NATIONAL BUREAU OF STANDARDS REPORT

2236

FIRST DRAFT

ACCELERATED DURABILITY TESTS OF ASPHALT ROOF COATINGS

I THE PRINCIPAL SERIES

by

Sidney H. Greenfeld

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Charles Sawyer, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director

ized research, development, and engineering in the field indicated by its title. A brief description

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NATIONAL BUREAU OF STANDARDS REPOE1

ms PROJECT ms REPORT

1004-10-1017 January 15, 1953 2236

FIRST DRAFT

ACCELERATED DURABILITY TESTS OF ASPHALT ROOF COATINGS

I THE PRINCIPAL SERIES

by

Sidney H. Greenfeld

Research Associate

Asphalt Roofing Industry Bureau

Floor, Roof and Wall Coverings Section

Building Technology Division

Sponsored by

Asphalt Roofing Industry Bureau

The publication, reprint

unless permission Is obt!

25, D. C. Such permlss

cally prepared If that a

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 201 5.

part. Is prohibited

dards, Washington

•t has been speclfit for Its own use,

ACCELERATED DURABILITY TESTS OF

ASPHALT ROOF COATINGS

I THE PRINCIPAL SERIES

ABSTRACT

The effect of six finely divided mineral materials in

three concentrations on the durability of three asphalts was

determined in accelerated durability machines. Numerous

physical tests were also made on the individual asphalts and

minerals and on their various blends. Although each system

had to be evaluated individually, in general, the following

trend was noted:

(1) Blue Black Slate and Mica improved the durability of

all three asphalts at all concentrations and film

thicknesses tested.

(2) Schundlers Dolomite and Low Carbon Fly Ash increased

the durability for many combinations, but for some

they did not change the durability appreciably.

(3) Erie Silica and Florida Clay generally did not modify

the durability, but in a few coatings increased it

slightly and in others decreased it somewhat.

1. INTRODUCTION

In February 193&? Research Paper No. 1073 , by Dr.

0. G. Strieter, was published as the final report on the

early work on the effects of finely divided mineral matter on

the durability of asphalt roof coatings. During the following

few years great strides were made in the petroleum industry,

uncovering new fields and developing new refining processes;

new asphalts became available for roofing manufacture, and

many of the older sources disappeared. New types of mineral
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matter came under consideration for blending with the asphalts

to improve their durability. Improved methods of manufacturing roofing made possible higher concentrations of mineral

matter in roof coatings. In order to take advantage of these

new materials and improved techniques, and to prevent the possible introduction of inferior materials, the Research Committee

on the Asphalt Roofing Industry Bureau outlined a program to

study many of the factors involved in the durability of roof

coatings and to find how these factors determine the suitability of the current raw materials for use in roofing.

This program was specifically designed to answer a number of questions which always arise when a new material is

considered for use in prepared roofing. These problems may

be summarized briefly as follows:

(1) What is the effect of the concentration of the mineral

matter on the durability of the coating?

(2) What is the effect of the thickness of the coating on

its durability?

(3) What is the effect of the mineral matter on the impact

resistance, or brittleness, of the coating?

(k) What is the effect of the mineral matter on the adhesion

of the coating to the saturated felt base and the

granules?
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- 3 - While the data being obtained on the project will eventually answer all of these questions, this report covers only

the early results of the accelerated tests of the durability

of the coatings and the physical tests made on the coatings

and materials that went into them. The answers to these

questions for felt-based specimens and aluminum- based specimens exposed out-of-doors will be reported later.

Three concentrations of six types of stabilizer were

evaluated in three different asphalts at three coating thicknesses in accelerated durability machines. A number of tests

were also made on both the individual asphalts and stabilizers

and on the blended coatings in order to correlate the accelerated durability data with the remainder of the program and

with more fundamental concepts.

2. MATERIALS

2.1 Asphalts

The three coating asphalts subjected to test were

typical of those used in making prepared roofing in the

United States. Each asphalt was commercially processed from

the crude oil into six products; a flux and five different

softening point materials, as shown in Table I.

Portions of Product 1 of each asphalt were ignited in

order to determine the inorganic matter present. Table II

lists the dominant lines in the ash spectra.
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TABLE I. PROPERTIES OF ASPHALTS

ASPHALT: CALIFORNIAN MID- CONTINENT VENEZUELAN

CODE DESIGNATION: C M V

Date 9/49 i/5ia 4/52 9/49 i/5ia 4/52 9/49 l/5ia 4/52

PRODUCT 1

S.P.. °Fb

Pen. c

d

Sp. Gr.

187

31

1.013

189

28

192

24

185

29

0.995

190

27

196

25

185

25

1.015

190

22

195

19

PRODUCT 2

S.P., °Fb 197 201 205 196 204 212 189 192 195

Pen. c 25 23 21 25 23 20 25 22 19

PRODUCT 3

S.P., °Fb 211 213 215 210 21

7

225 207 20 7 208

Pen. c 22 21 19 22 20 17 21 20 19

PRODUCT 4

S.P., °Fb 213 218 224 221 22 7 234 218 226 235

Pen. c 20 19 17 19 18 17 18 17 15

PRODUCT 5

S.P., °Fb 223 230 237 231 239 e 239 224 232 239

Pen. c 19 14 15 17 15 15 17 16 15

Sp. Gr

.

d 1.017 1.003 1.021

FLUX Viscosity at Gravity, °API Steam refined to

Seconds, Flash

Point (COC) 445° F

12.3. Flash Point

(COC) 580°F, Viscosity at 210°F

286 Furol Seconds

105° F Softening

Point & 160 Pen.

aBecause of the progressive increase in the hardness of all of the

products, the softening points and penetrations changed progressively. The time-weighted averages of the determinations of these

properties measured in 9/49 and 4/52 were used in estimating them

when the products were used.

^Softening Point, Ring and Ball - ASTM Method D36-26.

cPenetration at 77°F, 100 g, 5 sec. - ASTM Method D5-49.

bThe specific gravity at 77° F was determined only on Products 1 and 5*

e This product was not used because of its high softening point.

TABLE II. SPECTRAL ANALYSES OF ASPHALT ASH

Elements

Asphalt % Ash A1 Ca Cu Fe Mg Na Ni Pb Ti V

California 0.2% S S W VS S S S W M S

Mid-Continent 0 , 1% S s W VS s S S W M S

Venezuelan 0 , 1% s s w VS s M S w M S

VS = Very Strong M = Moderate

S = Strong W = Weak

2.2 Stabilizers

Six mineral stabilizers were selected from the large

number of materials currently being used in the roofing industry. These particular ones were chosen because they were

believed to cover the complete spectrum of performance, from

very poor to excellent, and were readily available and reproducible in form. The properties and attributes of these

six stabilizers are tabulated in Table III. Figure 1 contains

photomicrographs of these materials; they are included to

show the particle shape only and because each is at a different magnification must not be used to compare the particle

sizes of the various materials.

2.3 Aluminum Panels

Aluminum panels 2 3/4 x 6 x 0.064 in. were used to

support the coatings during exposure. These panel bases

were all made from Kaiser aluminum alloy 2S - 1/2 h.

3 . EQUIPMENT

3.1 Panel Making

The exposed panels were made with the aid of a hydraulic press, as described elsewhere CD.

3.2 Panel Exposure

The panels were exposed in six accelerated durability

machines constructed at the N.B.S. and described in (2).
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PHOTOMICROGRAPHS

OF

STABILIZERS

TABLE III. PROPERTIES AND ATTRIBUTES OF STABILIZERS

Stabilizer:

#50

Blue Black

Slate Florida Claya

Schundlers

Dolomite

Code Designation A B C

Source Quarry

Delta, Pa.

Mine

Edgar, Fla.

Quarry

Joliet, 111.

Particle Shape

Plates Blocky

,

Founded Edges

Blocky, Sharp,

Irregular

Particle Size, % Passing

Mils Microns U.S. No.

9.8 250 60 99.8 100.0 99.9

7.0 177 80 99.3 99.9 99.9

5.9 149 100 97.9 99.8 99.6

9.9 125 120 96.2 99.8 99.3

3.5 88 170 91.3 99.6 96.6

2.9 74 200 86.9 99.3 93.4

2.4 62 230 83.6 99.1 89.9

1.7 44 325 h 76.7 98.9 81.0

1.5 4o Sed. 68 97 73

0.8 20 t! 54 12 39

0.4 10 II 8 2 26

0.02 4 II 2 1 13

0.01 2

II 1 - 7

Specific Gravity 2.94 2.64 2.87

Surface Area, m2/g 1.0 27.2 2.0

Oil Absorption, lb/100 lb 29.5 63.9 19.4

Water Absorption, lb/100 lb 32.7 36.4 18.5

Loss on Ignition at 1000°F 2.1 11.8 1.8

Loss on Ignition at 1800°F 5.4 13.3 43.7

Moisture, % 0.2 2.7 0.1

Solubility, % 0.00 0 .04 0.00

Free Alkali, % 0.0 0.0 0.0 C

Chemical Analysis, %

Si02 56 47 6

R2

O:) 32 38 1

CaO + MgO 49

K2O + Na20 4

so3 Carbon 2

Mixture With Asphalt

Ease of Mixing G P F

Softening Point Increase,

op 15 28 13
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TABLE III. PROPERTIES AND ATTRIBUTES OF STABILIZERS (CONTINUED)

Low Carbon

Stabilizer: Fly Ash #160 Mica Erie Silica

Code Designation D E F

Source Philadelphia Pit Mine Dredged

Electric Johnson City Lake Erie

Particle Shape Spherical,

Irregular,

Blocky, Round

Corners

Sharp Plates

Particle Size, % Passing

Mils Microns U.S. No.

9.8 250 60 99.6 100.0 99.9

7.0 177 80 98.9 96.0 98.2

5.9 149 100 97.5 91.0 80.8

4.9 125 120 96.7 85.6 53.7

3.5 88 170 94.2 65.9 15.3

2.9 74 200 92.3 56.8 8.1

2.4 62 230 90.6 50.3 5.4

1.7 44 325 h 84.8 37.8 3.4

1.5 40 Sed. 73 65 9

0.8 20 " 60 22 6

0.4 10 " 43 4 4

0.02 4 " 15 2 1

0.01 2

" 2 - - Specific Gravity 2.62 3.01 2.68

Surface Area, m

2/g 2.0 2o7 2.5

Oil Absorption, lb/100 lb 30.0 97.2 19.5

Water Absorption, lb/100 lb 33.8 61.5 20.2

Loss on Ignition at 1000°

4.9 0.9 0.7

Loss on Ignition at l800°F 7.3 4.4 2.5

Moisture, % 0.4 0.2 0.2

Solubility, % 5.90 0.46 0.00

Free Alkali, %

Chemical Analysis, %

o.o

c

40

0.0 0.0

Si02 50

R2°3 48 35

CaOJ

+ MgO 2.5 1

K20 + Na20 10

so3

Carbon 7.6

0.5

Mixture With Asphalt

Ease of Mixing G G G

Softening Point Increase, 0 F 20 *40 5

aPlastic Index = 34. Plastic Limit = 34.

^Sedimentation in Isopropyl alcohol.

c Turns phenolphthalein pink in aqueous solution.
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3.3 Panel Inspecting

The panels were inspected weekly, both visually and with

a high-voltage probe (2), Representative types of failures

were photographed with a Speed Graphic View Camera containing a 6-in. F6.8 Goerz Dagor lens.

4. PROCEDURE

All coatings were blended from adjacent asphalt products

(Table I) and the desired percentage of stabilizer to have

softening points in the range of 217 to 227° F. In those

mixtures in which the softening point was in excess of 227° F,

only Product 1 was used; the softening point rise produced

by the stabilizer was too large to keep the softening point

within the range.

After the proportions of the two asphalt products were

determined, the asphalt was melted, the stabilizer added, and

the mixture stirred continually at about 4-20-430° F until the

surface became free from foam and bubbles. The temperature

was increased to 450°F and the viscosity measured with a

Brookfield viscometer. The temperature was permitted to

drop slowly to 190°F, viscosity measurements being made at

approximately every 10°F. The mix was reheated to its working range for the preparation of exposure panels (1).

Just prior to making the first panel, two specimens for

the softening point determination (2) and one shatter specimen
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were poured. Halfway through the panel-making procedure,

another shatter specimen and a water-absorption^^ specimen

were poured. A third shatter and two additional softening

point specimens were poured at the completion of the panelmaking.

Although thirteen aluminum-based panels and five felt27 based panels were made from each of the 48 coatings— , only

six aluminum-based panels were exposed in the accelerated

durability machines (2). (One felt- and one aluminum-based

panel were kept for reference, and the remainder were exposed out-of-doors.) These represented the coating thicknesses, 0.013, 0.025, and 0.043 in. Each of the duplicate

panels of each thickness was exposed in a different machine

in order to average the differences among the accelerated

durability machines. For, even though the six machines were

calibrated with an integrating light meter and set to give

approximately the same exposure conditions before the exposures were started, the normal wear in the parts of the

machines continually changed their operating characteristics.

Exposure of duplicate panels in two machines served to average

the constantly changing differences. As described in (2), the

1/

For a description of the water absorption and shatter tests,

refer to Appendix A.

2/ ~ Felt-based granule- surfaced panels were also made from 27

of these coatings and exposed out-of-doors.
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panels were inverted in their supports every other day and

the supports were inverted on the intervening days.

The accelerated durability machines were operated 22

hours a day, seven days a week, during the entire course of

exposures. The exposure cycle consisted of 51 minutes of

radiation followed by nine minutes of radiation and cold

(40±2°F) demineralized water spray, delivered at 25±5 psig.

Although the temperature program varied somewhat, depending

on the number of panels in the machines and the ambient temperature, it ranged from a low of about 50° F at the end of a spray period to l1+0-l45°F about 20-25 minutes after a spray

period and maintained until the beginning of the next spray

period. The exact conditions of each panel were different

because of the wide range in light absorption of the coating

surfaces, their shades varying from a matte gray-white

(clay stabilizer showing) to a glossy black, but the conditions were maintained for the straight asphalt from which

all of the coatings in that machine were made, for the temperature control was coated with that asphalt and revolved

with the coatings.

The exposure panels were examined weekly, both, visually

and with a high-voltage probe (3), and spark pictures were

taken whenever there was any break in the coating. The

pictures were examined through a transparent grid of 60
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squares covering the central 2-x 5-in. portion of the coating

(1/8 in. around the edge of the coating was not counted).

When exposed areas appeared on the photograph in a minimum

of 30 of these squares, the panel was removed from the

machine and filed away for future reference. Each panel was

classified into one of eight types of panel failure, as

listed in Table IV, according to the crack pattern which resulted in its failure.

This classification according to crack patterns was

designed to supplement the spark pictures in identifying

failure types. Its purpose is two-fold:

(1) Spark pictures cannot be used if the coating contains

material that conducts electricity (fly ash)

(2) There is little correlation between visual and electricprobe failures in many cases because of the large number

of breaks in the coating that are not visible to the

unaided eye, and some correlation must be maintained

among all coatings. For example, a coating containing

fly ash may have failed with a type A pattern, but it

cannot be removed from the machine until a visual failure

occurs, because the electric probe is nullified by the

conductivity of the fly ash. Hence the durability of

coating containing fly ash may be exaggerated.
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TABLE IV. FAILURE CLASSIFICATION

Failure Type Description

A Little or no visible cracking.

B Fine map cracks - less than 3/16" between

intersection.

C Fine map cracks - 3/l6"-3/8" between intersection.

D Coarse map cracks - 3/l6"-3/8" between

intersection.

E Map cracks with large uncracked areas.

F Straight line cracks.

G Ordered cracks (cracks seem to follow a

definite pattern)

H Large principal crack with smaller

tributaries

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Panels that fail in patterns toward the lower end of

the classification, E, F, G, H, generally have a large

span of time between the first appearance of a break in

the coating and their removal from the machines. Their

durability is very closely related to the arbitrary endpoint, which has been set as failures in 50% of the grid

areas for this paper. However, those panels failing

toward the upper end of the classification, A, B, or C,

tend to fail rather suddenly, in many cases spontaneously, and their durability would be almost the same

whether the end point was taken at 10% or 90% of the

grid areas. Classification D is the intermediate between these two extremes.

5. RESULTS

The data obtained in this investigation are of two

types: (1) Physical tests on the coating asphalts, and (2)

Accelerated durability tests.

5.1 Tests on Coatings

Each of the 48 coatings subjected to accelerated durability tests was examined rather critically in an effort to

/ find some property or combination of properties which would

aid in predicting the ultimate life of roofing made from

that coating, with a minimum expenditure of time. In addition

to the measurements made on the individual asphalts (Tables I
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and II) and stabilizers (Table III), a number of other tests

were made on each coating that was exposed. Table V summarizes

the data on the three asphalts exposed without stabilizer.

The tests made on the stabilized coatings are reported

in Tables VI to VIII, according to stabilizer:

Several calculated quantities are reported in Tables VI

to VIII along with the measured data. The volume composition

was calculated from the weight composition and the specific

gravity of the components as follows:

Table VI

)__(Blue Black Slate

)—(Florida Clay

Table VII )__(Schundlers Dolomite

)—(Low Carbon Fly Ash

Table VIII W!}1

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3- )—(Erie Silica

W = weight

V = volume

d = specific gravity

Subscripts

A = asphalt

S = stabilizer

C = coating

100 ws = % S by weight

100 v

s

S

= % S by volume
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TABLE V. PROPERTIES OF UNSTABILIZED ASPHALT COATINGS

ASPHALT: VENEZUELAN MID- CONTINENT CALIFORNIA

TEST

Softening Point1

9 22 7 224 223

Penetration at 32°

11.0 11.2 10.4

" at 77° F 13.5 17.0 17.0

11 at 115° F

Penetration Index2

20.8 26.0 30.1

4.5 4.7 4.7

Susceptibility2 0.73 0.87 1.16

Loss on Heating-^ 2 0.10 0.03 0.22

Penetration after Heating^ 13.9 17.1 16.

Specific Gravity at 77?

Viscosity cps at 400°F

1.018 0.999 1.015

375 420 280

" " at 450°F 130 140 100

" " at 500°

28 53 25

Water Absorption, g/ft2

at 28 days^ 0.34 0.43 0.67

at 56 days^ 0.52 0.70 1.00

at 280 days^ 1.61 2.20 3.00

at 609 days5 2.29 2.97 4.62

AVol., cc/ft2 at 609 days 0.70 1.63 4.11

Shatter^, inches (1) 2.5 8 5

M .. (2) 3.0 9 7

" " (3) — 8 7

" " Ave

2.7 8.3 6.3

•^ASTM Method D36-26.

2ASTM Method D5-25.

3 ASTM Method D6-39T.

Brookfield Viscometer.

x

y 3- x 3/1^-inch specimens submerged 1/4-inch in distilled water

at 70° F. See Appendix for absorption curves and method.

1/2-lb. weight on 3- x 3/l6-inch specimen in mixed ice and water

bath. See Appendix.

FIG.

TABLE TZT

T /TS PHALT

PHYSICAL

VEN&UElLn

IiiSTS

M/LOF? ON TU CO"went AT IliGS

! CAL/Pc f)/? N/A A t Ptr Ce/it Sfoiitixcr 0 2^ SO AO 0 3S So 0 o 0 3S SO 4a

0 'S.7 2S. 7 3*.l 0 /S.S IS* 33,8 O /f.7 2S. 7 2 ¥.S

/. 32 /.?/ /.a 0.989 /30 / *9 /.« /.s/s /• 32 AS/ A 68 227 2/2 11 / 2 Si 11 * 221 2/7 23? 213 111 22 f _ 2*0 227 19/ 11 * 2 // /?0 29.3 202 A/9

PeA •/ Ad C< *r 77/ ^ /* U n 11 /7 22 13 27 12. _ 23 28

*0/- 't/e - KJ? **!-*?

*6 ¥ *?0 */o-*0 * *S?-**0 **0 -*0ft *4? -*73 US-¥if S90 -*18 9/0 ' *2 7 **(, - */2 . 374- S&6 '98* /3 roo 2 80

$> *so *A /i* li* SIS 0100 /*o ifc Coo */So /O* /to SSo 3 900 iS i? 1*4 S3 S3* IP f / 8s* 2.S S8 2 60 2/60

Wkttr A&Strot'**

. . fl> It 2tvi q/tf ft 0.3* o. sr3 0. LC 0. 41 0.9x 0.91 0 SI o 2 * //9 ' 74 / s? /si A *7 ^ZtSS

/ </ 3- st Sff *. if C.St 9io 0 ._S/ 7.//

*.80 <91 sc. if 1.97 r.it 70S /2.3S *.<2 0 .*? J204 S/. 2 Z

tnt S3* 7. if it., it /<3 < 2 g S* 3* 9.s/ 7-07 '2.37 A/22

2.4 s /*.¥ 7l / 9 /2 /g.s > 2 s S /SJ — T 2 / ~Z 3.0 /s >2/ 9 /l /8 7 78 7 2/

9 /y T It ! A2 /I 7 // 0 s/.S- 7 IS

2.7 9.1 /ft: 7-1S 8.3 ii.e '8 / ~ri t 0.3 7/7 AUL -/ X'-O

* o. et 2 Q. 0 S 8 ft"tit*. <%y ' 0 / 7.3 17.8 IL.7 17, /0.9 2 7. S A£u3 o /? 3 ATP -U

/. o/g /3e s*7 /.</ _ 0. 999 A.2f / *f /• f? / o/r /.iO /*? A 0 / 227 12 / 217 11 ¥ 22/ 2 X 0 123 XSf" M n0 —

S.f. ,t Arf 227 20f /?0 — 11 * 2-OS '9' — 22 7 '99 /89 —

/y 21 .

A? 23 2 ? — /? 21/ il —

w/- y*7 *37- vi* ¥¥<*81 — *se-¥0 y **0- *?2 — 30S-V18 /SO - *12 93? —

US' 99.0 — 9xo SCOa — 2 la S9o I**, —

/30 Ilf /jr< — /0c 2 XS —

<S> V 19 //? 8fo —

S3 /iS 7oo — 2 S 9* S7o —

V«t(V

0. 1 * / 22 /<?/ — 0. s/3 2 ./f — 0- 4? A 32 1-90 Ofi i »s i-80 —

9.31 3.s? — / 9? 3.03 At/ *<Q — 2 . 1 C V.S* ?<o — 3 oc jr*<? J.SA.

2.i? 9.8

— I f? f.?2. 7-78 — *.02 7 89 9-3S

<? 1 c ?. 6 o 7 31 — A 03 Si? to. sx — *st S83 9.80

*<(}'!> t’A'M) . . IS /

•? — 8 ? SS. f —

s S /0 —

"2 10 r 08 — 9 s /8 r — 7 // 9 sx

"j - * /o ss — r 9 /J.S 7 ? £ —

Arerait *7 93 03 — P. 3 S’ 3 /S.7 — s? 87 9 a A2-0

* Ca(<u(»1tO r •» « /tVCtf T('4l»
•
TABLE. Tm

. PH/S/CfL . TESTS OF COAT/NGS

ASPHfiLT VINE? a £/./(>1 mid-cONT/ZYt iX_T C/U // \QRN/>W0 38 /<? 4o 0 38 80 4o 0 38 8 a La

9 ILL IV. 7 0 A58 75/ 7?. 3 o AA- « 2 6 , ' 9Y8L.

/If /66 Of99 '29 //v AO/

All asa LAA

111 21 / 212 33? 2 iy/ 228 2 /

22 3 XX 0 22 V 23 4

s.p. V Bam V

• 1X7 2 a? 22 ? 2/7 206 /?/ 223 2*8 /?8

jPi A flg. Bt»t /» iff '¥ XO 2/ 22 /7 20 23 28 A

22 22 28

318- vo/ VXF-YI7 235 8fo 6?A 88a AUO 2 fo 80/ 780

/3o 22 2 275 ?f* /vo 2VO ILF 880 // 0 'AIL 2 91 ¥38

<p no > ZS 80 /VO 230 83 /oo A80 2 60 28 96 /i 8 2 28

a. 2 v 0.9/ /. /< /. 2 6 0 . 23 a. j/l /. /r 0.01 0. 27 A. A? /. la ALJA / si J. 9s' 0 2/ AAA 2. '9 /-or A. 82 2/8

/. 6 / 3 38 Y.99 LA/ .. 2.20 9 AAA _ 4.9/ 3 (TO 81

4.8V . F.68 M? r. i? lUL 2 .f/ L >9 8-z? ?AA _ 9 34 // 68

(J.7<5 2-9L /O./C ALL _ 7 9? **? _ // 78 ¥ // /i. 03 , 2 .// 8 9*.

2. r 7 /? g /? At /V 8 8 8.8 A4

3FA 8 7 // 9 _ '8 A8 20 _ 7 2 4- 8 2

*3 ? f /2 F — _ ? 6_ 81 'A _ 1 7 7 l 8 3 2.0 83 '*

/f. r /2 3 LA /A 8-8 'V.o <0 0/ V A** CaAif, F(y /hf [ o f?.3 2 2-0 7 4.2 0 77A 74 V o '7 2 76/

A1/8 /;f / Vi. A- 6 o a. 999 / VV A 8? / VO - AAV

237 22 ? 2 2 ? ILL - 2/9 22 r 2 83 283 223 7/? 2 84 zn I*r A9

/?* 2 2* 2*5 A97 _ A?0 2X3 2*8 A/? A8F

// 20 22. 22 L2 23 2 8 77 AS 2 2 28 2 /

90/-Y27 ?/f- wo vs?-??* r<>9-S’*'2 ?/o- *<r Y35V<V VJP-V88 yjf-vj? 3/8- V*? '/VO * VA VJ/-V88 WK • y/t 374 920 Vxa 8/0 - 2 80 V9o

/ 30 120 Ho /vo — — 8?0

18 9? ILL *3 /2 O — 9L

SAL* 0-93 / V3 a 88 A 02 /23 0.47 0 . 98 AAV- o 84 lu,! CLAZ- A d>? f.3? -AMI... 0 ?0 A 28 A. 70 A. 2? I 9f. 2 ^ 6/

A. 6 / 2.7 3 9.37 2-2 0 878 /0.39 V/ <ro V8.30 3 880

2 Jl<) fc 2 9? 27-38 IV. Vv VA2 A.?. 30 72.2

a jo 2LA? 2.2 7 o AO At 6/ )A Of 3?. 9/ Ysa ? f Vt S88a ;,r ^ r /2 /2 7 7 /Y 8 7-8 /2

.3 o r so 9 7 7 /» 2 9 — // ‘3

' y.r /A '9 / 7 8 /a P 2/ 7 7 — —

flr.ri.c 2-7 8. 3 AO? . 83 7 3 /2-0 P 2 / 8? 7 3 — AA- 8

| + (W<t I'* tfd

TABLE -Zm PHYSICAL TCSTS OF COATINGS

^ ASPHALT YENS|Z UE LA N A7 /D - C0/V7- Y/V5/V T CA L A5

0 3 5 50 60 0 3 5 50 60 O 35 50 60 M/CA

0 /8.V 15.1 33.4 A8. 2 7?9 33 2 0 /5V 28.2 13-

_

A, 33 /.Si 0. 999 /3A A. 80 ALA YU A.52 A69

227 *170 * 2 ?a 2 23 7 2?o

SI .fit.,'/ * 22? /9a 21 Y A90 — 223 A89

Pth-i4 B* IV 32. A7 Z7 — /? 21 —

Tfty. VfrytaAi'/k *f •Of/

8// — — Y/0-V4V ?!*-??/ — — 365-V'5 vjr- VF4 — —

i

128 — — 2/0 — —

' <P 7/0 '/ 1A0 — —

— — — — — — —

It - —

83 -

— 28 — — — zz^L\

O >1 2?t/i oAf. // d.lv 0. 52. — 0. V3 0 . S3

0.6 7 2.08 — Oil 0 A3 — — 2.54 — —

A^C/ 1/2 — .

2-20 2 ?7__ — — 3. OO V 78 — —

2-2-9 . 1-04 .

— 2 97 3 9? — — V.62 6.3? — —

O')? _ 5*S .

— A-63 7.02 — V.// 8.57 —

*H8hKYi:P*i) 1.5 -vZ/ — — 8 72/ 5 >2/ —

"2 1,0 — — 9 ^ 2/ — — 7

-7-2/ —

m

3 — .

— F ^ 2 / — — 2_ 7-2/ — —

1-7 vlf — —f-3 -7 2 ' — — 4.? -P-2 A — —

F

Ptr Ft A * 0 A 6 - 9 2 7.8 34.2. 0 AL.y 27.2 3 88 a AL.P _ 77,5 36.7

L 6/8 AID AV7 A. 61 0 999 A. If ' V8 A, La A ?0 A, V? A-I* J

11L 127 7/2 3 XV 2 /f ' 2A? * 223 226 2/7 ' 1R fitst *L * 217 2-15 2 OO A?7 223 1/9 2 or AFL

AM 10 20 2- 2- <z 23 2? 18 A

2 / 22 25 1 W- fil A- ?/o YA9-VV4 9?4-?4V V/o -VLV U3-VO/ }?Z - fVo 3/S-*A? 365- V'

y/o -v? MAO -V3? ¥/? VV4 378 vxo vsa 760 270 600 790 —

. " 9 999*1 /At i/r 988 — 'VO — AOO 200 256 —

. - C35 800 *F U 65 — 83. 92 A?a — 18 80 27 —

© It Uyi qht.(t. 6. 2? 0.62 0. 59 6. S9 0 .Y2 0S6 0. LX 0-65 6. 67 0.4? 0.28 LAJ

© 54 llfi. ^ h Alt 016 0.21 A- 26 0.70 o.ss 091 a. 91 9. fi A. 09 a. a 7

1.61 2.18 i.tt l.VJ 2 . 1 a 1.5/ 1 . 1? 3. // 3. to

?. LX. 3.it V. VI 7. 9? 1.19 1 . 0 ? Tula l-/t 1-97 3,9/ 3/0 ?. 53 J.9A ; 236 'V. V2

0 la Ail* Ak.'lL 7 9o 1.63 ?./5 3.11 /. 16 i.tvc i. r. ay.a1

’Fi/Ctj'Jh^utX _JLX (0 7 1 ? /2 2A A6 5 / A8 A8

i.tf 7 ? r.s ? /I 721 7 7 88 A2

•3 6 7 s AA A

Af 7 AV /8 1 hriro.<ic 2. ? 4.3 7.3 y.j r.3 AA. 7 zoo A7. 7 57 7.3 'V

A42 CtUuUtc/ ® * ESti*\aA£)

• ?o*t Worn- pulmlf/ J.«V 4'fit*
.

.

*

*
11

The specific gravity of each stabilized asphalt coating

was calculated from the composition of the coating and the

specific gravity of the individual components.

dn = WA

+ WS

7TT

~Ti

w

w

d

A

* WS

AfJJs

A

dS

In order to check these calculations, for they are

again used in determining the volume changes taking place

in the water-absorption specimens, a number of specific

gravity measurements were actually made on some of the

stabilized coatings. Table IX compares the calculated and

observed specific gravity for 13 coatings.

The softening points and penetrations of the base

asphalts were estimated from those of the five products from

each source and the softening-point rise expected for each

concentration of each stabilizer. Because this rise is slightly different for each of the products of an asphalt, being a

function of the softening point of that asphalt, and because

the asphalts hardened progressively in storage in the period

during which these studies were made, the final softening

point of a stabilized coating could not be pinpointed closer

than within a 10° F range, and the estimated softening points

and penetrations of the base asphalts would, consequently,

be subject to the same order of variation, their being calculated from the measured softening point of the stabilized coating.
'

*'

V " y1 '
TABLE IX. SPECIFIC GRAVITIES

COMPOSITION SPECIFIC GRAVITY

Calculated Observed

California 50% BBS 1.51 1.50

ii - 35% Clay 1.30 1.30

m - 50% Clay 1.47 1.48

it - 60% Dolomite 1 . 66 1 . 66

ti - 35% Silica 1.30 1.29

it - 50% Silica 1.47 1.47

Mid-Cont

- 50% BBS 1.49 1.50

ii - 50% Fly Ash 1.44 1.39

ti - 35% Silica 1.28 1.24

it - 50% Silica 1.45 1.43

Venezuelan - 50% Clay 1.47 1.47

it - 50% Dolomite 1.50 1.49

ii - 60% Silica 1.62 1.62

12

The viscosity values reported at 400 and ^50°F are

values interpolated from a semi-logarithmic viscosity vs.

temperature curve of measurements made in the range of

390 to 480°F with a Brookfield viscometer. The 500° F value

was extrapolated from the same curve.

The water absorption measurements were made on specimens

three inches in diameter and approximately 3/16-in. thick.

The exact thickness was subject to slight variation because

the specimens were cast in an open-top mold and were not

trimmed. The specimens were submerged in distilled water to

a depth of 1/k in. and were weighed weekly for three months,

monthly for three months, and then quarterly until the test

was discontinued at 20 months.-3/ The specific gravity also

was determined at the final weighing of each specimen.

From the physical dimensions of each specimen the surface

area was calculated and the absorption data reported as grams

of water absorbed per square foot of specimen surface at 28,

56, 280, and 609 days. The change in volume for the 609 days

(20 months) of immersion was calculated from the final

measured volume and the original volume, which was calculated

from the original weight and specific gravity. Figure 2 is
' . • J ‘

«.
- 13 -

a graph of the change in volume vs. the change in weight

of the coatings at the end of 20 months submersion.

The shatter determinations were made on three specimens

of the same size as those used for the water absorptions.

One was poured when the first exposure panel was made;

the second, between the making of the aluminum- and feltbased specimens, and the third, when all of the exposure

panels were completed. In this manner, any changes in the

coating that occurred during the panel-making process were

taken into consideration.

The temperature ranges in which the exposure panels were

made are reported under "Temperature of Preparations".

5.2 Accelerated Durability Results

(a) The results of the exposure of the aluminum- based

panels in the accelerated durability machines are given in

Tables X and XI, as follows:

Table No.

X

XI

Stabilizer in Coatings

(Blue Black Slate

(Florida Clay

(Schundlers Dolomite

(Low Carbon Fly Ash

(Mica

(Erie Silica

The averages of the durability of the duplicate exposures

are reproduced on graphs in Figures 3 to 7.
f

:

'

. -!

...

• . :*• •,

'

’ ' ; r. .

•

'

C i-

'

'

;

. - •

i
TABLE J

PRINCIPAL SER/ES

/.? TkV VI

0 J5 *0 to 0 ?r ro 6o 0 20 k9 o if ffi UQ o if r* if f(J A fl<w« S(«c* SlaU c StUllu 47 kf 63 9i 69 //? "i Z2-9 277 276

67 U6 (0! i/i 67 m 7g? /*K 795 19? 776 69 . If 101 U9 p /0t /3f 717 //S' /?£ '23 '99

<9 if /n 37 /ry '?? '*0

/i6

/90 269 a

I 69 n* go w* /2S '21 /io* 240 200 </* ni 93* //? 7f tV /99 UY uf If* A)J 7SJ 767 72/

/ 7-69 /ff 7 69

Rati? At* /•?/ /9f 2il 7-66 £6/ J * 2JL c ft ft A f A £ £ £ />£ C£ //£

<r ft /} £ £ A/ 8 £ X (? <5* £ 19 77 2? 92 9/ 91 if* 76} 96 /V7 '5? 06

79 9t 46 /*o ?/ /vr /6? 20} ?£ /ft 202- 22/ U 76 9

/

/0f 96 u /02 76/ /»? 703 /66 715 7 0/ 67 /02- 4K j/n 96 /si t/r /03 7fJ- 736 Lt* 76 gf 91 99* /r* 9?* /J"6 Mi /IS a* 96 *r“ /*! 99* /fi 7fi 211 fyT /If 2-/f Fit 7 31 /rr /7i / /)£ 1-OL 3 3} ML 719 2-00 Rati/

/3 /?* A

10} 2-6f 203

o

2 a

<28 3/t G

/£

XOT

<2 7 33 i r, B 8 £ A £C 9 £ £4 c 77 £

A! A 1C /?<? H 3? 39 36 39 S7 YS 91 60 ?F 73 69 67

33 5f ¥0 44 93 li x< //f _27 ('1 //? /?/ 32 n IY li ft s? 67 6/ ?». ?£ 36 _____ i,

** 32 52 33 Yr 57 }f ?t //S 11 'i9 31 39 sf 33 S'* 57 £f 67 17 27

io 22

* Averaat ' 33 53 31* rr

r r/* eg tl j/f / i./g 10} 1 0i / 21 / Y> 72? 777 /if

/SV 7ft 2 Oh /.SI /a 1-67 7 /-a /6l 2 36 6 RB A G c C C C 3> 2> 2) 1> 8 8A A ft A c 88 G S Z> i <2 <? £

B Fll,,dc 0(«y D 61 !0i 97 76. 67 //V /Ol 9? 'Vf /vt 97 - a 91 If _ 6 ? 76, // — '29 '99 / }Q 69 /Oi /O? 12 9/ /*6 /*r /•3 //£ 759 //£ /*i 69 39 3C _ 2

75 r? — "5 "9 /ft — Lf /*7 99 If it* 7/9 7/3 /,** /// /£? 7/2 62* u' H _ 79* 76 rr £20* /IV 763 f

-20 /n /37 / /.f? 757 73

/Ml /33 099

Rll,,* o.te QU _ / 10/ //j — /// /3f — e s C c £ £ £ £ £ £ £ £

<* ce He — £ £ f — £ £ £ — 1Y u _4i u 9/ /Of 92

_

"? /2 f t/2 ?y r<- 9? 9/ Zo ?? — 96 9/ //? — /0 L ?f 96 95 796 /ft i# • 6 / 69 U — 96 A 9/ 9o — S01 //- //} _ tT 99 6f 69 99* //6 96 If* /7? 7S7 "A 62* 10 rr — 99* 16 if — 9f* /03 //f — /?? 7U 77V /.rr 760 7.l9 /V/ 'Y6 7

2 / At9 a. 93 — 7/5 yjf — / 7'4 /21 - 8 8 6 <T 4( £ £ £ £ $ £ — /3 A £4 — ££ £ £ — £ £ £ - 33 f

so S~1 £/ f? 5} 77 Lf 72 6 f C«(l(orM«K 1 Days 7? 20 if — r* ;? Jl — 72- 5f f? 17 if 3 3 33 sy 90 if i? 77 M 6/ £SL

x . 2S u. <7 92- Vo .

IF 70 Z2 — 33 i¥ 97 9/ »* 96 91* 91* 77. 61 79

33 ay *< — /•/’ 3/ 39 71 *7 ?/" — //£ 721 727 106 rot 0 961 69Off 703 07? — m; 69/ — 0g7 699 — 6 £ 73 6 c. C C c 1 l D 2> <9 8 6 — c c £ — Z> 2 3> —

"

FAitu-e cYt/er*. 6y * ^V^**^"* aiiVJCZ" /*>!• *nsraje +y C*fcm (m e*+f

' PRINCIPAL SERIES ACCELERATED DURABILITY DATA

Co4<m^ TIkIms: iu* A 013 I2f L D RF*

P«r C«y

V5f.l,(u«r P 3f 5(1 40 <? 35 SQ 69 fo 49 Dei1 m / “ 7 *V v

Ski -L Mica Sr, n, ///zr/F-q 227 66 6? 6?

y>*exu«/*h / Sa/i 41 3 74 — — 47 — — 72V — — V/'C/5' 727 Sf 55 — 55 6/

S2k — — 81. — _ 7'f — — Sr, n /'/iq/50 22? 66 — 1/ — 79

A rente* us •001 — — 1<? — — /to* — — v//t/r' 217 6? — 1/ — 75 75

Ratio 1 4.7 — — / — — / _ — Str.fe l '//2t/50 22? '29 7'5 — '20 c A — — F — — £ — — 22? — //£> — //a /'l

-JUidiCtotiA*ht lrJiaf£ 79 273 _ 9/ — —

96 _ - St r. B& s i* to*. - 0,0'3“

'//3q/50

l/'t/FS. 22'

22? 1

_ 93

1 6i Ho — _ 96 — — — - '95 'it S9 ft '/V '£

ArcrAge 6S* 369 — 9v — 99* _ 35% CL *2/ VL 30 36

Raf/e

9 AJ/ _ — ' — — — _ 3/25/52 22' 6' 67 Yf 92 53 91

a A _ _ AC — .£ _ — Soft 2? 111 63 — 70/ />

3 ? 'SI — — fi 4/9 — — 72 _ _ 3/ie/fl 270 99 76 76 If S4

32 761 — — £/ £11 — — 72 _ Str Ctrl 71/27/50 )if 79 67 61

A/eraae

Ratio

3 33 /}£ — — £7 S’.72 — — 72 _ 3/,3/fl lit v? 97 9? tr 91 135 — — /J-3 — — / _ — /l/i'/fe 22Y ?' 96 99

Crt.cK PaffjCM 8 A — — C D — — D — — 222 70 £6 6S 79 AT

S/iitsi 22? 7V 79 7t 76 75 75

f.*t. - 0. ) *2}" 229 9k '01 ??

r Erie Si hca 3'/79/51 m 9i ti fy ?. ?t 9,

47 39 35 32 41 is n Jl*

tie SAL tk¥ SOy. Bt 1 S >a fhLCi kt -l.oil l/t/St

3/I9/S2

66 6f 65 K " 4? , 732 30 21 S( ns (05 io? 2/9 199 !13 701 nv 'U "9

Areracxr “ u* 36 33 30 7v* 74 7 9 IU 11Q ^ LA2 •57 263 s> v. i{ t Aik u, Mi LCkktiMMi 3/31/51 115

12/

/*!

72 5

If' '27 Rat ifl_ ” OJxQ 0.5S LSI 70/ 7 0S Hi 1-63 '13 JJi /is MS MO /JO . CracR Patttra C A A A F A A f\ f A C A A SI, C.i 0 615“ 2/2/5/ 713 52 — 50 57 S& 57 3? 9' ?/ 91 767 1/9 5L 51 39 29 92 J

a. » ki 62 6/ V/ 9k uS un l'l 703 '9r '1/ '93 ft 9' 25 92 90 93 Avtragt u* 4o n )f 9f* 'Of 107 /At 9 9* 'll 766 't? 56 61 S n C.I. 7/6/5' 22 6 fo — 22 21 j

Ratio *

. tof 707 0.7/ / <Y0 /.?} 7. 09 '9/ '?6 /ft 3 J!?/52 1/9 3 5 6g 50 50 57 96 CrAtK Patter

G A A A AC AC A A e c AC A 'S 1 . flit 117/ft 2.Y0 66 95 55

13 <9 S3 }} 36 V? JA 59 Jf 37X0/52 2Y* 6? 79 77 A? 72 £6

31 2a 2k 76 57 V7 33 9* 72. 62 kS 79 St}, ft, f

/« Col. 0,093“ i///57

i/19/51

1 26 59 SI 77 Areraoff " 33 21 * r'* 32 96 71 51 56 S2 2 99 63 57 45 65 67 69

Ratio / 015 70? ' 35% a« i/tT/rt 73 — IAL — S7 2 3 3 A c c S £ 2> c 6 3/25/51 2(7 775 '/5 79 72 ?5 ts

(Ay* 2t tnift -a t 0.0*1* i/y/ft 3/3/n

2 iK 67 — 96 U

22 / '09 /of So 9v 91. 13. Ad 1, C.I 2/7i/57 2/9 57 If — 9i

220 V

9! 92 VI Y 9 ko% F/t 2/79/51 2 Cl 57 37 — 91

I/i 9/52 250 37 37 3? 3? 37 9/

0.073" 3/ i/5/ 226 79 11 22. y,j/f. 1U 27 17 22 22 12 22

» 'CK^ci’f'd* «r At4*frr Tmiftir <*>* **'*~+p€ M*/+y Ck7<*<mV'*y
.
TIME

TO

FINAL

FAILURE

(51-9

CYCLE

),

DAYS

TIME

TO

FINAL

FAILURE

(51-9

CYCLE

1,

DAYS

VENEZUELAN MID-CONTINENT CALIFORNIA

FIG.

FIG. 3

ACCELERATED DURABILITY DATA

COATINGS CONTAINING FLORIDA CLAY

COATING THICKNESS

0-0.013 IN. V-0.025 IN. A -0.043 IN.

A

i A

i S y

-A

1

i y H•

1

< k ( tH

> —

ry

'

O O 35 50 60 0 35 50 60 0 35 50 60

CONCENTRATION OF FLORIDA CLAY, PERCENT BY WEIGHT VENEZUELAN MID-CONTINENT CALIFORNIA CONCENTRATION OF SCHUNDLERS DOLOMITE, PERCENT BY WEIGHT VENEZUELAN MID-CONTINENT CALIFORNIA

FIG. 4 FIG. 5

VENEZUELAN MID -CONTINENT CALIFORNIA VENEZUELAN MID -CONTINENT CALIFORNIA

FIG. 6 FIG. 7
'

-
- lb -

The air content of a few of the coatings was determined

but proved to be too small to be measured by the techniques

employed.

(b) When the data were analysed to determine the degree

of difference between the duplicate coatings exposed in

different machines, it was found that in 92% of the cases,

the individual panels failed within ±15# of their average

durability. Figure 8 is a graphical presentation of the

failure probability curve showing the percentage of the total

failed

number of panels /vs. the percent deviation from their average.

All of the sets falling outside the ±15# limits were repeated;

the results are reported in Table XI.

6. DISCUSSION OF RESULTS

Since the durability data must be considered in respect

to the asphalts and stabilizers from which the coatings were

made, the results of the tests on these materials will be

considered first. The asphalts were obtained from three

roofing plants, where each had been processed into five

different products from the fluxes described in Table I.

These products, differing only in the length of time the

asphalt was blown, were classified according to their softening points, as shown in Table I. During storage, the asphalts

hardened progressively, but not uniformly, making it difficult

to pinpoint the exact softening point to which a coating
'
- 15 -

was blended. However, preliminary softening point determinations made shortly before a coating was to be prepared

for exposure permitted the estimation of which adjacent

products to blend to enable the coating to have a softening

point close to the 220-225° F range customarily followed

commercially and arbitrarily selected for these laboratory

exposures. The above considerations serve to explain why,

in Tables VI to VIII, some of the softening points reported

are as low as 217°F and others as high as 227°F.

In a few instances where it was physically impossible

to obtain a softening point as low as 227°F, because the

softening point rise produced by that particular concentration

of stabilizer was very great, all of Product 1 was used and

the softening point was accepted even though, as in the case

of 3 5% mica, it was very much higher.

The spectral analyses reported in Table II show that all

three asphalts had strong lines present for such metals as

nickel, copper, and vanadium. The consequences of the

presence of these catalytically active metals are not certain.

The stabilizers which were blended with the asphalts for

these studies were examined rather thoroughly and the results

reported in Table III. All of these materials were selected

on the basis of past experience to include stabilizers which

were known to perform well, materials which had caused
'

. .jf'

‘

> '
- 16 -

trouble, and materials which were used in large quantities,

but whose performance was reported to be variable. The

relations between each stabilizer and the durability of the

coatings made with it will be discussed later.

The physical properties of each of the unstabilized

asphalt coatings exposed are listed in Table V. These show

that all three asphalts are of the normal coating grade,

of high softening point and low penetration. The penetration

indices of all three are about the same and greater than 2,

testifying to the fact that they are highly blown. The

lowest susceptibility, shown by the Venezuelan asphalt, indicates that it should withstand temperature variations best,

followed by Mid-Continent and California asphalts, in order.

The California asphalt had the greatest heat loss at

163°C; none of the penetrations changed appreciably during the

five-hour exposure.

Although the viscosity measurements do not indicate it,

the California asphalt had a sharper melting point than the

other two. However, the Mid-Continent asphalt was the most

tacky as well as the most viscous.

The Venezuelan asphalt had the lowest water absorption

during any particular time interval and also the smallest

increase in volume during submersion. The shatter tests
.
- 17 -

showed it to be the most brittle of the three. However,

while the Mid-Continent asphalt fell between the Venezuelan

and California on most determinations, it was the least

brittle as well as the most viscous of the three. In general,

the properties of the unstabilized asphalts do not align themselves in a manner that would be a positive indication of

their relative durabilities.

When finely divided mineral matter is added to an asphalt

it stiffens the asphalt and increases the temperature to

which it must be heated to induce flow. The stabilizers

behave differently in each asphalt and in the different

asphalts. In Tables VI to VIII are listed the softening

points of the coatings and the estimated softening points

of the base asphalts. By subtracting the two (see Table XII),

it can be seen that the softening point rise increased with

concentration for each stabilizer. However, the effect was

different in each asphalt, being least pronounced in MidContinent and most in Venezuelan. The viscosity data show

that all of the stabilizers are influential in making the

coatings progressively more viscous as their concentration is

increased, but the effect is not so systematic as for the

softening point rise. To state this condition differently,

the temperature coefficient of viscosity is a function of the

stabilizer-asphalt combination. The same stiffening effect
•

•

V <
TABLE XII. EFFECT OF STABILIZERS ON SOFTENING

POINT AND SHATTER OF COATINGS

a Shatter Resistance

Softening Point Rise Increase 13 Asphalt: Ven. M.C. Cal. Ven. M.C. Cal.

Coating ideg Fahr deg Fahr deg Fahr in. in. in.

35$ BBS 13 11 12 6.5 3.7 5.5-

50% BBS 30 15 24 12.8 9.8 12.0

60% BBS 66 47 51 >18.3 >12.7 >14.7

35# Clay 16 15 20 6.

0 3.0

50$ Clay 37 29 37 3.6 7.4 3.3

35% Dolomite 17 8 11 4.6 7.4 0

50$ Dolomite 20 13 19 5.6 7.2 -0.5

60$ Dolomite 30 -- 28 9.3 10.0 7.7

35# Fly Ash 19 14- 18 2 .

-1.0 2.1

50$ Fly Ash 33 28 30 8.0 3.7 —

60$ Fly Ash 76 63 67 10.0 12.7 5.8

35% Mica >80 >80 >80 >18.3 >12.7 >15.7

35% Silica 20 10 _ — 3.6 3.4 1.6

50$ Silica 22 17 18 4.6 11.7 9.0

60$ Silica 31 25 21 5.6 9.4 11.0

Si The softening point rise is the difference between the softening point of the coating and that of the base asphalt.

bThe shatter resistance increase is the difference between

the shatter of the coating and that of the corresponding

unstabilized asphalt. The shatter of the unstabilized

asphalts are: Yen. = 2.7; M.C. = 8.3; Cal. = 6.3.

- 18 -

can be seen upon examination of the increase in shatter reported in Table XII. In all but four instances the stabilizers increased the shatter resistance of the coating; but

again, no quantitative correlation is apparent.

The water absorptions determined on 3- by 3/l6-in. specimens of each coating immersed beneath one-quarter inch of

distilled water revealed that all stabilizers increased the

water absorption of the asphalts progressively with increasing

concentration, but not always in direct proportion to the

concentration. The Venezuelan asphalt, itself, absorbed water

at the lowest rate and all of its stabilized coatings absorbed

water more slowly than the corresponding coatings made from

the other asphalts. The Mid-Continent asphalt fell between

the low rate of the Venezuelan asphalt and the high rate of

the California asphalt.

For comparison purposes the water absorptions at one

year have been listed in Table XIII-A along with ratio figures

to indicate the increase in absorption produced by the addition of the stabilizer. These data show that although the

Venezuelan asphalt coatings continued to have the lowest water

absorption when stabilizers were mixed with it, the increase

in absorption produced by the addition of stabilizer was

greater than for the other two asphalts in the case of Blue

Black Slate, Clay and Dolomite, less in Fly Ash, and equivalent
t . /

'

»
TABLE XIII. WATER ABSORPTION DATA

&

A. WATER ABSORBED IN ONE YEAR

ASPHALT: Venezuelan Mid-Continent California

g/ft2 ratio g/ft2 ratio g/ft2 ratio

Unstabilized

3 5% BBS

50% BBS

GO% BBS

35% Clay

50% Clay

60% Clay

35% Dolomite

50% Dolomite

60% Dolomite

35% Fly Ash

50% Fly Ash

GO% Fly Ash

35% Mica

35% Silica

50% Silica

60% Silica

1.85 1

3.72 2.0

5. :44 2.9

6.75 3.7

5.01 2.7

6.90 3.7

4.29 2.3

5-54 3.0

7.00 3.8

6.00 3.2

11.05 6.0

12.20 6.

2.46 1.3

2 .1+7 1.3

2. 66 1.4

2.97 1.6

2.50 1

4.28 1.7

5.55 2.2

8.0 5 3.2

4.84 1.9

7.52 3.0

4.94 2.0

6.31 2.5

7.86 3.1

7.45 3.0

14.30 5.7

23.60 9.4

3.19 1.3

2.80 l.l

3.02 1.2

3.45 1.4

3.38 1

5.25 1.6

7.96 2.4

8.64 2.6

6.80 2.0

8.67 2.6

11.33 3.4

6. 60 2.0

7.96 2.4

10.15 3.0

51.70 15.3

57.30 17.0

42.90 12.7

5.21 1.5

3.81 l.l

6.28 1.9

11.29 3.3

aThe complete water absorption curves are in the Appendix.
1
TABLE XIII. WATER ABSORPTION DATAa

B. WEIGHT INCREASE IN 20 MONTHS

ASPHALT

Vene zuelan Mid-Continent California

g/ft2 ratio g/ft2 ratio g/ft2 ratio

Unstabilized 2.29 1 2.97 1 4 . 62 1

35% BBS >+.86 2.1 5.61 1.9 6.49 1.4

50% BBS 6-93 3.0 7.65 2 . 6 12.06 2.

60% BBS 10.27 4.5 12.35 4.2 13.23. 1.9

35% Clay 9.81 4.3 5.72. 1.9 7 . 89k 1.7

50% Clay 10.57 4.6 7.78b 2 . 6 12.07, 1.6

60%> Clay — — — — 9.35b 2.0

3 5% Dolomite 5.34 2.3 6.19 2.1 9.36 2.0

50% Dolomite 7.16 3.1 8.24 2.8 11.14 1.4

60%> Dolomite 9.03 4.0 10.32 3.5 14.68 3.2

3 5% Fly Ash 9.56 4.2 12.90 4.3 69.30 15.0

50% Fly Ash 16.87 7.4 27.38 5.9 72.26 15.6

60%o Fly Ash 19.60 8.6 34.44 11.6 52.55 11.4

35% Mica 3.06 1.3 3.94 1.3 6.34 1.4

35% Silica 3.0+ 1.3 3.48 1.2 3-7lb 0.8

50% Silica 2.70b 1.2 3.80 1.3 8.36? 1.8

60% Silica 2.18 1.0 4.53 1.5 l4. I+7 D 3.1

aThe complete water absorption curves are in the Appendix.

Underwent a weight loss during the last 100-200 days of

immersion.
>

•

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TABLE XIII. WATER ABSORPTION DATAa

C. VOLUME INCREASE IN 20 MONTHS

ASPHALT: Venezuelan Mid-Continent California

cc/ft2 ratio cc/ft2 ratio cc/ft2 ratio

Unstabilized

3 5% BBS

50% BBS

60% BBS

35% Clay

50% Clay

60% Clay

3 5%o Dolomite

50% Dolomite

60% Dolomite

35% Fly Ash

50% Fly Ash

60% Fly Ash

35% Mica

35% Silica

50% Silica

60% Silica

0.70 1

5.34 7.6

7.68 11.0

11.69 16.7

7.60 10.9

7.32 10.5

7.91 11.3

8 . 66 12.4

10.16 14.

12.00 17.1

21.64 30.9

22.70 32.4

5.38 7.7

I.. 93, 2.8

3.76b 3.9

2.90 4.1

1.63 1

6.28 3.9

6.10 3.7

14.34 8.8

5- 2 7, 3.2

10.12 b 6.2

7.99 4.9

9.59 5.9

11.75 7.2

16.61 10.2

31.68 19.4

39.97 24.5

7.02 4.3

4.85 3.0

3.22 2.0

8,26 5.1

4.11 1

7.07 1.7

12.37 3.0

!3 . 72, 3.3

5.83 b 1.4

10 . 44 2.5

9.86b 2.4

10.03 1.4

12.11 2.9

8.94 2.2

73.10 17.8

75.40 18.3

55.80 13 o 6

8.58 2.1

2.94^ 0.7

6 . 52b 1.6

l4.02b 3.4

aThe complete water absorption curves are in the Appendix.

^Underwent a weight loss during the last 100-200 days of

immersion.
* '

'
- 19 -

in Mica and Silica. These data also show the difficulty involved in trying to draw generalized conclusions for all

stabilizers and asphalts; each system must be considered on

its own merits.

When the water absorption data at 20 months are examined

(Table XIII-B) , it is found that while the rate of absorption

generally had increased, the ratio of absorptions of the

stabilized coatings to unstabilized asphalt had remained the

same. The exceptions to this rule were the fly ash- stabilized

coatings, in which the ratio increased for the Venezuelan and

Mid-Continent asphalts and decreased for the California asphalts.

Table XIII-C also shows the volume changes involved for

the 20-month immersion and the ratio of the changes in the

stabilized coatings to those of the straight asphalts. Again,

though the volume changes in the Venezuelan coatings tended to

be lower than in the coatings containing the other two asphalts,

because of the extremely low volume increase of the straight

Venezuelan asphalt, the relative volume changes in the stabilized coatings were highest.

During the last 100-200 days of immersion several of the

specimens underwent a loss in weight, while the remainder continued to gain. Three of these contained clay and four, silica.

There was no apparent reason for the deviation of these specimens from the general trend.
?
20

Forty-eight coatings were subjected to accelerated

durability tests, each in duplicate, in three film thicknesses.

Because all of these could not be exposed simultaneously in

one accelerated durability machine and because no two machines,

or indeed no individual machine, operate identically at all

times, duplicate panels were exposed in two different machines

(odd-numbered panels in one machine and even-numbered ones

in the other) to average the machine differences. When the

coatings had been removed from the machines and the results

tabulated, it was found that differences in durability between

the two panels of each thickness of each coating never exceeded

22.5% of their average, as shown in Figure 8. (This graph

is the failure probability distribution curve of all of the

panels exposed in the Principal Series, in which the number

of panels that failed at any particular percentage of their

average, expressed as a percentage of the total number of

panels, is plotted against that percentage.) It was decided

to make additional sets of the 8% of the coatings falling in

the heels of the curve, outside of the ±15% limits, in order

to get more precise data on their durabilities. The results

of these exposures are reported in Table XI, along with additional exposures of all of the unstabilized asphalts and a few

of the coatings of which the durabilities seemed to be

questionable. In these "check" exposures, four panels of each

21

coating were exposed, two in each of two machines. These

results were used with the original exposures to figure the

average durability of the coatings plotted in Figures 3 to 7.

The data in Table XI show that even in these check exposures

some duplicate panels failed widely apart, but except in six

instances, the average was not shifted over nine days. In

one set of coatings, which had apparently failed prematurely

in both machines, possibly because of some fault in the panel

preparation, the average durability was increased 49 days.

It should be noted that this coating was only 0.013-in. thick,

as were most of the coatings in which large differences in

durability were present in duplicate exposures. Because the

top size of the stabilizer particles is of the same order of

magnitude as this film thickness, particle dispersion and

orientation would be critical in determining the durability

of the coating, and may be a partial explanation for these few

large discrepancies.

Of course, the nature of the method by which failure is

judged is probably the factor of greatest influence in determining the precise durability of a coating and possible

differences in duplicate coatings. Inspection periods were

seven days apart and a difference of as little as one pin hole

in the entire panel area might make that much (seven days)

difference in the reported durability of two panels. The
'
22

random nature of the cracking of the coating, just as in the

breaking of a sheet of glass, in many instances will relieve

the strains in one panel with greater than 5

% of the area

showing cracks and in its duplicate with somewhat less than

that number. It may require several hundred hours before

additional strain is produced sufficient to induce more

cracking. Thus, if the final failure crack level had been

selected at some other degree, the concordance would have been

reported differently.

The type of cracking, as has been discussed previously

(page 8), also entered into the determination of final failure. In the coatings in which types A to C crack patterns

appeared, the exact failure level was of little consequence,

for cracks appeared simultaneously throughout the major portion of the coating; but in those coatings which show types

E through H crack patterns, cracking was slow and progressive,

and the durability would be very closely related to the fractional area affected and adjudged to be final failure. All

of the above considerations must be kept in mind when reviewing

the durability data.

In interpreting the durability data there are several

ways in which they must be considered. The absolute durability is the primary consideration -— How long will each

particular coating last? Secondly, the way the durability
-

-

'
- 23 -

of an asphalt is modified by the addition of stabilizer -- What is the ratio of the durability of a stabilized coating

to that of a film of the same thickness of the same unstabilized asphalt? And finally, the film thickness must be considered — Will a thin film perform as satisfactorily as a normal or thick film? These points will be discussed for

each stabilizer and its effects on each asphalt.

The three asphalts used in this investigation came from

widely separated sources and varied considerably in their

durability. The California asphalt was a shorter lived

material than the Mid-Continent and Venezuelan asphalts,

which were of approximately the same durability. Only in

the 0.043-inch thick films did the Venezuelan prove to be

appreciably more durable than the Mid-Continent. When stabilizers were added to these asphalts, the same order of spread

was maintained.

In terms of absolute durability as determined in the

Accelerated Durability Machines, the coatings stabilized

with 3 5% mica have proved to be best. After more than 650

days, all of the normal and thick films, except for the

0.025-inch ones containing California asphalt, show no signs

of failing; the thin mica-stabilized films with California

asphalt failed in 175 days, with Mid-Continent asphalt failed

in 369 days, and with Venezuelan asphalt failed in ^02 days.
'
- 2b -

These are greater than the durability of any other corresponding coating of the asphalts tested even in the 0.043-in.

thickness range. But, of course, the California asphalt

stabilized with 35$ mica, 0. 013-in. thick, was not more

durable than some of the other stabilized asphalts of greater

film thickness.

The California coating, 0.025-inch thick, with 35$ mica,

failed in 572 days, which is more than 13 times the durability of the unstabilized asphalt of equivalent thickness.

The 0.013-inch coating lasted only 6.7 times as long as the

straight California asphalt, indicating that not only was

the durability greatly increased by doubling the coating

thickness, but the increase in durability was more than

proportional to the increase in thickness. All of the

mica-stabilized coatings that have failed did so in the

Type A pattern, with no visible signs of cracking.

The stabilizer that produced the next greatest durability was blue black slate; the magnitude of the durabilities of the coatings made with blue black can be seen

in Table X and Figure 3 ? and the ratios of these durabilities to that of the corresponding straight asphalts and the

failure crack patterns are also reported in Table X. Again

the California-based coatings were the least durable and the

Venezuelan and Mid-Continent ones about the same. However,
\ .7

'

.
- 25 -

in all instances the stabilizer increased the durability of

the coating. The smallest increase was 4l$ for 50$ blue

black slate in California asphalt 0.013-inch thick; the greatest increase was 315$, with blue black slate in Mid-Continent

asphalt 0.025-inch thick.

Another way of looking at these data, since each stabilizer-asphalt system behaves differently and must be considered

separately, is to calculate the thickness or weight of

stabilized coating equivalent in durability to some standard

material. Since in commercial practice unstabilized coating

asphalt on shingles is about 0,025-inch thick, Table XIV

contains these calculations referred to the straight asphalts

0.025-inch thick. It can be seen that for the Mid-Continent

and Venezuelan asphalts, coatings only 40$ as thick (limited

by the top particle size of the stabilizer) containing blue

black slate stabilizer and between 52 and 67$ as heavy provided the same durability as the 0.025-inch thick straight

asphalts. For the stabilized California asphalt it was

necessary to have 52$ of the thickness and between 68 and 86$

of the weight, depending on the concentration of the

stabilizer.

Since commercial roofing is made to a given weight,

rather than thickness, it would be of practical interest to

compare the durability of coatings equivalent in weight to
*

'

.

.
TABLE XIV. STABILIZED COATING THICKNESS EQUIVALENT IN

DURABILITY TO STRAIGHT ASPHALT COATINGS 25

MILS THICK

Thickness

ASPHALT: Venezuelan Mid-Continent California

(75 Days) (75 Days) (51 Days)

CONCEN:-

TRATION: 35% 50% 60% 35% 50% 60$ 35% 50% 60$

Stabilizer Mils Mils Mils Mils Mils Mils Mils Mils Mils

BBS 10 (6)* 10 10(7)* 10 11 0 TP *

11— 13 13 13

Clay 25 25 — 22 23 — 35 33 -- Dolomite 13 t 13 13 13 12 10 25 25 21

Fly Ash 10(4)* 10 10 10(5)* 16 16 25 25 25

Silica 25 25 19 18 18 20 31 40 31

*The figures in parenthesis are those actually obtained by extrapolation, but because the maximum particle size of the stabilizers

is ten mils, that has been taken as the minimum coating thickness.

TABLE XIV. WEIGHT OF STABILIZED COATING EQUIVALENT IN

DURABILITY TO STRAIGHT ASPHALT COATINGS 25

MILS THICK

Weight per 100 sq. ft.

ASPHALT: .. Venezuelan*" Mid-Continent* California*

(75 Days) (75 Days) (51 Days)

CONCENTRATION: 35% 50% 60$ 3 5% 50%o 60% 35% 50% 60%

Stabilizer lb. lb. lb. lb. lb. lb. lb. lb. lb.

BBS 6.9 7.9 8.7 6.8 8.5 8.6 8.9 10.2 11.4

Clay 16.9 19.2 -- 14.6 17.3 — 23.6 25.2 —

Dolomite 8.9 10.1 11.2 8.7 9.2 8 „ 5 17.0 19.6 18.2

Fly Ash 6.7 7.6 8.3 6 . 6 12.0 13.2 16.8 19.0 20.8

Silica 16.9 19.1 16.0 12.0 13.6 16.

21.0 30.6 26.1

*Weight of straight asphalt coatings 0.025-in. thick.

Ven. = 13.20 lb/100 sq.ft. - M.C. = 12.95 lb/100 sq.ft.

Cal. = 13.15 lb/100 sq.ft.

26 -

an unstabilized asphalt coating 0.025~inch thick. In

Table XV are listed the thicknesses of the stabilized

coatings of this weight and their durability. For lack

of data to make more precise calculations, these figures

were obtained from straight line interpolations between

the durabilities of the 0.013- and 0.025-inch coatings.

On this uniform-weight basis, the trends indicated by

the accelerated durability tests are somewhat different

from those reported on a film- thickness basis. For the

blue black slate in Mid-Continent asphalt, the durability

still increased with stabilizer concentration, despite the

fact that the coating thickness was decreased through 40

percent. However, the durability of the coatings with the

other two asphalts now appears to be almost independent of

the stabilizer concentration.

Blue black slate and mica are the only two stabilizers

that increased the durability of all three asphalts under

all of the test conditions. The behavior of clay, dolomite,

fly ash and silica varied somewhat among the three asphalts.

They will be considered in descending order of their general

effects.

Dolomite and fly ash were about equivalent in their

effects on the durability of the three asphalts. However,

because of the large number of type A failures and because
> ' s
TABLE XV.

DURABILITY OF COATINGS EQUIVALENT IN WEIGHT TO THEIR

UNSTABILIZED ASPHALT 25 MILS THICK

ASPHALT: Venezuelan Mid-Continent California

COATING WEIGHT,

(75 Days) (75 Days) (51 Days)

lb/100 sq.ft.: 13.2 13.0 13.2

CONCENTRATION: 35% 50% 60% 35% 50% 60% 35% 50% 60%

Stabilizer Days Days Days Days Days Days Days Days Days

BBS l4l 138 131 124 140 163 60 58 74

Clay 6k 52 — 75 62 — 31 30 —

Dolomite 92 99 88 88 107 Ill 45 42 3&

Fly Ash 112 100 84 107 86 75 4l 43 4l

Silica 59 48 53 86 75 56 32 25 23

STABILIZED COATING EQUIVALENT IN WEIGHT TO STRAIGHT

ASPHALT COATING 25 MILS THICK

Thickness

ASPHALT

CONCENTRATION:

Venezuelan

(75 Days)

: 3 5% 50% 60%

Mid-Continent

C75 Days)

35% 50% 60%

California

(51 Days)

35$ 50% 60%

Stabilizer Mils Mils Mils Mils Mils Mils Mils Mils Mils

BBS 19 17 15 19 17 15 19 17 15

Clay 20 17 16 20 17 16 20 17 16

Dolomite 19 17 15 19 17 15 19 17 15

Fly Ash 20 17 16 20 17 16 20 17 16

Mica 19 17 15 19 17 15 19 17 15

Silica 20 17 16 20 17 16 20 17 16

- 27 -

fly ash had to be inspected visually only (precluding the

possibility of a type A failure and thus prolonging the

reported life of the coating), dolomite was probably more

active than fly ash in prolonging the durability of the

asphalts. As a matter of fact, dolomite and fly ash were

the intermediate stabilizers, between the excellent

qualities of mica and blue black slate and the rather

doubtful qualities of silica and clay.

Dolomite showed marked improvement in the durability

of the Mid-Continent (Ratios from 1. 34—2. 32) and the Venezuelan

(Ratios from 1.4-3-1.71) asphalts. However, the durability

of Venezuelan asphalt with 3 5% of dolomite was increased

only lb% and only one combination of California asphalt

and dolomite exceeded the durability of unstabilized

California asphalt more than 30%. The coatings stabilized

with dolomite, equivalent in durability to the corresponding

0 . 025-inch straight asphalts, ranged from 0,015 to 0.025

inch thick. As in the case of blue black slate, only

in Mid-Continent asphalt did the durability continue to

increase with concentration when the film thickness was

adjusted so that the coating had the same weight as the

unstabilized asphalt coating. Again, in Venezuelan asphalt,

the durability was independent of the stabilizer
• .

v
- 28 -

concentration; but, in the California asphalt, the durability was slightly below that of the straight asphalt.

The low carbon fly ash improved the durability of

both Mid-Continent and Venezuelan asphalts, but did not

alter it for the California asphalt, when the results are

compared on an equal film thickness basis. In all instances the durability increased with film thickness for

any given stabilizer concentration, but went through a maximum around 50% stabilizer. When compared on an equal

weight basis, the California asphalt coatings with fly ash

reacted similarly to those containing dolomite, but the

durability of both the Mid-Continent and Venezuelan coatings decreased with increasing stabilizer concentration.

The Florida clay and Erie silica, although vastly

different in properties, behaved similarly in influencing

the durability of asphalt coatings. While the durability

in all cases increased with film thickness, only in the

O.O^l-inch coatings with Venezuelan and Mid-Continent

asphalts did it increase appreciably. For these two

materials, except in the thickest films, durability was almost independent of stabilizer concentration. The data in

Table XV indicate that on an equal-weight basis, at best,

these materials did not decrease the durability at lower
'
- 29 -

concentrations in Mid-Continent asphalt, but were definitely deleterious in all other combinations tested.

As constantly reiterated throughout this discussion,

it is extremely hazardous to attempt to draw generalized

conclusions from the data in this report. However, a very

rough listing of the additives tested would place them in

/ the following descending order of their stabilizer merits:

No matter how the results of the accelerated durability

tests are considered, the mica and blue black slate were always beneficial in all three asphalts. The dolomite and fly

ash increased the durability in most instances, but in some

did not affect it. Their relative order is opposite to

that in the above listing in some combinations. Similarly,

the order of clay and silica varied with their various combinations with asphalt.

In attempting to predict the performance of coatings

made with these asphalts and minerals, any properties or

combination of properties of the minerals which would

separate them into the above three categories would be

Good (1) Mica

(2) #50 Blue Black Slate

Poor

Fair

(3)

Schundlers Dolomite

(D Low Carbon Fly Ash

(5) Erie Silica

(6) Florida Clay
'
- 30 -

useful in estimating the value of a new material which

might become available. The only characteristic that fulfills this requirement is particle shape. The stabilizers

designated as "good" all have flat, plate-like particles;

the "fair" materials have sharp, blocky particles; and the

"poor" materials have rounded corners and edges. Thus a

new material would be expected to have sharp, irregular to

flat, platy particles to be considered for use as a

stabilizer. Of course, the other properties would have to

be considered as well. The particle size and size distribution would have to be considered as would the moisture

and free alkali content, loss on ignition, and solubility;

for, obviously, an inert material of suitable firmness is

required. Further work, to be reported later, will deal

with these characteristics.

7. CONCLUSIONS

Because the stabilizers behaved differently in each

asphalt, it was not possible to draw general conclusions on

the effects of the six stabilizers on the three asphalts

tested. However, several broad generalizations can be

stated:

(1) For every stabilizer-asphalt combination, the

durability of the coating increased with film thickness.
!: ...

; v.'4, . /

: I

"
- 31 -

(2) All stabilizers increased the softening point,

viscosity, water absorption, and impact resistance of the

coatings progressively with increasing concentration.

(3) California asphalt and stabilized coatings made

with it were the least durable, while coatings containing

Mid-Continent and Venezuelan asphalts were approximately

equivalent in durability.

(4) Blue black slate and mica increased the durability

of all three asphalts at all concentrations and film thicknesses tested.

(5) Dolomite and fly ash increased the durability of

the coatings in many cases, but in others had no appreciable

effect on it.

(6T Silica and clay increased the durability only in

some instances, mainly in the thicker films with Mid-Continent

and Venezuelan asphalt.
'
- 32 -

APPENDIX A.

- 33 -

SHATTER TEST ON COATINGS

Preparation of Specimen:

Several disks of asphalt 3" in diameter and 3/16"

thick are cast using a suitable amalgamated or glycerine

coated brass mold. After pouring to an excess thickness,

and cooling, the specimens are trimmed down to exact

thickness using a hot knife.

Test Method : The test apparatus consists of a means for dropping

a constant weight from a variable and measured height on

the cast disk as prepared above, recording the height of

drop required to split the specimen in one or more places,

each split extending from the center to the edge of the

specimen.

The apparatus consists of a 20" vertical brass tube

1" in internal diameter, a solenoid sliding within the

tube and adjustable to any height up to 20", an electrical

connection to a standard 110 volt line (either A.C. or

D.C.) with the solenoid in series with a 60 watt lamp and

a switch for shorting the solenoid, a falling steel weight

15/16" in diameter and weighing exactly 1/2 lb., and a

stationary steel contact rod 15/16" in diameter, weighing

exactly 1/2 lb. and having a hemispherical end contacting

the asphalt.

In operation the specimen is brought to a temperature

of 40°F. by submersion in a bath of ice and water for a

period of not less than one hour. It is then placed under

the vertical brass tube, being submerged in water at *+0°?.

during the test, and the contact rod placed in the tube

and in contact with the center of the specimen. The

circuit is closed to the solenoid and the falling 1/2 lb.

weight raised to a height of 1" by raising the solenoid

holding it. The solenoid is then shorted, the weight

allowed to drop, the specimen removed and quickly examined

for fracture. If it has not split it is replaced, the

weight raised to 1-1/2" and the drop again made. This

procedure is repeated with 1/2" increments in height until

the specimen fails. Subsequent specimens should be started

at a height 1" below the failing height of the first test.

At least three determinations shall be made on each asphalt.
/

. .. .

’

v\ >.

‘ i , ..

1

» /. :•

• f'Cv' , . :!

.

;

,

' /

.

.

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- 34 -

Results : Failure is recorded when the specimen splits, in

one or more places, from the center to the edge. Fractures

that do not extend to the edge of the disk are ignored.

The average height of drop required to break the specimen

is recorded as its impact resistance.

Test Method No. lyiB^

Johns-Manville Research Laboratories

Manville, New Jersey.

- 35 -

WATER ABSORPTION OF ASPHALT

DISC METHOD

Application : This method is applicable to all asphalts having

Softening Points (R & B) of 170°F or over.

Apparatus and Materials Required :

1. Brass mould 3/16" thick, 3" diameter hole.

2. Brass plate - 4" x 4".

3. Glycerine.

4. Hot plate.

5. Red marking pencil.

6. 100 grams of asphalt to be tested.

7. Pyrex glass tray, 1-1/2" deep, any convenient

length and width.

8. Distilled water.

Preparation of Specimen : Apply glycerine to the surface of the clean brass

plate and mould which will come in contact with the asphalt.

Assemble the mould and place it on the brass plate. Carefully heat the sample of asphalt to be tested until fluid

and free from air bubbles. If the sample contains filler,

the sample should be stirred slowly with a piece of stiff

wire so as to keep the filler properly suspended yet without incorporating air bubbles.

Pour a sufficient amount of the sample to barely fill

the mould. The pouring must be done with care so that air

bubbles are not created. The surface may be flamed lightly

to remove a few which might form. Not more than 1/16" of

the sample should show above the top of the mould. After

the specimen has cooled thoroughly, remove it from the

mould and wash thoroughly to remove the attached glycerine.

Allow the specimen to dry and mark identification on both

sides with the red marking pencil.

Procedure : Weigh the specimen and record the weight. Place the

specimen in the glass tray and fill with sufficient distilled water to submerge the specimen at least 1/4".
'

.

.

.
- 36 -

Procedure continued : Place the glass tray and specimen in a dark cabinet at

room temperature.

Make periodic weighings to determine the amount of

water absorbed as follows:

Remove the specimen from the water at the end of

each specified period. Do not wipe but blot both sides

and edges carefully so that each surface is as uniformly

dry as possible. Weigh the specimen and record the

weight. Return the specimen to the distilled water tray.

Renew with fresh water at each weighing.

Compute the water absorbed and convert the result

to grams of water absorbed per square foot of asphalt

surface exposed.

First 3 months

Next 9 months

Thereafter

Weekly

Monthly

Each 6 months

Test Method: WA-2

Johns-Manville Research Laboratories

Manville, New Jersey.

O 100 200 300 400 500 600

TIME SUB MERGED,DAYS

0 IOO 200 300 400 500 600

TIME SUBMERGED, DAYS
I "
WATER

ABSORBED,

g/ft*

__

WATER

ABSORBED,

g/ft

O 100 200 300 400 500 600

TIME SUBMERGED, DAYS TIME SUBMERGED, DAYS

O 100 200 300 400 500 600

TIME SUBMERGED, DAYS

0 100 200 300 400 500 600

TIME SUBMERGED, DAYS


..

..

'

•

.
REFERENCES

(1) Greenfeld, S. H., M A Method of Preparing Uniform

Films of Bituminous Materials", to appear in the

A.S.T.M. Bulletin.

(2) Greenfeld, S. H., Progress Report on "The Effects

of Refrigeration on the Accelerated Testing of the

Durability of Asphalts", July 12, 1950.

(3) Hunter, J. B c

, Gzemski, F. C., and Laskaris, L.,

"A New Method for Evaluating Failure of Bituminous

Materials Due to Weathering", A.S.T.M. Symposium

on Accelerated Durability Testing of Bituminous

Materials, 19^9
-

,

.
THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set forth in the Act

of Congress, March 3, 1901, as amended by Congress in Public Law 619, 1950.

These include the development and maintenance of the national standards of

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consistent with these standards; the determination of physical constants and

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Information on the Bureau’s publications can be found in NBS Circular 460,

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Bureau of Standards (25 cents). Both are available from the Government Printing Office. Inquiries regarding the Bureau’s reports and publications should be

addressed to the Office of Scientific Publications, National Bureau of Standards,

Washington 25, D. C.
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