Mil02

NBS

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PUBLICATIONS

NBSIR 82-2632

A Review of the Bituminous

Reference Sample Program of the

AASHTO Materials Reference

Laboratory

i

i*.. V X. BUREAU

OF STANDARDS

LIBRARY FEB 7 1983

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NBSIR 82-2632

A REVIEW OF THE BITUMINOUS

REFERENCE SAMPLE PROGRAM OF THE

AASHTO MATERIALS REFERENCE

LABORATORY

Peter A. Spellerberg

J. York Welborn

January 1 983

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS. Ernest Ambler, Director

ABSTRACT

The Bituminous Reference Sample Program of the AASHTO Materials Reference

Laboratory (AMRL) has been in operation for more than fifteen years. It is one of four sample programs conducted as a cooperative undertaking between

the National Bureau of Standards and the American Association of State

Highway and Transportation Officials (AASHTO). This paper provides an overview of accomplishments of this program.

In this paper information is presented on the development of standard

specifications and test methods, the AASHTO, and the AMRL. Details

concerning the operation of the Bituminous Reference Sample Program are reviewed. The value of the laboratory rating system and the laboratory

performance charts which have been developed are discussed. Conclusions are made regarding the effectiveness of the program and the accuracy of

established test precision limits.

KEYWORDS: Asphalt Cement, Cutback Asphalt, Laboratory Performance,

Reference Sample

iii
ACKNOWLEDGEMENTS

The authors gratefully acknowledge the contributions of Mr. John R

in the preparation of this report.

Dise
TABLE OF CONTENTS

PAGE

ABSTRACT iii

ACKNOWLEDGEMENT iv

1. EVENTS LEADING TO THE ESTABLISHMENT OF THE PROGRAM 1

1.1 Early Development of Specifications and Tests for Road

Materials 1

1.2 Origin of AASHTO Standard Specifications on Methods

of Test 1

1.3 The AASHTO Materials Reference Laboratory (AMRL) 2

2. THE BITUMINOUS REFERENCE SAMPLE PROGRAM 2

2.1 Frequency of Sample Distribution 2

2.2 Grades of Bituminous Materials Analyzed 3

2.3 Participation in the Program 3

2.4 Preparation of Samples 3

2.5 Testing Program for Participating Laboratories 3

2.6 Techniques Used to Analyze Test Data 4

2.7 Storage and Preliminary Analysis of Data 4

2.8 The Preliminary Report 4

2.9 The Final Report 5

2.10 Scatter Diagrams 5

2.11 Laboratory Performance Charts- 5

3. DISCUSSION OF RESULTS 6

3.1 Causes of Variable Results 6

3.2 Change in the Coefficient of Variation — 7 3.3 Continuous vs Limited Participation 8

3.4 Coefficients of Variation for Cutback Asphalts 9

4. BENEFITS PROVIDED BY THE PROGRAM 10

5. CONCLUSIONS 11

6. REFERENCES 12

v
LIST OF TABLES AND FIGURES

PAGE

Table 1. Bituminous Reference Sample Program

Participation from 1966 to 1982 13

Figure 1. Youden Scatter Diagram for Viscosity at 60°C 14

Figure 2. Performance Charts for Six Laboratories

Showing Normal Deviates for the Kinematic

Viscosity of Asphalt Cements at 135°C 15

Figure 3. Performance Charts for Six Test Properties

Obtained from Two Different Laboratories 16

Figure 4. Coefficients of Variation for Viscosity

at 60°C During Ten Years of Laboratory

Participation 17

Figure 5. Coefficients of Variation for the Penetration Test

Original Asphalt Cements and Thin Film Residues 18

Figure 6. Comparison of the Coefficient of Variation for

Kinematic Viscosity at 135 °C - Continuous and

Limited Participation Groups 19

Figure 7. Comparison of the Coefficient of Variation for

Viscosity Tests on the Original and Distillation

Residues for Cutback Asphalts 20
A REVIEW OF THE BITUMINOUS REFERENCE SAMPLE PROGRAM OF THE

AASHTO MATERIALS REFERENCE LABORATORY

1. EVENTS LEADING TO THE ESTABLISHMENT OF THE PROGRAM

1.1 Early Development of. Smclfiflatlons-and. Tests for Road Materials

In 1911 the Office of Public Roads and Rural Engineering (OPRRE) of the U.

S. Department of Agriculture published Bulletin No. 38 giving the first

description of specifications and test methods for bituminous road

construction materials. Bulletin No. 38 was later revised and published as Bulletin No. 314. In 1916 a survey of State Highway Departments by the

OPRRE determined that less than one half of the states had proper facilities

for testing highway construction materials. Some states did not have any

facilities [1]. A majority of the states indicated their willingness to

cooperate with the OPRRE and tentatively agreed to send representatives to a conference on materials used in highway work.

In 1917* as a result of the information gathered at the conference, the

OPRRE published Bulletin No. 555 "Standard Forms for Specifications, Tests,

Reports, and Methods of Sampling Road Materials." This bulletin covered

aggregates, Portland Cement, concrete, paving brick, and bituminous

materials. In 1918 the OPRRE published Bulletin 691 "Typical Specifications

for Bituminous Materials" and Bulletin 704 "Typical Specifications for NonBituminous Road Materials".

1.2 Origin of AASHTO Standard Specifications and Methods^oiU'e^t

The American Association of State Highway Officials (AASHO) was organized in

1914. After several meetings, the members concluded, in 1919 » that a need

existed for uniform standard methods of testing and a Committee on Tests and

Investigations was formed. Representatives from the States and the Bureau

of Public Roads (BPR), (the BPR became the new title for the OPRRE), met in

1921 to standardize the work of the state highway departments and the

Bureau's laboratories. This marked the beginning of the AASHO Committee on Materials. Bulletin 949 published by BPR in 1921 was the first set of

standards recommended by the Committee on Materials.

In 1924 the methods included in BPR Bulletin 1216 which superceded Bulletin

949 were adopted as an AASHO standard. This standard remained in effect

until 1931 when it was superseded by the first edition of "Tentative

Standard Specifications for Highway Materials and Methods of Sampling and

Testing."

During the sixties and early seventies many State Highway Departments became

Departments of Transportation. This conversion was the result of the State

Highway Departments taking on additional responsibilities in areas of

transportation other than highways. In recognition of this, AASHO changed

1
its name to the American Association of State Highway and Transportation

Officials ( AASHTO ) in 1973.

In addition to the early work by the OPRRE and the State Highway

Departments, The American Society for Testing and Materials (ASTM) played an important role in the standardization of test methods and specifications.

ASTM Committee D4 on Road and Paving Materials was formed in 1903. Many

AASHTO representatives are members of this ASTM committee. For this reason,

AASHTO generally adopts ASTM standards. In cases where the AASHTO standards

are similar but not technically identical to ASTM methods, the differences

are noted in footnotes in the AASHTO Book of Standards, Part 1 - Specifications and Part II - Methods of Sampling and Testing.

1.3 The AASHTO Materials Reference Laboratory ( AMRL )

Based on experience gained from a long involvement with the activities of

the ASTM Cement and Concrete Reference Laboratory, the American Association

of State Highway Officials proposed in 1961 that a Materials Reference

Laboratory, sponsored by the Committee on Materials, be established for

standardizing and improving the precision and reliability of test methods.

The AMRL began activities at the National Bureau of Standards in October

1965. Its primary responsibilities were and still are to promote uniformity

in the testing of construction materials and to improve the quality of test

results.

The four principal functions of the AMRL are: (1) Inspection of materials

testing laboratories subscribing to the service, (2) Distribution of

proficiency test samples to subscribers, (3) Study of testing problems, and

(4) Participation in the work of technical committees. An overview of the

AMRL is presented in a paper by Steele [2].

The remainder of this report is limited to a review of the second function

mentioned above, concentrating on the Bituminous Reference Sample Program,

one of four reference sample programs. It provides examples of the

activities and benefits associated with all the programs.

2. THE BITUMINOUS REFERENCE SAMPLE PROGRAM

2.1 Frequency of Sample Distribution

The Bituminous Reference Sample Program includes both asphalt cements (AC)

and cutback asphalts (CB). Since 1970, a matched pair of asphalt cement

samples has been distributed to participants twice a year (in March and

September). Prior to 1970, samples were not distributed at regular

intervals. Since 1 973 » a pair of cutback asphalt samples has been

distributed in June of each year. Prior to 1973, four pairs of cutback

asphalts were sent out at approximately six month intervals over a one and one half year period starting in August 1967 and ending in March 1969.

2
2.2

Grades of Bituminous Materials Analyzed

In the testing program, the same grade of asphalt was not distributed at

every interval. Instead, a variety of grades were used (see Table 1)

including penetration graded asphalt, original viscosity graded asphalt and

residue viscosity graded asphalt. For example, penetration graded asphalt

cements have included 60/70, 85/100, 120/150 and 200/300 grades. Asphalt

cements graded on the original viscosity included AC- 10 and AC-20 grades.

Asphalt cements graded on the viscosity of the residue from the rolling thin

film oven test included four samples of the AR-2Q00 grade. Cutback asphalts

included MC25Q, MC70, MC30, and RC250 grades. Details concerning each pair

of samples distributed are shown in Table 1

.

2.3 P^r.ti9i.p^.t.ipji. in. .tha. Prs&ram

The number of laboratories receiving asphalt cements has increased from 53

at the beginning of the program to 132 laboratories. The number of

laboratories receiving cutback asphalts has increased from 63 to 127.

The types of laboratories participating in the program include State Highway

and Federal test laboratories, producer and commercial test facilities, and

municipal, university, and national testing agencies. Most of the

participants are located in the United States or Canada. However, some registrants are located in Central and South America and South Africa.

2.4 Preparation of Samples

The bituminous reference sample program was the first program selected for

implementation by the AMRL because of the relatively small amount of effort

required to prepare test samples. The bulk material for the first pair of

samples was obtained in five-gallon (20 L) containers. The asphalt was processed and test specimens prepared and packaged at the Federal Highway

Administration (FHWA) Fairbanks Highway Research Station located in Langley,

Virginia.

All subsequent pairs of reference samples were prepared by AMRL personnel at

the National Bureau of Standards according to the guidelines recommended by

the FHWA. As the participation in the program increased, two 55-gallon (220

L) drums were used to acquire bulk material (one drum for each sample of the

pair). Preparation of a typical pair of test samples involves heating and

blending the asphalt material in 55-gallon (220 L) drums and quickly

dispensing it into one-quart (1 L) friction top cans (screw top cans are used for cutbacks). Two one-quart (1 L) cans, one drawn from each of the

two 55-gallon (220 L) drums, are then packaged together in a parcel weighing

about three kilograms. These quart (1 L) cans are then distributed to

participants.

2.5 Seating Program for Participating Laboratories

Pairs of reference samples are tested by the latest AASHTO or ASTM Test

Methods. A data form listing the tests to be made and special instructions

for testing and reporting the data accompany each pair of reference samples.

The following are included in the program:

3
Bituminous Asphalt Cement

Penetration of Bituminous Materials, 25 °C

Flash Point by Cleveland Open Cup, (°C)

Solubility of Bituminous Materials in Organic Solvents

Specific Gravity of Bituminous Materials

Kinematic Viscosity of Asphalts, 135 °C

Viscosity of Asphalts, T202, 60°C

Effect of Heat and Air on Asphalt Materials (Thin Film Oven Test)

Effect of Heat and Air on a Moving Film of Asphalt (Rolling

Thin Film Oven Test)

Penetration of the Residue, 25°C

Kinematic Viscosity of the Residue, 135 °C

Viscosity of the Residue, 60°C

gu.t.bftsk AffPtol.t

Kinematic Viscosity of Asphalts, 60°C

Flash Point with Tag Open-Cup Apparatus, (°C)

Distillation of Cutback Asphaltic (Bituminous) Products, T78

Penetration of the Residue, 25 °C

Kinematic Viscosity of the Residue, 135°C

Viscosity of the Residue, 60°C

2.6 Techniques Used to Analyze Test Data

Analysis of test data is based on the paired-sample system described in

papers by Youden [ 3 ] and Crandall and Blaine [4]. The analysis of test data

is performed using a computer program developed by H. T. Arni.

2.7 Storage and Preliminary. Analysis of Data

To prepare the data for analysis, data for each laboratory is entered into

a mass storage file and coded with laboratory numbers, sample pair numbers,

test numbers and other pertinent information such as the standard test

method used. This data is then sorted and a statistical analysis for each

test property made.

The first step in the analysis is to remove from consideration any test

values which can be justifiably considered invalid. In removing outliers a trial computer run is executed which repeatedly eliminates data beyond three

standard deviations. The test data to be eliminated are selected based on

the results of this trial run, the shape of the normal curve, specific

guidelines for the removal of outliers, and the statistics from previous

pairs of samples. Once the outliers have been selected the data are reanalyzed to develop valid data for averages, standard deviations and

coefficients of variation.

2.8 The Preliminary Report

A preliminary report is prepared and distributed to each participating

laboratory approximately six weeks after test samples are mailed. The

report shows the number of laboratories reporting test data at that time,

the average values, standard deviations, and coefficients of variation on

4
each of the tests included in the testing program. The purpose of this

report is to provide the participating laboratories with information for

identifying abnormal test results.

2.9 The FinalJtepgrt

As soon as possible after all of the test data are received and a statistical analysis is completed, an individualized final report is

prepared giving: (1) the results of tests and ratings for individual

laboratories, (2) a statistical summary of results, and (3) a scatter

diagram for each test property analyzed.

The results of tests by an individual laboratory are compared with the

averages. Ratings are then assigned to indicate how far the laboratory’s

data deviate from these averages. The laboratory ratings are based on the

following scale:

Rating +5, within 1.0 standard deviations of the mean;

Rating +4, within 1.5 standard deviations of the mean;

Rating ±3, within 2.0 standard deviations of the mean;

Rating +2, within 2.5 standard deviations of the mean;

Rating +1, more than 2.5 standard deviations of the mean;

Rating 0, data excluded due to a large deviation.

A summation of the ratings obtained by a given laboratory over a period of

time gives an indication of that laboratory’s proficiency. Significance

need not necessarily be attached to a single low rating or pair of ratings.

A continuing tendency to get low ratings on several pairs of samples,

however, indicates that a laboratory should reexamine its testing apparatus

and testing procedure.

2.10 Scatter Diagrams

To show how individual laboratory data compares with that of other

participants, scatter diagrams are prepared for each test similar to the one shown in Figure 1. For each pair of samples from each laboratory, the

odd-numbered test value is plotted on the "x" (horizontal) coordinate and

the even-numbered test value is plotted on the "y" (vertical) coordinate.

The horizontal and vertical lines represent the median values. The distance

of the point from the center gives an indication of deviation from this

median. A continued excessive deviation indicates some corrective action is

necessary.

2.11 Laboratory. Performance Charts

If evidence is provided that a substantial deviation in test results exists

within a laboratory, that laboratory should check the testing apparatus and

the procedures used by the operator. The best way of demonstrating how well

the program evaluates a laboratory's testing capabilities is to study the

performance charts shown in Figures 2 and 3. The horizontal axis labeled

"PAIR NO." shows a scale of numbers from 1 to 10. These numbers refer to

the sequence of sample pairs distributed at six' month intervals. The

vertical axis labeled "NORMAL DEVIATE" gives a scale of numbers from -3.0

to +3.0.

5
Each normal deviate represents the number of standard deviations the

laboratory’s reported data is from the average. For example, a normal

deviate of -1.7 is equivalent to a rating of -3. A limit of +3.0 standard

deviations from the average has been imposed on all data. Any data at or beyond these limits is plotted +3.0 or -3.0 on the graph. In figure 2,

octagons represent the first, or odd-numbered sample, and triangles

represent the second, or even-numbered sample. A graphic representation of

within-laboratory precision is given in the length of the vertical lines

connecting each of the sample pairs. The closer a pair of symbols for a given sample pair, the better the laboratory's repeatability. Conversely,

the farther apart the symbols the greater the laboratory’s random error.

The lines connecting the midpoints between each pair of symbols show the

trend in the laboratory’s performance over the period of time covered by the

chart. Midpoints between consecutive pairs are connected with a solid line.

A dashed line is used to connect midpoints if data points are missing.

The ideal situation is for a laboratory to have all symbols directly on the

center line, demonstrating exceptional precision and testing accuracy.

Points falling outside the range of +2.0 normal deviates are usually

considered suspect.

Figure 2 shows performance charts from six laboratories for the kinematic

viscosity test of asphalt cement. The charts for all six laboratories are based on test data from the same ten pairs of samples.

Figure 3 shows performance charts for six test properties of asphalt cement

from each of two laboratories. The charts are based on the test data from

the same ten pairs of samples. Laboratory ’’A" shows good control for all

six test properties while laboratory ’’B” shows poor control.

3. DISCUSSION OF RESULTS

3* 1 Causes of Variable Results

It is possible that one or more of the following factors cause or contribute

to the poor control shown in Figure 3:

•inexperienced operator

•deviation from standard method

•non-conformity of apparatus with specification requirements

•inaccuracy of thermometers

•lack of calibration where needed

•improper handling of sample

•improper cleaning of apparatus

•incorrect calculations

6
3.2 Change, in the Coefficient of Variation

To show how test precision varied from year to year, the coefficients of

variation for the viscosity and penetration of asphalt cements and thin film

residues were plotted chronologically (Figures 4 and 5).

Figure 4 shows the coefficients of variation for the viscosity at 60 °C for

asphalt cements and thin film residues. Only the coefficients of variation

for AC-20 grade asphalt cements were plotted to minimize possible

fluctuations caused by differences in the grades of asphalt cements tested.

The coefficients of variation for the original asphalt cements range from

about 2 to 7 percent compared to a range of 7 to 16 percent for the thin

film residues. The higher values for the thin film residues are partially

due to compounding test procedures and errors. The graph shows generally

higher coefficients during the first four years than during the last six

years of the program. This implies that the precision of test results from

participating laboratories has improved as a result of participating in the

program.

The ASTM multilaboratory one-sigma precision limit in percent (1S£) for the

viscosity at 60 °C of asphalt cements and thin film residues are also shown

in Figure 4.J/ The precision estimate for the original asphalt cements,

plotted as 3.53 percent, was calculated by dividing the ASTM multilaboratory

two-sigma precision limit in percent (D2S3&), given in ASTM D2171 [6], by

2.83. The precision estimate ( 1S% ) for the thin film residue, plotted as 11.6 percent, is given in ASTM D1754 [7].

During the 1972 to 1976 period the coefficients of variation of the thin

film residues were all above the ASTM precision estimate. From 1977 to 1982

the values were all below the ASTM estimate of precision. The data

indicates that with the improved testing capability of the laboratories the

ASTM precision estimates of 11.6 percent (1S$) and 33.0 percent (D2S%) could

be lowered at least for AC-20 graded asphalt cements to 10.0 percent and

28.3 percent respectively. The coefficients of variation for the original

asphalt cements are sufficiently close to the ASTM precision to warrant no change

Figure 5 shows the coefficients of variation for the penetration at 25 °C of

the original asphalt cements and the thin film residues for all asphalt

cement samples distributed between 1966 and 1981. The graph is broken into

three segments: (1) Restricted Participation, (2) Open Participation - AC-20* s, and (3) Open Participation - Mixed Grades.

The first segment includes the coefficients of variation for six pairs of

samples. These samples, which included a number of grades of asphalt

cements, were distributed primarily to State Departments of Transportation

before the program was open to general participation (see Table 1). The

coefficients of variation indicate a general tendency toward increased

iy A description of the ASTM terms of precision applying to the test methods

for construction materials is given in ASTM C670 [5].

7
precision over time for both the penetration of the original asphalt cements

and thin film residues.

The second segment of the graph shows the coefficients of variation for

twenty-six samples of asphalt cement distributed to participants between

March 1971 and March 1977. At the beginning of this period the program was opened to general participation. The number of participants increased from

77 to 122. Except for the first four samples distributed (see Table 1,

samples 21 to 24) all samples were either AC-20 or 85/100 graded asphalt

cements. The coefficients of variation of the original asphalt cements for

the twenty-two similar samples were very stable ranging from 3.15 to 4.27

percent. The gradual declining slope of the line connecting the

coefficients of variation for the thin film residues indicates improvement

in test precision during this period.

The third segment of the graph plots the coefficients of variation for nine

pairs of asphalt cements. The pairs distributed during this period varied

considerably in grade and source. As a result, the coefficients of

variation for both the original asphalt cements and the thin film residues

are generally larger than those at the end of the second segment.

The ASTM multilabcratory one-sigma precision limit in percent (IS?) for the

penetration at 25° C of asphalt cements above fifty penetration units, given

in ASTM D5 [8], is 2.8 percent. Except for six coefficients of variation in

the first segment of the graph, all values are larger than the ASTM

precision estimate. In general, the values are within one unit of the

precision criteria.

An estimate of the test precision for the penetration of thin film residues

is not provided in ASTM D1754.

3.3 g-ontinuous. _vs Limited Participation

Figure 6 compares the coefficients of variation of the kinematic viscosity

of asphalt cements at 135° C for continuous and limited participation groups.

The individual laboratories comprising the continuous participation group

performed the kinematic viscosity test on 80 percent or more of the asphalt

cement samples since the beginning of the program. The limited or discontinuous participation group tested fewer samples.

The plot of the continuous participation group shows declining coefficients

of variation during the first five years of the program (1966-1971). After

1971 the coefficients of variation varied between 1 and 3 percent for the

remainder of the program. Except for three cases the coefficients of

variation for the continuous participation group were lower than those for

the limited participation group, implying that consistant participation

improves test precision.

The ASTM multilaboratory one-sigma precision limit in percent ( 1 S% ) for the

kinematic viscosity of asphalt cements at 135° C, given in ASTM D2170 [9], is

3.1 percent. The graph indicates that the test precision for the continuous

participation group is usually better than the ASTM precision estimate while

the limited participation group, since 1975, performed much closer to the

ASTM precision criteria.

8
3.4 Coefficients of Variation for Cutback Asphalts

Figure 7 shows the coefficients of variation obtained from the viscosity

tests performed on original cutback asphalts and distillation residues.

Three sets of points sire plotted, one for the kinematic viscosity of the

original cutback asphalt, another for the kinematic viscosity of the

distillation residue at 135° C, and a third for the viscosity of the

distillation residue at 60 °C. The eighteen cutback asphalts analyzed were

distributed to participants between 1973 and 1980 as shown in Table 1. The

ranges in the coefficients of variation for the eighteen samples were:

1) 1.5 to 5 percent for the kinematic viscosity at 60°C on original.

2) 6 to 10 percent for kinematic viscosity at 135°C on residue.

3) 12 to 21 percent for vacuum viscosity at 60°C on residue.

The ASTM multilaboratory one-sigma precision limit in percent (1S$) for

liquid asphalts at 60°C having a viscosity below 3000 centistokes

(0.003 M

2/S), given in ASTM D2170, is 1.06 percent. This estimate appears

to be too low. The ASTM Test Method D402 [10] gives no criteria for judging

the viscosity tests on distillation residues, however, the values plotted in

Figure 7 could serve as a means of estimating multilaboratory precision.

9
4.

BENEFITS PROVIDED BY THE PROGRAM

The Bituminous Reference Sample Program serves the needs of the AMRL

sponsors and the participating laboratories.

The benefits include:

1. A means of checking both instrument and operator under actual

testing conditions.

2. A means of comparing individual test results with the average

of a large body of results so that corrective action may be

taken where wide discrepancies in test results occur.

3. A means of evaluating the quality of the individual measurement,

thereby reducing the risk of dispute due to testing errors.

4. A means of furnishing documentation of testing capabilities.

5. Improved reliability of asphalt cement and cutback asphalt

test measurements, and

6. Better definition of the precision of standard methods of test.

Providing these services is one way the AMRL meets its primary

responsibility of promoting uniformity in the testing of construction

materials and the quality of test results.

10 j
5. CONCLUSIONS

1. The individual laboratory ratings on a pair of reference samples

provide a good indication of the accuracy of laboratory test

results.

2. The laboratory performance charts provide a method of demonstrating

a laboratory’s testing capabilities.

3. The coefficients of variation for the viscosity at 60°C of AC-20

graded asphalt cements and thin film residues indicate that the

precision of participating laboratories has improved since 1972.

4. As illustrated by the test for the kinematic viscosity of asphalt

cements at 135°C, the precision of results is generally better

for laboratories that participate continuously in the bituminous

reference sample program than for those that participate infrequently.

5. Coefficients of variation for the penetration and viscosity of thin

film oven and distillation residues are higher and more variable than

those for the original asphalt cements and cutback asphalts.

6. A review of the coefficients of variation obtained from tests

performed on asphalt cement and cutback asphalt reference samples

provides a useful means of evaluating established multilaboratory

precision limits or determining test precision where estimates

do not yet exist.

I

11
6. REFERENCES

[1] Page, L. W. , "Standard Forms for Specifications, Test, Reports, and

Methods of Sampling for Road Materials", U. S. Department of Agriculture

Bulletin No. 555, Nov. 1917.

[2] Steele, G. W. , "The AASHTO Materials Reference Laboratory - Fifteen Years

of Service", AASHTO, Vol. 60, No. 1, 1981, p.35.

[3] Youden, W. J., "Statistical Aspects of the Cement Testing Program",

Proceedings, American Society for Testing and Materials, Vol. 59, 1959,

p. 1120.

[4] Crandall, J. R. and Blaine, R. L. , "Statistical Evaluation of Interlaboratory Cement Tests", Proceedings, American Society for Testing and Materials,

Vol. 59, 1959, p. 1129.

[5] ASTM C670, Standard Practice for Preparing Precision Statements for Test

Methods for construction Materials, Annual Book of Standards, Parts 13,

14, 17 and 19, American Society for Testing and Materials, 1916 Race

Street, Philadelphia, PA 19103.

[6] ASTM D2171, Standard Test Method for Viscosity of Asphalts by Vacuum

Capillary Viscometer, Annual Book of Standards, Part 15, American Society

for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103.

[7] ASTM D1754, Standard Test Method for Effect of Heat and Air on Asphaltic

Materials (Thin Film Oven Test), Annual Book of Standards, Part 15,

American Society for Testing and Materials, 1916 Race Street, Philadelphia,

PA 19103.

[8] ASTM D5, Standard Test Method for Penetration of Bituminous Materials,

Annual Book of Standards, Part 15, American Society for Testing and

Materials, 1916 Race Street, Philadelphia, PA 19103.

[9] ASTM D2170, Standard Test Method for Kinematic Viscosity of Asphalts

(Bitumens), Annual Book of Standards, Part 15, American Society for Testing

and Materials, 1916 Race Street, Philadelphia, PA 19103

[10] ASTM D402, Standard Test Method for Distillation of Cut-Back Asphaltic

(Bituminous) Products, Annual Book of Standards, Part 15, American Society

for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103.

12
TABLE 1

BITUMINOUS REFERENCE SAMPLE PROGRAM PARTICIPATION

FROM 1966 TO 1982

Sample

Nos

.

Material Grade

Date

Distributed State

Federal

ProducerCommercial

Miscellaneous Total

01 AC 85/100

02 AC 200/300 05/66 52 1 53

! 03 AC 85/100

04 AC 60/70 01/67 52 1 53

i 05 & 06 AC 85/100 03/67 57 1 — — 1 59

07 & 08 CB MC-250 08/67 59 3 — — 1 63

09 & 10 CB MC-250 03/68 59 3 — — 1 63

11 & 12 CB MC-30 09/68 59 3 2 1 1 66

13 & 14 CB RC-250 03/69 66 4 2 1 1 74

i 15 AC 85/100

16 AC 60/70 09/69 66 7 2 1 1 77

1 17 & 18 AC 120/250 03/70 66 7 2 1 1 77

1 19 AC 120/250

20 AC 200/300 09/70 66 7 2 1 1 77

21 & 22 AC 120/150 03/71 66 9 15 30 2 122

23 & 24 AC 200/300 09/71 66 9 15 29 2 121

25 & 26 AC 85/100 03/72 66 9 29 21 3 128

27 & 28 AC AC-20 09/72 66 9 29 17 2 123

29 & 30 AC AC-20 03/73 66 11 26 17 1 121

, 31 & 32 CB MC-250 06/73 65 8 19 18 3 113

33 & 34 AC AC-20 09/73 66 9 25 17 — 117

35 & 36 AC AC-20 03/74 75 6 28 14 3 126

37 & 38 CB MC-250 06/74 75 6 21 8 2 112

39 & 40 AC 85/100 09/74 76 6 23 12 2 119

41 & 42 AC AC-20 03/75 76 7 20 11 4 118

43 & 44 CB MC-250 06/75 76 7 17 7 3 110

45 & 46 AC 85/100 09/75 76 7 19 9 4 115

47 & 48 AC AC-20 03/76 79 7 22 10 4 122

49 & 50 CB MC-250 06/76 79 6 18 7 3 113

51 & 52 AC AC-20 09/76 78 7 21 11 4 121

53 & 54 AC AC-20 03/77 78 7 22 8 4 119

55 & 56 CB MC-250 06/77 75 6 19 5 3 108

57 & 58 AC AC-10 09/77 78 7 22 9 5 121

59 & 60 AC AC-20 03/78 79 7 25 9 6 126

61 & 62 CB MC-250 06/78 76 6 22 5 3 112

j 63 & 64 AC AR-20 09/78 76 7 25 9 6 123

65 & 66 AC AC-20 03/79 72 9 26 11 5 123

67 & 68 CB MC-250 06/79 74 8 21 7 3 113

69 & 70 AC AC-10 09/79 72 7 26 11 5 121

71 & 72 AC AC-20 03/80 72 7 27 13 6 125

73 & 74 CB MC-70 06/80 65 7 22 15 5 114

75 & 76 AC AC-20 09/80 65 7 28 18 8 126

1 77 & 78 AC AR-20 03/81 65 8 32 17 10 132

79 & 80 CB MC-250 06/81 65 7 27 18 10 127

! 81 & 82 AC AC-20 09/81 65 8 32 17 10 132

13
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‘POISES SAMPLE 83

FIGURE I - VOUOEN SCATTER DIAGRAM FOR VISCOSITY AT 60C

*NOTE : The SI unit of viscosity is 1 Pa-s {lN*s/m2

) and is equivalent to 10 poises.

14
I

15

FIGURE

2

-

PERFORMANCE

CHARTS

FOR

SIX

LABORATORIES,

SHOWING

NORMAL

DEVIATES

FOR

THE

KINEMATIC

VISCOSITY

OF

ASPHALT

CEMENTS

AT

135C
LABORATORY A - GOOD CONTROL

mir »e. PEN ON RES *;n vis res

LABORATORY B - POOR CONTROL

»

IS

MIR «0. RBS VIS RES

FIGURE 3 - PERFORMANCE CHARTS FOR SIX TEST PROPERTIES OBTAINED FROM TOO

DIFFERENT LABORATORIES. THE RESULTS OF LABORATORY A INDICATE GOOD

TESTING CONTROL; THE RESULTS OF LABORATORY B INDICATE POOR PERFORMANCE.
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17

FIGURE

4

-

COEFICIENT

OF

VARIATION

FOR

VISCOSITY

AT

60C

DURING

10

YEARS

OF

LABORATORY

PARTICIPATION

AC-20

ASPHALT

CEMENTS

AND

THIN

FILM

RESIDUES
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18

APPROXIMATE

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FIGURE

5

-

COEFFICIENT

OF

VARIATION

FOR

THE

PENETRATION

TEST

-

ORIGINAL

ASPHALT

CEMENTS

AND

THIN

FILM

RESIDUES
SOLID

LINE-CONTINUOUS

PARTICIPATION

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DASHED

LINE-LIMITED

PARTICIPATION

CROUP

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19
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20

FIGURE

7

-

COMPARISON

OF

THE

COEFFICIENT

OF

VARIATION

FOR

VISCOSITY

TESTS

ON

THE

ORIGINAL

AND

DISTILLATION

RESIDUES

FOR

CUTBACK

ASPHALTS
U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 82-2632 m

3. Recipient's AcC£$sioft:Nc<

4. TITLE AND SUBTITLE

A Review of the Bituminous Reference Sample Program

of the AASHTO Materials Reference Laboratory

5. Publication Date December 16,1982

$. Performing Organization

V

7. AUTHOR(S)

Peter A. Spellerberg and J. York Welborn

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City, state, ZIP) 13. Type of Report & Period Covered

15. SUPPLEMENTARY NOTES

| | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

16. ABSTRACT (A 200-word or less factual summary of most significant information . If document includes a significant bibliography or

literature survey, mention it here.) The Bituminous Reference Sample Program of the AASHTO Materials Reference

Laboratory has been operating for more than fifteen years. This paper provides

an overview of the accomplishments of this important cooperative undertaking of

the National Bureau of Standards and the American Association of State Highway

and Transportation Officials.

Background information on the development of standard specifications and methods

of test, the AASHTO and the AMRL, is presented to give a historical perspective

and to identify the need for the program. Details concerning its operation are reviewed. The coefficients of variation derived from the analysis of laboratory

test data from a number of selected tests are plotted and evaluated. The value

of the laboratory rating system and the laboratory performance charts which have been developed is discussed. Conclusions are made regarding the effectiveness

of the program and the accuracy of established test precision limits.

17. KEY WORDS (six to twelve entries ; alphabetical order; capitalize only the first letter of the first key word unless a proper name

separated by semicolons)

Test Precision, Laboratory Performance, Coefficient of Variation

18. AVAILABILITY I | Unlimited

For Official Distribution. Do Not Release to NTIS

Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

2M02, SD Stock No. SN003-003-

[TYOrder From National Technical Information Service (NTIS), Springfield,

^VA. 22161

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF

PRINTED PAGES

24

22. Price $7.00

USCOMM-DC