; and (2) through a statistical comparison of the means of the radar and core data. The latter comparison takes into account the fact that the cores are only a sampling, and that the real mean thickness may vary somewhat from the average of the cores.

Figures 23 and 24 compare the average layer thickness values for the three types of analyses, with the core data, for asphalt and base thickness, respectively. Table 8 summarizes the differences between the core data and the three types of radar analyses. Tables listing all of the individual core values and the blind radar predictions at each core location are presented in Appendix C.

DISCUSSION OF ASPHALT THICKNESS DATA

The data of Table 8 show the blind radar predictions to be very close to the cores (within 0.1 inch) for 3 of the 5 sites. The most significant deviation in the blind data is in Site 4, where the blind predictions underestimate the asphalt thickness by over 1 inch.

47

Asphalt Thickness (inches) 8~~----------------------------------'

6 .................... .

4 ....

2 ....

OL-~~L-~~~--~~~

2 3 4L 4R 6 1

Pavement Section

_ Adjusted

o Blind

o Calibrated

~ Core

Figure 23. Comparison of Means of Radar Predictions for Asphalt Thickness with the Mean Thicknesses From Cores.

Base Thickness (inches) 14~-------------------------------------'

12 ................................................................................................. .

10 ............................................ -8 0

6 0 ... ~

4

2

o 2 3 6 1

Pavement Sect,ion

Figure 24. Comparison of the Means of the Predicted Base Thicknesses with the Means of the Measured Thicknesses.

Adjusted

Blind

Calibrated

Core

Table 8. Calculated Differences Between Means of Predicted and Measured Thicknesses.

ASPHALT

Section Difference (in) between Core and: I

Blind Adjusted Calibrated

1 . 1 .1 · 1 2 . 1 . 1 .4

3 .5 .5 · 1 4L 1.2 .5 .5

4R 1.1 .7 .1

6 .02 .02 .02

Average .50 .32 .20

BASE

Section Difference (in) between Core and:

Blind Adjusted Calibrated

1 2.1 1.0 .5

2 .6 .8 .2

3 .7 .6 · 1 6 0 0 0

Average 0.85 .600 .200

50

The radar data for Site 4 showed a highly variable reflection from a layer of asphalt which was later identified to be a sand asphalt hot mix (SAHM) layer from the cores. Based on the fact that this reflection coincided with the reflective cracks in the asphalt, it was suspected that this variation was due to moisture trapped within the layer boundaries. The existence of this condition could introduce errors in the computation of the thickness of the sand asphalt layer.

An air voids analysis of the SAHM layer at 2 locations showed that the location with the high reflection had a relatively high air voids content of 9.7 percent at the top of the sample compared to air voids of 3.8 and 5.3 percent at the middle and bottom of the sample respectively. This gradient in the air voids within the SAHM sample may lead to conditions of trapped moisture as suggested above.

In order to adjust for this condition, the analysis was altered to ignore the variability of the SAHM reflectivity and use a baseline value. The "adjusted" results for Sites 4L and 4R represent the predictions based on this modification which was found to improve the agreement between the predicted and measured thicknesses. Such an adjustment may be implemented in the future when a highly variable asphalt layer reflection is observed in the radar data.

The core calibrations for asphalt thickness produce a further reduction in the average deviation between radar results and cores. Note, however, that there is not always an improvement for a particular site (e.g., Site 2). This can occur if the particular core is not representative of the deviation between radar and actual thickness.

DISCUSSION OF BASE THICKNESS DATA

The blind radar results for base thickness show a deviation from cores which ranges from 0 to 2.1 inches. Of particular concern was the 2.1 inch deviation for Site 1. A review of the radar data suggested that the layering within the asphalt was not fully accounted for in the blind analysis. The section was re-analyzed using a different model for the asphalt layers, yielding a higher dielectric constant for the base. This new analysis resulted in the "adjusted" value shown in Figure 24 and Table 8.

Using this adjusted value, the deviation for Site 1 is reduced to 1 inch, and the average deviation between core and radar data for the four sites is reduced from 0.85 inches to 0.60 inches. The use of core calibrations for base layer thickness yielded a further improvement in the accuracy. It is observed from Table 8 that a maximum deviation of 0.5 inches, and an average deviation of 0.2 inches is obtained after calibration of the base thickness predictions.

51

STATISTICAL COMPARISON OF MEANS OF PREDICTED AND MEASURED THICKNESSES

In comparing the radar predictions against the measured thicknesses, statistical tests were also conducted to draw inferences concerning the difference between means of the predicted and measured thicknesses. This was done in recognition of the fact that both the radar predictions and the core measurements are based on sampled data which will always have a certain amount of sampling error. Consequently, tests of significance were carried out to infer whether the difference between means of predicted and measured thicknesses for a given site may reasonably be attributed to random error, or whether the difference is significant enough to make such a conclusion not plausible. The results from this evaluation are summarized in Figures 25 and 26. In both figures, each vertical line represents the interval within which the true difference between means of the core and predicted thicknesses may be found at a probability level of 95 percent. A point estimate of this difference is also shown as a horizontal tickmark on each vertical line. Confidence intervals were evaluated for Sites 1 to 4, and Site 6, for the different types of predictions that were made, i.e., Blind (B), Adjusted (A), and Calibrated (C).

The results summarized in Figures 25 and 26 generally reinforce the discussions presented previously, and mirror the trends in the data shown in Table 8. However, the figures provide a bit more information since they tell whether the differences between means of predicted and core thicknesses summarized in Table 8 are statistically significant. Specifically, confidence intervals which cross the horizontal line, y=O, indicate that the difference in means between predicted and core thicknesses are not statistically significant.

It is observed from Figure 25 that in 3 of the 5 test sites, the means of the blind predictions for asphalt thickness were not significantly different from the corresponding core means. Not surprisingly, these were for Sites 1, 2, and 6 where the differences were within 0.1 inch as noted earlier. It is also observed from Figures 25 and 26 that, for cases where the means of the blind predictions were significantly different from the corresponding measured means, calibration generally improved the agreement between means as evident in the shift of the confidence intervals towards the horizontal line, y=O. For these cases, the agreement was improved to the point where the discrepancies were not statistically significant. The only case where this was not achieved was in the prediction of the asphalt thicknesses for Site 4L. However, it is observed that the discrepancy was still reduced with calibration, and it is possible that with another core, the difference in means after calibration may have turned out to be statistically insignificant.

52

U1 w

95% Confidence Intervals 1.5,---------------------------------------------~

.-en Q) .c 1-· .. ·· c..:> c --en -c C'il Q)

E .:!: C'il

0.5- . ... . .. ~ . ..... . ....... ~.. ..... . .... .

..c Q.. -en - -C'il C

OT-T---T---+-----------+-----------------------~--~r--~-~ -

Q) c..:> c Q) ~

Q)

;t:: -0.5-···........····· .. ······ ..................................... .

0

-1~TI--~I--~I--~I--~I---,I---,T---,I---,-I--~I---,-I--,-I--~I--~1

1 8 1 C 28 2C 38 3C 4L8 4LA 4LC 4R8 4RA 4RC 68 6C Site

Figure 25. 95% Confidence Intervals for the Difference in Means of the Predicted Asphalt Thicknesses and the Measured Thicknesses.

(J1

~

95% Confidence Intervals 1.0~----------------------------------------------~

0.5-.. .. ... HHH ...... .

.-en (]) ..c () 0.0+---------~------r-----------~------------~------4~--~ c: -en c: ~ -0.5-" I-

(]) t--

E (]) en -1.0- -~ .Q

c: (])

-1 .5- .... H.........HHH. . .....

() c: (]) ~

(]) -2.0- ... H"'H~H'

~ 0

_ 2.5 - ......... H .. H...HHH...·...H .. H. .. .HH..HH ..... H........................H ........................................................ · ....... H .. .

-3.0J---,-1-----,1,------,1-------,-1----~1-------~1-----,1,-----~1--~

18 1A 1C 28 2C 38 3C 68 Site

Figure 26. 95% Confidence Intervals for the Difference in Means of the Predicted Base Thicknesses and the Measured Thicknesses.

IDENTIFICATION OF BASE MATERIAL TYPE

Comparisons of the predicted base material type given in Table 7 with the base material identified from the ground truth surveys at the different sites (Table 4) show that the base material type was predicted correctly for 4 of the 6 test sites. The reflection from the bottom of the base for Sites 1, 3, and 6 were all well-defined, and were characterized by an inverted peak which was also observed in the radar data taken at the Florida DOT parking lot that was known to have a limerock base.

However, as mentioned earlier, the base/subgrade interface may also be indistinguishable if the dielectric constants of the 2 layers happen to be very similar. This was found to be the case for Site 2 which was found to have a limerock base as Site 1 but for which the base/subgrade interface was not as distinct. From the field survey, the subgrade material in Site 2 was observed to be a reddish brown sandy material. This subgrade material was also found in Section 1 of Site 5 which also has a limerock base, and for which the radar data did not show a distinct base/subgrade interface. In contrast, the subgrade material in Sites 1, 3, and 6 was a grayish fine sandy material. Obviously, further investigations have to be made to establish guidelines for determining whether a material is limerock, or some other granular or stabilized material . This capability is expected to improve as knowledge on Florida base materials is accumulated. For example, the high porosity characteristic of sand asphalt mixtures, found in Sections 3 to 6 of Site 5 will be useful in identifying this type of material in future radar measurements.

The identification of the base material beneath the left wheel path of Site 4 was based on visual observations of transverse cracking at this site, and the regular occurrence of peaks in the spatial variation of the dielectric constant of the asphalt layer determined from the radar data. The predicted dielectric profile for the second asphalt layer of Site 4L is illustrated in Figure 27. Note the regularly spaced peaks in the figure which indicate the presence of a jointed concrete base. It is probable that these peaks are caused by moisture infiltrating into the transverse cracks at the pavement surface, and entering laterally between asphalt layers. The reflection from the bottom of the base on this site was also weak further indicating the presence of an old concrete base layer.

LOCATION OF SECTION CHANGES IN SITE 5

Table 7 presented in Chapter 4 identifies the locations of changes in structural section from the radar data analysis. The core data from selected locations within these section were used to verify the validity of the segmentation of Site 5. Comparison of Table 7 with Table 4 show that, from Section 1 to 3 of Site 5, the changes in base material mirror the segmentation of the site into Sections 1, 2a, 2b, 2c, and 3. In general, it was possible to detect changes in pavement section from the

55

U1 0'>

xE0 18.0

14.0

10.0

6.00

2.00

...... ':" 'La~er2' '~-i e l'e:e1:r i'~" Gon:$·tan t······· .; ....... . · ...... : ....... ':' ...... ':' ....... : ....... : ....... -: ....... ':' ...... ':' ...... . · . . . . . . • •••• , •••••••••••••••••••••••••••••••••••••••••• - ••••••••••••••••• , ••••• I •• · . . . : : : · .... , ........ : ........ : ........ :. ....... : ....... ~ ........ : ....... '1.' ...... . · . . . . . ~ .. · . . . .. ···f····:·· 'j' ... : ........ ~ ....... ; ....... ~ .... l' .. :., . i ... illlr ..... . ". ~J "1\)l..· .~. ~ .... 'f.~ .. -1- .... ~ .. ~ .... ! ....... ~. '1' 'I\I~ ~'I~I n!I·lq~· r·· .. . }lllli: J.~ .. 1I~~:~ •. ~1~bJ~~\v.wl.0~~: :~r J:::::t:::::::

· . . · . . . . · ................ , ................ -......................................... . · . . . . . . . : : : : : : : : · ............... , ................................. -......................... . · . . . . . . . · . . . . . . .

1250 1350 1450 1550 165'l:E0

Figure 27. Predicted Dielectric Constants for Second Asphalt Layer, Site 4, LWP, Showing Regularly Spaced Peaks.

radar data. Only one section, 5-4, was erroneously identified as being different from the surrounding pavement.

A more detailed evaluation of Section 4 showed that the radar response from this section is highly variable. Evidently this variability was inadvertently mistaken for a change in structure. A review of the colorized data confirmed that there was no obvious change in pavement structure in.this area. The core data from Section 5-4 show the base material to be approximately 5.5 inches of SAHM. Laboratory tests on these cores at TTl indicate that the SAHM base is a porous material with a high potential for local moisture entrapment. This is indicated by the high air voids measured for this material (see Table 5 of Chapter 3). This characteristic may be responsible for the high variability observed in the radar data.

It is noted that although the base material is sand asphalt from Section 4 to Section 6, there is a localized thickening of the asphalt layer at the end of Site 5 that was observed from the radar data. This localized thickening, which was the reason for establishing Section 5, was confirmed from the coring done on this section, where a core with a measured asphalt thickness of 13.60 inches and a SAHM base thickness of 5.60 inches was obtained at a footage of 4481.

57

CHAPTER 6. ASSESSMENT OF RADAR PREDICTIONS

LAYER THICKNESS PREDICTIONS

The means of the blind predictions for 3 of the 5 test sites (Sites 1, 2, and 6) were found to be within 0.1 inch or 2 percent of the corresponding measured means. From statistical testing, the discrepancies between means for these sites were found to be not significant. The site with the largest error was Site 4 which has a sand-asphalt hot mix layer. Analysis of the error at this site points to this layer as one which has not been properly modeled in the radar data analysis. Laboratory tests indicate that the porosity of this material lends itself to local infiltration of moisture, which can lead to overestimating the dielectric constant, and underestimating the thickness.

This condition associated with the SAHM layer can be detected in the future by recognizing the rapid fluctuation in the layer properties. Once the discrepancy in the results was made clear, a re-analysis was implemented using the "background" level layer dielectric constant.

This particular characteristic of sand asphalt mixture also appeared to be responsible for the initial erroneous identification of Section 4 in Site 5 as different from the surrounding pavement. The problem of pavement structure identification was addressed by paying less attention to the details of the radar response, and focusing on the broader spatial pattern.

Since errors in this Phase I effort were associated with the presence of a SAHM layer, it would be useful in future work to be aware of the presence or use of such a paving material. In this way, some of the potential analysis problems can be anticipated and the appropriate methods can be incorporated into the analysis.

PREDICTION OF BASE MATERIAL TYPE

Unlike the determination of pavement layer thickness, there is no previous work supporting the determination of pavement material type using radar data. However, the radar signal is influenced by material properties such as density, moisture content, presence of reinforcement, and material composition. Consequently there is some basis for an effort to develop such a capability.

The discussions in Chapter 4 showed some of the criteria which were used to identify base material type. These criteria were based on the judgement and field experience of the project investigators, but not on any past field data. The data collected in Phase I, therefore, constituted the first supporting data for the determination of base material type. Of particular concern is the differentiation between limerock and other granular or stabilized base layers. The results

58

------------------------ -----------------

indicate that this is a capability which will have to be developed over time, as knowledge on Florida base materials is accumulated. In this regard, one important item learned in Phase I is the use of a low density SAHM layer as a base material. This material showed up in the radar data with a negative reflection at the top and a large positive reflection at the bottom. In the future, the presence of these characteristics can be used as indicators of a SAHM base layer.

Already, a significant amount of data has been collected from the ground truth surveys with which to begin evaluating characteristics of various Florida base materials that may be used to establish decision rules for classifying a base as limerock, concrete, or "other" material. Should the decision be made to continue with the project, one of the research areas in Phase IIA would be to develop a data base of base material types and associated radar signatures, and to develop decision rules that can be used to classify a base into the aforementioned categories. These will be needed for the district and statewide radar surveys planned for Phase lIB and Phase III respectively.

PREDICTION OF BASE LAYER THICKNESS

For sites where predictions of base layer thickness were made, the means of the predicted thicknesses were found, on the average, to be within 0.9 inch of the measured means, and that the discrepancies were significantly reduced with calibration. For 1 site (Site 6), the mean of the blind thickness predictions was not statistically significant from the measured mean.

It was not possible for all cases to predict the base thickness due to the inability to detect the basejsubgrade interface from radar measurements made at the different sites. In Site 2 for example, the reflection from the top of the subgrade was generally weak for the first 500 feet of the site, and becomes very faint thereafter. Consequently, predictions of base thickness for this site were only made for the first 500 feet.

Laboratory tests of soil samples from Site 2 test pits revealed base and subgrade layers that were dielectrically similar. This is observed from Table 9 which show measured dielectric constants for base and subgrade samples obtained at various test pits.

In the laboratory, dielectric measurements were made on samples of base and subgrade materials compacted at different moisture contents. The dielectric constants given in Table 9 correspond to field moisture contents obtained from moisture content determinations on dry samples of base and subgrade materials taken from test pits. Note how much different the base and subgrade dielectric constants are for Site 1, where the radar reflections from the top of the subgrade are clear, as compared to the differences in base and subgrade dielectric constants for Sites 2 and 5-1, where the basejsubgrade interface was not clearly seen in the radar data. Also, observed from Table 9 that the absolute

59

Table 9. Measured Dielectric Constants of Base and Subgrade Materials from Test Pits.

Site Location Dielectric Constant Absolute (feet) Difference

Base Subgrade

1 350 11.04 6.28 4.76

1 780 13.38 4.97 8.41

2 260 6.93 9.37 2.44

2 890 10.50 9.90 0.60

5-1 600 8.72 7.55 1.17

60

difference in base and subgrade dielectric constants is higher at location 260 than at location 890. This is consistent with the observation made previously that the reflections from the top of the subgrade are generally weak for the first 500 feet and become very faint thereafter.

The inability to detect a base/subgrade interface may also be attributed to the presence of a concrete layer within the pavement. This was found to be the case for Site 4L where the radar data did not show any clear base/subgrade interface. From previous experience and from measurements made in the laboratory, concrete is a lossy material characterized by a dielectric constant with a relatively high imaginary part. This characteristic is responsible for the attenuation of the energy of the radar wave propagating through concrete. Thus, it is generally difficult to observe a reflection from the bottom of an intact concrete layer.

The base/subgrade interface was also not detected in the radar data for Site 4R. From the test pits, the base material on this widened section of Site 4 was identified to be soil cement. This base layer is overlying a reddish brown sandy subbase on top of a grayish fine sand subgrade. Dielectric probe measurements on a sample of the soil cement material showed the imaginary part of the dielectric constant to be significantly lower than those measured for concrete, and were comparable to the values obtained for asphalt. Consequently, for this case, the inability to detect the bottom of the base from the radar data, may be due to similarity in the dielectric constants of the soil cement~ and the underlying subbase material.

61

CHAPTER 7. CONCLUSIONS

The capability of current GPR technology to predict pavement layer thicknesses and identify base material type was evaluated herein using test sites that covered a variety of Florida pavement materials, with asphalt layers that consisted of multiple lifts, and on which no supporting informa­tion were initially provided that could be used to interpret the radar measurements made. Based on the results presented in this report, it is con­cluded that a potential exists for developing the technology to a level where it can be reliably used to predict pavement layer thicknesses and classify base material type on an inventory basis. What needs to be done is to adapt existing radar analysis procedures to Florida pavement conditions. This is indicated by the Phase I results that are summarized below:

1. Of the 5 sites considered in the demonstration of radar's capability to predict layer thicknesses, the means of the blind predictions for asphalt thickness on 3 sites (Sites 1, 2, and 6) were within 0.1 inch or 2 percent of the corresponding measured means. It was also found that on Site 4 where the largest discrepancies between means of predicted and core thicknesses were obtained, it was possible to reduce the discrepancies to within 10 percent of the measured means when the effect of the sand asphalt hot mix layer was correctly accounted for in the analysis procedure. This result reflects the potential improvement in prediction capability that may be obtained as knowledge and experience with Florida pavement materials are accumulated and the analysis software is adapted for these materials. It also indicates the potential improvement in accuracy that is possible when supporting information are available for interpreting the radar measurements. This information need not necessarily come from cores.

2. For sites where predictions of base layer thickness were made, the means of the predicted thicknesses were found, on the average, to be within 0.9 inches of the measured means. In one site (Site 6), the mean of the blind predictions was equal to the measured mean. The largest discrepancy between means (2.1 inches, or 23 percent of the measured mean) was obtained for Site 1. This discrepancy was reduced to 1 inch (11 percent of the measured mean) when the layering within the asphalt was correctly accounted for in the analysis. In all cases, the differences between predicted and measured means for base thickness were reduced to within 0.5 inches after calibration.

3. The base material was correctly classified for 4 of the 6 test sites, or for 8 of the 14 classifications that were made (1 in each of Sites 1, 2, 3, and 6; 2 in Site 4; and 8 in Site 5). The presence of a concrete base was found to be indicated by the appearance of regularly spaced peaks in the dielectric profile of the asphalt layer, attributed to moisture infiltration through transverse cracks on the surface, and by the absence of a clear reflection from the bottom of the concrete base due to the lossy characteristic of this material. On the other hand, the presence of a sand asphalt base was found to be indicated by the variability in the reflections from the base, and by negative and

62

positive reflections at the top and bottom of the layer respectively. These results again show the benefit of knowing certain characteristics of a given material that would leave specific signatures in the radar data which may be used for identification. The task at hand is to establish a data base of base material types and associated radar signatures which may be used to reliably discriminate between limerock, concrete, and "other" base material types.

4. In general, radar was used to detect changes in pavement section in Site 5. Only 1 section (Section 4) was erroneously identified as being different from the adjacent sections. This was again attributed to the presence of a SAHM base layer which was associated with highly variable reflections in the radar data. This result again shows the benefit of knowing something about a given material that may be useful for correctly interpreting the radar data.

In summary, it is concluded that existing radar technology can be used with success to predict layer thicknesses and identify base material type. Implementation of this technology for these purposes on a network wide scale is feasible, and will require adaptation of current analysis procedures to handle Florida pavement materials. This will require evaluation of a variety of Florida pavements to develop guidelines for interpreting and analyzing radar data.

63

REFERENCES

1. Berg, F, Jansen, J.M., and Larsen, H.J.E., Structural Pavement Analysis based on FWD, Georadar, and/or Geosonar Data, Proc. 2nd International Conference on the Bearing Capacity of Roads and Airfields, Plymouth, U.K. 1986.

2. Rosetta, Jr., J.V. Feasibility Study of the Measurement of Bridge Deck Overlay Thickness using Pulse Radar. Report R-35-80, Prepared for the Massachusetts Department of Public Works by Geophysical Survey Systems, Inc. Salem, New Hampshire. 1980.

3. Eckrose, R.A., Ground Penetrating Supplements Deflection Testing to Improve Airport Pavement Evaluations, Non-Destructive Testing of Pavements and Back Calculation of Moduli, ASTM STP 1026, A.J. Bush III and G.Y. Baladi, Eds., ASTM.

4. American Society for Testing and Materials. Standard Test Method for Determining the Thickness of Bound Pavement Layers using Short Pulse Radar. ASTM Standard 04748-87. 1987.

5. Maser, K.R., "Automated Detection of Pavement Layer Thickness and Subsurface Moisture using Ground Penetrating Radar." Report submitted to the Texas Transportation Institute and the Texas State Department of Highways and Public Transportation. November 1990.

6. Maser, K.R. and Scullion, T. "Automated Pavement Subsurface Profiling Using Radar - Case Studies of Four Experimental Field Sites." TRB Preprint No. 91-0796, January 1991.

7. Maser, K.R. "Radar Pavement Thickness Evaluations for Varying Base Conditions: Case Studies at 14 Kansas Sites." Report Prepared for the University of Kansas, Department of Civil Engineering. December 1991.

8. Roddis, W.M. Kim, Maser, K.R. ad Gisi, A.J. "Radar Pavement Thickness Evaluations for Varying Base Conditions. TRB Preprint No. 920682. January 1992.

9. Lau, C., Scullion, T., and Chan, P., "Using Ground Penetration Radar Technology for Pavement Evaluations in Texas," paper submitted for the 3rd International Conference on Ground Penetrating Radar, Finland, June, 1992.

10. Maser, K.R., "Bridge Deck Evaluation Utilizing High Speed Radar." Report prepared for the NH Dept of Transportation. Bureau of Materials and Research. November, 1991.

11. Maser, K.R. and Rawson, Alan. "Network Bride Deck Surveys Using High Speed Radar: Case Studies of 44 Decks." TRB Preprint No. 920751. January 1992.

64

-- ------ -- -- -------- ------------------ ------

APPENDIX A

TABLES OF THICKNESS DATA FROM GROUND TRUTH SURVEYS

65

----- ---------------- -------------

Table A.l. Measured Asphalt and Base Thicknesses at Centerline of Site 1.

Location Total Thickness (inches) (ft)

Aspha It Limerock Base

200 5.90 9.20

300 5.60 9.80

390 5.60 9.50

590 6.25 8.50

790 5.50 9.60

990 5.55 9.00

1190 5.90 9.00

1290 5.30 9.00

1440 5.50 8.70

66

Table A.2. Measured Asphalt and Base Thicknesses at Centerline of Site 2.

Location Total Thickness (inches) (ft)

Aspha It Limerock Base

30 6.60 9.00

130 7.00 9.00

240 6.70 8.00

300 6.70 8.30

400 6.60 8.20

580 7.10 8.70

600 7.10 8.70

780 7.50 8.50

1050 7.05 8.30

1390 7.10 8.80

67

Table A.3. Measured Asphalt and Base Thicknesses at Left Wheel path of Site 3.

Location Total Thickness (inches) (ft )

Aspha lt Limerock Base

50 4.35 9.60

140 4.90 10.00

270 5.00 9.60

420 5.00 8.30

640 4.50 10.20

950 5.10 10.20

1090 4.70 9.50

1470 5.90 - --

68

Table A.4. Measured Asphalt and Base Thicknesses at Left Wheel path of Site 4.

Location Total Thickness (inches) (ft )

Aspha It pee Base

100 7.20 8.50

300 6.90 - --

400 7.15 - --

490 7.95 - --

610 6.50 - - -

690 7.10 - - -

790 6.50 8.70

920 7.30 - - -

990 7.60 - - -

1260 7.20 - - -

l390 7.20 8.25

69

-------------------------------------- -

Table A.5. Measured Asphalt and Base Thicknesses at Right Wheel path of Site 4.

Location (ft )

200

300

490

590

690

890

990

1090

1260

Total Thickness (inches)

Aspha It Soil Cement Base

7.30 8.60

7.00 7.50

7.10 4.00

7.20 6.50

7.20 6.50

7.70 7.00

7.70 5.50

7.50 7.50

7.00 7.20

70

Table A.6. Measured Asphalt and Base Thicknesses at Left Wheel path of Site 5.

Section Location Total Thickness (inches) Base ( ft) Materi a 1

Aspha It Base

5-1 640 4.10 9.50 Limerock

5-1 1190 4.05 9.20 Limerock

5-2a 1340 6.80 7.30 Reddish brown sand

5-2a 1440 6.20 10.30 Reddish brown sand

5-2a 1560 6.70 11.50 Reddish brown sand

5-2b 1640 8.55 5.70 Limerock

5-2c 1880 6.75 9.50 Reddish brown sand

5-2c 2210 8.00 9.00 Reddish brown sand

5-2c 2470 6.50 10.90 Reddish brown sand

5-2c 2870 6.75 8.90 Reddish brown sand

5-2c 3170 8.00 9.20 Reddish brown sand

5-3 3280 5.50 5.60 SAHM

5-3 3460 4.90 5.50 SAHM

5-3 3610 5.10 5.50 SAHM

5-4 3810 5.00 5.40 SAHM

5-4 3960 5.55 5.70 SAHM

5-4 4160 4.00 5.50 SAHM

5-5 4260 4.20 5.00 SAHM

5-5 4400 3.70 5.60 SAHM

5-5 4481 13 .60 5.60 SAHM

5-6 4700 5.15 5.50 SAHM

5-6 5940 3.70 5.35 SAHM

71

Table A.7. Measured Asphalt and Base Thicknesses at Left Wheelpath of Site 6.

Location Total Thickness (inches) (ft)

Aspha lt Limeruck Base

50 3.10 11.40

150 3.05 10.80

250 3.00 11.20

350 3.10 13.60

72

Table A.8. Measured Lift Thicknesses of Cores from Centerline of Site 1.

Location Lift Thickness (inches) ( ft)

FC-2 + Type II Crack Leveling Type I Binder Type S Overbuild Relief

200 1. 00 0.50 0.60 0.50 1.10 2.00

300 0.90 0.60 0.60 0.50 1.00 2.00

390 1.10 0.50 0.60 0.30 1. 00 2.10

590 1.00 0.70 0.60 0.30 1. 20 2.25

790 0.80 0.50 0.60 0.50 1.00 2.00

990 1.00 0.60 0.60 0.20 1.00 2.20

1190 1. 10 0.50 0.50 0.50 1.00 2.20

1290 0.90 0.50 0.60 0.20 1.00 1.85

1440 0.90 0.50 0.70 0.20 1.00 2.00

73

Table A.9. Measured Lift Thicknesses of Cores from Centerline of Site 2.

Location Lift Thickness (inches) (ft)

FC-2 + Type II Crack Leveling Type II SAHM Type S Overbuild Relief

30 0.90 0.70 0.60 0.20 3.20 0.90

130 0.80 0.60 0.60 0.20 3.40 1.10

240 0.80 0.60 0.70 0.20 3.20 1.00

300 0.90 0.50 0.70 0.20 3.30 1.10

400 0.70 0.70 0.70 0.20 3.10 0.80

580 1.00 0.60 0.80 0.50 3.10 1.10

600 1.00 0.50 0.70 0.60 3.10 1.00

780 0.90 0.80 0.80 0.25 4.00 1.00

1050 1.00 0.70 0.50 0.30 3.60 0.70

1390 1.00 0.60 0.50 0.40 3.70 0.80

74

Table A.10. Measured Lift Thicknesses of Cores from Left Wheelpath of Site 3.

Location Lift Thickness (inches) (ft)

FC-2 + Type II Crack Leveling Type S Type S Overbuild Relief

50 1.10 0.50 0.60 0.50 1.60

140 1.10 0.60 0.50 0.30 2.30

270 1. 20 0.50 0.50 0.60 2.15

420 1. 40 0.50 0.60 0.50 2.00

640 1.30 0.50 0.60 0.40 1. 50

950 1.30 0.50 0.60 0.40 2.00

1090 1.30 0.60 0.60 0.50 1.80

75

Table A.11. Measured Lift Thicknesses of Cores from Left Wheel path of Site 4.

Location Lift Thickness (inches) (ft )

FC-2 + Type II Crack Leveling Type II + Type S Overbuild Relief SAHM

100 1.10 0.70 0.50 0.50 4.20

300 1. 25 0.25 0.70 0.50 4.25

400 0.90 0.85 0.60 0.50 4.70

490 1. 20 0.60 0.55 0.40 5.25

610 1.00 0.50 0.50 0.50 4.00

690 1.00 0.60 0.60 0.30 4.50

790 1.00 0.50 0.50 0.40 4.05

920 1. 20 0.50 0.50 0.50 4.20

990 1.10 0.70 0.50 0.40 5.00

1260 1.10 0.70 0.50 0.50 4.40

1390 1.10 0.30 0.60 0.50 4.40

76

Table A.12. Measured Lift Thicknesses of Cores from Right Wheel path of Site 4.

Location Lift Thickness (inches) (ft)

FC-2 + Type II Crack Leveling Type II + Type S Overbuild Relief SAHM

200 1.10 0.70 0.50 0.40 4.70

300 1. 20 0.20 0.75 0.30 4.25

490 1.10 0.70 0.50 0.30 5.10

590 1.00 0.50 0.50 0.60 4.60

690 1.00 0.60 0.50 0.20 4.70

890 1.00 0.50 0.60 0.50 5.20

990 1. 20 0.40 0.60 0.20 5.30

1090 1. 20 0.60 0.60 0.50 4.75

1290 1. 20 0.60 0.50 0.30 5.00

77

Table A.13. Measured Lift Thicknesses of Cores from Left Wheel path of Site 5.

Section Location Lift Thickness (inches) (ft )

FC-4 Type I Type S SAHM

5-1 640 1. 20 1.10 1. 90 ---

5-1 1190 1. 30 0.90 1.60 - - -

5-2a 1340 1. 40 3.55 - -- 1.10

5-2a 1440 0.85 3.80 - -- 1.00

5-2a 1560 1. 20 2.50 0.90 1.00

5-2b 1640 1.10 3.90 - -- 3.60

5-2c 1880 1.00 2.40 1. 20 0.70

5-2c 2210 1. 25 3.50 1. 40 0.90

5-2c 2470 1.00 2.60 1.00 0.70

5-2c 2870 1.10 2.80 1.60 0.50

5-2c 3170 1.80 2.20 1.00 1.60

5-3 3280 1.00 3.40 1. 25 - --5-3 3460 0.80 2.90 1.00 ---5-3 3610 0.80 2.90 1.40 - --

5-4 3810 0.80 3.20 1.00 - --

5-4 3960 0.80* 2.30 1. 50 ---

5-4 4160 1. 20 1. 30 1.40 ---5-5 4260 1. 60 1. 10 1.60 - --

5-5 4400 1.80 1. 00 0.80 - --

5-5 4481 1.80 2.50 2.70 6.20**

5-6 4700 1. 90 0.90 2.30 - --

5-6 5940 2.10 0.90 1.00 - --

* first lift classified as FC-2 from location 3960 onwards ** Type I lift

78

ST

- --- --

0.50

0.75

1.00

- --

1.00

0.90

1.00

1.40

1.30

- --

- --

- --

- --

- --

---- --- --

- --- --

- --

Table A.14. Measured Lift Thicknesses of Cores from Left Wheel path of Site 6.

Location Lift Thickness (inches) ( ft)

FC-l Type II

50 1. 50 1. 60

150 1.10 1.80

250 1. 25 1. 75

350 1.30 1.80

o.

79

<

APPENDIX B

BLIND PREDICTIONS OF LAYER THICKNESS PROFILES OF FLORIDA TEST SITES

80

co I-'

~.0

1.0.0

6.00

Figi!rpG,l.

~.0

10.0

6.00

...................... T·o·ta·!-· ·Th·i Clo¢neS5 ........... ' ............... . • • • • • • 0 •

• , Q 8 • •

o •• 0

o ., •

• 0" • · ..... ': ....... ': ........ :' ....... ~ ....... : ....... ~ ....... ': ........ :' ...... . · . . . . . . . : : : : : : : : : : . : : : : :

· ...... : ........ : ........ : ........ :.. ....... i ...•... .: ........ : ...•.... : .......• · . . . . . . . : : : : : : : : : : : : : : : :

· ..... 0: ....... 0: ........ :0 ....... ; ....... i ..... I . ~ ....... 0: ........ :0 ...... .

j ~ ~ ~ ~ ~ ~ ~ ~'I,;-. ..,j ... , ..... ,....'I), r'r';'(+ ,~" • L J;-,-..~. . . . . . • . . . . . . . . . . . . . . , .• .,. . . . , . . ... . . . . . . ... . . . . . . . ,.,. ".4~.,., . .,.,...,.,.... .'., '.. r:' I • ~. • ..... ........ ..-<-' ...

"1 .: ~ • ' • ..1. ~ .~ .... \ .......... --. .. ,Jl.',.., ... ,........ . ............. ',.."" ............ .,. .... ~-~~ : : T: ~/T" ... :.......... : \,1.. :.,: .: • • • "0' • • · . .

200. 6~0. Distance

'1000 (. f"ee t )

Predicted Asphalt Total Thickness, Site 1,

1400

· ..... ':' ...... ';' .... T-~·ta 1· '';l'h'i c~~ness: ';' ....... : ....... ':' .... "':' ...... . · . . . . . . . . • • • • • • • I •

• • I • • • • • • · . . . . . . . . · . . . . . . . . · ..... ': ....... ': ........ :' ....... : ....... : ....... : ........ : ........ :' .... , .. : .. , ... . · . . . " .. • • 0 • •• •• • • • • •• o. • • • • • 0 ••

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• 0 • • • 0 0 • 0 • •• , 0 • '00 , ••••• 0 0 0 ••••• 0 0 0 0 0 •• 0 • 0 0 " ••••• 0 0 I •••••• 0 ......... 0

0' ••• 0 •••

00 •••• 0 0 0 I' 0 0 •••• 0

o • 0 • • • • • • · . . . . . . . . o 0 • • • • • • • · . . . . . . . . · . . . . . . . . o • • • • • • • • · ...... ; ........ ; ........ ;. ~ ...... : ........ ~ ........ ; ........ ; ........ ; ........ ; ....... .

..Jrr;',... : ri,J ." , ~, tfo :. ..... ..,. "I./~ ~\; ,'~.)~ .; ;

f~:~ .. t .~~~·~>f<~':' .. -.' .1. ~rll. ~ .. i~f'~<' f~· ... <~~·.':'r .............. . 1400 180~0

Figure B.2. Predicted Asphalt Total Thickness, Site 2.

co N

xEm.0 ,,' ," ':""'" ':"" 'T'q'ta -1, '~h'i c~ness ':""'" ';""'" ':"'" '" • • • • ~ 0 0

I · . . . . ~ . · . . . "" . • 0 • • 0 0 0 . . . . .

• ••••• ': ••••••• ': •••• , ••• :' ••••••• : ••••••• : ••••••• -: ••• '0' •• · . . . . . · . . . . . · . . . . . · . . . . . · . . . . . 9.00 · . . . . . • ••••• '0' •••••• 'I' •• , ••• '.' ••••••• .,. ...................... " ••••••• '0' •••••••••••••• · . , . . . · . . . . . · . . . . . · . . . . . · . . . . . · . . . . .

· ...... : ........ : ........ : ........ ~ ....... ! ....... ..: . . . . . .. . ....... : ....... . · . . . . . · . . . . . · . . . . . · . . . . . · . . . .. . 5.00 , ,,,"'.' , , ~ , III' ""~ "~':',"; " ":' 'I;~i ' '~' ':'" ',~' ":' " " , ',": • .1.'" ',L,I..::" , "'; .... ' ''''I,'' ':" , " '"

.,.' ..., .... ' .. , • .,....... Or .... r "'I ".,L. ,I" I... '0 • • ".-............ ,.,..· ____ t .. • -..:.. , ,.'·.l \..... ,. ........ _.... " .. : I • .., ....... : .. -. : "'""," - .. r t.(~"''''r'''~''': :.~) ~ roo- "'~-r'

200. 8~0 . 1. 000 DIstance <. f"eet:>

1400

Figure B,3, Predicted Asphalt Total Thickness, Site 3, LWP.

><£m.0

9.00

5.100

, " " ",' , " , , ",' " , 'T'o'ta ,1 "Th'i cl.::::ness'," , " "',""" "," '" "',' " ,," , • • • • • • • 0 •

• 0 • 0 • • • • • · . . . , . . . . · . . . . . . . . o 0 • • • • • • 0

, , • 0 • • • • •

, •• 0 0 • ': •••••••• : •••••••• :0 ••••••• : ••••••• : ••••••• ~ ••• '0' ••• :' ••••••• :' ••••••• : •• 0 ••• 0 · . . . . . . . . · . . . . . . . . · . . . ~ . . . . : : : : : : : : :

• •••••• : •••••••• : •••••••• : •• 0 •••• 0 ~ •• , •••• i ....... .: ........ : ........ : ........ :. ...... . • ., 0 ••

• •• • o. • o. • •• · .. . .. · ., . .. • •• • • 0 •

• ••••• to •••••••• 0 ••••• ' , • '0 ••••••• '0 ••••••• , ••••• , 0 .... 0 •• 0 • 00

0 •• , •••• '0 •• , ....... 0 • 0 0 ••

: ~: , ...... ~Jo.. ~: : ;..,\ ~ --¥..,( ... ~ ~I ~: :

,,',~'IJ(lr:~~r1.' ... , ~~~~·y\jn'f:l"~~: . ~ ~'. , ~ t~1~ r: ~~'vf< .. , . . [ . , ..... 2100. 8~e

DIstance 101010 (f"eet)

1400 18~Ee

Figure B,4, Predicted Asphalt Total Thickness, Site 4, LWP.

co w

xEI).0

8.00

· ..... '.' ............. T·o·ta·1· ·Th·i cl<:ness·.····· .. '.' ................ ,' ....... .

~ ! j ! ~ ! j ~ j l · ..... T ...... T ....... j' ....... f ....... ~ ...... '1' .. " ... 'j' ....... ~ ........ r ....... ~ · . . . . . ':' . . . . . . ':' . . . . . . ':' . . . , . . . ~. . . . . . . . ~ . . . . . . . ~ . . . . . . . ':' . . . . . . .:. . . . . . . . ~ . . . . . . . :

4.00

[ ~ [ ~ ~ .~.~ [ . " '" · ..... ':' ...... ':' ...... ';' ... .... : ....... : ....... : ...... . ':' ...... ';' ...... , : .. ..... : .r- : __ .. -.-.. i... .... : __ : .,"'-, .. _: _,.--.. :.. ..~ I"'~: : :

,-, ,r_ '-'. '--'-'.-. ,t' • --.. .... '-_ • _-_ .... ~ ... -.... .. ... I' ""-i" .- -,' ...,....-- v-... '" ,I I' ~. I

I :. . . . ... . j' . .': . . . . j' . ~ . . :·:-;·r . . . . . . . ~ . . . . :~,I. j .'~ . . . . . ~ . . . . :.~: . ~ !.-(~.,-:-: . "'1"~~"'/ 'r·' •... :...:...:.; .. .:-:...:...r • .:..'r:l · . . . . . . . . . · . . . . . . . . . · . . . . . . . . .

164. 1145 147~E0

Figure B.5. Predicted Asphalt Total Thickness, Site 5, Section 1.

><£10.0

9.00

5.00

· ..... ';' ...... ';" ... T·~·ta 1· ·rh·j ck;ness: ';' ...... ';'" .... ';' ...... ';' ...... . · . . . . . . . . . · . . . . . . . . · . , . . . . . . · . . . . . . . . · . . . . . . . .

• •••• • I •• ••••• • II •••••••• II ............................ I •••• II •••••••• ,0 ............... . · . . . . . . . . · . . . . . . . . · . . . . , . . . · . . . . , . . . • • • • 0 • • • • , . . . . . . . . , • • , • 0 • • •

, •••• • '.' •• , , •• '.' , ••••• '.' ••••••• " • , ••••• I' ........ 0 •••••• '0' ••••• , '.' ••• 0 ••• " •• , •••• · . . . , , . . . · . . . . . . , . • • • • • • • 0 • · . . , . . . , . • • • • • • 0 • • · . . . . . . . ,

• •••• •• : ••• 0 •••• : ••• , •••• : •••••••• : •••••••• ! ........ : ........ : ........ ; ... 0 •••• : •••••••• · . . . . . . . . • ./1, : : : : : : : : : ',. • • • • • 0 • •

· ,\·..:.-·~:-,,:,--,,~~-,,···<>~,,:r-:·-......... -, .. : ....... : . ..:-:....:-: .. ; ...... +-.... -~-.-.. ~-:-~-:-..... . · .. , '" · .. . '" · ,. . '" · .. . ...

13105 1465 (f"eet)

1545 18~E0

Figure B.6. Predicted Asphalt Total Thickness, Site 5, Section 5-2a.

:><EJD.0 ...... '.' .......... " . T·o·ta·1 . ·Th·i ok-ness:·.··· ............. '.' ....... ,' ...... '. • 0 • • • • • • • •

• • • • • • 0 • • •

• • • • 0 • • • • • · . . . . . . . . . : : : : : : : : : : ....•. 0: ..•...• ': ...•.... :' .•••••. :' •.•.••• : •.•.••• ~ •• " •••• ': .••••.•• :' ••..•.. ~ .•.•..• : · . . . . . . . . . • • • I • • • • • • · . . . . . . . . . · . . . . . . . . . · . . . . . . . . .

9 .. 00 ...... ':' .... , . ':' ...... ':' ....... ~ .... "'! .. '" .. ':' ...... ':'" .... ':' ...... ':' ....... : · . . . . . . . . . · . . . . . . . . . · . . . . . . . . . . . . . . . . . . · . '.' . . . . . . ....... ~ ........ ~ .. '/: . ',' '?-··'.~.~t\;_: ~ ........ ~ ........ ~ ~.,' ...... ~ ........ ~ ........ ~ ........ ~

. : : (\ ... ) Il : \ .. _ ..... -"\"'........ :.. ;.1 \,,'''1 /-11 ~r-"'--'" ., r~ : I It :

5 . 0 0 ""('.~~",:.-.. ~.-: .... < ... \~ ... : .... : .... :~,:.J.... .~. . . . . . . . ~ . . . . .: ... ~ ... '~ .. ~ .. ':',' :-~'~'l,.:~ . . . L:'~:-~ . T . . . .' :'/' . (~~·':-·'-··:···':r:"~1 V'. '7·!-t~ ., .... . .. .... . .. .... .

1851 ;2468 (. teet:>

2776 308ijE0

Figure B.7. Predicted Asphalt Total Thickness, Site 5, Section 5-2c.

xE0 6.50

5.50

4.50

3.50

2.50

· ..... ':' ...... ':' .. Lay,er' '1.':' ·Th i·.c:knes:~··· .. " ':' ...... ':" .... ":' ...... ': · . . . . . . . . . • • • • • • .:. • • • • • • .:. • 0 0 0 0 0 0:0 • • • 0 0 • • :. • • • • • • • ~ • • • • • • • ~ • • • • • • • .: 0 • 0 • • • • .: 0 • • • 0 • 0 0 :. • • 0 • • • • :

• • • 0 • • • • • 0

• • • • • • • • 0 0

• 0 0 0 • 0 000 0 • 0 0 ••• 0. 0 ••••• ,'0 •••• 0 • 0 • 0 •••••••••••••• - ••• 0 ••• '0' •••• 0 • "0 0 0 ••••• _ ••••••• 0

• • 0 • • • • • • •

., •••• 0 • •

• • • • • • • • • 0

• •••• 0 '.' •••••• 0 ••••• 0 •• '.' 0 ••••• 0 __ ••••••••••• 0 ••• , •••••• 0 '0' •• 0 0 •• 0 o. 0 •••••• to •• 0 •••• 0

• • 0 • • • • • • 0

o • 0 • • • • • •

o • • • 0 • • • • • • ••• 0 • '.0 •••••• '00 •••• 0 •• 00 ••••• 0 • __ •••• 0 • 0 ••••• 0 •• , •••• 0 •• 0.0 •••• 0 • 000 ••• 0 •• 0 00 • 0 • 0 0 •••

~<:'T'>(T>·/':··:1\/>?:..:·;,:;»;.;<j~>t'),~>~ ... : :'~'"1\ : : : : ..• • •••••• ;. 0 •• 0 0 0 .:. 0 ••• 0 •• : ••• 0 0 •• 0 : ••••••• : 0 •••• 0 0 -: ••••• 0 • 0: 0 0 •••• 0 0: ••• 0 • 0 •• : 0 !o •• ~ ..... _: .. ,.~

o 0 • • • 0 0 0 0

o 0 0 • 0 • • • 0

• •• 0 ...... 0 •••• 000 •• 0 ...... 0 0 ••••• _ 0 ...................... 0 to ••• 0 ................ 0 •• 0 •••

• • • • • • • • • 0

• • • 0 • • 0 • • 0

• • 0 • • • • • • • • ••• 0 • '00 0 0 , ••• '00 • , •• 0 •• ,0 0 •••• 0 • ,0 •••• , 0 0 ••• 0 ••• 0 , • 0 •••• 0 '0' 0 •• 0 ••• ,0 ......... 0 •• 0 0 • 0 •

o • 0 • , • 0 • • 0 · . . . . . . . . ,

3310 3411 3512 3613 371"iE0

Figure B.8. Predicted Asphalt Total Thickness, Site 5, Section 3.

.--------------------------------------~~----------

co <..n

xE0 5.50

4.50

3.58

2.58

1.58

, , , , . , ':' . , , . , . ':' , . La~'f!r' . t· 'Th i-c:kne s'\i' .. , , . ' ':" .. , ' . ':' ...... . , . . . . .

.. • .. .. ... • .. :.. .. .. • .. .. .. ..;.. ~ .. .. .. .. , .:.. .. .. .. .. .. .. I .............. ! .............. ~ .............. : .............. :' .......... .. , . . .. .. .. D . . , . . .............................................................. .. ................ #' ......... _ ........... , .................. o. .. , ........ .. · . . .. .. .. .. · . .. . .. .. , . . .. .. .. .. .. .. .. .. .. . .... .. ... .. .. .. .. .. " ............................ .. ....................... I .... " ................................. o. ........... .. · . . .. .. .. .. · . . .. .. .. .. .. .. .. ..

....................... , .... , ............. e ..... " ....................... ..

.. .. .. .. .. .. .. .. I' .............. : ............... : ............. .. . , · .

.. l' ....... : .............. :. , I ......... : ............. .. .. .. .. .. .. .. .. ! .............. ~.. .. .. .... . , •. · . , , . · . , , .

.... .. , .... II ............ , ... , ........ e .............. .. ............. , ......................... , .o. ...... . , . , · . . · , . · . . · . .. .. .... .

................... , ..... 0 .... , ........ #' r • .............. ........................ _, ........... , ............................. I ........... , · , , · . .. .. . , , . , .. .. . .. .. , · . , · .." ~ .. , .... .. .... . .. ' ...... , , .. -." .. , • ' .... -.O' ............. .. ..... , ..... C .................... - 4 ... _." ......... " .......... - .. , , .. r ...... ' • , . . " .. .. . .. , , . . ~ .. .. .. .. ,

3831 3934 4t48 424~E0

Figure B.9, Predicted Asphalt Total Thickness, Site 5, Section 4.

xE0 5.50

4.50

3.50

2.50

1.50

, , , ,. , ';' , " , , . ';' . 'Lay,-er" t·;· ·Th ,ic:knes!!i-'···, " ':' " , . , ":'" , , "':' , , , .. , '; , • I • • • • • 0 •

• •••••• : I • I ••••• : •••• I ••• : •• ~ ••••• ~ ••••••• ~ • I ...... ~ ........... ; .... I •• I .: ........... ~ I •••••• :

• • • • • • • I • •

• I I • • • • • I •

I I ••••••••• I ••• II ••• I ......... I •• I •••• I 0 ............. _ ........ 0" • 0 ••••• O. I •••• I •• , • , • I • I ,

, I I • • • • • • •

• • , • • Q • • • •

I • • • , • • • I • • , , I I • '.' • I , , , I ',' , , I I I I ,,, • I ••••• I' • , ••• , I , .. 0 I 0 •• 0 ..... I ••• '0' •• I •••• 0' I I I , • , I " I • I 0 • I • I

• I , • • • .. • • •

I I • • • • • • • ,

I • • • • • • • • •

, ••• , , ',' • , • , • , 'I' •••••• '.' , , ••••• " •••• , ............ , ............ 0 ..... 0 ••• '.' •• , ..... " •••••• , •

, . . . . . . . . . I • I • • .. • • , •

, •• , , , , ', , • " I • I' •••• , , • ,', •• , •• 0 • '0' , , ••••• I ••• I I I I"' •• I , I I .', I " • I • ,,, , ••• , I I'. , ••••• "

; : : ' :..----: : : : --~ , .. _____ ' __ -.. __ ~_ ___. • __ ......-.-._-- I

• :_.:....:.~:' , 0 , 0 I :_.....-:- I • ~ ••••• , • : •• 0 ....... : .......... ': ..... -:-..... -:--..........:-:..:.;.:._ ........... ": • 0 : •• I •••• :

... - I • I I I • .. • .. • '1 I I , ••••••••••• 0" • I • I I •• II 0 0 • 0 ............. I ......... _ ••• I ........ 0 • 0 • 0 .......... 0 _ I , I • I I I • · .. . . . . .. . . ,

• • • • • • • • I I

I .. • • • • • • • I

, ••••• '0 I • I 0 I •• II I I • I • I • I.' 0 • , • I ••• I I • 0 •••• I •• I ........... 0 .................... _ •• I I I • I •

I • , , • • • • • •

I • • • • • • 0 • •

• I • I I • I: I I •• , ... ,: ...... I •• : •••••• 0 .. :' .......... i .. I ..... -= ....... 0 .: ••• I ••• I: ••• I •• I • ~ ••• I •• , : · . . . .. . . . . . • • I I • • .. • • •

4282 4331 4380 4430 447~E0

Figure B.10. Predicted Asphalt Total Thickness, Site 5, Section 5.

· ..... ';' ...... ':' .... T-~·ta -1 . ·';fh·i cJ.:~ness·:· ...... ';' ............... . · . . . . . . · . , . . . . · . . . . . . · . . . . . . · . . . . . . . · .............. '" ................ - ............................................ . · . . . . . . . · . . . . . . . · . . . . . . . · . . . . . . .

7_00 : : : : : : : : · ...... : ........ : ........ : ........ :. ....... ; ....... .; ........ : ........ : ....... . " . . " . . " . . .. .

3_00

. , .. : ... : .... < ... ~ ... \_<;..: ~f' ~'I' ... ~ ........ ! ........ : ........ i ... :.' .... ~ .. " ..... ! .. IA··,;~,I;·(~J·Jr: .... . · ~, • ~. . . ~ .. I.... /·,..L/·, ~'. II.. . 1'1 . : , r~".,:"-I r ~ I ' .. Jr- d~· . ..,~ •. , ~ ,'.·f'll/·' 1\ ... ~/ ~ "OJ': Tl' \.1" ~:,'t~.-... , .. , ,,' ........ ''''!o.... :

· ...... : ..... ~ ~.~.l~", ... f . . I~: .•• :" \1 ..... ' ••• " •• : ••••••• ~ •••• Il~" .: .••••••• : •••••••• : : : : : : I: : · . . . ... . . · . . . . . . . · . . . . . . . · . . . . . . .

5079 S679 (. -tee t ) 7479 827~E0

Figure B. 11. Predicted Asphalt Total Thickness, Site 5, Section 6.

><'Em_0 ....... ~ ........ ~ ..... T·~·ta ·1 ... !h·i cJ.:~nes9 .~ ........ ~ ........ ~ ...... ";' ..... ..

: :: . : : : : : . . . . . · ...... : ....... ': ... , , , .. :' , , , , , .. ~ . , . , ... : ...... , : ' , . '.' ... : ........ : ... , .... ~ ..... , . · . . . . . . . . , . . . . . . . . · . . . . . . . . 8_00

: : : : : : : : ~ · . . . . . ':' . . . . . . ':' . . . . . . ':' . . . . . . . :' . . . . . . . ~ . . . . . . . ~ . , . . . . . ':' . . . . . .. :. . . . . . . , ~ . . . . . . . · . . , . . . , . . , , . . · . . . . . , · . . . . . . · . . , , . , . .

· ...... : ........ : ........ : ........ : ........ ! ... , .... : .... , .. ,:, ... , ... ; ........ : ....... . · . . . . . . . . · . . . . . . . . · . . . . . . . . · . . . . , . . . 4_00 : : : : : : : : :

~,~'~~~~~~-"-'~~f~~~' ·:~·~~~;~~~~~~~~~;~~~~~~~··:-·-··~~~-~~~~:·'··f···'··· . iii Iii iii

50 _ 0 1 S0 - ;256 _ ~~0 _ 45f.O\.-.J-E

i:. Distance (f"eet) -.-x ILl

Figure B.12. Predicted Asphalt Total Thickness, Site 6.

14

13

,! i _ 12~ __________ ~l_'li+IJ __ ~~~ __ ~4-________ ~~~H-__ ~ __ __ U) (1)

..c u C

'r-- "n U) ... .1.. U)

(1) C

.Y. U 'r-..c t- I:;

11 ! (1) -U)

to co

I""-"-:--:~

_'--! !I I ',-,il . .-!'i_,i n

'-"

Figure 8.13. Predicted Base Thickness, Site 1.

1000

Di s.tance (feet)

ICn=-1 I ...LI.-it_.t _.I

-Vl <lJ ~ u ~

'r--Vl Vl <lJ ~

.:x. u 'r-.s::: I-

(J) Vl

00 CO

00 CO

1) ..1'::""

7 iT! 1_.iI_.I ..... 1 550

Figure B,14. Predicted Base Thickness, Sit~ 3, LWP.

r:JCln .. --" ...... ' ......

Distance (feet)

U') Q)

.r:: u c .,....

U')

U')

Q) c

.,:,£ u .,....

.s::: r-

oo Q)

\.0 U')

ro co

1~

14

'i 1.::.

j :j '-'

I I I

r: i i

-. .'-'.

\\ '-----

'11,.,

'I~_._'·"" / ..... . "--" ','

1C!4 _' J.

.. -"--", l'~ I L /1 ... I"", "1' I ,I

'

} •..• _._.' I ..... 1 •••• / .. II o 'I ,I ~

,"--', I " ..•...•.. _-_.. .., ...... - -'-,'

.. -...... -.....•.•...

/1 1J.1 " I, I

" ',I I .. (I I I

... ··· ... -·1 .• / '1./ I .<

.. ··1 ...... I,

" I •• ,..... II . L-'

iei t::J .. _I W

Distance (feet)

Figure B.15. Predicted Base Thickness, Site 6.

-··\1 I~ r·· . .,/ ii, /1 I

I I 'I ,'i I I, .t. I I II \1 \., .... \1 I11I

II

,..

/ 1 1

/

4· "In 1:-IL.

APPENDIX C

TABLES OF PREDICTED AND MEASURED THICKNESSES AT INDIVIDUAL CORE LOCATIONS

90

Table C.1. Summary of Predicted vs. Core Thicknesses at each Core Location on Site 1.

Location Asphalt Thickness (in) Base Thickness (in) (feet)

Predicted Core Predicted Core

200 6.0 5.9 10.8 9.2

300 5.7 5.6 11.6 9.8

390 6.1 5.6 12.8 9.5

590 6.3 6.25 10.2 8.5

790 4.8 5.55 9.7 9.6

990 5.5 5.55 11.0 9.0

1190 5.8 5.9 12.0 9.0

1290 5.2 5.3 11.8 9.0

1440 5.3 5.5 10.5 8.7

Mean 5.63 5.68 11.16 9.14

Std Deviation .48 .29 .98 .42

91

Table C.2. Summary of Predicted vs. Core Thicknesses at each Core Location on Site 2.

Location Asphalt Thickness (in) Base Thickness (in) (feet)

Predicted Core Predicted Core

30 7.1 6.6 9.9 9.0

130 6.8 7.0 8.2 9.0

240 7.1 6.7 8.6 8.0

300 7.2 6.7 10.0 8.3

400 6.7 6.6 8.5 8.2

580 7.3 7.1 - -- 8.7

600 7.2 7.1 - -- 8.7

780 7.0 7.5 - - - 8.5

1050 6.6 7.05 - -- 8.3

1390 7.1 7.1 - -- 8.8

Mean 7.01 6.95 9.04 8.55

Std Deviation .23 .29 .84 .. 34

92

Table C.3. Summary of Predicted vs. Core Thicknesses at each Core Location on Site 3.

Location Asphalt Thickness (in) Base Thickness (in) (feet)

Predicted Core Predicted Core

RWP LWP

50 4.3 3.9 4.35 10.2 9.6

140 4.7 4.5 4.9 10.6 10.0

270 5.1 4.5 5.0 10.4 9.6

420 5.3 4.3 5.0 9.3 8.3

640 4.3 4.0 4.5 11.2 10.2

950 4.8 4.5 5.1 11.6 10.2

1040 4.5 4.4 4.7 10.6 9.5

1470 6.1 5.0 5.9 9.6 - --Mean 4.89 4.39 4.93 10.44 9.63

Std Deviation .61 .34 .47 .76 .66

93

Table C.4. Summary of Predicted VS. Core Thicknesses at each Core Location on Site 4L.

Location Asphalt Thickness ( in) Base Thickness ( in) (feet)

Predicted Core Predicted Core

100 5.7 7.2 - -- 8.5

300 5.5 6.9 - -- - --400 6.0 7.15 7.7 - --

490 6.7 7.95 - -- - --610 5.4 6.5 - -- - --

690 5.8 7.2 - - - - --790 5.2 6.5 6.9 8.7

920 5.7 7.3 - -- - --990 6.5 7.6 - -- - --1260 5.9 7.2 - -- - --1390 6.3 7.2 - -- 8.3

Mean 5.88 7.15 7.30 8048

Std Deviation .46 .42 .57 .23

94

Table C.5. Summary of Predicted vs. Core Thicknesses at each Core Location on Site 4R.

Location Asphalt Thickness ( in) Base Thickness (in) (feet)

Predicted Core Predicted Core

200 6.2 7.3 - -- 8.6

300 6.0 7.0 - -- 7.5

490 6.5 7.1 - -- 4.0

590 6.1 7.2 - -- 6.5

690 6.2 7.2 - -- 6.5

890 6.3 7.7 - -- 7.0

990 6.9 7.7 - -- 5.5

1090 6.5 7.5 - -- 7.5

1290 6.2 7.0 - -- 7.2

Mean 6.32 7.30 - - - 6.70

Std Deviation .27 .27 - -- 1.32

95

Table C.6. Summary of Predicted vs. Core Thicknesses at each Core Location on Site 6.

Location Asphalt Thickness (in) Base Thickness (in) (feet)

Predicted Core Predicted Core

50 3.1 3.1 11.4 11.4

150 3.0 3.05 11.5 10.8

250 2.9 3.0 11.8 11.2

350 2.9 3.1 11. 1 13.6

Mean 2.98 3.06 11. 45 11. 75

Std Deviation .10 .05 .29 1.26

· "

96