and the iowa highway research board iowa dot project...
TRANSCRIPT
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D.Y. Lee T. Demirel August 1987
Final Report
Beneficial Effects of Selected Additives on Asphalt Cement Mixes
Submitted to the Highway Division, Iowa Department of Transportation, and the Iowa Highway Research Board
lae · ring resear~"?8~itute
iowa state university
Iowa DOT Project HR-278 ER! Project 1802
ISU-ERI-Ames-88070
/;ti Iowa Department ~l of Transportation
D.Y. Lee T. Demirel August 1987
Final Report
Beneficial Ettects of Selected Additives on Asphalt Cement Mixes
Submitted to the Highway Division. Iowa Department of Transportation and the Iowa Highway Research Board Iowa DOT Project HR-278 ERi Project 1802 lSU-ERI-AMes-88070
Engineering Research Institute Iowa State University
Iowa Department ot Transportation
iii
TABLE OF CONTENTS
ABSTRACT
1. INTRODUCTION
2. PROGRAM OF STUDY
3. EFFECTS OF ADDITIVES ON THE PROPERTIES OF ASPHALT CEMENTS-PHASE I
Materials Procedures Results and Discussions 3.3.1. Rheological Properties 3.3.2. Tensile, Ductility and Elastic Properties 3.3.3. Chemical Properties 3.3.4. Temperature Susceptibility .3.3.S. Potential for Cracking and Rutting
4. EFFECTS OF ADDITIVES ON THE PROPERTIES OF ASPHALT CONCRETE
Page
xiii
1
2
5
5 .8 14 14 29 34 so 56
MIXTURES-PHASE II 61
4. L Materials 4.2. Procedures 4.3. Results and Discussion
4.3.1. Marshall Properties 4.3.2. Resilient Moduli 4.3.3. Tensile Strength 4.3.4. Moisture Damage
4.3.4.1. Marshall Immersion 4.3.4.2. Tensile-Strength 4.3.4.3. Resilient Modulus 4.3.4.4. Life Benefit-to-Cost Ratio
4.~.s. Fatigue Resistance 4.3.6. Rutting Resistance
S. STRUCTURAL AND PERFORMANCE EVALUATION-PHASE III
5.t. The Asphalt Institute Method 5.2. The University of Nottingham (Brown) Method
6. SUMMARY AND CONCLUSIONS
7, RECOMMENDATIONS
8. ACKNOWLEDGMENTS
9. REFERENCES
61 63 67 67 74 74 74 80 80 86 87 88 96
105
105 112
123
133
135
137
iv
TABLE OF CONTENTS ('Cont'd.) Page
APPENDIX A: TENSILE STRENGTH TEST 143
APPENDIX B: ELASTIC RECOVERY TEST 145
APPENDIX C: DROPPING BALL TEST 147
APPENDIX D: NOMClGRAPH FOR PREDICTING ASPHALT STIFFNESS 149
APPENDIX E: NOMOGRAPH FOR PREDICTING CRACKING TEMPERATURE 151
APPENDIX F: SAMPLE COMPUTER PRINTOUT FROM DAMA 153
I
v
LIST OF TABLES
Table 1. Sample identification~Phase I.
Table 2. Rheological properties.
Table 3. Tensile properties of binders.
Table 4. lJuctility and elastic properties.
Table 5. Temperature susceptibility.
Table 6. Low-temperature cracking properties.
Table 7. Mix identification~Phase II.
Table Sa. Mix properties, LS/AC-5. b. Mix properties, G/AC-5. c. Mix properties, LS/AC-20. d. Mix properties, G/AC-20.
Table 9a. Indirect tensile strength and resilient modulus, t.S/AC-5.
b. Indirect tensile strength and resilient modulus, G/Ac-s.
c. Indirect tensile strength and resilient modulus, LS/AC-20.
d. Indirect tensile strength and resilient modulus, G/AC-20.
Table 10. Results of fat'tgue analyses (microstrain).
Table 11. Results of DAMA structural analyses.
Table 12a. Summary of structul'al analyses by Brown method, LS/AC-5.
b. Summary of structural analyses by Brown method, G/AC-5 (Mixes 2, 4, and 6).
c. Summary of structural analyses by Brown method, LS/AC-20 (Mixes 7, 9, and 11).
d.. Summary of structural analyses by Brown method, G/AC-20 (Mixes 8, 10, and 12).
6
15 .
30
33
51
59
64
68 69 70 71
75
76
77
78
94
107
114
115
116
117
Table 13. Summary of effects of additives on binder properties. 124
Table 14. Summary of effects of additives on mixture properties. 125
vii
LIST OF FIGURES
Fig. 1. Binder study flow chart.
Fig. 2. Dropping ball test, definitions of times.
Fig. 3. Definitions of toughness and tenacity.
Fig. 4. Penetration at 77° F (25° C).
Fig. 5. Penetration at 41° F (5° C).
Fig. 6. Ring-and-ball softening point.
Fig. 7. Viscosity at 140° F (60° C) and 275° F (135° C).
Fig. g, Viscosity at 77° F (25° C).
Fig. 9. Viscosity ratio at 77° F (25° C).
Fig. 10. Percent of retained penetration.
Fig. 11. Typical Class S, B, and W behavior of asphalt.
Fig. 12a. BTDC of Asphadur-modified AC-5. b. BTDC of lime-modified AC-5. c. BTDC of Styrelf-modified AC-5.
Fig. 13a. BTDC of Asphadur-modified AC-20. h. BTDC of lime-modified AC-20. c. BTDC of Styrelf-modified AC-20.
Fig. 14. Toughness.
Fig. 15. Tenacity.
Fig. 16. Results of dropping ball test.
Fig. 17a. HPLC chromatogram of AC-5 without additives. h. HPLC chromatogram of SBS in AC-20.
Fig. lR. Percent of LMS determined by HPLC.
Fig. 19. Fluorescence micrographs of Asphadur in AC-5.
Fig. 20. Fluorescence micrographs of Asphadur in AC-20.
Fig. 21. Theta/two-theta scan, AC-5 versus AC-20.
9
12
12
17
18
19
20
22
23
24
26
27 27 27
28 28 28
31
32
35
36 37
38
41
42
44
viii
LIST OF FIGURES (Cont'd.)
Page
Fig. 22. 'rheta/two-theta scan, AC-5 with additives. 45
Fig. 23. Theta/two-theta scan, AC-5 with additives (vertical scale offsets). 46
Fig. '24 .• Two-theta scan, lime (5%) in AC•5. 48
Fig. 25. Two .. theta s·can, Asphadur (4%) i.n AC-5. 49
Fig. 26. Penetration index. 53
Fig. 27. Viscosity temperature susceptibility. 54
Fig. 211. Penetration-viscosity number (PVN) • 55 a. AC•5. b. AC-20.
Fig. '29. Low-temperature cracking prop!!rties. 58 . .
Fig. 30. Aggregate .r,iradations. 62
Fig. 31. Mixture evaluation flow chart. · 66
Fig. 3?.s. Marshall stability. 72 b. Marshall stiffness. 73
Fig. ~3. Indirect tensile strength <ITS). 79
Fig. 34. Moisture damage, Marshall immersion stability. 81
Fig. 35a. Moisture damage, ITS, and -resilient modulus, AC-5/LS. 82 I b. Moisture damage, ITS, and resil~ent modulus, ' ' AC-5/G. 83 I
c. Mobtute damage, ITS, and resilient modulus, AC-20/LS. 84
d. Moisture damage, ITS, and resilient modulus, AC-20/G. 85
Fig. 36a. Percent change of design life artd benefit-to-cost ratio, AC-5/LS. 89
b. Percent change of design life arid benefit-to-cost ratio, AC-5/G. 90
c. Percent change of design life and benefit-to-cost ratio, AC-20/LS. 91
d. Percent change of design life and benefit-to-cost ratfo, AC-20/G. 92
ix
LIST OF FIGURES (Cont'd.)
Fig. 37. Fatigue strain. 95 a. AC-5. b. AC-20.
Fig. 38. Typical strain versus time curves, Mixes C9 and AH9. 97
Fig. 39. Effect of aggregate type on Smix versus Sbit curves, Mixes Cl and C2. 98
Fig. 40. Effect of AC grade on Smix versus Sbit curves, Mixes C3 and C9. 99
Fig. 41. Effect of AC content on Smix versus Sbit curves, Mixes KS, KlO, and Kl2. 100
Fig. 42. Effect of additives on Smix versus Sbit curves. 101
Fig. 43. Rut ~epth estimation by Shell procedure. 103
Fig. 44a. Structural analyses by DAMA procedure, Hl • 4 in., SGE • 4,500 psi.
b. Structural analyses by DAMA procedure, Hl. • 4 in., SGE • 12 ,000 psi. .
c. Structural analyses by DAMA procedure, Hf'• 8 in., SGE • 4,500 psi.
d .• Structural analyses by DAMA procedure, Hl • 8 in., SGE • 12,000 psi.
108
108
110
111
Fig. 45a. Structural analyses by Brown procedure, LS/AC-5. 118 b. Structural analyses by Brown procedure, LS/AC-20. 119 c. Structural analyses by Brown procedure, G/AC-5. 120 d. Structural analyses by Brown procedure, G/AC-20. 121
· xi
CONVERSION FACTORS, U. S. CUSTOMARY TO METRIC (SI) UNITS OF MEASUREMENT
U. S. customary units of measurement used in this report can be converted
to metric (SI) units as follows.:
MULTIPLY
inches
feet
square inches
square yards
knots
pounds
kips
Pounds per cubic foot
pounds
kips
pounds per square inch
pounds per cubic inch
gallons IU. S. liquid)
Fahrenheit degrees
BY
2.54
0.3048
6.4516
0.83612736
0.5144444
0.45359237
0.45359237
16.018489
4.448222
4.448222
6.894757
2.7144712
3.785412
5/9
TO OBTAIN
centimeters
meters
square centimeters
square meters
meters per second
kilograms
metric tons .
kilograms per cubic meter
newtons
kilonewtons (kN)
kilopascals
kilopascals per centimeters
cubic decimeters
Celsius degrees of Kelvins*
* To obtain Celsius (C) temperature readings from Fahrenheit (F) readings, use tile following formula: C = (5/9)(F-32). To obtain Kelvin (K) readings, use: K • (5/9)(F-32) + 273.15.
xiii
ARSTRACT
Effects of polyolefins, neoprene, styrene-butadiene-styrene (SBS)
block copolY111ers, styrene-butadiene rubber (SBR) latex, and hydrated
lime on two asphalt cements were evaluated. Physical and chemical tests
were perforn)ed on a total of 16 binder blends. Asphalt concrete mixes
were prepared and tested with these modified binders and two aggregates
(a crushed limestone and a gravel), each at three asphalt content
levels.
Properties evaluated on the modified binders (both original and
thin-film oven aged) included: viscosity at 25° C, 60° C and 135° C with
0 0 capillary tube and cone-plate viscometer, penetration at 5 C and 25 C,
0 softening point, force ductility, and elastic recovery at 10 c,
dropping ball test, tensile strength, and toughness and tenacity tests
at 25° c. From these the penetration index, the viscosity-temperature
susceptibility, the penetration-viscosity number, the critical
low-temperature, long loading-time stiffness, and the cracking
temperature were calculated. In addition, the binders were studied with
x-ray diffraction,. reflected fluorescence microscopy, and
high-performance liquid chromatography techniques.
Engineering properties evaluated on the 72 asphalt concrete mixes
containing additives included: Marshall stability and flow, Marshall
stiffness, voids properties, resilient modulus, indirect tensile
strength, permanent deformation (creep), and effects of moisture by
vacuum-saturation and Lottman treatments. Pavement sections of varied
asphalt concrete thicknesses and containing different additives were
compared to control mixes in terms of structural responses and pavement
lives for different subgrades.
xiv
Although all of the additives tested improved at least one aspect of
the binder/mixture properties, no additive was found to improve all the
relevant binder/mixture properties at the same time. On the basis of
overall considerations, the optimum beneficial effects can be expected
when the additives are used in conjuncti6n with softer grade asphalts.
1
1. INTRODUCTION
Because of the inherent properties of paving asphalts traditionally
produced as waste products and because of the inadequacy of current
specifications, asphalt paving mixtures~even those designed and
constructed with the best of current technology and knowledge~fre-
quently do not possess all of the desirable characteristics at the same
time. Wtth heavier truck loads and higher traffic volumes as well as
decreased resources for timely maintenance, asphalt pavements have
eXJ>erienced accelerated deterioration.
In an attempt to improve the performance of asphalts and to
increase the service life of asphalt pavements, additives have been
incorporated to change the characteristics of the asphalt or the asphalt
mixture. Some of these additives are hydrated lime, sulfur, anti-
oxidants, antistripping agents, carbon black, asbestos fiber, and a
variety of polymers (11,12,19,22,2.3,24,26,34,37,40,46,47, and 50).
' . Highway Research Project HR-278 was initiated in 1985 to study three of
the more promising additives (hydrated lime, Asphadur, and Styrelf) and
to identify their beneficial effects. A project progress report
summarizing the results of Phase I (Binder Evaluation) during the first
year was submitted in August 1986 (25). Phase II (Mixture Evaluation)
of the project was modified in October 1986 to include four more
polymerized asphalt cements (PACs). This Final Report describes all
work conducted and the findings resulting from HR-278.
3
2. PROGRAM OF STUDY
Since most of the asphalt pavement problems that can be attributed
to binders are stripping, thermal cracking, rutting, and hardening of
the hinders, the study was mainly designed to evaluate the effects,
benefits, and mechanisms of additives on these properties.
The research was conducted in three phases. Phase I was the
evaluation of the effects of selected additives on the durability and
rheological properties of asphalt cement binders and their effects on
the rutting and low-temperature cracking susceptibility of the asphalt
pavements. Phase II was an evaluation of the effects of these additives
on asphalt concrete mixtures in terms of rutting, stripping, stability,
and low-temperature cracking potential. Phase II.I was the prediction of
performance with a pavement design and. analysis system, such as DAMA.
3. EFFECTS OF ADDITIVES ON THE PROPERTIES OF ASPHALT Cl!:MENTS--PHASE I
3.1. Materials
Two asphalt cements, one from Bituminous Materials of Terre Haute,
Indiana, and the other from F.xxon of Baytown', Texas, were evaluated in
conjunction with three additives. Two of the additives (Asphadur and
lime) were added to the two asphalt cements at two levels of concen
tration each; the third additive (SBS~styrene-butadiene-styrene) was
incorporated in the .these asphalts. by the supplier at one single
"optimum" concentration and were received and tested as modified
asphalts (Sty~elf). The factorial combination and sample identifi
cations of the 16 binders are given in Table 1.
Styrelf was developed by the French Highway Department and was
introduced in the United States by Group Elf Aquitaine. Styrelf is a
unique combination of asphalt cement and the polymer SBS. It involves a
chemical reaction between the polymer and the asphalt. The reaction
starts from the small chain polymer and then increases in size while
linkinl! irreversibly to the bituminous matrix. The ouantity of polymer
and reactant have been selected to obtain optimum performance (10).
Usually 3% of the polymer is added. Chemical analysis shows that with
thi.s concentration the reactional places of the bitumen have been
blocked by a polymer-bitumen bond or a bitumen-bitumen bond. Therefore,
no further reaction, such as oxidation, can take place. Different tests
performed by the manufacturer have shown that the Styrelf will improve
the performance of the pavement.
6
Table I. Saaple Identification - Phase I.
AC GRADE AC·S · AC·Z8
ADDITIVE CONTENT 0 L II 0 L H
ASPHAOUR I, . 2A .. 3A 1 .8A 9A A: PARTIALLY DISSOLVED 28 38 88 98 8: TOTALLY DISSOLVED. (4~) 1611 (4\) (6\)
HYDRA TEO LI NE . 4 ~ 10 11 ftlXIHG 6 NIN f 280 f (5\) (IOU (5\) (10\)
STY RELF 6 12
O : no additive I control l. l : low level. ' H : high level. A : 1lxlng 3 aln.@ 400 F. 8 : 1lxlng 3 •In. t 320 F follow~ by heating In oven f 320 F for 12 hrs.
7
~ydrated lime has been used in pavements as an antistripping agent
for a long time. Recently, a number of studies have been carried out to
evaluate the performance of lime in asphalt pavements, not only as an
antistripping airent but also an an agent to improve the other qualities
of asphalt. 'l'be National Lime Association's bulletin (37) has presented
the beneficial effects of lime in asphalt pavements. In addition to
functioning as an antistripping agent, hydrated lime may also act as a
modifier in asphalt cement by reducing the rate of hardening.
Considering these properties, we selected lime for this study, and
its performance was evaluated when it was added only in the binder.
High-calcium hydrated .lime of the Snow-flake brand was used. This lime
met the ASTM specifications C207 (Type N) and C6 (Type N) and Federal
specifications SS-L-351 (Class M).
Asphadur is a grained, mixed polymer, known as polyolefin, and is
manufactured by Schiker and Company of Austria under the trade name of
Asphadur. This material was distributed in the United States by the
Minnesota Mining and Manufacturing Company of Minneapolis, Minn., under
the trade name "Stabilizing Addi.tive 59'l0" (48). The process of
preparing asphalt mix with the additive polyolefin was patented in the
United States by Paul Raberl of Austria in December 1974 (14). The Iowa
Department of Transportation, after using this additive in different
pavements across Iowa, stated that "this additive is capable of
improving the viscosity, stability, flow and strength characteristics of
asphalt cement concrete, making it less susceptible to rutting and
shoving" (17). Although Asphadur is generally added to the asphalt mix,
the research on Phase I was done by adding it in the binder.
8
3. 2. Procedures (See ~.chart in Fig. 1.)
The samples with Asphadur were prepared with two different mixing
plans, as shown in Table 1. The samples tabelled "a" were mixed for 3
minutes at 400 • F to get partially dissolved Asphadur. The samples
labelled "b" were mixed for 3 minutes at 320° F and then followed by
heating in oven.~t 320° F for 12 hours to get totally dissolved
Asphadur. Hydrated lime was mixed for 6 minutes at 280° F and
transferred into the cans. In each case, 800 grams of asphalt cement
were taken and heated to mixing temperature. The additive was mixed in
with a motorized stirrer while constant temperature was maintained.
In order to evaluate heat stability and the effects .of hot plant
mixing on these modified binders, the 16 binders were treated by
following the thin film oven test ('l'FOT) procedure. The samples before
and after TFOT treatments were.identified as 0 and R samples,
respectively.
In order to determine rheological·properties, penetrations at 41° F
(~· C) and 77° F (25° C), the softening point (R & B), and viscosities'
at 77° F (25° C), 140° F (60° C) and 275° F (135° C) were determined on
both original and thin-film oven test residues of all binder blends.
From these results, the penetration index, the viscosity-temperature
susceptibility, the penetration viscosity number, the critical
low-temperature, long loading-time stiffness, and the cracking '
temperature were calculated.
I i
HR-278 P.hase I Test Program·
Penetration @41 & n F
Rheological properties
·softening point
Viscosity i1. 140, 275
I
'----1 Correlations 1-----'
G\sphalt cement
prt>perties
Temperature susceptibility Classification
·Additives
Chemical Proll9rties
m.A
properties
Rutting
Stiffness
Fig. 1. Binder study flow chart.
pattern
"'
10
Additional nonstan<lard physical tests that have been used to
characterize polymer-modified asphalts were also explored.
• Tensile strength: At the Elf Aquitaine Asphalt Laboratory,
Terre Haute,. Indiana, tensile stress at 68 ° F (20 ° C) and 800%
elongation (or at fracture) of all binders were determined, with
an Instron tensile tester, at the rate of pull of SO cm per min.
This procedure is basically ASTM D412 (Standard Method for
Rubber Properties in Tension), which is used routinely by the
rubber industry to evaluate tensile strength. The modified
procedure is given in Appendix A.
• Force ductility: The maximum force required to pull the
standard ductility specimen with cross-sectional area of 1 sq
cm, at rate of pull of S cm p~r min and at a temperature oj: ·
10° O (S0° F), was determined by attaching a load cell to one
end of the ductility mold (2).
• 'l!:lastic recovery: The procedure developed by the Elf Mineraloel
Laboratories in Germany (23) was used to measure elastic
recovery of all binders (Appendix B). A standard ductility
spec:l.men is stretched to 20 cm at 10° C (so·• F) and held for
five minutes. The specimen is then cut in the middle with a
pair of scissors and allowed to stand undisturbed. .After one
hour, the combined length of the. two sections is determined.
The percent recovery is defined as follows:
20 - L ' % recovery •
20 x 100
where L • length after one hour.
11
• Dropping ball test: A very simple procedure for characterizing
viscoelastic materials under constant stress conditions was
developed in the Elf Aquitaine research labs in Solaize, France
(23) (Appendix C). Exactly 8.0 grams of asphalt are poured into
a machined metal cup and a ball of specified size and weight is
embedded to a predetermined depth. The apparatus is inverted so
that the ball is free to fall. The time required for the
embedded portion of the ball to reach the point tangent to the
surface of the cup is defined as tl. The time required for the
ball to drop from that tangent plane to a point 30.0 cm below is
defined as t2 (Fig. 2). Time tl is closely.related to the
viscosity of the asphalt or its initial tensile strength. Time
t2 depends somewhat on viscosity, but it is primarily affected
by the tensile strength or elastic flow of the asphalt as it is
stretched by the weight of the steel ball. The ratio t2/tl
provides a rough relationship of a material's elasticity or
tensile stength after elongation to its original viscosity. The
test was run at ambient temperatures.
• Toughness and tenacity: Another constant strain method for
monitoring tensile strength of modified binders is the toughness
and tenacity test (40). A metallic hemispherical head is
embed<ied in hot molten asphalt to a depth of 7/1.6 in. The head
and the asphalt are cooled . . to 25 C (77° F). The head is then
pulled from the asphalt at the rate of 20 in. per min, and a
load-deformation curve is plotted. Toughness and tenacity are
VI
!!l
12
~ .·
l+J SL (+)
~ .....
~ 0 0 "' .., ...
II . {+J . .
TIME t = 0 TIME t = t 1 TIME t = t 1 + t 2
Fig. 2. Dropping ball test, definition of times.
50 ..._
40 -
TOUGHNESS • A + B TENACITY • B TOUGHNESS • 41.8 IN. LBS. TENACITY• 27.8 IN. LBS.
• 30 ...
~ ~
20 ...
10 ....
I A I i8 I . . .
' 0 I
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 EXTENSION, IN.
Fig. 3. Definitions of toughness and tenacity.
16
13
defined by the areas under the force-deformation curve (Fig. 3).
The areas under the curve were measured by a planimeter.
Tenacity is the wor~ performed tn pulling the binder material
away from the tension head to its maximum extension. Toughness
is the total work performed in pulling the tension head out of
the sample as well as stretching the material while it is still
attached to the head.
While chemical characterization of asphalt and polymer-modified
asphalts is difficult, since no two asphalts are chemically identical
and no conventional chemical methods are readily adaptable to the
modified asphalts, three special techniques have been found to show
potential in identifying effects of these additives:·x-ray diffraction,
reflected microscopy, and high-pressure liquid chromatography (RPLC).
• High-pressure liquid chromatography (HPLC): Samples of all
binder blends were sent to Montana State University for
determination of molecular.size-distribution (MSD) by
high-pressure liquid chromatography (RPLC) with a Waters
Associates instrument and ultrastyragel columns (18).
• Reflected fluorescence microscopy: The homogeneity of
dispersion for microstructure) of the additives in asphalt was
observed by using an Olympus light microscope (Model BHM) with
reflected fluorescence attachment under blue excitation (8).
14
• X-ray Diffraction: This technique was used to determine any
change in the strocture and composition of asphalt, especially
any chemical change, because of the additives (.53). The technique
uses an x-ray beam deflec'ted from the surface of the material
with a certain wavelength and at a certain angle. The wave
length of this deflected ray depends on the spacings between
the planes (d) and angle of incidence ($). The following
relationship governs in this case.
n:\ • 2d sin e
where ;\ • wavelength
Samples l, 2b, 4, 6, 7, Sb, 10 and 12 were selected as
representative samples for the x-ray diffraction. Two different
types of scans, i.e. 6/26 scan and 26 scan with e = 5,0 and 10•,
were used for the above samples (1).
3.3. Results and Discussion
3.3.1. Rheological Properties
For all the samples tested, the penetration values at 25° C and
5° C, are given in Table 2. Asphalt cement AC-5 and AC-20 were used in
samples labelled 1-6 and 7-12 respectively. The results, listed in
Table 2, are for both original and thin film oven test residue samples.
15
Table Z. Rheological properties.
BATER I Al SAKPLE VIS, 60 VIS, 135 P1,Z5 Pa,5 S.P VIS,25 No. poise stokes c poise
I I
AC-5 1-0 459 1.1 IU 10 39 2.38E+05 AC-S+4l ASPHAOUR 2b-O 1149 3.4 115 z 44 6,38E+OS AC-5+6\ ASPHAOUR lb-0 11500 9.5 98 12 49 l.33E+06 AC-5+5\ ll"E •-o 1100 1.5 Ill 8 42 2.40£+05 STYRELF IN AC-5 6-0 908 3.8 135 12 44 2.93£+05
AC-20 1-0 2215 3.4 55 2 50 2.38£+06 AC-2BHl ASPHAOUR 8b-O 50000 12.0 35 5 56 S.96E+06 AC-20+6' ASPHAOUR 9b-O 10000 16.0 20 4 58 8.48£+06 AC-ZOtS\ LIKE 10-0 4100 4.4 44 4 Sl 2.79E+06 STYRELF IN AC-20 IZ-0 2812 6.Z 35 z 53 3.38£+06
AC-5 1-R 868 z.s 90 3 43 5.02£+05 AC-5+4\ ASPHAOUR 2b-R c 8.8 35 I 61 8.53E+06 AC-5+6\ ASPHAOUR 3b-R c c 19 6 59 l.l0Et07 AC-5+5\ LIME 4-R c c 33 5 57 6.56£+06 STYRELF IN AC-5 6-R 8935 8.2 36 4 59 7.39£+06
AC-20 7~R 4264 9.0 35 0 63 t.53E+07 AC-20+41 ASPHAOUR 8b-R c c 12 l 66 2.49£+07 AC-20+6\ ASPHADUR 9b-R c c II I. 11 2. SOE+07 AC-ZO+S\ LIKE 10-R c c 13 2 67 2.88E+07 STYRELF IN AC-20 IZ-R 11914 18.1 u I 66 3.97£+07
a : partially dissolved. b : totally dissolved. c : could not be deter1lned due to high viscosity and/or nonh0110genelty. VIS, 60 : viscosity @ 60 C. VIS, 135 : viscosity @ 13.5 c. P1, ZS : penetration @ 25 C, 100 g, 5 sec. Pl, 5 : penetration @ 5 C, 100 g, 5 sec. S.P : R & 8 softening point. 0 : original. R : thin fll1 oven test residue. VIS, ZS : viscosity @ 25 C and shear rate of 5 x E-Z/sec.
16
Note that samples 2a, 3a, 5, Sa, 9a and 11, for both original and thin
film oven test residues, may give erroneous results because of
nonhomogeneity. For all other samples, a general decrease in penetra-
tion values is clear. The point to be considered is that samples 3b and
9b (with the higher percentage of Asphadur) and samples 6 and 12 (SBS)
have lower penetration at 25° C but have higher penetration at 5° C than
the nontreated asphalt. The penetration values are also represented as
bar diagrams in Figs. 4 and 5.
Tab.le 2 also lists the values of ring and ball softening point.s for . . all the samples. The samples with additives have higher softening
points than the base binder in all the cases. Also the softening point
increases with the increase in percentage of additives (Fig. 6) .•
Viscosities at 60° C and 135° C were determined by capillary tubes.
Because of the nonhomogeneity of some sa~ples, a Brookefield viscometer
was used to estimate the viscosities at the above-mentioned
temperatures. The viscosities are listed in Table 2 and plotted in Fig.
7. Because most of the entries for thin film oven test residue are
missing, only the results of the original samples will be discussed
here. The samples with additives show a substantial increase in
viscosit1.es at both temperatures with the exception of sample 2a-O at
~0° C and sample 4-0 at 135° C. This discrepancy may be due to the
nonhomogeneity of the samples. Also the samples with Asphadur show a
hi~her viscosity than the samples with lime and SBS.
I 0
' .. f l.
17
Penetration @ 25 ° C AC-5 170...---------------------...;_;._ ____________________ __,
110 J'7-rl
150 140 130 120 110 100 10 10 70 IO 50 40 30 20 10 o..i::...~~..;:i......J~"'P~:l.-..L.t;...(.µ...;~~.t:..-'..q.:~.:s...-1:~~~
. .••. 2b 3b 4
~P~ lder!l~ca~on
Penetration @ 25° C AC-20
•
IO...-------~------------------------------------~
so
llO
20
10
7 lb lb 10 .12
"7jpl• ld•ntlflcotlon 0 cs:sl R
Fig. 4. Penetration at 77° F (25° C).
19
70 AC-5 + additives
AC-20 + additive.s 70
80
u
~
f 40
30
20
10
7 So Sb 9o 9b 10 11 12
WJi'ple ldentiflcotion 0 ISSI R
Fig. 6. Ring-and-ball softening point.
.. • .!!';" o.,. a.c .o ,. .. ~" l~ ~c >
9
8
7
6
5
4
3
2
11
10
1-0
1-0
Fig. 7.
2b-O
2b-O
20
3b-O
3b-O
Somple ldentlflcotlon
60°C
4-0 6-0
135°C
4-0 6-0
Viscosity at 140° F (60° C) and 275° F (135° C) (AC-5).
21
Viscosities at 25° c, which were determined with a cone-plate
viscometer, .are listed in Table 2 and plotted in Fig. 8. The
'viscosities were determined for a shear rate of 5 x 10-2 sec-l The
samples with additives showed higher viscosities than the base asphalt,
especially for Asphadur-modified binders.
The effect of heat, as determined by viscosity and penetration at
?.5° C, on the thin film oven test residues, are shown in Figs. 9 and 10,
respectively. The hardening of modified asphalts in terms of retained
. penetration varied from 19% to 30% for AC-5 and ranged from 30% to 55%
for AC-?.O. These values were considerably lower than the reported 54%
to 78% penetration retention for SBS-modified asphalts (24). The
drastic hardening of modified asphalts is also reflected in increases.in
viscosity. Modified AC-5 asphalts were more sensitive to thin film oven
heating than those of modified AC-20 asphalts. The only data on
viscosity ratios at 60° C for modified binders were those of Styrelf;
the viscosity ratio was 9.8 for ~BS modified AC-5 .and 4.2 for SBS
modified AC-20. These were much higher than the reported values of 1.7
to 2.Q (?.4). The asphalt cements without additives had a viscosity
ratio at 60° C of 1.9 for both AC-5 and AC-20. The normally specified
maximum ratio (e.g. ASTM D3~81) is 3 to 5.
Viscosities at 60° !'! and 135° C, penetrations at 25° C and 5° C,
and softening points were used to determine the penetration index (PI),
viscosity-temperature susceptibility (VTS), and penetration-viscosity
number (PVN) at 60° C and 135° c. The effects of add:l.tives on
temperature susceptibility will be discussed later.
II
e
7
8 I • li 5
j§ i.! 4
• " 3
2
35
10
22
Viscosity@ 25 C Olfglnol
1-0 2b-O 3b-O 4-0 5-0 6-0 7-0 8b-O 9b-O 10-0 11-0 12-0
Sample ldentlftectlon
Viscosity·~ 25 C 1'FOT Mll:fdu•
1-R 21>-R 311-R 4-R 15-R 11-11 7-11 Bb-R lb-R 10-R 11-R 12-R
Semple ldontlftcot!on
Fig. 8. 0 0 Viscosity at 77 F (25 C).
23
VISCOSITY RATIO AT 25 C AC-5
:io~~~~~~~~~~~~~~~~~~~~~~~~--,
28
28
24
22
20
18
16
14
12
10
8
8
4
2 -i,-.,-.,-,,...,.,
o...t....:;...:;,,c...::.J....L-'..<:;,.L.-<::.J....LL.J.;...i:::..~-1:,,c...o;..::....:.i.,.....r::...::...o;..::..4..l......r::...:...;..::.LJ
ASPHALT IDENTIFICATION
VISCOSITY RATIO AT 25 C AC~20
:io~~~~~~~~~~~~~~~~~~~~~~~~--.
28
28
24
22
20
18
18
14
12
10
a 6 _i-,,.--r..,...,,..,
4
2
o..L.<~.L.<:..l-..t...:;...:;.L.<:..i_..L~.-C-U..-L.L.<;,4-~-t..L..<;..::....:.i.,.....r:..L..c,.t...LI
ASPHALT IDENTIFICATION
Fig. 9. Viscosity ratio at 77° F (25° C).
"'l ,... OQ . ..... 0
"' "' '1
" ~ rt
0
"' '1
"' rt
"' ,... l:l
"' "" .., "' l:l .. rt '1
"' rt ,... 0 l:l
Retained Penetration, n
Ill 0
0
....
-0 ... 0
Ir {' Asphadur,
~
4%:::'\J
l 3!10.._~ Asphadur, • ~ :1 .: ::'I g -;, .: 0
Lime, !>'I; '~ 0 :s
:: ~ ~"'~\" "-'-\ ~
... 0
6%
N""I"-'-' ~t:.vre.i.r '-'-'-.I
UI 0
~~
... 0
f; I
IV 0
~
I
I
I
I
Retained Penetration, X
0
"' ...
0 ... 0
Ii' 1 Asphadur,
...
UI
6%
·~~~~
"'
~ .... 0 g ...
0
f; I
U1
-I 0
I N
"'"
25
Data on original samples were plotted on the BITUMEN TEST DATA
cHAtlT (BTDC) for compadson and classifcation. Rased on BTDC, Heukelom
(8) defined three classes of asphalts: Class S (comprising straight-run
residual ancl. cracked asphalts), Class B (blown asphalts). and Class W
(waxy asphalts). For Class s, both penetration and viscosities fell on
the same straight line, but for Classes B and W, there was a departure
from this simple relationship (Fig. 11). Also, Heukelom showed that the
slope of the line :f.n the chart indicates temperature susceptibility.
The penetration index can also be obtained by this chart.
Samples 2b, '.'b, 4, and 6 were plotted with Sample 1 (Figs. 12a,.
l2b, and 12c) and Samples Sb, 9b, 10, and 12 were plotted with Sample 7
(Figs. 13a, 13b, and 13c). Samples 1 (AC-5) and 7 (AC-20) are
classified as Class W asphalts. Although it showed an increase in
viscosity, Sample 2b with 4% Asphadur totally dissolved in AC-5 is also
a Class W asphalt, but Sample 3b with 6% Asphadur totally dissolved in
AC-5 indicates a Class B asphalt. Sample 4 (5% lime in AC-5) also falls
in the category of Class B asphalts. Sample 6 (SBS in AC-5), however,
int!icates a Clas!'! W asphalt, because it exhibits a waxy nature.·
For AC-20, the same additives were used in the same quantity but
the results were not· the same. At low Asphadur conten.t (Sample Sb) the
binder behaved as Class B; but at high Asphadur content (Sample 9b), the
hinder behaved as Class w. In Sample 10 (5% lime in AC-20) the binder
changed from Class W to Class S. Sample 12 (SBS in AC-20) behaved in
the same manner as Sample 6 and fell in the Class W asphalts.
1~· .. - ... ~ .. i !
i I I
i ~I §
I '~ I !
ill ~= ,. I:! !•
i i
I
·~· !
i ' ' .l i ' ;:
'! i
I ... ' ... I I ' I ... ' ... ~-:: I• . : . ' I ... -=- '11 : ~ I
I -; I !J : ~" I I " ~ . l ,-. : ' : ill!
I 6 ~ ' " . i : !
I 6 ": i ! I !: j
I b I I ! l• I b ' ! !
I I 'l· I 'i I I I!
'' i ,. ! I I i i I I ! l "' ' I ' I
' I l i I ' i
' i i ' .. -i i ! ! i I !
' I !
! ! 0
' .. i i ! i / ..
' :_, / i '!' L,, ! i. ' & i !
•
i I ' i '
~
I I ' -~ .. - •
26
-g ......... - . ·- . -Ji '
I I
'
/
·: /
... ;: ,,
" /
I ! I ! I
'
I
'
" I
' " ~
'
'
....
I
__ , ... . - - -' I /l
i i !A I ! I I/! I '
Al i I ,;. I , iii ct I
' ! ' I !
I I ' I I ' ' I ! I i ' I
! i i I I ' ! ! ! I ' !
i ' '· . ' ~ .. 9.! f / ... ,,,
I
I , I
I • ::! I , ::! ! ,, YI
I i j
.· '
I
I ' '
i I
'I I
I II I 11 I '
i
'
! I
' .
j
I
!!
!!
!!
II
a
" .. "
27
-•o 0 40 80 120 160 200 140 T••p•ratur•, •c
Fig. 12a. BTDC of Asphadur-modified AC-5.
_f __ _
10•
10•
10'
10
-·· 0 40 80 120 160 100 240 tempereture, •c
Fig. 12b. BTDC of lime-modified AC-5.
Fig. 12c. BTDC of Styrelf-modified Ac..:s.
28
Tempel'ature, •c
Fig. 13a. BTDC of A~phadur-modified AC-20.
-•o 0 •o Teoperature, •c
Fig. 13b. BTDC of lime-modified AC-20.
-40 0 40 120 160 200 240
FIG. 13c. BTDC of Styrelf-modified AC-20.
29
These classifications indicate that the asphalt matrix changed
notably with the additives, and in most of the cases the temperature
susceptibility of the asphalt was improved. The data also indicated
that the changes in temperature susceptibility depended not only on the
type and amount of additives but also on the base asphalt.
':\.1.2. Tensile, Ductility and Elastic Properties
Previous work on rubber- and neoprene-modified asphalts (22,23,24,
and 40) indicated that tensile properties provide useful data on the
degree to which polymers benefit asphalts. Toughness, tenacity, tensile
stress, and elongation of modified asphalts were determined and the
results are given in Ta.ble 1 and shown in Figs. 14 and 15.
Both Asphadur and SBS increased toughness and tenacity of the
asphalts, while lime, as expected, had no effects. However, only SBS in
AC-20 met the suggested specifications for polymer'"1llodified asphalts of
minimum values of 75 in.-lbs toughness and 50 in.-lbs tenacity. Except
for the toughness of AC-5 binders, the thin· film oven heating decreased
the toughness and the tenacity of binders.
While both Asphadur and SBS increased tensile stresses of asphalts
at !lll01. elongation, only SBS in AC-20 met the recommended stress of 4.3
psi. Furthermore, the. improvements diminished upon thin film oven test
heating.
• Results of force ductility and .elastic recovery of samples at 10 C
are given in Table 4. Asphadur increased ductile force for both
asphalts but did nothing to improve t;!lastic recovery; SBS, however,
reduced the ductile force but increased the percent elastic recovery
significantly, Hydrated lime had no significant .effects on either
30
Table 3. Tensile properties of binders.
"ATERIAL SA•PLE l TOUGHNESS l TENACITY I TENSILE STRESS ' ' Mo. In-lb ' In-lb :stress, psi l I efong, i I
AC-5 1-0 I 11.3 4.0 o.ooo 800 I
AC-5+41 ASPHAOUR Zb-0 I Zl.4 6.1 o.ooo 800 I
AC-5+61 ASPHAOUR 3b-O I 24.8 6.3 0.142 800 I
AC-5+51 ll"E 4-0 ' 12.1 3.Z 8.000 800 I
STYRElf IN AC-5 6-0 I 32.9 28.9 1.565 800 I I I
AC-20 7-0 , I 73.6 11.9 0.853 800 . I
AC-Z0+41 ASPHAOUR 8b·O ' 70.6 15.1 2.418 6. I
AC-20+61 ASPHADUR 9b·O ' 100.4 4.9 o.ooo 207 I
AC-20+5\ ll•E 10-0 ' 73.4 12.6 o.853 800 I
STYRELF IN AC-20 12-0. I 227.5 163.8 13.227 800 I
AC-5 l~R 22.5 5.9 0.000 . 800 AC-5+41 ASPHAOUR Zb-R 59.9 0.9 o.ooo 189 AC-.5+6' ASPHAOUR 3b-R 65.6 3.4 8.616 4 AC-5+51 l UE 4-R 79.6 4.3 1.138 800 STYRElf IN AC-5 . 6-R o.o o.o 0.853 772
AC-20 7-R 68.9 o.o o.ooo 267 AC-20+41 ASPHAOUR 8b-R 32.6 o.o o.ooo 10 AC-20+61 ASPHADUR 9b-R 25.9 o.o 0.000 14 AC-20+5\ ll•E 10-R 27.6 o.s o.ooo 190 STYRElf IN AC.-20 12-R 78.8 o.o o.ooo 714
a: partially dissolved. b: totally.dissolved. 0 : original, R : thin fil• oven test residue.
260....-~~~~~~~~~~~~~~~~~~~~~-.
240
220
200
180
AC-5 + additives
,e I 110 · .s ,; t40
j 120 .. :;) 100 ~
,e I .s
t ~
80
60'
40 ~ l'.:z+2I V/ r cl 20 . V/fl V/;/1 lf,·A ~ 4 0 lz72! rzpi
1-0 2a-o 2b-O lo-0 lb-o 4-0 5-0 6-0
280.,--~~~~~~~~~~~~~~~~-i
240
220
200
180
180
140
120
100
80
60
40
AC-20 + additives
2
: V4Lf V/+/f v44 t%( 4 V/(/1 V/(11 Vfl v44 7-0 80-0 8b-O 9o-O 90-0 10-0 11 -:-0 12-0
l 1 !
1 ! 1
2so....-~~~~~~~~~~~~~~~~~~~~--,
240
220
200
rso ISO
f40
120
100
so so
AC-5 + additives
~w~~~~~~ .1 ,_,. 2o-R 2b-lt 34-ft .JD-ft _,. 5-R 8-R
2so..-~~~~~~~~~~~~~~~~~~~~~~~~~
240
220
200
180
180
..... 120
100
10
80
40
AC-20 + additives
2: V/+4 ·WA V/fA V/+/.f vpt WA U72' WA 7-R ao-R lib-R 9a-R 9b-R '0-R , , -R 12-R
Semple Identification . Sample ld•tstlflcotlon
a. ORIGINAL BINDER BLENDS. b. THIN FILM OVEN RESIDUES. Fig. 14. Toughness.
"' ....
30 30
28 211
26 AC-5 + additives 26 J AC-5 + additives
24 24
22 22
20 20
~ 18 ,e
18 I .s te .s 16 ~ 14 i- 14 u "ii ~ • 12 c 12 ~ ~
10 10
a a a 8
4 .. 2 2
0 0 1-0· 20-0 20-0 30-0 3b-o 4-0 s-o 6-0 1-R 2o-R 2b-R 3o-R 3b-R 4-R S-R 6-R
170 30 160 281 I "' 150 AC-20 + additives AC-20 + additives N
2• 140
24 130
120 22
110 20 ,e ... I 100 T 18
.s .s .. €
90 80 i 14
• 70 c c 12 ~ 60 ~
10 50 40
e
30 6
20 .. 10 2
0 0 7-0 8a-O Sb-0 9o-O 9b-0 10-0 11-0 12-0 7-R 80-R 8b-R Sa-R 9b-R 10-R 11-R 12-R
Sample Identification Sompl• ld«1nt1ffcotlon
a. ORIGINAL BLENDS. b. THIN FILM OVEN RESIDUES. Fig. 15. Tenacity.
33
Table 4. Ouctllfty and elastic properties.
NATERIAl SA"PlE DROPPING BALL :FORCE OUCT. : ELA. RECOV. Mo. t2/tl lbs. I
AC-5 1-0 0.221 1.45 o.oo AC-5+41 ASPHADUR 2b·O 0.113 3.45 c AC-5+61 ASPHAOUR 3b-O 0.069 2.91 c AC-5+51 LIU 4-0 0.034 1.50 2.50 STYRELF IN AC-5 6-0 0.923 1.27 61.25
AC-20 7-0 0.046 17.45 c AC-20+41 ASPHAOUR 8b-O 0.047 18.90 c AC-20+61 ASPHAOUR 9b·O 0.062 29.30 c AC-20+51 ll"E 10-0 0.047 15.64 c STYRElf IN AC-20 12-0 0.615 10.00 65.00
AC-5 1-R 0.248 3.64 5.00 AC-SUI ASPHADUR 2b-R d 11.82 c AC-5+61 ASPHAOUR 3b-R 0.021 13.27 c AC-5+51 Ll"E . 4-R 0.048 8.10 . c STYRELF IN AC-5 6-R 0.334 13.64 c
AC-20 7-R d 27 .10 c AC-20+41 ASPHADUR 8b·R 0.040 23.64 c AC-20+61 ASPHAOUR 9b-R 0.351 26.91 c AC-20+51 LINE 10-R d 32.73 c STYRELF IN AC-20 12-R d 38.00. c
a : partially dissolved. b: totally dissolved. c : the s1111Ples were broken before reaching 20 cm. d : no flow. 0 : original. R : thin fll• oven test residue.
34
property. Another measure of the elastic property of modified binders
is the ratio t2/t1 obtained from the simple dropping ball test (Table 4,
Fig. 16). The only significant improvement resulted from Styrelf.
However, the benefits of Styrelf seemed to have diminished after thin
film oven heating.
3.3.'.I. Chemical Properties
High pres.sure liquid chromatography (HPLC) is a technique whereby
the molecules in an asphalt are separated according to relative size, as
in sieve analysis. Although it permits the largeat molecules to pass
packed columns more quickly, it successively retards the passage 6f
smaller ones. The area under the chromatogram is divided into three
portions by selected elution times as the large molecular size (LMS),
medium molecular size (MMS), and small ~olecular size (SMS). The
dividing elution times·were selected to maximize the differences among
asphalts with respect to LMS which is found to correlate with cracking
of asphalt i:>avements (11!). Figure 17a shows the chromatogram f.or sample
J.-0 <AC-5). Figure 17b shows the chromatograms of AC-20 (7-0) and AC-20
modified by SBS <12-0). Potentially this technique could be used to
determine the percent of polymer in.polymer-modified asphalts as shown
by the shaded area at short retention time. Figure 18 presents the
i:>ercent LMS for the 16 binder blends, original versus TFOT residues.
llata indicate that the two grades of asphalt were very similar in
their molecular size distributions and that additives had little effects
on i:>ercent LMS, with maximum increase of about 1% for Styrelf. However,
I
I I
I
I I
.. ..
a.SI
a.a
a.7
a.a
' a.5
.. -
...
0.4
a.:s
a.2
a.1
0.1
0.5
0.4
- 0.3
a.2
a.1
35
AC-5 + additives
2b 31:1
AC-20 + additives
7 llb 9b 1a 12
So'"pl• ldentlflcotlon IZ2J 0 cs:::sJ R
Fig. 16. Results of dropping ball tests.
"LMS "1.MS . - NI NI "' "' - - NI NI "' "' 0 IJI 0 IJI 0 IJI . 0 ::~ IJI Q IJI 0 IJI 0 IJI 0 IJI
~~~- .. · .. ' .', . ' : f; I -I
"' "<I t" """" "" '""' 0 .... OQ
I NI . :~ _A;>J?~a~~: 1 1 ~ ~ 77777777/A .. ,.... co . "' : f · A.sphad:iir-, · 4 % I N .. 77777771 II' '1 n
~~ .. ::I ...
0 } ff Asphadur, 6% I II' -9 Asph~dur, 6% 17.777·777]- I "' 0 7T co "' ~ t
El~ .,. &!f, Asphadur~ _6~_ 7777/A I Li .. n II' ... :u~ .. ~
0 :J ....
::I () -J-7 T.;m,o a;~ ) ) )' > , , > > > :; > , • I • .. .,. .,. '<
~ :,;+7T.imP. lo~>>',,,,,,;;,,. I IJI .... C"l .
;:; -f-3 C~•?v-c.1 f= ~ ~ ~ ~1, > >,,:; >, > >' I "'
39
the increases in percent LMS because of thin film oven treatment, which
simulates hot plant mixing, were large. Excluding samples 2a, 3a, Sa
and 9a because the dispersion was nonhomogeneous, the increases in
percent LMS as percent of LMS in original asphalts varied from 62% for
Asphadur <6%) in AC-20 to 119% for lime (10%) in AC-5. The increases in
L~~ for AC-5 and AC-20 without additives were 34% and 91%, respectively.
rhe net increases in percent LMS because of thin film oven treatment
ranged from 5.0% for Sample 1 (AC-5) to 16.9% for Sample 5 (10% lime in
AC-5). 'l'bese increases were unusually large compared to the normally
expected increase of 2% to 5% based on data ·from asphalts extracted from
pavements without additives.
On the basis of limited performance data, the maximum percent LMS
recommended for climatic zone for Iowa was estimated to be about 26%
(18). According to this criterion, the only satisfactory binder was
AC-5 without additives. Rinders with Asphadur and hydrated lime would
be considered marginal and those with Styrelf would be critical with
respect to cracking.
However, thE>se.remarks must be viewed with caution because of the
problems of solubility of lime and Asphadur in THF (tetrahydrofuran)
solvent used for the mobile phase in HPLC and because of the
nonhomogeneous dispersion of some of the binder blends. Furthermore,
the recommended criterion was based on asphalts in pavements without
additives. It is likely that separate HPLC techniques and/or criterion
must be developed for asphalt pavements with additives.
40
The reflected microscopy technique was explored as a possible means
to better understand the polymer dispersion and the structure of the
polymer-in-asphalt system and ultimately to provide information on the
optimize.tion of polvmer modification.
Pure asphalt (AC-5) does not produce observ:able fluorescence under ·
'lilue excitation. Likewise, aaphalts with lime additions (Samples 4, 5,
10, and 11) showed no fluorescence. While .samples 6 and 12 contained 3%
to 5% SBS polymer, the reflected fluorescence micrographs indicated no
fluorescence particles. This result indicates that SBS is not in a·
physical dispersion but rather forms a new cross-linked homogeneous
reaction product because of the blending techniques and secondary
additives used in the manufacturing process.
Of interest are the' eight blends containing Asphadur (polyolefins).
Figure 19 shows typical micrographs of 4% and 6% Asphadur in AC-5.
Continued heating, either during blend preparation (2b and 3b) or thin
film oven treatment (?.a-R and 2b-R), appeared to have reduced the
particle size and increased the uniformity of size distribution (2b-O,
2b-R and 3b-O). Higher polymer content is reflected in the higher
particle density (3a-O and 3b-O}. Figure 20 shows the micrographs of
Asphadur in AC-:10. The same observations made for samples 2a and 2b
(Asphadur in AC-5) can be ·made here. However, undissolved large
Asphadur particles are more evident f.or. high viscoSity AC-20 (Samples Sa
and 9a). The significance qf particle size and size distribution and
the halos surrounding larger particles in partially dissolved samples
f8a and 9a) need further study.
2a - O
2a - R
3a - O
41
AC-5
ASPHADUR, 4 %
ASPHADUR, 4%
ASPHADUR, 6%
2b - 0
2b - R
3b - 0
Fig. 19. Flourescent rnicrographs of Asphadur in AC-5.
42
AC-20
8a - O ASPHADUR, 4% 8b - 0
9a - O ASPHADUR, 6% 9b - 0
Fig. 20. Flourescent micrographs of Asphadur in AC-20.
43
Eight samples from the original (0 series) were selected for x-ray
diffraction study. The standard procedure is a 9/29 scan for the
analysis of the materials. But because of some preferred orientation of
asphalt molecules, using only a 9/26 scan may not show the complete
picture; therefore, a 29 scan was also done for all the samples.
In a 9/29 scan, both 9 and 29 vary; and whenever the Bragg equation
is satisfied, it gives a diffraction peak. The Bragg equation is
An = 2d sin
where :\ = wavelength
d = interplaner spacing
9 • angle of incidence.
In a 29 scan, 9 is fixed and 29 varies. If there is any preferred
orientation of molecules, the diffraction peak appears when the Bragg
equation is satisfied·, and the orientation can be calculated (1).
Results obtained with 9/26 scans are presented in Figures 21-23.
Figure 21, which compares the two asphalts AC-5 and AC-20 used in this
study, indicates that molecules of both asphalts are arranged in the
• horizontal direction with an average separation of 4.7 A. Both peaks
• have a breadth of about 9.8 A at half maximum intensity, which indicates
the same size of minute clusters of molecules. The main difference
between the two asphalts is in the height of the shoulder to the left of
the peak. This shoulder is due to low-angle scattering of x-rays and is
a measure of the size and abundance of dispersed particles of
asphaltenes dispersed in resinous and oily fractions of asphalts (53).
=r~O~I~FF~A~AC::.....,!.V~~~~~~....;......~~.....-~~~~.--..,_..-.-.~~~ ~ a fii•
t I s ~
£i 0 fj ;; u.
ON "8 "'. !
UllQ ... . :z:;;i. ::> •• 8fii ~ Ill .. 2·
~
i::· !;/ ... •• .. .... Ill 0
: .,
vi)
·~, ... ,~........ . . t\tal......~. . . . ' . ...... ~ ··~"'~
:.vOQ"?50 i'.oo. 1b:50 1~.00 1S.ii02[00 2•.50 2L:ii0 3\.50 i!i.oo 31i.50 .L.oo aw-.ll:ooti[iio tih.oo 5L.oo aS.ao ob.5o7o.oo -- 25.22312.8188.418 8.321 5.004 4.227 3.630 3.181 2.838 2.582 2.338 2.149 1.902 1.857 1.142 1.841 l.fi52 l.•74 1.405 1.343
nm - TllElA -- d SPACING
Fig. 21. Theta/two-theta scan. AC-5 versus AC-20.
.... ....
" ~. OIFFAAC V rJ a Iii .; f.J·
= m .. '!
£i 1:1 ri
fJ -... o~ -0 *o ~ ••
Ulftl I- • z• 5~ ulii
!i Ill ~· .. -~·
1:1 -· .. -... Iii g "ii~Oili'.50 · 7'.oo 1L.so 1too 1S.so 2\.00 2•.w~iiii 31.50 ali.oo ili.50 J.oo Ji.50 •L.oo tit50 iili.oo tiL.50 u§.oo llll.5o 1&.00
-- 25.22312.8188.418 8.321 5.084 4.227 3.830 3.184 2.838 2.fi82 2.3'111 2.149 1.8112 1.857 1.742 I.Bl! 1.552 1.474 1.405 l.l4l nm - HIElA -- d SPACING
Fig. 22. Theta/two-theta scan, AC-5 with ,additives.
,,. \JI
" M DIFFAAC V Ill a Iii ..; lil•' II! I!! :!.
~· ':I
i\i ;:
C)~ ... o
*" 0 ... ~
mm !Z.; fl~·· ~ 18 ~-:!. I:: et c:-·1 t-o ~ tu·
g <ii1.-oo--,3'.r5-o-1,-'.0_0_1TL-.50·-,~.-.o-o-1'S-.50--,2\r.-oo-2rt-50-2~L-.o·o--3"'\-.50--,3fi~.o0 311.tiO •tao 6.tiO .L.o~:6ii. 5L~oo 5L.ti0 ef.OOlili.so 10.00
Z!>.22312.8188.418 8.321 5.ll04 4.227 3.830 3.184 2.838 2.582 2.3311 2.148 1.092 1.857 1.142 I.BU 1.652 1.4U l.405 1.lll ltlO - 'TllET A -- d. !lPAC ING
Fig. 23. Theta/two-theta scan, AC-5 with additives ve~tical scale offsets).
c:::----~-
""" ""
-
47
According to Williford (53), the higher the shoulder the better
the asphalt. Effects of additives, for example, lime, Asphadur,
and SBS, on AC-5 are compared in Figs. ?.2 and 23. As can be seen from
Fig. 2?., the most significant effect is demonstrated by Styrelf in
raising the low-angle scattering shoulder. The reduced intensity of the
sample containing lime is probably due to absorption of the copper
radiation by calcium. The crystalline peaks observed with this sample
correspond to lime crystals and indicate that the lime did not
chemically react with the component of asphalt. The sample containing
.. Asphadur also produced a sharp crysta Uine peak ( d-spacing of 4 .1. A).
Since a diffraction pattern of Asphadur alone could not be obtained at
the present time, it is not yet possible to state whether this peak
corresponds to Asphadur or to a reaction product.
The 2e scans performed indicated that major alignment of molecules
• with about 4.7 A separation occurred in the horizontal direction. When e
angle was fixed at 5, 10, and 15 degrees, the peaks were flattened out,
peak intensities were reduced, and noncrystalline peak positions were
shifted. These results support the hypothesis that a horizontal
orientation is preferred. Figures 24 and 25 show 26 scans for samples
containing lime and Asphadur. The reduction of intensities and
broadening of the peaks of not only the asphalt matrix but also of the
crystalline peaks suggest that even the crystals of Asphadur and lime
are also oriented in the matrix, possibly by attaching themselves to
asphalt molecules. This may explain the observations made in viscosity
stu1Ues.
I -·'.,. ., .
48
~--:--::;::[~·' -,...-1--T.= l..'.
i • ' /
---;r----r. . -·--·
. .
I
I
49
_,_ __ . ...... ··- ·-· --
·.·
-"' ,
: ~· : l ' ! i ; ~
I ·'' ! ., '
I '
·. ' ,.::;.:-~-· ·-!f-,.;.;..-+.--'
' '
I' !~ ,,
I . ,..._ i· ' ; ~
• •
"' I
'.;;! ;l
• "' "'
50
From the above discussion, we can conclude that the introduction of
the additives did change the structure and behavior of the asphalt.
Increasing low-angle sc".lttering and pref erred orientation of the
particles are .to be noted. We expect that identification of additives
and their effects on asphalts can be rapidly and.economically determined
by x-ray diffraction techniques based on low,-angle scattering
intensities arid the shape of the amorphous peaks.
In the future, we suggest that mor.e comprehensive studies be
undertaken using e scans and especially diffraction ;l.n transmiss'ion mode
(1) for a complete understanding of molecular make-up of asphalts and
the effects of additives as related to their engineering p~rformance.
3.1.4. Temperature Susceptibility
Asphalt cements of high-temperature susceptibility may contribute
to rutting at high pavement temperatures and cracking at low pavement
temperatures. One of. the often-quoted benefits of polymer additives is
the reduction of teinperature susceptibility of paving asphalts.
Temperature susceptibility of an asphalt can. be evaluated by using
the Shell Bitumen Test Data Chart (B'l'DC) (15), the Penetration Index
<PI) (52), the Pen-Vis Number (PVN) based on viscosity at 60° C or
viscosity .at 135°. C (33), the viscosity-temperature susceptibility
(VTS), and the Asphalt CJ.ass Nlllllber (CN) (4). The basic rheological
data as plotted on .'BTDC are shown in Figs. 12 and 13; and the derived
PI, PVN, VI'S and CN of the binder blends studied are given in Table 5.
The CN sho\is the difference between measured and predicted
penetration at 25 ° c. A small negative or positive CN value indicates a
Class S (straight run with a straight line, temperature-viscosity-
51
Table 5. Te111erature susceptfbl I lty.
MATERIAL SAMPLE CM Pl• VTS PVM,60 PVM, 135 No.
AC·S 1-0 9.28 -1.336 3.618 -0.832 -1.012 AC-5+4\ ASPHAOUR . 2b-0 s.az -0.613 3.420 -0.387 -0.327 AC-5+6\ ASPHAOUR 3b-O -25.97 0.347 3.499 1.829 1.080 AC-5+5\ LIME 4-0 -22.45 -0.939 4.318 0.281 -1.475 STYRElf IM AC-5 6-0 10.50 -0.286 3.211 -0.375 0.011
AC-20 1-0 6.46 ·1.105 3.675 -0.854 -l.073 AC-20+4\ ASPHAOUR 811-0 -36.10 -0.601 3.827 1.415 0.152 AC-20+61 ASPHADUR 9b-O 30.24 -l.247 3.089 -0.830 -0.047 AC-20+5\ LIME 10-0 0.75 -1.354 3.708 -0.578 -0.935 STYRELF IN AC-20 12-0 26.63 -1.245 3.292 -1.244 . -0.695
AC:S l·R 13.56 -1. 748 3.546 ·1.084 . -1.034 AC-5+4\ ASPHAOUR 2b-R ·285.19 0.390 c c -0.249 AC-5+61 ASPHAOUR 3b-R c -l .239 c c c AC·S+51 LIME 4-R c -0.516 c c c STYRElf IN AC-5 6-R -1.ss -0.033 3.514 -0 •. 135 -0.304
r AC·ZG 1-R 22.11 o.su 3.178 . -0.860 -0.222 AC-20+41 ASPHAOUR 8b-R c -0.695 c c c AC-20+61 ASPHAOUR 9b-R c -0.078 c c c AC-20+51 LIKE 18-R c -0.493 c c c STYRElf IN AC-20 12-R -12.12 -0.454 3.011 -l .116 -0.227
a: partially dissolved. b : totally dissolved. c : could not be deter1fned due to absence of viscosity data. CM : c.lass nullber. Pl• : 1easured penetration Index. VTS : Vlscoslty-te1111erature susceptibility. PVN,60 : Penetration-viscosity nllllber f 60 C. PVN,135 ·: Penetration-viscosity nullber f 135 c. O : orlglnal. R : thin fll1 oven test resld.ue.
52
penetration plot) asphalt. High positive CN values indicate Class W
·(waxy) asphalts, and high negative CN values indicate Class B (blown)
asphalts. Either case reflects substantially high-and low-temperature
susceptibility. On the basis of CN, Asphadur (except 6% in AC-20) and
lime deer.eased the temperature susceptibility; and SBS increased the
temperature susceptibility, especially in AC-20.
According to the PI, all additives decreased the temperature
susceptibility of ,AC-5, but increased the temperature susceptibility of
AC-20, except Asph;1dur at 4% (Fig. 26). In general, temperature
susceptibility (VTS) at a high-temperature range (60° C to 135° C)
seemed to be decreased because of polymer modification but increased
because of hydrated lime (Fig. 27) •.
On the basis of the PVN, data indicated decreases in te~perai:ure
susceptibility because of additives. The exceptions were the. effects.of
lime on AC-5, based on PVN from viscosity at 135° C and the. effect of
SBS on AC-20, based on PVN from viscosity at 60° C. Both of these ·
estimates showed increases in temperature susceptibility (Fig; 28).
When all the indices were considered, all the additives appeared to
decrease the temperature susceptibility of the asphalts studied,
especially for AC-5 and at higher temperature ranges 7 .Temperature
susceptibility of asphalts can be reduced by (a) increasing viscosity at
high temperatm:es, (b) decreasing viscos:i.ty at low temperatures, and (c)
increasing viscosity at high temperatures substantially more than the
viscosity increase at low temperatures. The apparent decrease in
temperature susceptibility of polymer-modified asphalts in this study
resulted from a combination of mechanisms.
"'1 ..... °" . N
"' . "' g ro ... rt
"' ... ..... 0 ::i ..... g, ro ><
b
I I I I ... -- ... . . . . ,._UN ...
!i Ill D 3
! "1 IL IF ~ I s 0 n D !t D :J
!1
'I' 0
Penetration Index
111111111 I f>~Pf>Pf>f>PP PPPP -u:a• .... •c.•t-tN-o-Nu.a.
Asphadur, 4~ l "-" , .. ,:," "'\.:
~ I
U1
"""j Asphadur, 6%
L"-"-"-"-
~,1:1~~'~
I
I
I I ~ ~ • i.a j-l
t1 r.; I
N 0
• .,. I 0
.. .,. I 0
0 I 0
II> I 0
I
Penetration lnde•
I I I I I I e I I . I I ~ ~ I p 0 0 p p 0 p p i.> . m :., i.a ~ ~ .. "' .. II> ~ 0
10-.'""""""'""""""" "'-'-~~ ln
"'
.vr.; vrs
O .- Ni lll 0 _. Ni CA • 0 (,. ... in ~· iJI CA (,. .fl. 0 (,. _. iw .N Le «A i.w + i.a
-~""~W I -~~"~~~ . "1 I . . AC-20 '\.. '\.: · I ~ 0 ' ' ' '- ' ,, "-:.. 0 . N ..... . ~ f 0-.".; Asphadur, 4% f < ~~~::---:: ~~ I ,., g 0 ,,,,,,,,,,,~. 0
"' ,... UI rt 0 '< 3
~ l. ~"""'-~ ~""'""'".~· k\\\..""'""'-""'-""'-~"""1 I ~ s - "' "' 'g· II" er Asphadur, 6% ~ cr1 >t :J I CU· !!; 0 '-'-'-'-'-'-'-"-'-'-'-'-~ 0 rt :!I " n >t D ID !!;
0 ., ~
" l X~~--~i~~--~ I ! ~ .... !-' .... 4
. f~~-~t:~~l-f,~ I i
I I - -• N
1 0
PVN080C
I I I I I p p p p. p p p ~ • a • N a N • •
55
---N • a. ~· ..
~
' '
I I :" I p - - ..
pm 0 1:SS C
b 6 "' ii :.., • I I I I I p p p p p t11•t.1N""O
p p - "
r ~ 0 0 r .I,()
3 < " • • - . . - ' ~ f f 'f Asphadur, 6% ,.... s 0 b ~ g "" "' ~ 0 . ~
<:I - - ~ 'I' 'I' g 0 0 =
>... .... "' . . . . 0
NJ N Styrelf ~ I if J. ~ '\\ Styrelf ~ I ~ b I ~,,,,,,~ o I ~'''''''''~ ";! I
= 0 .... , PVN O 80 C pm O 1:Sll C ';;:
1b666 C>OOO ---- !.!.·!.,6666 0000 - t ... e.a.•NoN•c.c. ... N•GtillN Gtt..N ... t.t.•NoN•c.a. .. N ~
"" j i " AC-5 J I j J ~ AC-5 ~ I . 0 I "'''''-J 0 I ~ ............ ,,~ <X)
N . ~
N N1 f<.o ... " 0 I I N 0 0 I
r ~ ~ . . ~
i l: Asphadur, 6% l: ! I · ~ I J 0 ',,,,,,, ... ,,,, 0
t I ~~~e I t 0 1 l,, 0
I I Styrelf
56
Haas (13) recently suggested a minimum PVN to avoid low-temperature
cracking. If we use his suggestion and assume a minimum design
• • • temperature of -23 C (-10 F).for Iowa, the required minimum PVN would
be -0.5 and 1.4, respectively. On the basis of these criteria, asphalts
AC-5 and AC-20, used in ~his study without additives, would be
considered susceptible to low-temperature cracking; and AC-5 with either
Asphadur or SBS would be crack resistant.
3.3.5. Potential~ Cracking and Rutting . .
Other factors being equal, increases in viscosity at the 60 C· td
1.35 ° C range will benefit the rutting resistance of asphalt pavements •.
On the basis of substantial increases in viscosity at 60° C and 135° C
(Table 2) and.a decrease in temperature susceptibility (Table 5), we may
infer that both Asphadur and SBS should improve the rutting resistance
of asphalts.
Reduced temperature susceptibility, for exam.ple, increases in PVN
(Table 5), would lead one to expect imprdved low-temperature cracking
resistance of polymer-modified asphalts. Low-temperature asphalt
stiffness has been correlated with pavement cracking associated with
nonload conditions. The effects of additives on low-temperature
behavior of asphalts can be evaluated either by estimating the
temperature at which asphalt reaches a certain critical or limiting I '
stiffness or by comparing the stiffness of asphalts at low temperatures
(long loading times) (3).
Table 6 presents the results of estimated low-temperature cracking
properties of bf.nders involving two asphalts with three additives. The
I I. I
I
!
57
properties include cracking temperature (CT), temperature corresponding
to asphalt thermal cracking stress of 72.5 psi (5 x 10 Pa), based on
penetrations at 5° C and 25° c, temperature of equivalent asphalt
stiffness of 20,00Q psi at 10,000 sec loading time (TES), estimated
• • stiffness at -23 C and 10,000 sec loading time, and stiffness at -29 C
and 20,000 sec loading time. Tue following can be observed:
• Softer grade AC-5 had a lower cracking temperature and reached a
critical stiffness of 20,000 psi at a lower temperature than
harder asphalt AC-?.O (Fig. 29).
• Harder asphalt AC-20 benefitted more from additives than softer
asphalt AC-5. Lowered cracking temperatures occurred in AC-20
in every case, but in AC-5 lime and Asphadur increased the
predicted cracking temperature (Fig. 29).
• On the basis of temperatures predicted to reach critical
stiffness of 20,000 psi (TES), only Asphadur at 6% and Styrelf
showed beneficial effects on AC-5.
• Stiffness at low temperatures and long loading times increased
in every case when additives were used. However, on the basis of
critical cracking stiffness of 20,000 psi criterion, only
• Asphadur and lime in AC-20 will be expected to crack at -29 C
('-20° F).
Data in Table 6 and the above observations must be viewed with
caution because the limiting stiffness criteria for asphalt cements may
or may not be satisfactory for additive-modified asphalts.
Temperature, C T emperoture, C
I ! I I I I I I I I UI u .., .. UI • u .., ... 0 0 0 0 0 0 0 0 0 0 0
"h I
·v~ -12 "1 ... OQ • N
"' • :~ !::::.'-~' I ..,
' Asphadur, 4% er
~ f1 rt
"' .!l a
"' !lJ 8i !::::.~'' Asphadur, 6% )I "' '1 er I v /////////;/////////hi VI
"' !//////// 00 rt r:: iL. 1"I ..
"' El n '1
"' n
- .I I'\ ":\ ) ' T.lmo_ <;,. ~ • aa n Ir 0
~ " .. 'd '1 0 'd - .I I),'-').:> T.imP.:. 10% ~. Ill
"' .. '1 rt ... "' tll .
.. J .. ~;:;..:,;;~ OI
-~
59
Table 6. lov-tesperature cracking properties.
MATERIAL SAHPLE CT,C TES,20ksl S,-23,IOKs S,-29,ZOKs Mo. c ksl ksl
AC·5 l·O ·34.00 ·38.00 o.508 1.890 AC-5+41 ASPHAoua 211-0 -20.00 ·38.00 0.798 2.900 AC·5+6l ASPHAOUR 311-0 ·41.00 ·43.00 0.725 1.450 AC·5t51 LIHE 4·0 ·32.00 ·38.00 0.725 2.900 STYRELF IN AC·5 6·0 ·38.00 ·42.00 0.435 1.450
AC-20 7·0 ·ZI .00 -za.oo 0.435 1.450 AC·Z0+41 ASPHAOUR 8b·O ·33.00 ·26.00 10.200 ZI .800 AC·20+6l ASPHAOUR 911-0 ·33.00 ·19.00 43.500 72.500 AC·Z0+5l LIHE 10·0 ·28.00 -26.00 5.800 13.100 SllRElf IN AC-20 12·0 -22.00 ·24.00 17.400 36.600
AC·5 l·R -24.00 ·31.00 4.350 11.600 AC·5+4l ASPHAOUR 211-R c ·31.00 17 .400 29.000 AC·5+61 ASPHAOUR 3b·R ·45.00 ·18.00 43.500 72.500 AC-5+5l LIKE 4·R -34.00 -27 .oo 10.200 21.800 SllRElf IN AC·5 6·R ·30.00 ·29.00 5.800 10.200
AC-20 7·R c ·33.00 4.350 8.700 AC·20+4l ASPHAOUR 811-R c ·16.00 43.500 102.000 AC·20+6l ASPHAOUR 911-R c ·17.00 145.000 174.000 AC·20+5l LIKE IO~R c ·18.00 43.500 72.500 STYRElf IH AC·ZO 12·R c ·56.00 29.000 58.000
a 1 patlally dlssoolved. b : totally dissolved. c : outside llllllOgraph range, but higher than ·20 C. CT,C : cracking te1111erature In C. TES,20ksl,C : te111erature of equivalent stiffness f 20 ksl. S,·23,lOks : stiffness @ ·23 C, 10,000 sec. S,·29,ZOks : stiffness t ·29 c, 20,000 sec. 0 : original. R : thin fll1 oven test residue.
61
4. EFFECTS OF ADDITIVES ON THE PROPERTIES OF ASPHALT CONCRETE MIXTURES--PHASE II
4.1. Materials
Seven series of asphalt concrete mixtures were prepared with the
two asphalt cements studied in Phase I (AC-5 and AC-20) and in
con.1unction with five a-'ditives and two aggregates (limestone and
gravel). In addition to the additives and polymer-modified asphalt used
in Phase I of the study (Asphadur, hydrated lime, and Styrelf), two
additional types of polymer-modified asphalts (PACs) were included.
these were PAC-5 and PAC-20 from Koch Asphalt Company of St. Paul,
Minnesota, and PAC-5 and PAC-20 from Jebro Inc. of Sioux City, Iowa.
These PACs were identified by the suppliers as neoprene-modified
asphalts and styrene-butadiene-rubber latex-modified asphalts,
respectively~ Both PACs were prepared at respective plants and
containing about 2% to 3% solids. As described in the previous chapter,
Styrelf binders as received .and used in this study were SBS-modified
AC-5 and AC-20 asphalts. Asphadur and lime were added to the mixes
during mixing. The limestone aggregate (LS) consisted of 60% 3/4-in.
crushed limestone and 40% sand, both from Hardin County, Iowa •. The
gravel aggregate (G) consisted of 55% 1/2-in. natural gravel, 30%
11'--in. crushe<l gravel, and 15!!: sand, all fom Sac County, Iowa. The
gradations of the aggregate blends are shown in Fig. 30.
100
90
80
70
CJ z 60 gj 1t ... 50 z w l.)
~ 40 ll.
30
20
10
0
. . . . . .
. . . .
' . . . ' I I . . ' ' . . . . .. . . I .. . . ' " I .. ' . .
' . .. .. . ., . " . " .. . . , . ' . . . .. ..
0 .. z& .00 0 • 5p zo,. NoBO 40
.t\._1MtS. S.YMBOI.. f10(NTrf1£S ·s1»"1.W1Ct1"
PAAtllCE ANO CCJilPAlt8t£ Sl('v[ S1?£"i ~------------
, .,
20
GRADATION CHART - - - - - - - - -SIEVE SIZES RAISED TO 0.45 POWER
. . , . . . ~ SERIES . . ,
- , LS SERIES ,,
, . J ,
.
. , -. .
. , . , . I . . . . .
-. . . . . . . . .
IO ' "··· Iii"'· "l:Dt. ..... ....
SIEVE SIZES
14en•t<Cot1on of ~rod01•°""
---<>-----LS SERIES --e--G SERIES .· 1 - -· ·--------------
Fig. 30. Aggregate 'gradations.
. . KlO
I 90
I 80
I 70
,, CJ 60 ii!:
"' "' t 1, 50 1-
z
~ 40.., ... 30
20
10
0 . ...
'"···
E:=l L:J
"' ,,,
63
4.2. Procedures
Seven series of 72 batches of mixes were prepared and tested,
including 12 control mixes containing no additives (Table 7). For each
aggregate-binder combination, three mixes were made at 1% binder content
increments bracketing the optimum asphalt content estimate.d ·by the
Marshall method of mix design. The additives were introduced into the
mixtures with methods as close to field conditions as possible.
Mixes of 50 lbs each were mixed in a heated twin-shaft pug-mill
mixer. Mixing procedures for controls (mixes Cl to Cl2), mixes
containing Styrelf (mixes Sl to Sl2), mixes containing neoprene-modified
PAC-5 (mixes Kl to K6), mixes containing SBR-modified PAC-5, and mixes
containing hydrated lime (mixes LLl to LL12 and LHl to LHll) were as
follows: Place aggregates at 125 +/- 10° F in pug-mi11 mixer and dry
mix for 10 sec. Add. 'binder at 275 +/- 10° F, mix for 30 sec and
discharge. Hydrated lime, at 1% (LL series) and 2% (LH series) by
weight of aggregate> was added to the heated aggregates before the
addition of asphalt for the wet-mixing cycles. The same mixing
procedure was followed for mixes containing PAC-20 (mixes J7 to Jl2 and
K7 to Kl2) except that aggregates were heated to 340° F and binders were
added at ?.90° F. For the AH series, asphalt cements at 400 ° F were
added to aggregates at 450° F. After the wet-mixing of 20 sec,
Asphadur, at 6% by weight of asphalt, was then added to the mixture; and
mixing'continued for an additional 30 sec to complete the mixing cycle.
64
Table 7. "Ix identification - Phase II. ,j'
AC GRADE I AC-5 AC-20 I
• I
SERIES AC CONTENT .. OPT-I OPT OPHI OPT-I I OPT OPT+! I I I I I I
AGG. TYPE I LS · G LS G LS G LS G I LS G LS G I I I I I I
c CONTROL I 2 3 4 5 6 7 8 . I 9 10 II 12 I I I I I
Alt ASPHAOUR-61 I I 3 5 I 7 I 9 ll I I I I I I I I I .
LL LIHE-ll I z 3 4 5 6 I 1 8 I 9 10 II 12 I I I
LH LlftE-2\ I 3 s 1 I 9 11 I I I I I I
s STYRELF (SBS) I 2 3 4 s 6 1 8 I 9 10 II 12 I I I I
!( llEOPREME 2 3: 4 5 6 I 7 8 I 9 10 11 12 I I I I
J SBR 2 3 4 5 6 ., 1 8 9 10 11 12 I
Total number of batches : 72.
65
Eighteen Marshall specimens were prepared from each batch.
Compaction was accomplished by a mechanical Marshall compactor with 50 0
blows per side at a mix temperature of 275 F for all mixes except for 0
mixes J7 to J12 and K7 to Kl2, which were compacted at 290 F and mixes
0 AHl to AH12, which were compacted at 375 F.
The following tests were performed on the mixtures and the
compacted specimens, as shown in Fig. 31:
• Sample height and bulk specific gravity (ASTM D 2726)
• Theoretical maximum specific gravity (ASTM D 2041)
• Marshall stability and flow, air and .VMA (ASTM D 1559)
• Marsha.11 stability and flow after sp.ecimens immersed in water • 0
at 140 F for 24 hrs (45, 49)
• Indirect (splitting) tensile strength at 77° F and a loading
rate of 2 in. per minute (21)
e .Indirect tensile resilient modulus at 77° F and a frequency of
0.31. hz. measured with a Retsina Mark IV resilient modulus
device (41)
• Shell uniaxial compression creep test at 104° F (40° C) at a
stress level of 14.5 psi (0.1 MPa) for a loading time of
?. hrs <51)
• Indirect tensile strength and resilient modulus after vacuum:-
saturation (4?.,45) and after an accelerated Lottman condition-
ing procedure (27,?.R).
Mix & compact 18 specimens
Rice max. heoretical
sp. gr.
Bulk sp. gr.
*Shell
66
Marshall @60C (1,2,3)
R@_25C
Indirect tensile
Vacuum Saturation
3
R@25C
0.1 sec (4·5) .
strength !--+-' @25C
Indirect tensile ·
strength
(10·12)
Marshall 3 Immersion
@60C
(16·18)
Lott man treatment~__..
(6·9)
Indirect tensile
strength
AC MOO AS
HR-278 Phase II Test Program
Fig. 31. Mixture evaluation flow chart.
67
4.3. Results and Discussion
4.3.1. Marshall Properties
Marshall properties (stability, flow, voids, and bulk specific
,i:ravity) of the 1?. mixes are given in Table a. Marshall stability
results are shown in Fig. 32(a\ and the results of Marshall stiffness or
Marshall quotient, defined as ratio between stability and flow, are
shown in Fig. 32(b). As expected, stability values of mixes containing
AC-20 were higher than corresponding mixes containing AC-5, and
stability values of mixes made with limestone aggregate (LS) were higher
than corresponding mixes made with gravel (G). With the exception of
Series J (SBR modified AC-5) with gravel aggregate, all other mixes at
optimum asphalt content of about 6% would have met design criteria for
heavy traffic in terms of stability (1500 lbs +) and flow (ll-16). There
were significant increases in stability because of the addition of
Asphadur (AR) and Styrelf (S) as compared to control mixes (C), slight
increases in stability for neoprene mixes (K), and no significant
differences because of other additives. One of the reasons for
focreased stability for AH and S mixes was that polymers added to AC-5
or AC-20 base asphalts resulted in a higher viscosity binder. However,
PAC-5 and PAC-?.0 binders used in K and J mixes were polymer-modified
binders in the AC-5 and AC-20 viscosity ranges.
It is significant that Asphadur and Styrelf increased the stability
of AC-5 mixes to that of AC-20 mixes without additives. This makes it
possible to use softer AC-5 with these additives for both
low-temperature cracking resistance and high-temperature stability
requirements.
68
Table 8a. Klx properties, lS/AC-5.
---------------------------------------------------------DOOO-------------------------~-------------------------I I
Serles : I I
AC i by litl YnA
of Nlxl (J) air m
"arshall Karshsll-llllll!rslon RKS Glib I stab. flow stiffness stab. flow
I (lb) (.01 In.) (lb) (.01 In.) ---------1-------------------1---------------------------1-------------------------------------------G---·------
I opt-I I 5.213 I 16.97 6.84 2.270 I 2058 8.8 233.1 2293 .9.9 1.114 C I opt I 6.103 I 16.46 4.12 2.306 I 1708 11.s 148.5 2128 10.8 1.246
I opt+I I 6.977 I 16.68 2.23 2.314 I 1858 12.2 152.7 2392 13.Z 1.287 ••••W••••l•••••-•••l•••••••••i-•••••••••••••••-••••••-•••l•·--••••••••-••-••••--•~••••••••••-••-•••••••-•••~----
1 opt-I I 5.213 I 16.16 6.73 2.293 I 3367 9.7 348.Z 4930 10.6 1.464 AH I opt I 6.103 I 16.93 5.57 2.293 I 3825 8.5 450.0 6443 9.6 t.684
I opt+I I 6.977 I 16.61 3.19 2.324 I 2675 14.3 187.7 3020 15.2 t.129 ---------1---------1---------1---------------------------1-----~----------------~-------------------------------
I opt-I I 5.164 I 14.39 3.22 Z.340 I 2158 12.2 177.3 2347 10.6 1.087 LL : opt I 6.047 I 14.95 1.10 2.346 I 2117 11.1 181.4 2837 10.2 1.340
I opt+I I 6.91Z I 16.04 0.83 Z.338 I 1567 14.5 108.0 1877 11.7 1.198 ---------1---------1----~----1---------------------------1------------------------------------------------------
l opt-I I s.116 I 14.48 2.99 2.336 I 2658 10.3 251.3 2841 1e.1 1.071 lH I opt I 5.991 I 15.03 1.47 Z.343 I 1875 12.7 148,0 2595 11.8 1.384
I opt+I I 6.849 I 16.20 0.72 2.332 I 1392 15.7 88.8 1670 14.S 1.200 -------~-1---------1---·-----1--------------~------------1------------------------------------------------------
1 opt-I I 5.213 I 16.04 6.76 Z.296 I 2875 9.8 Z9Z.5 3243 9.7 1.128 S I opt I 6.103 I 16. 92 5.61 Z.342 I 2050 15. 7 130.8 2650 13. 7 1.293
I opt+I I 6,977 I 16.Z6 Z.71 Z.333 I 1775 15.8 112.1 ZZ22 14.0 1.252 ---------1--~------t---------1---------------------------1-----------------------------------·------------------
I opt-I I 5.213 I 17.Z7 . 6.90 2.262 : 1667 a.a 188.7 2407 10.3 1.444 K I opt 1 6.103 I 15.79 3.07 Z.324 I 2083 13.5 154.3 Z883 15.0 1.384
: opt+I I 6.977 I 17.64 3.04 2.296 I 1400 .11.Z 125.3 1708 15.0 1.220 ---------i---------i---------1---------------------------1------------------------------------------------------
1 opt-I I 5.213 I 17.18 ~.56 2.265 I 1617 8.2 197.9 2020 7.4 1.249 J I opt I 6.103 I 16.31 5.44 2.310 I 214Z 11.3 189.0
: opt+I I 6.977 I 17.68 4.88 Z.294 I .1333 11.0 121.2 2225 11.8 1.669
-- : Oata not available. R"S : "arshall stability ratio.
69
Table 8b. Hix properties, G/AC-5.
AC S l I Marshall Karshall-l11111erslon RNS Serles I by rl! VffA air i
m Glllb I stab. flow stiffness stab. flow
I I of Mlxl (1) I (lb) (,01 In.) (lb) (.01 In.)
---------:-------------------:-------------·--·--~-------:----~~---·~--------------------------------~----------: opt-I I 5.213 I 20.18 9.ZO 2.250 I 1517 9.0 168.5 1102 11.6 0.727
c I opt I 6.103 I 19.68 6.51 2.Z86 I 1750 9.0 194.4 1215 9.8 0.694 I opt+! I 6.977 I 19.65 4.34 2.308 I 1333 8.3 160.t 1488 9.9 1.116
•••••••••t••••••-~•t•-•••••~-1-----~--m•••••--•••-••-·-~•1••--•-•-••~•••••-••--••••-•-••••••-•••-••-•-•••••••-••
I opt-I l 5.164 I 16.36 5.77 2.357 I 1583 !0.7 148.4 1808 10.2 1.142 LL : opt I 6.047 I 19.51 7.21 2.289 I 1450 9.0 161.l 1613 8.2 1.112
I opt+I l 6.912 I 18.86 4.34 2.329 l 1583 9.7 163.7 1395 9.7 o.aa1 --------- l----.. ----1---------1------.. --.. ----..... -.................. - .. l-.... -.... ----..... -................. _ ................. _ .. ___ ..............................................
• opt-I I 5.213 I 19.66 9.42 2.265 I 1775 8.5 208.8 1597 10.z 0.900 ' I
s I opt I 6.103 I 19.01 6.55 2.305 : 1475 8.3 177. I 1633 13.7 1.107 I I I opt+l ' 6.977 l 19.19 4.61 2.321 I 1392 14.3 97.1 1118 10.8 0.846 I I I
---------:~-------~:----.. --~-:-----------.. ~---~----------:·-·~----0---------~---------·----------------------~--l opt-I I . 5.213 I 18.80 6.94 2.289 l 1833 10.3 177.5 2225 13.l 1.214
K I opt I . 6.103 I 18.25 4.14 2.326 I 1783 11.0 162.! 1988 14.7 t.115 I .opt+! I 6.977 I 18.87 2.71 2.330 I 1550 14.D ll0.7 2037 14.7 1.314
---------;-~------~1---------1•--•-a-•--~----------~-----;o--••••-~-~-------•--•••--••--•-•••••-••••--•--•-••-•• I opt-I I 5.213 I 19.49 9.25 2.270 l 1325 15.0 88.3 1240 10.4 0.936 I I
J • opt I 6.103 : 18.13 5.55 2.330 I 1325 9.5 139.5 1735 12.2 1.309 I I I opt+ I I 6.977 l 19.19 4.62 2.321 I 1233 10.5 117 .5 1658 10.8 1.344 I I I
70
Table 8c. ntx properties, LS/AC-20.
• AC \ I ' "arshall Marshall-l11111erslon RMS I I I
Serles I by )ftl VNA air.\ Glib I stab. flow stiffness stab. flow I I
of Mix: m IU I (lb) (. 01 In.) (lb) (. 0 I In.) I ........................ 1 .. --....................................... 1 ..................................................................... , ............................................ - ............... .,. .............................................. _ ..................
I opt-I I S.213 : 16.79 6.33 2.275 I 2550 9.3 273 •. 3 3693 11.6. 1.448 I I
c I opt I 6.103 I 17.26 4.83 2.284 : 2483 12.0 206.9 2650 11.8 1.067 I I I I OPt+i I 6.977 : 16.57 2.00 2.325 : 1975 18.2 108. 7 3153 ~0.5 1.596 I I
....................... 1-----·---t---------1---------------------------1---~-------·------------------------------------------I opt-I I 5.213 : 15.50 4.83 Z.311 I 3783 12.7 298.6 8380 12.7 2.215 I I I
AH I opt I 6.103 I 16.89 4.38 2.294 : 5067 12.5 405.4 6130 ti .o 1.210 I I I opt ti I 6.977 I 16.83 2.29 2.317 : 3633 16.2 224.7 7892 10.8 2.172 I I I
---------t---------:---------l-.. --------·------------·--·t------------------~-------------·------~-·------------I opt-I I 5.JU l 15.58 4.41 2.307 : 3092 11.0 281.I 2990 10.9 0.967 I ' tL I opt I 6.047 : 14.62 3.38 2.334 : 4284 15.5 276.4 2902 12.5 0.677 I I I opt+ I I 6.912 : 16.15 1.06 2.335 : 4522 14.3 315.5 2777 14.0 0.614 I I
---------1---------t-----~---1-------- ... ------------------1-----~--~-------·--------------------------~----------I opt-I ' 5.116 : 14.47 3.32 2.337 : 2783 13.8 201.3 3193 10.7 l.147 I I
Lff f opt I 5.991 I 15.18 Z.09 2.339 : 3125 14.0 223.2 3292 13 .• 0 l .053 I I I I opt+! I 6.849 I 16.00 1.02 2.337 I 1825 20.3 89.8 2888 15.5 1.582 I I
.................... 1------·--1-----..... -.. , ............................................................. 1---.;. .................................... _ ............................ ____ .......................................... I opt-! I 5.213 : 16.01 5.53 Z.297 I 3717 11. 7 318.5 4208 11.8 1.132 I I
s I opt I 6.103 : 16.55 4.05 2.304 : 3238 15.2 213.5 1463 12.5 0.452 I I I opt+I I 6.971 I 16. 79 2.25 2.319 I 2467 19.5 126.5 3227 16.8 1.308 I I I
-~----·--:---------1---------1---------------------------1-------------------------------------~----------------I opt-I I 5.213 : 15.65 4.45 2.306 : 2683 16.8 159.4 3053 12.8 1.138 I I
K i opt i 6.103 : 15.49 2.29 2.331 I 2242 19.5 115.0 2600 17.5 1.160 I I I opt+ I I 6.977 : 17.06 1.81 2.311 I 1658 21.7 76.5 2363 15.6 1.425 I I
--·--·---:---------1---------1---------------------------1------------------------------------------------------I opt-I I 5.213 : 17 .39 6.97 2.259 : 2217 9.5 233.3 2925 9.5 1.320 I ' J I opt I 6.103 I 16.49 3.85 Z.310 I 2650 13.0 203.8 I I I I opt+ I I 6.977 : 11 .45 2.86 2.300 I 1883 12.7 148.6 3213 14.7 1. 706 I I
Table 8d. Hix properties, G/AC-20.
l Serles l
AC t l by vtl VHA air $
of ftfxl (II (%)
71
Narshall Marshall-lllllllerslon RHS Gab I stab. flow stiffness stab. flov
l (lb) (.Ol In.) {lb) (.Ol fn.) ---------t·--•--••••-•-•••--•l••••&••-••-----•••••••----•l••n--•--a••-••--~•-•••-••--••••••--•-•••-•---••-••••••
l opt-I I 5.213 I 19.17 7.96 2.279 I 2167 9.8 220.4 1878 13.4 0.867 c I opt l 6.103 I 19.65 6.48 2.287 l 1700 11.z ISZ.Z 1850 10.8 1.088
l opt+l I 6.977 l 19.20 3.92 2.321 I 1792 12.3 145.3 2367 13.5 1.321 ---------1---------t---------1---~-----------------------1-------------------------------~-----~----------------
I opt-I I 5.164 I 19.18 8.18 2.277 l 2475 11.3 218.4 ll I opt I 6.047 I 18.65 5.54 Z.314 I 2283 IZ.3 185.2
l opt+! l 6.912 I 19.03 3.96 2.324 I 2567 12.0 213.9 •••••••••l•••••-•••t••-••••••t•-•w-•••••••••--•-•••-•-••-(•~----------------•a•--•••------------------------~---
1 opt-I I 5.213 l 19.49 8.74 2.270 l 2525 10.2 248.3 2277 11.Z 0.902 S l opt l 6.103 l 19.40 6.57 2.294 l 1925 IZ.O 160.4 2170 12.7 1.127
I opt+I l 6.917 l 18.34 3.24 2.346 l 2567 14.3 179.l 2565 12.0 0.999 ---------t---------1---------1·--~~--------~------------0 (---------------------------------~--------------------
l opt-I I S.213 I 18.42 7.80 2.300 I 2358 14.Z 166.4 2377 15.0 1.608 K I opt I 6.103 I 18.32 5.55 2.324 l 2250 12.2 184.9 2467 ll.l l.096
I opt+! I 6.971 l 18.36 3.44 2.345 I 2183 18.S 118.0 2638 18.0 1.208 ---·~----:----·~---1•••-•a---l••-~a•~--~-~~~-------~----•l-d•••••••--·~---a•••-•••••••••-••••-••-•••••••••-•w•••
l opt-I I 5.213 l 18.55 8.81 2.296 l 2025 10.3 196.0 2583 13.8 1.276 J I opt I 6.103 I 19.73 8.04 2.284 I 1950 11.3 172.1 2338 15.2 1.199
l opt+! l 6.977 I 18.62 4.64 2.338 I 1758 16.5 106.6 2260 17.9 1.285
MARSHALL STABILITY _.,. ... •
... •
•-;;
~1 ...
~ 2
~ ~ ... l7:?L-W,?,I
~a~~~~ c u. s K J
IZ2I opt-1 d"";. ~ opt+1
MARSHALL STABILITY N:.-4/UI
·:1 ~ l
"
u i~I~~ l~ J "'
0
c ... u.
t22J opt-1
LH
MIXES IS:5l ...
s
IZ'::ZI opt+1
• J
... •
" •
~1 ... 3 2
...
"' 0
c
•
• 4
~1 . 2
2
0
c
Fig. 32a. Marshall stability.
-~
MARSHALL STABILITY ,.,__ .. /G
u. • K J
IZ.2J opt-1 ~ f??.lJ opt+t
MARSHALL STABILITY .... N:.-'JD/1.$
..,
... u. LH s K
tz:ZJ (1$>t-1 d""!t ~ ept+1
·-,..--~
'B ~
I
MARSHALL STIFFNESS ... ~~~~~~~~~·~'~~-~~=---~~~~~~~~~ -.... ,.. ... ... 150
100 .. o VA\.. vm • v~ v&·'* •
c u.
1Z2l ept-1
• ..... = ... • ~-1
MARSHALL STIFFNESS LS/AC-2:0
J
... ~~~~~~~~~~~~~~~~~~--,
... ""' ,.. ... ... '"' 100 -VA-.. 'l:?ol
.. o V1)Ji:%1 l'A)l0 Vl)W Vl)W r.1y
c '" u.
fZZl opt-1
"' •oo:s = .. · s
~ oi>t+t
K J
I
I
MARSHALL STIFFNESS ... ~~~~~~~~---'~~,,...~·~~~~~~~~ -.,,, ,.. ... -1SO
100 .. o VA\)£
c u.
!ZZI -·
• """" J'S:sJopt
• ~ opt:+1
MARSHALL STIFFNESS
'
... ~~~~~~~~U~/_,,._.~~~~~~~~~~
...
.,,,
...
... -. .. 100 .. •
c "' !ZZJ opt-I
u. U<
woo:s =opt
s
~··1
• J
Fig. 32b. Marshall stiffness.
" <..>
74
Marshall st;l.ffness or Marshall quotient has been used in the United
lCingdom and South Africa as a criterion in mix design and has been
correlated to rut depth. For example, in South Africa, a minimum value
of Marshall stiffness at 140° F (60° C) 'of 1 to 2. kN/mm (5700 to 11400
lbs/in.) has been suggested to control excessive permanent deformation
or rutting (6, 30). Marshall stiffness, stability in pounds divided by
flow in 0.01 in., of the mixes are shown in Fig. 32(b). No significant
additive effects can be ob9erved except large increases in stiffness
because of Asphadur. All mixes exceeded the minimum stiffness value
needed to prevent excessive rutting.
4.1.2. Re!ililient Modulus
The results of the resilient modulus tests are given in Table 9.
No significant additive effects are seen except large increases are due
to Asphadur (AR) and somewhat low values are observed in mixes
containing SBR (J). Their effects as manifested in moisture damage and
structural capacity will be discussed in the following sections.
4.3.~. Tensile Strengths
Indirect tensile strength results are given in Table 9 and plotted
in Fig. 33. Asphadur increased tensile strength significantly; SBS
increased the strength slightly; and SBR decreased the strength
somewhat. The effects of other additives were not obvious.
4.1.4. Moisture Damage
~esistance to and effects of additives on moisture-induced damage
of asphalt concrete mixtures were evaluated by using Marshall immersion
75
Tallie !a. Indirect tensile strength end mlllent modulus, LS/AC·5 •
............... -......................... _ .. _ ............................................................................. _ ................................................................................................................ .. ' ' . ' INDIRECT TENSILE Sll1EN6Tff
Rlxes I \ Sat. llolst Pi ITSB ITSAY RV I TSAl I (psi I (psi) (psi)
RL : I RR8 i (p•I)
RESILIENT llODULUS ('100000) !RAV ftRY KRAL MRl (psi) (psi)
... -------l--·-·-···-.. - ........ , .. - ........................................... _ ......................................... , ........................................................................................... .. oPl·I I 92.24 2.804 I 132.Z 112.4 1.303 : 116.3 0.879 I 3.16 4.54 1.436 : 2.19 o.m
C Ollt I 13.41 1.308 i llZ.I 149.6 1.334 i 105.9 G.944 i 2.ll 2.52 1.065 i I.SS G.656 011t+I i 108.46 1.192 I 96.l 188.6 1.IZ8 I 184.l 1.983 i 1.63 Z.32 1.423 I 1.14 0.699 _ .... ---1------.............. , ....... - ............................................... ,_ .. ,. ............................ , .. ___ ., __ ................................... , ................................... .. Ollt·I I 18.11 2.281 I 276.1 224.6 0.813 I 192.1 U95 I lo.90 1.45 0.683 I S.35 0.191
Alt Ollt. I 19.52 1.939 I 258.8 266.8 l.031 I 218.3 1.045 I 16.31 13.85 o.eso I 10.01 D.614 opt+I I 65.9! Mt! I 199.8 164.l 1.824 I 181.3 0.931 I 6.3! 4.25 o.m I U6 0.864
_,. ................... -1-------......... ____ , __ .. ___ ......................................... , .............. _ ................... :------·-··----........................ :-----·---................. .. 01>t·I I 58.91 0.801 I 151.1 111.0 0.135 I 161.l 1.071 I 3,30 1.12 0.520 I l.73 l.130
u Ollt I llS.16 8.830 I 140.7 131.4 o.m I 151.0 1.013 I Z.59 2.11 l.046 I 2.40 o.m Ollt+I I 156.!0 a.m I 109.B 94.l 0.862 I 14.6 8.619 I 1.58 1.37 0.861 I 1.09 0.690
----1-·---... -: .. --.... - ........................................ , ________ .... 1 ... ----·--·--·----.................. 1-----------··~ .. --0llt· I I 95.55 1.222 I 142.1 m.o 1.216 I ISG.4 1.059 I 4.08 4.15 l.Ol6 I l.50 o.m
lK oPt I Ill.ii 8.111 I 128.6 llS.I 1.048 I 125.Z o.m I 2.11 2.28 0.842 I 2.81 1.136 Ollt+I I 156.81 0.483 I 94.1 IOU I.Ill I 81.l Mll I 1.23 1.19 0.966 I 1.03 e.m -----:··------:---------··· ............. :--·-----........ , ...... -............... ----------·---:·--------··· .......... .. Ollt-1 I 11.03 2.266 I 145.1 195.3 1.345 i 147.1 1.011 I 3.54 l.19 1.0TI I 2.03 0.173
s Ollt . 1 55,40 o,m 1 111.4 m.a 1.130 : m.s 1.m 1 2.u 2.I! o.m 1 2.01 0.112 Ollt+I I 66.13 o.m I 118.8 121.5 1.023 I 147.0 1.m I l.59 1.92 t.208 I 1.48 o.m
........ =="="'"'l"'""'"''"',,,;,,,.,,,====:=-·""""'"''""'"'"'"""'"'"' .. "'"''"'""'"'''"'"'"'1""'""'"'"'"'"'""'"'"'""'""""~=;"'====""'"'"'"'"'"'"'"'°"'"""'"'=""'""'"""'1="'"""""'"'"'"'"'""'"'""''"''""' 011t·I I 103.23 3,159 I 139.9 121.2 0.909 I 110.2 0.188 I 2.62 1.50 e.m I 1.16 o.m
K Ollt I 101.23 1.m : 106.9 111.2 1.0'6 I 111.5 1.043 I l.21 1.26 1.041 I 1.28 ·1.1sa 011tt1 I 101.11 t.420 I 95.1 115.1 1.112 I 88.3 G.929 I 1.59 1.16 1.m : 1.01 0.639
·-·-.. --.. :---· .. -·---.. --:--.................................... - ........... 1 ........ _ ........ _ ........ _ .. : .. --............................................... : .................................. .. 011t·I : 13.45 2.116 I 91.6 au Q.912 I 94.2 0.965 I 2.10 9.91 o.m I 1.25 0.595
J Ollt I 63.49 1.m I 81,8 100.l 1.142 I 92.8 1.058 I 1.13 1.33 I.Ill I I.II 0.!82 011t+I I 15.72 1.621 I 82.6 77.l 9.936 I 79.1 8.946 I 1.24 1.47 l.181 I 0.7S a.m
l Sat. : t Saturation. Holst P : Moisture plckuPo i vt,, ITSB 1 lndlrett tensl le strength btforo treatment. ITSAY 1 Indirect t .. olle strength after '"'""" saturation. ITSAl 1 Indirect tensile strength after Lott.an treat .. nt. RV 1 Ratio, IT5AY/ITS8. RI. : Ratio, ITSAL/ITSB. 11118 : Resilient-••• before treata2ftt. MRAV : Resl llent -I•• after '"'""" .. turatlan. llflAL 1 Resilient -l•• after lottun treatHnt. llflY I Ratio, Hm/llfl8. llflL 1 Ratio, KRAL/MAB.
76
Table 911. Indirect tensile str .. gth and reslll,.t IOdulvs, 6/AC·5,
' ' ' ' IMO I RECT !ENS I LE STRENGTll I \ Sat. lloltt Pl ITSB ITSA Y RV ITSAL
I (psi) (psi l (psi) RL
I I RR8 I lpsll
RESILIEllT llOOULUS ('I 00000) RRAV HRY ftRAL RRL (psi) (psi)
__ .. __ ... _ ,_ ................. -~-----:---.............................. - ......................... - ............. --1-----·-----------...................................................... .. oPt-1 I f8.Z3 3.995 I 97.6 118.4 1.m I 6'.7 0.1U I Z.tl 2.25 1.105 I 1.18 0.815
C opt I 100.ll Z.B67 I $8.S 128.3 1.450 I 10,.4 1.134 I 1.94 2.11 t.123 I 2.11 1.120 opttl I 103.64 1.'54 I 92.5 91.9 1.05B I 103.6 t.IZO I 2.15 Z.Zl 1,056 I I.IS 0.535
-------i·--·-·-·-·-··----1-·-----·---................................ t-----·----------1·----.. --..................................... 1--·-.......................... .. opt·l I 54.40 1.343 I 119.1 138.0 t.159 I 110.s o.928 I Z.'6 2.29 . 0.861 I 1.56 0.586
LL oPt I B5.49 2.661 I 112,4 105.1 0.934 I 8B.O o. 782 I 5.15 t .1B 0.346 I 1.41 0.285 opt+l I 11.19 1.446 I 95.5 93.0 o.m I Bl.O G.911 I 1.25 1,09 O.Bl2 I 1.11 O.BBB
.......... ~ .. :.. ...... , ..................................... J ··~-................................................ I ....... _ ...... - ................ 1 ....................................................... 1-................................... .. oPt·I I 19.39 3.616 I 113.8 136, 1 1.311 I 92. l 0.893 I 2.07 Z.31 1.145 l 1.26 0.609
5 oPt I 82.16 2.352 I 126.1 124.3 G.981 I 126.S 9.998 l 1.49 1.39 o.m I 1.34 o.m oPt+I I 63.69 1,251 I 125.6 151,l 1.205 I 121.3 a.966 l 0.76 8.91 l.2BO I O.B2 1.081
---.. ---:--.... - .... -----l-.......... _ ............ _ ...................... , .............. - .................. , ................................... ------·J-..................... _____ _ oPt·I I 95.12 2.B15 I 131.8 m.e 1.204 I 125.1 0.90B I 2.62 1.98 8.981 l l.lB UBI
K oPt I 105.68 1,880 I 124.9 282.7 1.623 I 125.3 1.003 I 1.10 2.22 1.308 I 1.52 0.893 oPt+l I 133.60 1.568 I 181.3 m.7 1.1$2 I 122.s 1.132 I 1.19 1.53 1.2B6 I 1.01 0.845
-~-................ 1--------·----... -1----·------------·--·-·--:·---.. .;. .......... - .... :--.. ----···--·-------1--............................... .. oPt·l I BU! 3.450 I 66.6 68.8 1.034 I 48.6 o. 130 I 1.00 O.B9 O.BB1 I 8.49 0.486
J oPt I 6!.11 1.648 I 13.2 81.6 1.115 I 69.Z 0.945 I 1.13 I.Bl 0.846 l 0.82 o.m oPt+l I B2,91 1.655 l 11.1 B!.5 1.010 I 85.0 1.102 I 0.11 1.66 0.92B I O.ll 1.007
77
Table 9<. Indirect tensile strength and resl llent IOdul..,, LS/AC·!O.
I I INDIRECT TENSILE STREMGlff I RESILIENT llDOULUS ('100000) llxes I I Sat. llolst P I ITSB ITSAV RY ITSAL AL I RAB KRAV !RV ftAAL ftRL
I I (pslJ (psll (psi) I (psi) (psi) (psi) ----t .. -·-------··-· l·· .............. _ ............. _ ............ ____ .... _ ................... 1 .... --............................... _ ..................................... _ .... _ ... ..
Ol>t-1 I 81.88 z.m I m.z 219.J 0.961 I 156.6 0.538 I lo.67 8.49 0.796 I S.44 0.510 c ""t 1 as.s1 1.10& 1 m.s zaz.2 1.m 1 166.a o.m 1 11.as 9.S9 e.845 : 6.65 o.586
opt+l I 54.71 8.471 I m.1 ZZ6.I G.955 I 2!6.3 0.956 I S.55 3.99 0.719 I 4.82 0.868 ·-·-----1-.................. - .... ---1----.. ------.. --................. 1---·------· .. ·---1-................................................ _ .. , .................................. ..
opt·I I 11.'1 1.495 I m.a 388.7 I.Oil I 341.! o.m I 11.30 14.93 G.863 : 9.81 1.571 Alt Giit I 88.01 1.614 I m.1 144.8 t.867: m.o 0.187 I IMO 24.00 1.206: 11.98 0.602
Ollt+I : 82.10 0.808 I 385.8 m.z 1.095 I 427.6 1.108 I 18.60 11.25 0.605 I II.SO 0.618 ---... --1-.. ------···---l·--............. _ .... ____ .......... , ...... ____ ............ 1-·-·-.. --................ _ ........... _ .. 1-----------·-· .... --
opt·I I !4.21 1.825 I 155.6 389.l l.'14 I m.a 1.646 I 13.00 10.10 0.771 I 8.53 0.656 LL opt I 11,72 9.748 I m.l ZlS.4 1.m I 294.1 t.335 I 8.85 6.45 0.129 I '·'' 0.784
opt+I I 117.36 1.481 I %61.7 m.6 1.011 I Z95.4 1.129 I 1.50 5.43 e.m I 7.42 G.98! ___ , .. _________ .. ,_ ..................... -----l .. ----.. - .... , ................................................. _ .. , .................................. .. opt-I I 59.11 8.039 I m.s llt.6 1.ZIZ I Ill.I o.626 f 8.66 8.59 o.m I 7.57 0.874
LK opt I 72.13 G.649 I 215.4 108.9 1.259 I 321.0 1.388 I a.38 I.SO 0.894 I 8.84 1.055 opt+I 1 is.as e.m 1 188.9 m.c 1.m 1 m.a 1.m 1 1.21 1.60 a.110 1 6.81 o.m
-·---:-·-···---·-:--·-······-··-··-.. f·-· .. ---· .......... : ........................ "'. .... _ ................... J .................................... ..
opt•I I 10.41 1.m 1 210.7 . 328.9 1.215 I 151.9 0.561 I 8.85 9.51 I.OJI I Z.08 o.m s opt I 83.98 1.479 I 254.2 303.5 1.194 I 186.0 8.llZ I 6.16 . 8.87 1.uo I 2.91 o.m
opt+I I 112.88 I.Ole I 253.9 348,Z 1.lll I Z49.0 0.981 I 4.23 9.50 2.246 I 5.17 1.364 ---1-----1·················-·······l·--·············l···························I-·········-·····
Ollt-1 I 19.06 1.527 I 225.5 221.1 9.983 I 182.1 0.807 I 4.94 4.00 0.810 I 3.69 o.m l opt 1 13.00 a.nz: m.a m.1 o.m 1 1aa.s 1.085: z.11 z.45 o.m: l.39 1.m
opt+! I 114.78 f.818 I 165.6 UM U09 I 155.0 8.936 I 1.44 1.39 0.96$ I 1.3! D.965 ---·-t·----.... --·t .......... "!'..._ ............ _ .............. ,-............................... , ..................................................... 1 ...................... _ .. ___ _
Ollt·I I 84.78 z.m I 154.0 154.5 t.004 I 130.6 0.848 I l.4Z 3.87 l.ll2 I 1.76 0.Sl5 J Ol>I I IS.79 J.433 I 167.6 182.9 1.091 I 151.8 8.942 I 3.69 l.60 0.916 i 2.40 0.650
opt+I I IZl.18 1.550 I 146.2 184.8 1.264 I 149.0 1.019 I 2.76 !.44 1.246 I 2.22 0.804
78
Table 9d. Indirect tensile strength end rtstllent llDdulus, 6/At-20.
I IMDIRECT THSILE STRENGTH I RESlllENT llOOULUS ('190000) Nixes : ' Sat. ltolst Pl ITSB ITSAY RY ITSAL RL : MRB NRAY NRY llRAL !RL
I I (psi) (psi) (psi) I (psi) (psi) (psi)
-----1- -1----·--------------·-----······-·-·--··-1----··-·····-----·············---------·-•pt-I : 82.4, 2.813 I m.7 W.8 1.214 I IZO.S o.m : 6.26 9.16 1.m : 6.84 1.09!
t opt I 91.15 2.161 I 199.3 165.4 0.6!0 I IU.9 0.526 I 5.38 7.78 1.446 i 5.41 J.006 oPt+I 1 1u9 1.339 1 220.a 288.5 1.m : 180.s o.818 : 6.so a.12 1.182 : 5.06 o.744
..... ~------.. l-------··---.. --.. t-·--------..................... - ........... 1--------------· 1---· ............................................... 1-----·----------opt• I I 9U9 3.395 I 229.2 203.J 0.893 I 115.6 0.506 I 11.90 9.61 0.808 I 5.18 0.431
LL oPt I ll.17 1.847 I 2'4.l 162.3 0.992 I W.6 o.9U I 9.38 7.59 8.809 i 7.56 0.806 opt+I : 101.os 1.815 : m.1 m.o 1.m : 10.4 o.148 : 8.65 6.Z6 o.m : 4.lZ o.m
................ --, ··---------·-----1-·-.. ·---·--· ............................ 1----·----................ 1-·---------·----------.. ---1 ·--.... -~ ..................... .. opt-I I 80.9' 3.107 I 231.8 m.a 1.m I 156.9 UH I 6.51 6,43 0.988 : 4.14 0.728
s oPI I 75.94 z.m I 316.2 109.S 0.979 I 169.4 1.m I J.82 l.31 0.935 : 4.15 0.531 oPt+I I 90.00 1.244 I 300.S 345.2 1.10 I m.1 o. 146 I 6.80 6,46 1.m : 4.06 o.671
........... ---·l·---·------.. l··----·---............ - .... ~ ...... _l ... - ..... - .......... _ .... _,_ ........................... --............. 1 ..................................... .. opt·I I 73,71 Z.490 I 111.1 24G.I 1.398 I 146.2 8.851 I 4,61 1.84 1.256 I 3.42 o.m
K opt I Jl.48 1.106 I 222.3 219.9 t.989 : 178.Z 0.802 I 6.34 5.17 o.815 : 3.78 0.59' oPt+I I 12.36 1.062 I 194.0 211.1 1.091 : 195.9 I.Oii I l.89 2.88 0.148 I Z.93 o.m
.............. _ .... 1--............................. , .. _________ ,, __ .......................... , ---··-~--.......... , .................................... ___ ........... 1----··------------opt-1 1 6s.Jl 2.m 1 149.3 153.l 1.021 : m.1 o.m : 3.44 z.n e.m : 1.18 o.m
J oPI : 62.24 2.179 I 146.9 189.6 1.zz9 : 135.1 0.920 I 2.38 2.56 1.076 : 2.03 0.853 opt+I I 51.39 1.140 I m.z 128.2 1.935 : 14o.t . I.OZ! I Z.33 1.94 0.833 : 1.9! 0.814 -··-··----·--·----·------·--·-·-·-·---·-------.. -----------.. -...... -........................................... _ .. _ ......................... ,._ ............ ..
INDIRECT TENSILE STRENGTH AC-5 G SERIES
<DO~~~~~~-'-''-=--"-;:.;;_~~~~~~~
350
300
1. 250
! 200
! 150
100
50
0 c LL s K J
1221 apt-1 MIXES
£S:S1 opt ~ opt+1
INDIRECT TENSILE STRENGTH Al'::-5 LS SERIES
<DO-.-~~~~~~~~~~~~~~~~~~~~~,
350 ...
I 250
200
150
100
50
O c AH LL LH s K J
llZJ opt~1 MIXES
IS:sJ opt ~ opt+ 1
l
I
i i
INDIRECT TENSILE STRENGTH AC-20 G $ERIES
400,.-~~~~~~~-=--'--.:.....::::..-.-~~~~~--,
350
300
250
200 _L_ t/'.M
150
100
50
· O V/f\.. '11'"/4 V/f\. '\ ~ ~
c LL • • J
1ZZ1 opt-1 MIXES
ts:SI opt IZ!lJ opt+1
INDIRECT TENSILE STRENGTH AC-20 LS SERIES
400.,-~~-...r-~~~~~~~~~~~--,
350
300
250
200
150
100
so
O [!T\IZI [/l')M [/!)"
c AH LL LH s K J
IZ2l opt-1 MIXES
[SS! opt ~ opt+ 1
Fig. 33. Indirect tensile strength.
-.t
'°
80
(24 hrs. at 140° F), retained tensile strength ratio and retained
resilient modulus ratio after vacuum saturation and after
Lottman-accelerated moisture conditioning (vacuum saturation followed by
freezing and warm water soaking). (See Fig. 31.) The Lottman
wet-to-dry tensile strength ratios :were used in conjunction with the
ACMODAS <Asphalt Concrete Moisture Damage Analysis System) computer
program developed by Lottman·and Leonard (28) to predict changes in
fatigue life. because of additives and to predict field life
benefit-to-cost ratios for .different additives.
· 4. '.'I. 4. 1. Marshall Immersion
Marshall immersion stability results are given in Table 8, and the
retained stability expressed as ratios are shown in Fig. 34. The only
asphalt-aggregate combination with additives that showed improved
stability ratios was gravel with AC-5; here the mixes without additives
(control) would have a problem meeting the usual criterion of minimum
. ratio of n.85.
4.3.4.2. Tensile Strength
Indirect tensile strengths after vacuum-saturation and after
Lottman-accelerated conditioning are given in Table 9. Also given were
percent resistance pick-up by weight and degree of saturation of
vacuum-saturated samples. The degree of saturation, expressed as
percent, was calculated by dividing the volume of moisture pick-up by
the volume of air content. The retained tensile strengths, expressed as
ratios, are shown in Fig. 35.
0
~ 5 ~
I
• i 5 !
I
MOISTURE DAMAGE, MARSHALL STABIIJTY 1.4 ___ ,,.
... ... 1.1
... o.e 0.7 ... ... o.• .... ... 0.1
o~ c u. $
fZ2l opt-t ~ • J
~ op:+t
• i
I I
MOISTURE DAMAGE, MARSHALL STABIIJTY t.4 ~,.
u ... 1.1
... ... ll7 ... ... ... ... ... ..,
0 c u. •
fZ2l _, ~
• , l!!Zill .... ,
MOISTURE DAMAGE, MARSHALL STABIIJTY ~· AC-20/LS
MOISTURE DAMAGE, MARSHALL STABIIJTY
•.7 T----r~:J" ____ _:A<-ll~~{l.S~--------==~-'·· -... 2.2
2
...
... u
1.2
... 0.6
o.4 .! /l'.. VA
0.2
0 c .. u.
1221 o,t-1
Ui
MIXES =op•
• i
I I
, .. u 1.2
LI
u ... 0.7
o.• ... ... o .• -rA-.~ ... 0.1
0 lt'l'}m t&,W L1)WI IA)l $ • J c AH
~ opt+1 fZ2l opt-I
Fig. 34. Moisture damage, Marshall immersion stability.
u. Ui
d"';..
~
• • J
~ opt+1
co ....
I I
I I
••• 1..a 1.a t.1
... u 0.7 ... ... 0.4
u
KOISTIJlUI DAKAGB. ITS
u '.l l\ If'.' I\ j«A !\ jZ4 o.: !\ lf'J " If' I\ lf'J " ~
, .. ... 1..a 1.2
1.1
... ... 0.7
OA
ILi
a.• 11.1
11.2
O.t
0
c ....
cs::J IOOC/SAf
u. Ill s -liZJumMI "'
KOIS'l'OU DA1WIS. lllrSIUBMT KODVWS .VO-SJl,8,-1 .......- .
c .... cs::JvllC/SAl
u. Ut -· IZil LmlWI
s •
1~4
t.0
..a 1.1
·I ... ... .. ., ... ... 0.4
u·
D.11
0.1
0
1.a I.I
1
11.t ... 0.7
.,,. OJI
·o.4 u
"(la
0.1
0
. KOISftlBI IWIAGB, rrs -...... ~----J ·---- .
- .~ rq
c .... IL Ill S -IS:Jwt;fSM l2ZJ l.OllllMI
MOIS'l'tl1Ul lWWIB, iUISIUllNT _KODUWS
c "' IL
cs::JVllC/SAT
AC-e/l.S. ~----
UI,
UlllEi 12Z!l..01'11MM
g K -~
-1..a. -1.2
t.1
....
.... 0.7 ... ... IL4
u 0.2
0.1
KOIBTUU JWU:GB, 1'1'B ·
0 I' V' ,....., P"' '' V 4 '' IZ' f\ JZA ,, J( 4 [''>rt='
I.I
IA
1.a
1.2
1.1
1 ... .... 0.7
II.II
DAI M
OJI ... 0.1
0
c ....
cs::JVN:/IM
u. Ut s -~- M
KOISTUall DAllAGB, BBSJIDN'l KODUWS
c .... IL'
cs::J VllC/W
-!LS.-•
ut -~UlnWN
s K
Fig. 35a. Moisture damage, ITS, aud resilient modulus, AC-5/LS.
(lD N
... u ... •••
~ o.• ~ ... I o., 11 ... ...
o.• o.• .. 0.1
llOIS'l'llBB DAllAGB, l'I'$ AC-&/0. MixtS 2
0 h VJ h 'f'.d1 h 'Y11 h 'Y11 "' y...n
~
I
• u.
ts:) VAC/SAT
• ..... liZil """""
K
llOIS'l'llBB DA»AGB, ·BllSIUJINT JlODULUS
1.2 __..,,_ ..
•••
0.1
o.a .., ... ... ... o.• ... 0.1
0 t. 'f«d " +ud " +ui " T"'' " V'' • u.
· ts:JVN:/W
s .... liZil ..,,...
K
llOIS'l'llBB DAllAGB, ITS
1.7 .---------:::..::0
':.: .. :."""'==-=·-------~ • •• ... ... u .. ••• ... ... 0.1 ... ... ... ... ... ... o " V"' " V'A' " VJ " ¥V " ¥V • u.
l.'S:J WC/W
• ..... liZil """""
K
llOIS'l'llBB DAllAGB, BllSIUJINT llODULUS N:-6/G. YX£S •
1A ..,---------------------,
u ... 1.1~
... ... 0.7 ... ... ... ... ... 0.1
0 h 'fd'.l h 'fd'.l h 'fd'.l t>. 'fd'.l .., 'f?'.I • u.
rs::J VAC/SAT
s .... liZil """""
•
llOIS'l'llBB D.UWIB, ITS
N.>-e/O. ams • ul .. 1.1 ~hi
... ... 0.7 ... ... ... ... .. •••
O 1'\ fU,f '' lf/.t "· JHd (), JUd !'\. f//d
• u.
ts:J VN:/BIJ
• ..... liZil-
•
llOIS'l'llBB DAllAGll. illllllLDINT llODUWS
'
•~ I r;:-, Kl I ... 1.1
... ... 0.7 ... ... ... ... .. 0.1
0 .., VJ .., 'f?'.I .., 'fl.?1 .., 'f#l .., 'P'.l • . u.
rs.::J V/C~T
s .... liZil"""""
K
Fig. 35 b Moisture damage, ITS, and resilient modulus, AC-5/G.
00
"'
I I
! I
VOIS'l'llllB D.&JIAGB. rrs I~ ,...~~~~~~·~= ..... :..::'°~VIS..:::~"""'==~7~~~~~~~---.
... 1.1
... ... u
••• ·~ ... ... u 0.1
0 I\ f't'd I\ 19.'d I\ fXA [\ JZd [\ fZA !'\ f"' f\ f'' c ...
rs:J VM/SAT
1L U1 S ..... =l.OITIWI •
VOIS'l'llllB D.&JIAGB. BBSILIBNT VODULUS
1.2 11:-'ID_/Ui.. Mlm 7
I.I
... ... 0.7 ... ... ... ... G.2
0.1
'
• " i«' " I«' " i«' " i«' " rr' " i«' " i«' c "' 1L
cs:Jv~/SAT
"' .... i;z:;i '°"""'
s • '
VOISTUllB D.&JIAGll. rrs
1A.--~~~·~~ ..... ~'"~VIS.__c_ ..... ___ •~~--~~~~
I~ ... ..,
... ... 0.7 ... ... ... ... G.2
0.1
• " j:?'J " fi2 " C AH
IS:] VliC/SAT
fi2 " fi2 " fi2 " fi2 " fi2 u. "' • .... =-
• ,
VOISTUllB D.&JIAGB. JlllSILlBNT VODULUS
,.. 1.• u 1.2 ..,
... ... 0.7
...
... ... ... ... ~h~~~"~"~"~"~"fi'J
c "' u.
lS:) VIC/SAT
Iii .... ="""""
s • '
1.4 ,----
1~
1.2
1.1
... ... 0.7 ... .. . ... ... ... 0.1
VOISTUllB D.&JIAGB. rrs -- ,._ ..
• " fi2 " If'.! " fi2 " fi2 " fi2 " fi2 " fi2 c "'
ts:) Vl&/t/AT
U. UI S ..... =-•
' VOIS'l'llllB D.&JIAGB. JlllSILlBNT VODULUS 2.4 AC-20,Aa. lil:Cl:S 11
... 2
,.. u
... 1.2
... ... .... ...
'
• l:..T£:J h. lf'.I h.1£1 h. w h. w h. w h w c ... 1L
rs::J VIC/SAT
Iii .... i;z:;i """""'
$ • '
Fig. 35c. Moisture damage, ITS, and resilient modulus, AC-20/LS.
00 ..,.
I I
~
I
llOISTUllB D.UUGB, ITS N:-20/0. MIGS 10
l.S ~--------'"-'-----------, ... ... ... ... .., .. ... ... ... ... 0.1
o I'> W " 'fd'J ti VJ " ltYJ " VJ c
IS:J""""'1
u. • .... llZI"""""
llOISTUllB D.uwJB, BBSIUllNT llODUWS ID-20/0. MDl£S 10 ... ,..---------'"-'------------, ...
l.S
1.2
1.1
... ... 0.7 ... ... ... ... ... ... • " W I'> VJ t:. TffA t:. VJ " vo
c
ts:J VJi;/SAT
u. • ..... 122'.J .......
llOISTUllB D.UUGB, ITS
•.• ,.-------'-::...="::..10."""'"""'"-•-,,....,,.----..., u ... I.I
I· ... ... 0.7 ... ... ... ... ... 0.1
• " 'f4'.I " 'f4'.I " 'f'.11 " 'f'.11 " 'f'.11 c u.
IS:J VN>/fAT
• .... llZI"""""
•
llOISTllllB O.UUGB. BBSIUllNT llODUWS ID-'111/0. YllCEI •
1.6 ..---------~'---------~ 1.4
l.S
1.2
••• ... ... 0.7 ... ... ... ... ... 0.1
• " 'f'.11 " 'f'.11 t:, 'f'.11 t:, 'f/Ll t:, V1 c u.
IS:J VN;/SAT
• ..... (iZJUJTIIWI
•
llOISTUllB D.UUGB, rrs
1_. i.c-20/0. Yl(£I 1a
u . .. 1.1
.. . . .. 0.7 ... ... .. . ... ... o.: I\ w " "f.f'.I I\ 'f#1 I\ 'f#1 " 'f'.11
c u.
~V/IC/811.T
• .... 122'.J-
•
llOISTUllB D.uwJB, BBSILlllNT llODUWS l.J N:-20/0. ..m 12 .
... •••
... ... 0.7 ... ... . .. ... ... . .. • " "UI " 'U1 " 'U1 " "f.f'.I I\ 'f4'.I c u.
ts:J VN;/SAT
• .... llZIUJTIIWI
•
Fig. 35d. Moisture damage, ITS, and resil:tent modulus, AC-20/G.
00
"'
86
With a few exceptions, the tensile stength ratios after Lottman
treatment were lower than those after simple vacuum saturation. The
retained ratios ranged from about 0.50 to 1.4. The moisture pick-up
raUos ranged from 0.4%. to 4.0%. All except two mixes had percent
saturation exceeding the recommended 551'; (49). In several samples the
degree of saturation was greater thanthe theoretical 100% because of
fl) small moisture pick-up values, (Z) small air content values, and (3)
the different number of specimens examined· for (1) and (2). The
moisture pick-up values were based on an average of 3 to 6 specimens,
but the air content values were determined for an average of 15 to 18
·specimens. '!'he following observations <:an be made.
• AC-5/Limestone: Lime, SJIS, and SBR seemed to have improved the
moisture resistance determined by the Lottman procedure; but no
additives showed improvements based on vacuum-saturation
treatment.
• AC-5/Gravel: No significant effect.
• AC-?0/Limestone: Lime, SBS and SBR reduced moisture damage
while Asphadur and neoprene showed improvement only by the
Lottman procedure.
• AC-20/Gravel: Whereas SBS and neoprene showed beneficial
effects, lime and SBR made little difference in retained tensile
strength ratios.
4.3.4.3. Resilient Modulus
Resilient modulus data for mixes before and after moisture
treatments are given in Table 'l and shdwn in Fig. 35, ln the majority
of the mixes, the resilient modulus ratios were parallel to and were
87
lower than those of tensile strength ratios. In other words, they were
most sensitive to moisture .. induced damage. Again, as in the tensile
strength ratios, Lettman conditioning resulted in lower retained ratios;
and no additives showed consistent improvements for all
asphalt-aggregate combinations and with all binder contents, although
AC-20/limestone mb:es seemed to have benefitted by the additives more
often than other mixes. Contrary to previous beliefs, gravel mixes did
not show more moisture susceptibility than corresponding limestone
mixes, and hydrated lime did not improve moisture resistance in all
cases.
4.~.4.4. Life Benefit-to-Cost Ratio ---Dry and wet accelerated-conditioned indirect tensile strength data
were used to calculate the field dry-wet lives and the percent changes
from all-dry ~esi11t1 life because of moisture damage. The subroutine LCO ·
of the ACMOnAS program was used for all control (C) mixtures. From dry
and wet stren11:ths of treated mixes and the predicted field dry-wet life
of corresponding control mixes, field dry-wet lives and the percent
changes· from the all•dry design life of additive-treated mixtures were
calculated with the subroutine LBC. By using the same LBC subroutine,
the field life benefit-to-cost ratios were calculated for scenarios
where the costs of the additive-treated mixes were 5%, 10% and 20%
higher than the corresponding control mixes (cost ratios of
additive-treated mixtures of 1.os, 1.10 and t.20). The pavement and
environmental data assumed were:
Regional factor: 1 (severe)
Field a11-ifry des:l.gn life: 16 years
88
Percent allowable reduction of all-dry design life: 10
Field dry stage time: 4 years
The percent changes from all-dry design life and the life
benefit-to-cost ratios for additives cost ratios of 1.05, 1.10 and l.20
were plotted in Fig. 36a (LS/AC-5), 36b (G/AC-5), 36c (LS/AC-20) and 36d
fG/AC-~O). The only consistent trend that can be deduced from the
analysis is the decreased benefit-to-cost ratio as the cost of additive
is increased. '!'he effects of additives in terms of changing the design
life and benefit-to-cost ratio with respect to moisture-induced damage
depend on the asphalt-aggregate combination as well as asphalt content.
While limestone (LS)/AC-20 mixes·seemed to have benefitted by all
additives, no significant differences can be seen for mixes containing
AC-5. Neoprene (K) and SBR (J) improved the moisture resistance of
AC-20 mixes but not AC-5 mixes.
At an additive cost ratio of 1.05, 63% of the 60 mixes containing
additives had life benefit-to-cost ratios of greater than one. At an
additive cost ratio of J. .20, only 37% of the mixes had benefit-to-cost
ratios greater than one. Ranking of the additives based on percent of
mixes containing the respective additives with a life benefit-to-cost
ratio exceeding one is as follows: high lime (LH), 83%; SBR (J), 75%;
Asphadur <AH), 67%; SBS <S) and neoprene (K), 58%; low lime content
(LL), 50%.
4.3.5. Fatigue Resistance
Fatigue resistance of asphalt concrete mixes can be determined
experimentally by repeated flexure, direct tension, or diametral tensile
tests, either at controlled-strain or controlled-stress mode; However,
I
~
I f
Percent CbaDC• _of Delip Uf• .. LS/NHl. ..... 1
.. 10
I I\ >J " ,, I\ ,, O K\: i I '('(I
I -•o • ....
.... -40 I t I\ i'\J I I ,....-7-,.--·
C1 ... U.1 lH1 ., l(l " -We --to-Cod Ratio
1.2 I ..;.c-e. .... •
1.1 ~ -
I J •
... ... I : ~ ... ... ... ...
.. : ml>.~1'4 !>.~ t...l!;I'il b"tt>I t...t;r"I ... U.I lffl •• Kl JI ..... is:J 1.00 '2J t.10 ~ t.20
Percent Chtmti• of Deatcn We
.. .,.--------=Pl.~ ...... =="-="'"'::::.~·------~ .. .. .. .. "' II
10
• 0 I\ I)..) f\, I'\) " ·.'\'f I\ >J " i>J " i'>J " ,>J .. .... IJ.I ... .. .....
We lleJlortt -to.co.t Ratio LS/AC-I, .._a
I~ ~
1.2
I.I
0.9 . .. D.7 ... ... ... ... ... 0.1
.. ...
0 " ~ " ip;.1.;51 " tyi:3I " tyi:3I " tyi:3I t>. tyi:3I "" IJ.I uu .. .. ... .... is:J 1.00 ~1.10 ~1.20
Perc:ont Chtmti• of llulcn We .. ,-- ··-~- ....,~~-~---~
·i ~~ I .. _, ~~ I ~' d I-': . ~ '
. ...:i.l.b....Sl.~·-, t_·~ Q ~ I . ,,
-10~ ,·... '
~<i ' _,.1 l:::::i ' . _. J.._, __ ---,---- ··--r----·r~ ---- ,....---·-.,.. J
m ~ ~ ~ • • • .... Ufe lleJlertt-to·-Coet Ratio
ts/AC-I. ..... u 1-·-· --· ---·-----------100
1.14 ~ 1'° I 1 ~
=~-i ~km,"- ~ l ,., + ,., . ~ k ... +.··.~, ~- ~, ~ r. ... iv.~~ t~ ~"t · ul~ ~~~ ... -tli . H.~ r·~ tli"t-N ~~ ... + <t." t·fH tJ I ",;
1 •':-.: l YJt'::x I {I !'- "- '
... 1 ti~11~f*~ ~-!" ~ ~' ' ~ ti 0.1 -!'ll-t ~ '{ l.J' t::»J ' \(.' ' .
0 ~.J ' :i._ ' 'µ._ . !..;; k " ' ' ... IJ.I ... .. .. .. .... cs:J 1.o& ~ t.to [§11.20
Fig. 36a. Percent change of design life and benefit-to-cost ratio, AC-5/LS.
Percent Ch&DC• of Dnto Life P011::eu.t Chant• of Beaten Ute PercoDt Clllm&• of D""'-" Lite .,----___ _,,,0/10-6. ..... 2
~ -~]--~~_,-_-~-~I ~ R_ ,~- ----_ --· ---,
, -• ;,:.-. - ,'-. ' 10 J--;, _ · '! ~- ~-0j I !I ·.·, ',·.i .1 .... ,"\ ·,"· ,, .
~~ --·~ l .. ~'i ~~: I ... ' ' i .f ,, ' . ' I
f : ·---~~i ~\~-~---~-,- : i}:] - -~-~:(i b~~~ t<,~·41 :: '· "'- l ' " ' ., i ''·>... '; ' ... ' "
-to _,, ', "-.i ·\ ... ' .. :- o ·- -- --~- , ., to t , .. ~ ..... ,. "'"\] -I _,, -,: ... ; L~ -•, 1·~ _,, , •
• _,. ;._;~ I ::: J K< <~_ ·: • ',, '\,.::-J i - i t.. '2'" 'i ' 4 -t• '' . ·. -a , ~ '· , .... _' '
·<· ' ~"
~~ ~~>.~~ ., "" ' ~ ''
~' ·..: --~-, ~'
<~
.. -,, ..J -10 ..t , ,..... • .. 'i ! 2
-1• ---..--- .L ,.. .._,, 'f J -.--·-· _,. -,----- -"' ~ I u.a a a .12 - -· ---.----·--r-··-- -r ,_ - ::-..
o..£::..._~l__t,~>.L.e...,:~_i:,.~J_J:>.....::~
... ... •••
..
o.t -f,_"'-f#l'
I : I • I ~
... OJI ... ... ... ...
IDD ~ u.4 M M * .... Ufe -etlt-to Coat Batto Ufe -etlt·to-CHt Batte
·1··::-. ~ . c·-w r-;: ~~ v, f.;.t,; ' k ., -. '_ -~ - ,,_ -~ ~-:r~/ "'~ ~--~ •, " ~ ~ :i l. 1, ,._ , ,.. , -~---:I'_·~-~ '\j l_ '- '. -~ ~- ';: ·,
..
...
... 0.7
... OJI
...
...
... "'-Y.-11'-."-1
0.1
... .. .... .. We -otlt-to-CHt Batto
..
"' -~o
0 I\ It.{J..-S:J I\ LfJ,,'>N I\ if{ A>>' D 14.j .+.'->" 0 I\ ~-,;., '\j
~ ~~-~~ P __ -· ;~~ t-- ~,"'~-~. ~t-~.:"l !--.~~~rm,_ -~ v~.'1 "' .~ " ,. - , ., l <bt\l ll~-- - , .
I o u u;·+>.J I\ k('*-'W " 14"&>'1 " 1«"'+>-·J U2 ..
cs::I 1•5 rcZ;a' 1.IQ
"' .... ~t.20·
... UA .. =· ... t!ZJ 1.10
.. ... UA ..... r;s.;i .... ts:J 1.00
Fig. 36b. Percent change of design life and benefit-to-cost ratio, AC-5/G.
.. li2J 1.10
.. .... 1::§,)1.20
..
Percent ~ af Deolp Life Percoat Clum&• of Deolp We Percent Clum&• of Doolp Ute
·gr·'.' .·~.s:i r:r1zrK_~-~11~~ ·=r-~...,----· l ·:r-·-----~~" --1 -to . ·~ l~\,~.~·:;.~ ;' :. i k. '.:j I • . ''.-~ ·.'~.; · 1
-~~ r~J ~<·1 t>~l ~~::J i
1. : 1. ~~ ~:, i .. ~>-. 1
~ t-.. ''< t ·:j ""-'I , ,. J K .-i t .~<:i. - f-\:·1 ~>-~ . : ..... ~ . ~':.,:~ . -.~ I .. I ~ "'i I I " . ·1· . ~ 'l ~<'- " I .. ~ ~' ' ,, I I·' J i ... 1-::-. · • -~,j l._ ----1 ' .. ,', ~- r~ .. 1 * K. ,~ .k-,_~ .. k:J I .. " '·, ~-~-J ·- .. -j I l -40 .;'>. I "" ': - k . .... I 0 " ~- ' I
• . ~<.·.~·· . [:::_,1 t .. ';:~ ! -·· ,, . •
f. ~---:J ~'- -; ·1 .... ., . I .. -IO ' b:· -~.1 ... '
-t0 ~~·---,-·-·· -·r-o···----:~--r·-0-l:: -.,---,---r--.-·- -,---,--J t: .C....::>Lt..,:>Jc..A...;:.:J_Jt....:::,;Lt:..~.r...:>.LI>-.:.J ~ - ~ - c ~ n ~ - ~ - • a ~ w - ~ ~ ~ m m - - -
Life llel1eftt'to-c.t BaUa Life Bauetlt·to·Cotlt BaUa We Bauetlt·to·Colt Bat!<!
'° -----~ ... ~~------~ ~ '....._ .... ....
--· ·-----'°"~_!>,'.':"!~ - -·----· - ~1-1 : Tj ·-------
·" :'.._ . : •
W/N;-'JO.Mt.-1 __________ ---, , .. .,.
----- ! :~ ~ I , .. ;
...
'" ' ~ t • "":i-- ....
:: '. -~-~ ' ·. i ~- ~ l:~~ I '::..; ;-f'. 'i "i" ,, l • u 1 ... .,. ·<:. f~ ,, .• , ~-m ... _ & -. t'·t-~, t "f ' · . I • t "/ ~ !'.J:' <l !., ,- ~. . -~ I'\, " I
I ... }r: ~ ~~·-¥~ r-· 1'~.· ~ .. ·~ ~ .. ~ ~ ~1· . 'f;,:; ~ 'f .. ~ :-. ' ., "!""'·' ~t'i;:.!o.~ ' . U ;.' \f '" d · ' if. ·~ I .'I
I ... "' I , ..
.•.• 1''VA-~ 1
OJI ... ..1·,
0.7
~ t: -~ ~ '.f-: ~ :<-:, t . .'j t_ .>ii:\ l. ..• ... . . . , ... i.f-1\., ,r-'t'i tj ~'fl ... ~. ri~ :I,:. ' . n~ t-.q";; f>l?,J.'~ H',J.~-~ I, _4'.1 '-:'i?;~ i '(/)...~ · ~' .. •, ·
0
t\lf'))I f\ , - 4 03
1 .~'*-~ b V~·~ " ~-s ~ +-.: · ,. r~1·-,.:1 r .l"' ., .n 0 ............,-- I 17 IC1
i',Y.'.l-~ J>fll'Si f'\F,l,.'i !'-.tr•.L·"il f\.t;J.~SI t-..t;J,,' 0 4 •
JM1 u.7 lH7 ... ... .... .. .. .. .... """" ....
ts:]t.oo ~t.10 ~t.20 l'C)1.00 l'J::'.".J t.10 ~ 1.20 CS:--11JJI
Fig. 36c. Percent change of design life and benefit-to-cost ratio, AC-20/LS.
U.1t ""' ... Ktt "' -fZi'.'J 1.10 ~ t.20
Percent Ch&DC• of Dulp We Percent Cban&• of Detdp. We Percent Cban:p of Dnlp. We O/M:-20. ..._ • _ 0111:-». ..... 111 o/,,,;,...a .._ 1a
_,: ~~\~ ~\i t'\' ' -~, ·: i:-. -_---,_---.~~--~~~-;~-~-- : ~ --- ···--··--·---.----~-~ ,',,"i , .,1 ~-..; , ~-, ~~lS-,~~-:--l ~s::fl I ,.,.,. t· ,,, .J~ "'"'l ~ ''1 ~~,] l_~, -·· '~:: l~,-~ '.<'i '~~'--J l ! ',::i . ~--
§ -20 -~·'1 -~~ ~."! I "-'·."-· .,,,, ' ~j 0 \'!- - ...
~' "~ I '>'~~ ', ~ i \ -20 ; ~~ ·,~~- ~ '~. ' ~ '-' ·--~-, '1 ' • -- !
"' , ! ,~ ~ . _.. , . '· 1 k, ·-~ L "" I . , k"'-' l - ~~ ··,) "·· '• . '• <'-! i--:-,_ '·, !\_'· '·'~ -20 ·::: 1· '· '-" ::::;,_-,,:..] I\'- '::1 ; ' " ~ "·, I . "J 1· " ' '• '-'
~"-~·-·' . 1-oo '-~'..J ~-.. _·-~·· f·,'-·~' I · . i '·"- ~ ·,:_ •. '<1 .! • '' ! ··. '"• I j ~' ,. . '
-ao i ' ' ' ' j '·, ; ... "'-' I
l ~~ . '-- ---- --- I - i ~~: ~ ! -- ·. .
j ! • I !
-.0 ,.--- ,--- ..,.- l' .--J -10 l.·-·r-· -·-··· ·· -·-1--·· ··- ---·, ·-- - --· -1-· .. ---~ -40 - r· ---T--·---~·r-··--,--·--_,J ~ ~ • • a - - - ~ ~ = ~ m m m
1.7~ ... ~ ... •.• 1 ... ... •••
I ... .. ~'
M
:rtt~ 0.1 ·,. '~ 0 . <.
u.o
ts::lt.00
- - .... We BODeftt-to -Ooot llaUo We Beneftt-to-coot llaUo Life BODeftl.-·to·Coll\ llatto
O/NJ-'11...._12 8/ID-20. ... • O/llJ....20. ... 10 ------· -------·-··--, ... r-·--------------------r'l '•!1
:~ r----------"N,~
..
.,r.t./. - ·1-~ -.,, ,. , .. '~~ -~ ~,[> ~ ,;~:{~ • ...... '!<-~ l'-: 11: :-f-: ·'.'l : •¥'.:f:'-1 k,~_'<R2'! ' / .. " , -·~ j...--. r~:~ I 'f;f'i i'j0>-J .. ..... ...
,.. i
1.7< j ... ... ... -l :~ j 1.1 J
:: ~ :f~. 0.0 '·· ~ ., 0.4 '- /: ..:-~ cu . /' - ,_. 'i G.2 :· . ,. '~ 0.1 ,.._ ,,';;: . .
U.10
··:·":~ '·
~;', <.:'j "' ;, . -~
~. '(; ~
~< :~· ·. . ;. ;~ l'- ,.: ~' '-; l'• < .. · ... , ·:,i l '-' . !'\.. , . "· '~--J : , ·. D V{" ·," ... . .. ... -
• ••
... ...
• ..C>...14'.J..::»L U.'2
l2Z.J 1.10 t'.SSl 1.20 !'D•.OO 12:2 1.10 CSS11.20 lS:] 1.00
Fig. 36d. Percent change of design and benefit-to-cost ratio, AC-20/G.
... . .. ..... ~ 1.10 C§J 1.20 -
"'
"' "'
93
fatigue experiments are extremely time-consuming and expensive and
require a minimum of 42 specimens per mix (a minimum of 7 specimens per
each of 3 stress levels at each of 2 temperatures). As an alternative,
three indirect methods were used to compare the fatigue properties of
the mixes studied. They were based on the fatigue life and allowable
tensile strain relationships of existing fatigue data. The fatigue
relationships used were:
• The Shell France method (5) is based on 150 fatigue curves for
both constant stress and constant strain tests. Fatigue life is
a function of the stiffness of the mix, the penetration index,
and the .percent by volume of bitumen. The stiffness of the mix
is determined from the volume percent of bitumen, the volume
percent of aggregate, and the stiffness of bitumen that is
obtained.from van der Poel nomograph (52) on the basis of the
penetration index and softening point of the bitumen,
temperature, and loading time.
• The Brown (University of Nottingham) method (7) is based on 50
fatigue curves conducted at 10 ° C in controlled-stress tests.
The fatigue life depends on the softening point and the volume
percent of bitumen.
• The Maupin method (32) is based on relationships between
constant-strai~ fatigue tests and indirect tensile strength.
The relative fatigue resistance of different mixes were compared on
the basis of calculated allowable tensile strains for a fatigue life of
one million cycles. The results of fatigue analyses are given in Table
10 and shown tn Fig. 37.
94
Table 10. Results of fatigue analyses, 1icrostraln.
·-----------------------------------------------------"Ix I SHELL-SN SHELL-SS "AUPIN BROWN I
------------------------------------------------------LS/AC-5 c 131,94 62.25 389.91 131.14
AH 117.94 80.79 479.99 148. 72 LL 152.36 72.56 422 •• 4 155.91 LH I 155.50 73.79 410.68 143.24 I
s . I 156.32 11.11 413.43 143.43 I
K 233 .• 70 102.23 382.10 169.38 J 130 •. 40 58.45 345.43 125.39
G/AC-5 c 188.37 82.21 347.os 139,55
LL 152.36 72.56 390.34 155.91 s 197.86 88.55 408.37 155.64 K 310.46 130.86 406.33 181.37 J 191.34 83.66 304.57 144.43
LS/AC-20 c 208.45 94.50 418.82 180.81
AH 116.10 55.98 503·61 204.17 LL 100.33 49.69 468.09 173.08 LH 126.87 62.19 476.28 190.40 s 133.03 64.ZO 478.76 194.23 K 194.12 88.45 446.58 185.79 J I 204.61 92.U 442.79 183.ZO
G/AC-ZO c 249. 75 110.11 459.64 187.35
LL 152.99 72.58 481.40 190.58 s I 156. 13 73.54 492.29 . 197.05 I
K I 221.10 97 .15 468.81 182.02 I
.J ~ ' 225.18 97.46 427.80 174.22
------------------------------------------------------
MC Cll""'-M . -~
! i § • § § § 0 i 0
. . . . . n n
I§ I§ z • F
"' . ,,. ("')
~· .. I U'I
i ..
~ ! !
~ F ll :ii
! I ~- s: I . i ~ • J.
.·
~ ~ .. J L J L ,.,, ... ..
• ...., ..... . ~ '.: ... ·-... nww .. "' ~ "' .. ! ... .., 1" i § I § § § ... 0 i 0 = . . . . .
.
n· n
I§ I§
! F
er . ,,. ~I .. ("')
I
"' 0 I ..
= ! !
ti
i F
! I QI '" 1. I ~ • ~
lz::zzi .
~ ~· .. f L I L
96
Strain yalil,es determined by the Shell nomograph that is based on
the controll~d-11tress mode and by the Brown (Nottingham) nomograph are
comparable•· Strains.determined by the Shell ce>nstant'-strain fatigue "'
curves, wei:'.e lower, and those calculated from the Maupin expressio!ls were'.
consistently higher.
No 'sigrilficant effects resulted':be\:ause of additives, except that
Asphadur (AH) and neoprene (K) seemed• to have increased the fatigue
resist~pce f.~r AC;.,5 mixes; and Asphadur, lime (LL !ind LH), .and ,Styrelf
rs) decreased t!>e fatigue resistance for AC-20 mixes based on Shell' ' ' '
methods. Also, higher allowable strains'were obtained for AC-20 mixes
by the Maupin and .,Brown methods, but lower strains were obtained for
AC-20 mixes by Shell nomographs, especially for contolled-strain
fatigue. Types of. aggregates made little difference in fatigue
resistance.
4. ".\ .6, J(ut~Urtg Resistance
The effect of additives on the resistance to permanent deformation · . . ' ' ..
or rutting·of the asphalt concrete mixes studied.were evaluated by the
Shell procedure (43) by using the .results of uniaxial creep tests. The
creep ·:test11 were performed at 40 ° 'c and at a stress level of 14'. 5 psi
(100 kPa) fo.r 2 hrs after conditioning or prel9ading of l .• 45. psi (10
kPa) for 2·min. Typical strain-time creep curves ~re shown in Fig. 38.
The results of creep.tests for each mix were plotted in terms of the
stiffness of the mix (Smix) versus the stiffness of the bitumen_ (Sbit)
curves. The effects of aggregate type (LS vs G), asphalt grade (AC-5 vs
AC-?O), asphalt content, and type of additives on the creep curves are
shown in Figures iq, 40, 41, and 42 respectively.
~ .... ~
Ji . -2 .10
z .... ;;2 I;;
TEMP: 40° C (104° F) STRESS: 105 Pa (14.5 psi)
-
101
-
102
TIME, sec 103
---~ -
MIX CODE AH 90 C 9A
104
Fig. 38. Typical strain versus tble curves, mixes C9 and AH9,
105
'° .....
----·
~
"' 0.. ~
>< ~
0
•
107 ~ • • • ~
• •
•
106
Smix vs. Sbit, EFFECT OF AGGREGATE TYPE
.
--- - -- -. . .. .
fl!IX Cl p-s}o C2 G) A
. . • I • • ... I . . • I .. • _ ... I . ·-··-·-· -10°
·-
101
Sbit (Pi!.}
Fig. 39. Effect of aggregate type on Smix versus Shit curve11, Mixes Cl and C2.
102
"' "'
I-
i.. Smix vs. Sb it, EFFECT OF AC GRADE
I I I I I······' 61 I I I I I '.-' ! e ' ' I I e '_ 2 w J ~ w
Sbit (Pa)
Fig. 40. Effect. of AC grade on Smix versus Shit curves, Mixes C3 and C9;
~107
~
)( ·~
Ji
io6
•
•
,_ " • • . • .
Smix vs. Sbit, EFF'ECTOF AC CONTACT
a s -:Q =Q: Q . --- -
'
MIX K8 tPT-1) O KIO . OPT) . 4 Kl2 OPT + l)o
. • I • • • I ·-
. •I*·•-• . . . 101 -
102
Sbit (Pa)
Fig. 41. Effect of AC content on Smix versus Sbit curves, Mixes K8, KlO, and Kl2•
2 $=
-
.... 8
. . . . - . 103
~
"' e:.107
x ~
~
Smix vs Sbit, EFFECT OF ADDITIVES
::::;f:;:::;;;g;~~~<>-<J>.~~~~~=o~:=~~~~~~~~~~~:::. -...,..=====<CP():,....,...~'P.': ·~ u A e I A c .. ·e; , I, ' • .. • • • • • . Q! c C • MIX AH30
10 101 102
Sbit (Pa) io3
Fig. 42. Effect of additives on Smix versus Sbit curves.
104
C3A . J3D
K3V. LH3<> LL3e S3•
... Q ...
102
To compare rutting resistance of various mixes, we calculated rut
depths or permanent deformations occurring in the asphalt concrete
layer. To make these calculations, we ·followed the Shell procedure for
a standard pavement structure of asphalt concrete with a surface course
130 mm thick (subdivided into three layers of 40, 40 and 50 mm) on top
of a subgrade of CBR of 2.5 (E3 • 25 mPa). The design life was 20
years. The traffic wss assumed to be 100 (18 kip SAL) per lane per day
with a growth of 3~. The mean monthly air temperatures (MMAT) for Iowa
were used and resulted in effective mean annual air temperatures
(MAATeff) of 19° C (66° F) for AC-5 and 20° C (68° F) for AC-20.
T)1e estimated rut depths occurring in the 130 mm (5 in.) asphalt
concrete layer and calculated from creep data based on .the Shell
procedure are shown in Fig. 43. As we expected, raising the binder
content and udng softer binders resulted in larger rui: depths. There
was little difference in the type of aggregates used. Asphadur appeared
to be the most effective additive in reducing rutting or permanent
deformation in the mix. Other additives had no significant effects.
With additives such as Asphadur, and perhaps hydrated lime, the rut
· depths of softer grade AC-5 mixes can be reduced to those of AC-20
without additives. These results seemed to confirm data provided by
Marshall stiffness.
I I
I
I ~
I
I ~
•·-··--····
BUT DBPTll DTDIATJON
14 OJ'MHI,
ti
Ill
u 10
• • 7
• • ' I :a
0 t>Ki,1:,)l '>J<11 '''<t"!'V ''KJQ>V l>K14':N
c u. • IC J
llllCES IS:J•-· m::a ... [SS! •• ,
BUT J>BPTB BSTDL\TION O/<IC-IO ,, ....-~~~~~~~__;~~~~~~~~~--.
11
1ll
t1
10
• -· 7
• • I
:a -1
I\ tfJ."\j I\ W)'~I h ~Si !\. l(J,~ -f\ I I:~ 0 · 1 I
-C u. $ K J
lllC£$ IS:)apM
IZa• ~···
I ( ~
I
I ~
BUT DBPTB DTDIATION ,. ~.- -
1ll
1:1
u :10
• • 7
• • 4
ll
ll
o l"Vt$ 1 1V# 1 1Yl'>t ''11"': 1 •Y.&l 'Vf>' l'f'1>' 'f>' c - - u. !JI • IC "
UllG -IS:Jopt-1 m'.l ept ~ .,t+-1
BIJT DBPTll ·BS'l'JW.TJON Ul/M-20_
14 ~-~~~~~~~~..;;._~-'--~~~~..,.-~.....,
ti
1:1
11
to
• • 7
• I
' ' 2
o • !11 p , , v r- l •,.•.a. , , ,., , .... 1 cvr,, , ,, r r , ¥ r ' yr , c AliG Mtb- u. IH s K " WES.
lS:JG!ll-1 IZZJ 4IPI tS9 .j,t+1
Fig. 43. Rut depth estimat-ion by Shell procedure.
.... 0 w
105
5. STRUCTURAL AND PERFORMANCE EVALUATION-PHASE III
In addition to evaluating the.effects of additives on the
properties of the asphalt cements (Phase I) and on the properties of
asphalt concrete mixtures (Phase II), the effects of additives on
structural and performance characteristics of the mixtures containing
the additives as surface courses in pavements were evaluated. In the
final analysis, it is the effect of these additives on the mixtures as a
structural layer in the pavement that ultimately determines the benefits
and usefulness of the additives.
Two pavement design and analysis methods, both based on
elas.tic-layered theories, were used: the Asphalt Institute method (44)
and the University of Nottingham (Brown) method (7).
5.1. !!.!! Asphalt Institute Method
The computer program DAMA (Chevron) was used to compute pavement
lives for the 24 mixes at optimum binder contents in full-depth asphalt
pavements of 4 and II in. on subgrades of CBR of 3% (subgrade modulus of
4,500 psi) and II~ (subgrade modulus of 12,000 psi). A mean annual air
temperature (MAAT) of 60° F, appropriate for Iowa conditions, was used.
The traffic was assumed to be 1,000 equivalent 18 kips SAL per month.
It was also assumed that the pavements were opened to traffic in July..
'rile resilient moduli of the mixes determined in Phase II were used in
the analyses. A .total of 96 computer runs were performed.
106
The results of computer analyses are tabulated in Table n. A
sample of the computer i>rintout for Mix :g3 (Styrelf at the optimum
binder content with AC-5 and limestone) of 4 in. and subgrade modulus of
4500 psi (CBR of 8) is given in Appendix F.
The results presented in Table 11 are given in terms of surfac.e
deflection (Dz), tensile strain in the asphalt la,yer (Et), compressive
strain :l.n the subgrade (Ee), nuniber of standard loads to cause fatigue
failure (!If), and number of standard loads to cause rutting failure
(~r). '\'he strain and deflection values are the averages of their
respective monthly values at the critical response point (at the center
of one tire of the dual-tire system of an 18 kip single axle load) over
a 12-month period.
To show the additive effects, we compared these five responses to
the respective responses of the corresponding control mixes and
expressed as ratios. Figure 44 shows these ratios at optimum binder
contents (Mixes 3, 4, 9 an 10).
While increased asphalt concrete thickness and subgrade modulus
reduced the strains and deflections and increased the numbers of loads
to fallure, the relative effects of the additives did not change. For
the same asphalt, H.mestone mixes performed better than the gravel
mixes; for the same aggregate, AC-20 mi*es performed better than the
AC-5 mixes. Asphaour improved the structural capacities of all mixes.
Hydrated lime increased the structural capacities of gravel mixes, while
SBR (J) decreased the structural capacities of all mixes. Styrelf (SBS)
and neoprene (K) improved the behavior ~f gravel mixes with AC-20, but
had little effect on the other mixes as·compared to the responses of
control mixes with no additives.
Table II. Results of OAKA structural analyses.
HI : 4 In.
107
I OZ,/IOOOln. i ET ,1lcrostraln i EC,1lcrostraln I Mf ,xE06 i Mr ,xE06 -~~~!~~!.1 ••• ~=~------!~----1---~=~------!~ ____ 1 ___ ~:~------~~----1---~=~------~~----1---~=~------!~----ftlxes 3 I I I I
c I 55.ao 25.80 I 736 485 1 1160 1100 1 0.064 0.26• I 0.001 0.005 AH I 34.20 16.70 I 193 U8 I 558 383 I 0;350 0.917 I 0.149 0.882
t~ I ~::~' ~~:~: ' 702 :~t I 1687 rn~~ I ~:~~l ~:u~ I ~:~~1 ~:u~ S I 55. 78 25.89 ! tn 486 I l~l~ 1103 I 0 122 0.502 I 0.001 0.004 K 11 64.62 29. 73 •1 1094 672 1
1 2514 1soo 1
1 0:059 0.305 ! 0.001 0.001
J 64.87 29.85 1104 676 2534 1509 0.012 Q.064 : 0.001 0.001 ---------1------------------1------------------1------------------1------------------1------------------
Kl~~s 4
j ~~:n U:i~ I t~1 ii~ I rn~~ 1 ~~i I ~::~I ::ni i ::::1 :::~~ s •1 .61.80 28.49 11 911 s6s I 2251 1368 1 0.014 0.065 I 0.001 0.002 K I 60.16 24.79 I 904 576 I • 2114 1293 I 0.057 0.263 I 0.001 0.002 J 66.88 30. 75 I 1195 719 2125 1603 0.015 Q,080 I 0.001 0.001
---------1------------------!------------------1------------------1------------------1------------------Klxes 9 I j · I I 1 C I 37.73 18.21 I 253 189 I 700 473 I 0.349 0.993 I 0.056 0.352
AH I 32.40 15 .• 80 I 166 128 I 492 340 I 1.045 2.623 I 0.259 1.478 LL I 40.38 19.35 I 304 223 I 819 547 I 0.415 1.260 I 0.028 0.188 LH I 40.90 19.58 I 315 230 I 843 563 I 1.097 3.370 I 0.025 0.167
~ :I ~~:~~ g:1: ! in i~~ l IU~ l~~i l ~:~n ~:~~~ I ~:~Af ~:~'~ J 48.93 22,99 I 514 356 1285 830 0,147 0,534 I 0,002 0,032 _________ 1 __________________ 1 __________________ 1 __________________ 1 __________________ :------------------
Mixes 10 f ! ! ! l c : 45.80 21. 10 : 429 303 i 1100 119 I 0.010 0.241 : 0.003 0.058
LL : 39. 72 19.06 I 291 214 I 789 528 I 2.181 0.651 : 0.033 0.220 s I 41.66 19.91 I 331 241 I 881 586 I 0.106 0.332 I 0.021 0.141 K • 43.98 20.90 I 383 275 I 999 658 I 0.118 0.391 I 0.012 0.085 J l 55,68 25,85 : 133 484 I 1753 1097 t 0.012 0.046 t 0.001 0,005
HI : 8 In.
l DZ,/lOOOtn. I ET ,1lcrostraln i EC,alcrostraln ! Nf ,xE06 ! Mr ,xE06 SGE,ksl 1 4.5 12 ' 4.5 12 4.5 12 . 4.5 12 4.5 12 _________ 1 __________________ 1 __________________ 1 _________ "--------1------------------1 _________________ _
Hfxes 3 ! I I I c I 33.60 16.90 I 313 229 I 709 484 I 0.851 2.536 0.052 0.328 AH I 19.30 9.50 69 57 : 189 UI 8.996 17.270 17.770 67.090 LL ! 32.87 16.54 ! 297 219 I 675 465 I 0.395 1.148 0.064 0.393 LH I 32.29 16.23 I 284 211 I 649 448 I 5.699 16.270 0.076 0.456 s I 33.u 16.941 314 230 I 110 4861 1.616 4.820 0.052 0.325
~ I :1:~1 ~~:~~ I ·~~: i~l 1 rn~: ~:~ I ~:tn ~:~~: ~:~~i ~:~i~ _________ 1 __________________ 1 __________________ 1------------------1------------------1··----------------
Hl~s 4 ! I I 1 ·I C I 35. 70 18.00 I 362 26 I 806 544 I 0.259 0.825 I 0.030 0.203
LL I 26. 76 13.40 I 174 136 I 422 303 I 0.760 1.832 I 4 •. 943 2.405 S I 38.60 19.48 I 434 405 I 950 627 I 0.156 0.542 i 0.015 0.112 K I 37.19 18.77 I 399 283 I 880 587 I 0.681 2.211 I O.OZI 0.148 .J I 43.13 21,88 · 557 374 1186 757 0, 149 0,5% 0.002 0.051 ---·-----!------------------1------------------1------------------1------------------1------------------
N I x~s 9 j 21.31 16 89 I 93 76 I 244 180 I 8.014 16 540 I 5.677 22.600
AH I 18.20 . 9:01 I 58 49 I t65 123 I 288
•• 8570! s2: 160 I 33.340 123.800
LL I 22.91 11.42 I 114 92 I 291 214 I , 19.090 •. 2.566 10. 780 LH I 23.24 11.59 I 118 95 i 302 215 i 22.900 50.070 ! 2.197 9.341 S I 25.39 15.38 I 151 120 I 373 270 I 4.110 9.537 I 0.851 3.926
~ 1 u:~~ it~~ 1 ~~~ fM 1 ~~t ~:: 1 ~:i~~ tin 1 t~~~ tni _________ I __________________ I __________________ 1_ _________________ 1_ _________________ 1 ____ " ____________ _
Nixes 10 I I I I I c I 26.40 13.30 ! 16s 132 1 410 z94 ! 1.212 3.031 !
LL I 22.50 11.21 I 108 88 , 279 205 I 4.721 10.110 I S I 23.71 11.82 j 125 100 j 316 231 I 2.163 4.791 i K I 25.17 12.59 I 148 117 I 366 265 I 2.254 5.200 I
J I 33.56 16,88 I 312 229 : 706 483 I 0.149 0.442 I
0.564 3.122 I. 772 9.288 0.053
Z.708 12.930 7.667 4.252· 0.332
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112
5.?.. The University~ Nottingham (Brown) Method
In this method design charts were developed (based on the computer
program BISAR for the analysis of multilayer elastic pavement system)
for a three-layer pavement system consisting of an asphalt surface
course With a fixed base course of 200 .mm (8 in.) placed on a subgrade
of varied subgrade modulus (CBR). The surface course is characterized
by the stiffness modulus of the mix. The Poisson's ratio of the asphalt
layer and that of the subgrade was assumed to be 0.4, and the Poisson's
ratio of the base was assum.ed to be o.3. The elastic modulus of the
base layer was assumed to be twice that of the subgrade.
Critical subgrade strains and critical asph~lt tensile strains were
determined for all the mixes for each of four pavement sections.
Pavement lives in terms of numbers of standard 40 kN wheel loads. (18
kips SAL) to cause fatigue failure (Nf) and rutting failure (Nr) were
computed for the mixes used as surface courses of 100 mm (4 in.) and 200
m (~ in.) on su~grade of 20 MPa ~CBR of ?.) and 70 MPa (CBR of 7) with a
constant granular base of ?.00 mm (8 in.). The stiffness modulus of the
mix was calculated from the stiffness of the binder (van der Poel
nomograph), binder content by volume, and the volume percent of
aggregate. A loading time of 0.02/sec: (corresponding to a traffic
speed of 50/100 km/hr) and a temperature of 13° C (corresponding to MAAT
of 10° C or 50° F for Iowa) were used in the determination of binder
stiffness.
113
~able 12 gives the results of the structural analyses by the Brown
(Nottingham) method in terms of numbers of standard loads required to
cause fatigue failure (Nf) and rutting failure (Nr). As shown by the
results of DA}!A analyses, pavement 1ives increased with increasing
thickness and subgrade modulus. Similarly, higher pavement lives were
obtained for AC,-?.0 than AC-5 mixes, and higher lives were obtained for
limestone than gravel mixes.
~e relative pavement lives for the four combinations of asphalt
grades and aggregate types at optimum binder contents (Mixes 3, 4, 9 and
10) are shown in Fig. 45. Significant improvements were observed in
fatigue resistance when Asphadur, hydrated lime and Styrelf (SBS) were
added to the asphalts. These additives also provided moderate
improvements in rutting resistance. Neoprene. ('K) and SBR (J), in
general, ·reduced both fatigue and rutting resistance. as compared to the
· control mixes. Asphac!ur, lime, and to some extent Styrelf increased the
pavement lives of AC-5 mixes to equal or exceed those of corresponding
AC-20 mixes without additives.
114
Table 12a. Su1111ary of structural analyses by Brown 1ethod, lS/AC-5.
-----------------------------------------------------------------------------------E3 I 20 KPa 70 KPa I
---~---t-~-----------------------------------1------------------------------------~ H,1111 I 100 200 100 200 I
--~----:--------~---------:------------------:--~---------------:----------~-------xE06 I Mr Mf I Mr Nf I Mr Nf I Nr Nf I I I I I
.... :.. ......... l ................................................ , ................................................. f-------------·-........... I .......... :.. ............................... I c-.1 I 0.04 0.08 I 1.70 0.36 I 0.70 O.Z9 I 13.10 2.69 I
AHa-1 I 0.06 o.sz I 3.08 3.32 I 0.81 0.58 I 16.90 7.84 I
AHb-1 I 0.24 1.58 I 11.10 57.70 I 2.50 6.19 I 74.90 132.00 I
ll-1 I 0.21 o.ez I 13.10 23.30 : 2.05 3.11 I 58.10 54.50 I I
LH-1 I 0.21 0.59 I 12.70 13.90 I 2.&1 2.10 I 55.30 30.90 I
S-1 I 0.08 0.19 I 4.08 3.86 I 1.10 0.74 I 22.10 9.98 I
K-1 I 0.01 0.03 I 0.37 0.39 I 0,31 0.22 I 3.85 1.87 I
J-1 I 0.03 o.u I 1.10 o.o I 0.53 0.15 : 9.6i l.23 ·-----.-1-------'.'"·---------1--------........................ t--------·---------1 .. -----:--·--------·
C-3 I 0.06 o .17 I 2.05 Z.81 I 0~70 0.60 I IS.SO 8.84 ,. AHa-3 I o.os 0.11 I 2.05 4.98 I 0.73 0.93 .. l 13 .10 IS.BO AHb-3 I o.ZI 2.04 I 13.10 103.00 : Z.05 9.7Z I 56.70 278.00 ll-3 I 0.18 0.87 : 8.31 44. 90 l I.SS 5.ZI I 45.80 116.00 I
LH-3 I 0.17 0.72 I 8.31 26.30 : I .SS 3.46 I 49.10 75.60 I
5-3. I 0.06 O.S3 I 3.08 6.79 I 0.81 0.60 I 16.90 15.90 K-3 I o.oz 0.07 : 0.70 .z.zz : 0.39 O.S4 : 6.31 9.25 J-3 : 0.04 0.01 I l.4S I.SS I 0.61 0.37 I 10 .• 40 5.06
-------1·-----~-----------l------------------,------------------1------------·-----C-5 I 0.06 . o.zo : Z.09 S.39 : 0.70 0.98 I u.zo 17.30
Affa-5 I 0.06 0.38 : 2.22 10.40 : 0.73 1.66 : 16.30 42.00 AHb-S I 0.22 4.03 I 13.10 298.00 : z.os 23.40 : . 64.20 919.00 Ll-S I 0.12 0.60 I 4.89 48.20 I 1.48 s.so : 32.90 144.00 LH-S I 0.12 0.6S I 4. 77 30.20 I 1.46 3.67 I 32.20 79.90 S-5 I 0.07 0.'1 I 3.U 22.30 I I.OZ 2.54 : 22.10 64.10 I
K-5 I 0.01 0.04 I 0.32 0.86 I 0.29 0.41 I 3.64 S.98 I
J-5 I 0.02 0.07 I 0.98 1.66 I o.so 0.39 I 9.47 4.82 ---------·----------·-----------------------·--------------------------------------
l
115
Table lZb. SUllllilry of structural analyses by Bro•n method, G/AC-5.
E3 I 20 "Pa 70 "'• _.,. _____ t----·----------------......................... ______ , .................................................................................. .. H,a I 100 200 100 zoo
-------t------------------t------------------t------------------f------------------xE06 I Hr Mf I Mr Hf I Mr Hf I Mr Nf
........ ..:--1-------.......................... t ............................................. , ........................................ t -----------------C-2 I 0.02 0.8' : o.57 o.ss I 0.37 0.52 I 4.89 6.10 I
lL-2 I 0.09 o.27 I 4.33 6.78 I 1.30 1.15 I 29.70 17 .60 I
S-2 I 0.04 0.01 I 1.30 1.27 I 0.55 0.35 I 9.19 4.03 I
K-2. I 0.01 0.02 I O.Zl 0.34 I 0.22 0.19 I Z.50 1.86 I
J-2 I a.oz 0.02 I 0.55 0.31 I 0.34 0.16 I 4.83 1.35 I
-------1------:------·------:------------------:------------------1------------------C-4 I o.oz 0.06 I 0.70 0.94 I 0.39 0.29 I 5.54 3;68 ' LL-4 I 0.04 o." : I. 70 3.86 : 0.70 0.69 : 13.10 IJ.90 I
S-4 I 0.04 0.12 : 1.42 3.04 : 0.57 0.61 I 9.61 IZ.50 I
K-4 I 0.01 0.03 I 0.31 0.57 I o.zz 0.29 I Z. 71 3.68 I
J-4 I 0.02 0.06 I 0.11 1.12 I 0.40 0.32 I 5.69 4.32 I
. -------1-----------.. ------1------------------1---------------"':·· I-----------.................. C-6 I 0.02 0.05 I 0.70 1.54 I 0.39 0.43 I 5.54 6.84 I
ll-6 I 0.06 0.29 : 2.01 9.21 : 0.70 1.48 : 15.50 34.ZO I
S-6 ' 0.04 0.13 I 1.36 5.87 I 0.57 0.95 I 9.19 24.10 ' K-6 I 0.01 0.031 0.21 o. 71 I 0.22 0.36 I 2 •. 50 5.27 I
J-6 I o.oz. 0.04 I 0.56 0.90 I 0.35 o.39 I 4.89 5.35 I
-----------------------------------------------------------------------------------
116
Table IZc. Sut11111ry of structural analyses by Brown 1ethod, LS/AC-ZO.
__ .., _______ .., ________ .. _______ ................................................................................................................................. ... El I ZO HPa I 70 ftPa I ' -------1-------------------------------------1---~---------------------~-----------
H,• I 100 ' zoo ' 100 I zoo I I I
-------1.------------------1 ·-----------------1----... -------------1------------------xE06 I Nr Hf I Nr Nf I Mr Nf I Hr Nf I ' I
-------, .. ;.. ............ ~---------- t--·---------------1-----------.. -----"".1-----............................... c~1 I 0.06 0.3Z I 2.Z6 1.0 I 0.73 1.44 I 16.00 31.60
Affa· 7 I 0.34 8.29 I 18.40 658.00 I · 3.02 42.20 I 95.90 1570.00 AHb-7 I 0.33 10. 30 I 18. 40 930\00 I 2.98 5Z.IO I 95.90 zz90.oo
LL-7 I 0.34 6.70 : 18.40 300.00 I 3.oz 23.00 I 95.90 678.00 LH-7 I 0.36 6.84 I 23.90 408.00 I 3.56 Zl.30 I 111.00 872.08 I 5-7 I 0.25 3.76 I · 15.50 241.00 I 2.63 19.00 : 81.ZO 631.00 ' I K-7 I 0.06 o.35 I 2.15 9.22 I 0.71 1.52 I 15. 70 36:30 J-7 I 0.04 0.11 I 1.36 3.31 I . 0.56 0.69 : 9.33 13.00
-------1--------·--------·;; :------------------1 :-------------............ , ................ ~----------C-9 I 0.06 0.31 I 2.os 1s.10 I 0.70 2.1~ I 13.10 54.20
Affa-9 I 0.22 7.01 I 13.10 759.00 I 2.05 49. 70 I 65.80. 2320.00 . Affb-9 f 0,21 7.17 I 13.18 813.00 l. Z.OS 60.60 I 62.60 2950.00 LL-9 I 0.37 7.63 I 26.80 474.00 I 3.85 29.90 I 114.00 1040.00. LH-9 I 0.34 9.27 I 18.40 868,00 I 3.08 51.00 I 9B.6o. 1900.00 5·9 I O.Z2 S.IZ I 13.10 454.00 I 2.05 31.70 I 65.80 1480.00 K·9 I 0.06 0.54 I 2.22 19.00 I 0.73 2.64 I 16.30 85.80
. J-9 I 0.04 0.30 I 1. 70 2.68 I O. 70 2.01 I 13.10 50.30 -------1------------------1------------------l~------~----------1----·-------------
c-11 I 0.06 0.67 I Z.77 48.40 I 0.81 4.92 I 18.40 185.00 Affa-11 I 0.22 11.60 I 13.10 1730.00 I 2.05 89.20 I 65.80 6480.00 AHb·ll I 0.21 IZ.ZO I 13.10 2170.00 I Z.05 96.90 I 61.00 8160.00
LL-11 I 0.31 11.90 I 16.90 1470.00 I Z.77 69.10 I 85.70 4660.00 LH·ll I 0.25 9.93 I IS.SO 1140.00 I 2.63 63.20 I 81.20 3440.00 5-11 I O.Zl 7.66 I 13.10 950.00 I 2.05 51.50 I 61.00 3290.00 K-11 I 0.04 0.19 I t.34 11.60 I 0.54 1.89 I 9.19 61.ZO J·ll I 0,04 0.18 I t.30 10.ZO I 0.55 1.77 I 9.19 49.40 ·
117
Table 12d. SU11111ry of structural analyses by Bro~n 1ethod, G/AC-20.
-----------------------------------------------------------------------------------£3 I 20 KPa I 70 KPa
-------1-------------------------------------1-------------------------------------"·· I 100 zoo 100 I 209
-------:------------------:------------------:------------------:------------------xE06 I Mr Mf I Mr Mf I Mr Mf I Mr Mf
-------1------------------l------------------1------------------1------------------C-8 I 0.03 0.10 I 1.10 4.28 I o.S3 0.74 I 9.61 15.40
ll-8. I 0.13 I.OS I 5.54 61.40 I I.SI 6.27 I 36.60 169.00 S-8 I 0.12 I.OZ I 4.89 63.60 I 1.48 6.73 I 32.90 182.00 K-8 I 0.02 0.08 I 0.81 1.88 I 0.41 0.47 I 6.31 7.67 J~8 I O.OZ 0.07 I o. 94 1.14 I 0.47 0.42 I 8.31 S.62
-------:------------------1------------------1------------------t------------------c-10 I 0.02 0.13 I I.OZ 5.80 I 0.50 I.OZ I 9.61 Zl.10
LL-10 I 0.16 Z.13 I 7.2Z 199.00 I I.SS 13.90 I 40.90 S91.00 S·IO I O.IZ 1.69 I 4.89 142.00 I 1.48 13.10 I 32.90 480.00 K·IO I O.OZ 0.11 I 0.87 • 3.88 I 0.44 0.79 I 7.ZZ IS.80 J·IO I o.oz 0.04 I 0.56 1.ZI I 0.37 0.50 I 4,89 7.92 -------t------------------l------------------t------------------1----~-------------C-IZ I 0.03 0.18 I 1.10 13.40 I 0.53 1.75 I 9.61 59.50
ll-12 I 0.13 2.80 I 5.54 324.00 I I.SS ZZ.00 l 36.60 1070.00 5-IZ I 0.15 3.80 l 6.31 58Z.OO I l.5S 33.40 l 40.90 1900.00 K-12. I 0.02 0.11 I 0.70 S.56 I 0.40 1.07 I 6.31 30.00 J·IZ 1 · o.oz 0.13 I 0.94 6.08 I 0.47 1.08 I 8.31 Z5.00
I l ~
I I ~
... ~ • ... ... ::; , ... :l ... j uj 1.2 i 1.1 .,
1 ... ... .., ... ... ... ...
Reoulta of Brown Jnai,.ea
... I\ 1v J I\ in rsr d ....f'? =VA o.! . tsiV rsf.J " IV c ....
110 ... .. .. 70 .. .. .. .. ..
-ts:J ..
LL
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IH s
Reaulta of Brown Jnai,.oa LS/AC-6;. .... J. 20 lliPa. 200mlft
K '
•: lp afJ U?1 q?1 Oi'J csf'l P I I c - - LL "' • • ' .....
ts:J"' IZ1'.J NI
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Reoutta of Br0WJ1 Anol)'llO• LI/AC-I. .._ J. 70 Wq, 100rnrn
10 -;---·~~~~·~'--~~~~~~--~~~~~,
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• • 4
• • ••
o t> IV t> fV " lf4 t> in t> fV t> in KVJ " 171 c - ... LL Ut • .....
ts::!"' IZ1'.J ..
Reoulta of Brown Anai,.H -lS/AC-9. ... 3. 7o- .... 200mll'I ... . -... ... ... ....
110 . .. . .. ... .. so .. 20
• '
• b IV rs:yJ 1>. I?'' 1>. trJ " l?'J b r1 rs=f7J rq.-.1 c .... ....
ts:J"'
u.
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Fig. 4Sa. Structural analyses by Brown procedure, LS/AC-5.
-----·~ ----
..... ..... "'
I I ~
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Reault. of BrDW1l Anal3w•• ·: r -~"!'~!·~-·~.--·-·1
~l I
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',,. ~-~ ~ ./. . ~ ~ ~. ~ ~ ·~ ~~ ~
-,
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Reault. of BrOW1l Anal79ea Ll/AC-20. ...... 10.-~. t00mm. _____ _
•• 0 hp IS'f"d CS"f'A I\ 1:0 D f'"d rqr; ....y.> =f? CAHa~U..LHI K -IS:J "' IZ?:J NI
Re1ult.. of BrD1111 Ana17911 LS/AC-20 • ... '· 70 UPa. 2flOrMl
..:~~ - ~ .
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Fig. 4Sb. Structural analyses by Brown procedure, LS/AC-20.
.... .... "'
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0.1 .... .... o.t11 .... .... .... .... ....
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Fig. 45c. .Structural analyses by Brown procedure, G/AC-5.
,_.
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1! 1 I il~~~~ ill .. I- """"'...,,..,.,
'
L...,.--,.-,-,--,...,..~ ... - 0 - --.. ,.. .... ""
1-·-·--1
I • I
121
if1i .a -
1 ! I ....,,..,"""'""~"""""'~~~.. 1. 111 . . ~ i !! ~~~~~\:::· ill "I ~ .... ~*
I '
L-r-,~T-r-r·--,--..,......-,--.--'I
(~) SHO"">AM G'f'0'1
123
6. SUMMARY AND CONCLUSIONS
The effects of three additives (Asphadur, SBS, and hydrated lime)
on two grades of asphalt cements were evaluated in Phase I of the study.
Thirteen physical and chemical tests were performed on a total of 16
binder blends, both before and after thin film oven tests. From these
tests, six additional index properties were calculated.
In Phase II the effects of five additives (Asphadur, hydrated lime,
SBS, neoprene, and SBR) on mixture properties were evaluated in
conjunction with the two asphalt cements studied in Phase I and with two
aggregates (limestone and gravel). Eight engineering tests were
·performed on more than 1300 specimens from a total of 72 mixtures.
nata from Phases I and II were used to perform 3114 structural
analyses for eight hypothetical pavement sections by using the DAMA
computer program and the Brown (Nottingham) procedures.
nata analysis and interpretation were difficult because an enormous
amount of data were obtained, and because the effects derived from one
test on one binder or mixture sometimes contradicted those derived from
another test. To help show the meaning of the data, we prepared Tables
· 1:l and 14, somewhat subjectively, to summarize the effects of additives
on the important binder properties and mixture properties, respectively.
Changes due to additives that led to bet.tar stability; strength, rutting
resistance,· fatigue i:-esistance, durability, low-.temperature cracking
resistance, resistance to moisture-induced damages and structural
capacity in a pavement system were considered improvements.
124
Tat> le 13. Sumary of effects of additives on binaer properties.
---------~---------------------------------------------------------Property AC Grade AL AH LL s -------------------------------------------------------------------Retained Penetration
Viscosity at 60 C ++ ++ + +
Vlcoslty Ratio, 25 c AC-5 AC-20 ++ ++
PI AC-5 + + + + AC-20 +
VTS AC-5 0 0 + AC-20 + 0 +
PVN AC-'5 + + 0 + AC-20 + + + +
Tensile Strength, O 0 0 0 ++ R 0 + + +
Toughness, 0 0 0 0 ++ R AC•5 + + + +
AC-20 +
Tenacl ty, 0 0 0 0 ++ R AC-5
AC-20 0 0 0
Force Ductility, 0 + + 0 R + + +
Elastic Recovery, O ++ R 0 0 0 0
Dropping Ball (t2/t1), 0 ++ R 0 0 +
HPLC, %LMS, 0 0 0 0 0 R
Cracktng Temperature AC-5 0 + + AC-20 · + + + +
Temp. EqUIV. Stiffness AC-5 0 + 0 + AC-20 0 0
------------------------------------------------------------------++ Improves significantly AL Asphadur, 4% + Improves sl lght I y AH Asphadur. 6% 0 no effects LL hydrated l lme. 5%
worsens slightly s SBS worsens signlf lcantlY 0 ortglnal
R TFOT residUe
125
T.Wle l4. Sumarv ot ett~cts of addjt1v,s on mixture PrOPtrtieo.
Property
Marshal I .Stab1I1 ty
Tenst It Strength
"olsture Resistance
AC
5 5 20 20
s s 20 20
AGG
G LS G LS
G LS G LS
AH
++ .. .. ++
Addtt1ve
LL
0 0
++
+ +
LH
+
0
s 0
+ +
++ 0
K
0 0 + 0
+ 0 0
J
0 0 0 0
.... -------.. ---------------------------·------------·------------------· Marshall 111111ersion 5 G + + ++ ..
5 LS 0 0 0 + + 20 G + 0 0 + 20 LS ++ 0 0 0 0 ----------...........................................................................................................................
Tenst le strength• 5 G 010 +I• +10 -10 <vac-sat/Lottman> s LS -10 -/+ 0/0 01+ 010 -/+
20 G 010 +/+ +I+ O/+ 20 LS O/+ 01++ +I++ +10 01+ +I+ .................................................................................................................................................
Res1 I lent modUIUS 5 G -10 0/0 +10 -10 <vac-sat/Lottman> s LS -10 01+ ·/+ •/+ 0/0 0/0
20 G -1- -1- ·I· -10 20 LS 0/0 01+ O/+ ++10 01+ +10 -------------------------------------------------...............................................
B/C ratio s G 0 0 0 0 s LS 0 0 + 0 0 20 G + + 20 LS + ++ ++ 0 ..
Fat19.1e Resistance ............................. ,.. .................................................................................................................... Shtl 1-straln 5 + 0 0 0 + 0 Shel 1 .. sireeS 5 + 0 0 0 + 0 !!!.!.!Ptn 5 0 0 0 0 Browri s + 0 0 0 0
Shel 1-otrat• 20 0 0 Shtl 1-etreas 20 0 0 Maupln 20 0 0 0 0 0 0 Brown 20 0 0 0 0 0 0 .......................................................................................................................................................
Rutt 1 ng Ree i stance 5 LS + + 0 0 0 s G 0 0 0 0 20 LS ++ 0 0 0 0 20 G 0 0 0 . ......................................................................................................................................................
DAMA Anal vst's 5 s 20 20
LS G LS G
++
++
Brown <Nottln9hanU Analvsls
Rutting cNr>
FatHJJe <Nf>
++ + 0
s 5 20 20
s 5 20 20
LS G LS G
LS G LS G
++
++
Improves slgnlftcalttly ll!IPtOVff slightly no effects lo'Ol'ftftS SJ lght!V worsene slgnlfieantly
0
0 ++
+
+
++ ++ ++
AH LL LH s l J
0
0
+
+
++
0 0
+
+ +
+ + ++ ++
Aophalt, 6'
0
0
hydrated I lme. hydrated 11111it, SBS neoprerie SBR
0
0
I' 2\
126
The following conclusions, first wit'h respect to binder properties
and then with respect to mixture properties and finally with respect to
overall evaluation, were drawn from examining the data and these two
tables. It must be emphasized that the conclusions on the beneficial
effects are applicable only to the materials and material combinations
tested. Because of the enormous variety of polymers available and the
fact that each may behave differently in a different asphalt, no claim
will be made that these conclusions will be applicable to other
at!ditives or the same additives in combination with different asphalts
and aggregates.
Additive Effects ori Binder Properties
ASPl'IADUR
Although adding Asphadur (3 min. at 400° F) and hydrated lime at
high concentrations (10'-'.) were more appropriate fo.r conditions in the
field with aggregates, they resulted in ndnhomogeneous, partially
dissolved/dispersed asphalt binders when they were added to asphalts.
Therefore, data on these samples (Samples 2a, 3a, 5, 8a, 9a and 11) were
often erroneous and misleading. Their berleficial effects can only be
evaluated in Phase II when asphalt concrete mixes with aggregates are
examined. Ba.sed on tests of nearly homogeneous modified binders, the
following conclusions are drawn.
• Asphadur significant'ly increased the viscosity of asphalt at
high temperatures. This leads to the expectation of improved
resistance to rutting.
•
•
127
Asphadur increased penet~ation at 5° C somewhat but decreased
penetration at 25° c. This is reflected by the decreased
(improved) temperature susceptibility as measured by VTS, PI,
and pVN,
Asphadur seemed to have improved the low-temperature cracking
resistance of asphalts as measured by the calculated cracking
temperatures and critical stiffnesses at low temperature and
long loading time.
• Asphadur d.:l.ssolves better in AC-5 than in AC-10.
• Asphadur, added to asphalts, did not result in significant
improvements in toughness, tenacity, and tensile properties.
• Large increases in percent LMS based on RPLC data on TFOT
residues may suggest increased susceptibility to cracking.
• The optimum beneficial effects of adding Asphadur are expected
when Asphadur is used in conjunction with softer grade asphalts.
RYD'RA'l'ED LIME
Although it has been suggested that hydrated lime reduces the
hard.ening rate of asphalt and thereby increases durability or useful
life of pavements ('19), the major beneficial effect of hydrated lime is
in improving the moisture susceptibility of asphalt mixes by serving as
an antistripping agent (37,49). This effect can be verified only when
aggregate is introduced in the asphalt concrete mixes. The relative
benefits of adding aggregate as compared with other additives will be
discussed later. The effect of lime on asphalt binder without .aggregate
will be based on low-concentration blends (5% lime) because of the lack
of homogeneity in high-concentration blends (10% lime).
128
• Increases in viscosity at high temperatures (60 ° C to 1;15 • C)
because of lime suggest improved:resistance to rutting.
• Temperature susceptiblity, low..,.t~mperature cracking r!l.sistance,
toughness, tenacity, tensile and elastic properties of 1tsphalt
are not signficantly affected by lime.
• Although there was little increase in percent LMS based on RPLC
data on original asphalts, there were significant incr!)ases in
percent LMS in TFOT residues. I~ current correlations between
percen.t LMS and pavement cracking hold for asphalts with
additives are assumed, these increases may signal increased
susceptibility to cracking.
STYR'F.LF ( s:Bs)
• Styrelf appears to be a uniform, homogeneous, polymerized
asphalt formulation rather than a dispersion.
• Styrelf increased viscosity of base asphalt at high temperatures
(~0° C and 135° C); thus it is e~pected to increase rutting
resistance of asphalt pavement.
• ·By most measures, Styrelf reduce~ the temperature susceptibility
of base asphalts. However, its effect on cracking temperature
was inconclusive.
• Although there were improvements in the elastic properties of
asphalt because of Styrelf moclif:ication, not all of the benefits
were retained when exposed to :thin film oven agit1g•
129 ,
• There wer.e si~ificant improvements on toughness, tenacity and
tensile pr.opert:l.es because of Styrelf modification. However,
some of these improvements were drastically reduced due to thin
film oven aging.
• The increase in percent LMS based on HPLC because of Styrelf was
small. However, additional increases in percent LMS after thin
film oven aging were significant.
• Resistance to heating and aging of asphalts containing Styrelf
should be carefully examined.
Additive Effects on Mixture Properties '~
M!PHADUR
• Asphadur significantly increased the Marshall stability,
Manhall stiffness, and tensile strength values of all mixes.
• The effects of Asphadur on moisture resi,stance were mixed and
not significant.
• Asphadur increased the fati~e resistance of AC-5 mixes but
showed no improvements on the fatigue behavior of AC-20
mixtures.
• Asphadur improved the rutting resistance of the mixes on the
basis of results of creep tests. This is consistent with the
observation of increased PVN, pigh-temperature viscosity, and
increased Marshall stiffness.
• Asphadur improved the structural capacities of mixtures compared
to the control mixes.
130
HYDRA'l'ED LIME
• Lime treatments increased the moisture resistance of most. mixes
as determined by the Lottman pro~edure. The effects on moisture
resistance measured by warm water immersion and vacuum-
saturation treatments were not all clear. Lime treatments
improved the benefit-to-cost rati·os for AC-20/limestone mixes.
• Lime treatments improved the Marshall stability for limestone
mixes and tensile strength for Ac:...5 mixes.
• Lime used at low levels had little effect on fatigue and rutting
resistance; there were some improvements in rutting resista~ce
when lime was used at high levels.
• Lime treatments resulted in improved structural capacities,
especially for gravel· mixes and by Brown analyses.
SJIS (Styrelf)
• SBS improved ~~rshall stability', .l'...arshall stiffness, and tensile
strength of most mixes.
• SBS had little effect on mixture resistance to moisture,
fatigue, and rutting.
• SBS-modified asphalts improved .structural capacity of mixtures,
especially when they were based on the Brown (Nottingham)
method.·
N'F.OPRENE (K)
• There were little differences between neoprene-modified asphalts
and control mixes in terms of stability and tensile strength. I I '
131
• In the majority of the mixes, neoprene improved the moisture
resistance and the associated henefit-to-cost ratios.
o Neoprene improved the fatigue resistance of soft grade AC-5
mixes.
• Neoprene had mixed effects on structural capacity.
SBR (J)
• SBR-modified asphalts had little effect on stabilities of
mixes but reduced the tensile strengths.
• SBR improved the moisture resistance, especially measured by
Marshall immersion, the tensile strength ratio and the benefit
t:o-cost ratio.
• Compared to the control mixes, there were little other
beneficial effects.
OV1':11ALL CONCLUSIONS
t. Each additive showed some degree of improvement in at least
one of the desired. properties. However, no additive tested showed
consistent improvement in every binder as well as mixture property.
2. Improvements in binder properties may or may not be reflected
in mixture or structural performance •
. 1. Sof.t grade AC-5 seemed to have benefitted more from additives
than Ar.-20.
4. Heat stability of the polymer modifications may be a concern
as reflected in penetration retention, viscosity ratio, and large
increases in percent LMS by HPLC analyses.
132
5. It is difficult and perhaps inappropriate to compare, or. rank
the additives tested because many polymers are asphalt specific,,
Although Asphadur and 1
SBS were added to AC-5 and AC-20 grade asphalts
and made the modified aE!Phalts at least one grade more viscous, SBR- and
neoprene-modified asphalts were supplied in the AC-5 and AC-20 viscosity
ranges with different base asphalts.
133
7. RECOMMR~IDATIONS
1. There is sufficient evidence, both from this study and studies
conducted elsewhere (especially in Japan and Europe), to indicate that
polymer additives have enormous potential in improving some aspects of
asphalt properties. It is reconnnended that research on asphalt
additives be continued, including laboratory evaluation of new additives
and field tests of promising additives.
2. Structural, distress, and performance analysis should be an
integral part of mix design and additive or new material evaluation.
The approach taken in this research or similar methodology presented by
Monismith et al. (::19.) is reconnnended.
3, Softer asphalt AC-5 seemed to have benefitted most from the
additives studied. Modified softer asphalts can combine the normally
expected better low-temperature cracking resistance and thus the
improved temperature susceptibility with increased stability and rutting
resistance for high temperature and traffic conditions for improved
overall performance. Field trials of polymer-modified soft grade
asphalts are reconnnended.
4. It is reconnnended that the PVN (penetration-viscosity number)
be considered in studying or specifying modified asphalts to assure
low-temperature cracking resistance .and that Marshall stiffness be
considered (in lieu of more time-consuming creep tests) in evaluating
mixes containing additives to assure resistance to rutting.
134
5. Because none of the additives studied showed consistent
improvements in every aspect of binder and mix properties, one must
first decide what specific improvement is desired before choosing an
additive.
6. Spe.c:i.fications for polymer-modified asphalts must be
performance based. To ensure the enhanced performance properties of
the;~· new materials, additional tests for heat stability, tensile, and
elastic properties should be considered·. However, to encourage the.
development of competing materials, the specifications should be g.eneric
and not based on one part.icular product.
135
8. ACKNOWLEDGMENTS
This research was sponsored by the Highway Division of the Iowa
Department of Transportat~on (DOT) under Research Project HR-278. This
study, under the same title, was also supported by and ~esignated as
Pro.1ect 1R02 of the Engineering Research Institute, Iowa State
University.
The support of this research by the Iowa Highway Research Board and
the Iowa DOT is gratefully acknowledged. The authors wish to extend
sincere appreciation to the engineers of the Iowa DOT, especially Bernie
Brown, Vernon Marks, and Rod Monroe, for their support, cooperation, and
counsel. The authors would also like to thank Joan Pribanic for the
HPLC tests, Marvin Exline for the tensile stress tests, and Tim
O'Connell for toughness and tenacity tests.
The following individuals contributed, in various capacities, to
this investigation: Jerry Franklin, Barbara Hanson, Sang Soo Kim, Kiet
T. Ly, Thulan Ly, Jay McGinness, Shelley Melcher, Glenn Oren, Due Tran,
"Eric T.Tner, and Zia Zafir.
137
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143
APPENDIX A: TENSILE STRENGTH TEST
The tensile strength tests conducted were modifications on ASTM standard
test methods for rubber properties in tension D412-80.
Apparatus--Instron table·model universal testing instrument.
Temperature Cabinet--Righ temperature cabinet including temperature
controller, prol)e and attachment for liquid carbon dioxide or liquid
nitrogen coolant.
toad Cell-Metric 5 kg capacity, 0.500 g. lowest range.
Chart Recorder...-Strip chart recorder standard with instrument.
Sample Size--3 cm x 0.3 cm x 0.3 cm sampies are cast in rubber molds.
Testing Conditions-Specimen is stretched to 800% elongation at +20° C
at rates of ~00 mm/min. The temperature should be specified, depending
upon the end use of the material.
EXAMPLES :
MATERIAL TEMPERATURE LOAD RANGE
Asphalt Cement 20° c 5
Emulsion Residue 4• <seal Coat) c 10 - 20
Emulsion Residue • (Mixing Grade) -10 c o.s PAC-20 20 • c 5
t>AC-10 20 • c 5
145
APP.l!NJlIX B: ELASTIC RECOVERY BY MEANS OF DUCTILOMETER
PROCEDUR!!-The hrass plate, mold, and. briquet specimen are prepared in
accordance to the ASTM Test Method for Ductility of Bituminous
Materials, D113-79. After the ductilometer and specimen are conditioned
• • at 10 C (50 F) for 85 to 95 minutes, the specimen is elongated to 20
cm at a rate of pull of 5 cm/min. After elongation, the ductilometer is
stoppe.t and the sample is held in the stretched position for 5 minutes.
At this time, the sample is cut in half with a pair of scissors or other
suitable cutting device. The sample is left undisturbed for one hour,
when the half sample specimen is retracted until the two broken ends
touch •. The new pointer reading is recorded in cm.
INTERPRETATION OF RESULTS - The percent elongation recovery is
calculated as follows:
10 - L l'.: Recovery • --- x 100
20
where L • Final reading in cm.
147
APPENDIX C: DROPPING BALL TEST PROCEDURE
PROCEDURE-The sample to be tested is heated slowly, With frequent
stirrin~, to approximately 149° C 000° F). Approximately 8.0 + 0.1 g.
of the sample is poured into the dropping ball container, avoiding
inclusion of air bubbles. The container is covered with the ball
centering guide and the ball is placed on the guide. The assembly is
cooled for 30 minutes at ambient room temperature.
After ~n minutes, the timer is started as the assembly is placed
uoside down on its support, a ring stand with a flat notched plate 30 cm
above the base. (The plate is notched. to hold the assembly while
alloWing the ball to drop freely.) When the top of the ball is tangent
to the edge of the centering guide, the time is recorded at Tl. When
the ball hits the base of the support, the total time, T, is recorded. 1
INTF.RPRETATION OF RESULTS-T2 is obtained by subtracting Tl, the initil.al
time, from T, the total time. (Tl is the time from start to tangent, T2
is the time from that point to when the ball strikes the base and T is
the total time.) Since Tl is primarily dependent upon the viscosity of
the material and T2 is a measure of the material's tensile strength
~fter being stretched the ratio of T2/Tl is a measure of the elasticity
of the sa.mple. A large ratio, therefore, indicates more elastomeric
character.
.. ·•.
i • •. i : ·1!i, fl ..... ~ '!.·' •.
.. .. (~.
• i i l
•
•
!
. •
. ,
I I l
..
•
.. 0.
•. .. ..
151
APPENDIX E: · NOMOGRAPH FOR PREDICTING CRACKING TEMPERATURE AFTER HILLS (18),
u 300 'to N
~ 200 , , , z 150 I
Q -30 , , ~
I I ,
Q: 100 I
I .... , YJ , I
z I I , I
~ I I
-25 I , ,
I I
~ I I
I , <( I I , I
J: , • a. 40 I I
I en ,
I I I <( I I
I , , I , , I I I I
20 I
2 3 4 6 8 10 15 20 30 40 ASPHALT PENETRATION AT 5°C
153
APPENDIX F: SAMPLE COMPUTER PRINTOUT FROM DAMA
DDDDDDDD AAAAA - MMM DDDDDDDDD AAAAAAA - MMMM DD DOD AAA AAA MMMMMMMMMM. DD ODD AAA AAA MM MM-MM· DD DD AAA AAA MM MMM MM DD DD AA AA MM MM DD DD AAAAAAAAAAA MM MM DD DD AAAAAAAAAAA MM MM DD DOD AA AA MM MM DDODDDODD AA AA MM MM DDDDDDDD AA AA MM MM
THIS PROGRAM HAS BEEN DEVELOPED SOLELY FOR
THE ASPHALT INSTITUTE COLLEGE PARK. MARYLAND
B.V PROF. M. W .. WITCZAK AND OAEKVDD'-HWANG.
AAAAA 222222 AAAAAAA 22222222
AAA AAA 222 222 AAA. AAA 22 AA AA 222 AA AA 2222 AAAAAAAAAAA 2222 AAAAAAAAAAA 2222 AA AA 22 AA AA 2222222222 AA AA 2222222222
THE SOLUTION USES •CHEVRON N-LAVER• PROGRAM AS THE ANALYTICAL STRESS-STRAIN-DISPLACEMENT MODEL.
... ..,. ,,..
$3 H1•4 in. $.G.E••500 pai
SECTION ANO.MATERIAL PROPERTIES
LAYER -·· ' 2
LAYER -··
lllTERIAL
A. C. ...... POISSON'S RAtlO
0.35 0.45
CURING CONDITIONS
•TERIAL
A. C.
CURE TIME'. (MQNTtt$}
o.o
TRAFFIC CONDITION
THICKNESS (IN)
4.00
MONTH OPENED TO TA:Af-fJC
JULY
MONTHS CURED BEFORE OPENING
0
NUMSER Of REPETJTIOHS PER MONTH 1000
JAN.
•5.0
FEB.
38.0
ENVIRONMENTAL CONDITIONS (MEAN MONTHLY AJA TEMPERATUKES. otu. f)
MARCH APRIL
43.0 45.0
... .... -· 10-0
...LY AUG.
78.0 81.0
SEP.
78.0
OCT.
73.0
LOAD CDNfJGURATlDN ANO cOMPuT-ATlDNAL POINTS
LOAD PER TIRE TIRE PRESSURE RA01US Of LOAD LOAD SPACING
COMPUTATIOHAL POINT 1 COMPUTAJIONAL POINT 2 COMPUJATlDNAL POINT 3
4500. LBS 70. f>SI
•.52 IN 13.5 IN
X • Q.O IN ( CENTER OF ONE TIRE ) X ~ 4.52 JN (RIM Of ONl TIRE) X • 6.75 "JN (MIDPOINT OF TWO TIRES!
NOV.
58.0
DEC.
s.a.o
.... "' "'
I L
MODULI CONDITIONS
ASPHALT STABILIZED LAYERS
LAVER NUMBER MATERIAL
A. <;.
TEMPERA·TURE/MDDUl:cUS (DEG. F / PSI)
POINT 1 2. 3
TEMPERATURE 40. 50. 55.
MODULUS El 873200. 660800. 554600.
SUBGRADE LAVER
LA)'ER NUMBER· MATERIAL .JAN. f.EB.
-<,· ·~,.
sliBGR. 2 450(>:' 116·zs·:- ·
4 5 6 7
60. 65. 70. 75.
448400. 377600. 306800. 236000.
SUBGRADE MODULUS BY MONTH(PSI)
MARCH A.PRIL MAY JUNE JULY
18750'. 2'700: 3150". 3600. ·4050.
8 9 10 11 12
80. 85. 90. 95. 99.
188800. 155760. 122720. 101480. 77880.
AUG. SEP. OCT. NOV. DEC.
4500 .. 4.500. .,/4500--. 4f?OO. .4.500. .... ·.:,, a-
DAMAGE MODELS
fATlGIJE DAMAGE
RUTTING DAMAGE
NF • (FO) • {fl) • (IO••M) • (ET)••(-f2) • (MOO)••(-F3)
WHERE
NF IS LOAD REPETITIONS TO FAILURE FO IS DISTRESS TO PERFORMANCE FACTOR IO••M IS MIX FACTOR {M• F4*{VB/(VB+VV)-F5)
. . .. ' VV IS VOLUME OF VOID IN ASPHALT (PERCENT) . VB IS VOLUME OF BITUMEN IN ASPHALT {PERCENT)
ET IS TENSILE STRAIN IN ASPHALT-LAYER MOD IS MODULUS OF ASPHALT Fl, F2 AND F3 ARE COEFFICIENTS OF LAB FATIGUE EQUATION
GIVEN BV NF• Fl • ET .. (-F2) • MOD••(-F3)
PARAMETERS OF LAYER I
FO • .1840E 02 Fl •.4325£-02 F2 •.3291E 01 F3 •.8540E OD
F4 •.4840E 01 FS •.6900E OD VB s 15.2 vv • 3.6
••••• FINAL FATIGUE EQUATION NF •.2953E OO•{ET) .. (-.3291E 01)•MOD .. {-.8540E 00)
NF • 00 • EV••{-01)
WHERE
NF IS LOAD REPETITIONS TO FAILURE DO AND DI ARE COEFFICIENTS OF RUTTING MODEL EC IS VERTICAL COMPRESSIVE STRAIN
DO • . I 365E coa DI • .4477E 01
..... "' ...,
--· _,, ...... ~, ,,... .... ~
----
IO]N L t f I 1 t 2 2 1 2 t • • 3 t 3 3 4 4 4 5 5 5
• 6
t
• 1 t 2 t t 2 t t 2
PVT. TEMP
92 92
95
•• 92 92
86 86
68 68
63 63
6 7
-.:.1 1
t 53 1 . 53-~ 2
8 1 44 8 1 44 8 2 9 t so 9 1 50 9 •
to 1 53 10 1 53· to 2 11 1 66 1 t 1 66
" 2 12 1 82 12 1 82 12 2
NDOULU-5-(PSI l 1·1-2661. t1266f~
4050. 9616&. 96168.
4500. t 1266-1. 1-t2661.
4500. 146311. 1463'1-1.
4500. 326519. 326519.
4500. 394175 . 39-4175.
4500. 593559-. 59355!1>
4500. 764922. 764922.
ff625. 645071. 645071.
t8750. 593559. 593559.
2-100. 360364. 360364.
3tso-. 169845·. l69845.
3600.
• ••• • MONTHLY STRUCTl.IRAL RESPONSE ANO OAMAGf •••·••
TYPES OF STRUCTURAi:. RESPONSE-S ·
OZ VERTICAL DEFORM.lTlON- AT THE TOP Of LAYER- (IN) ET TENSl-LE STRAIN AT THE BOTTOM Of LAYER (IN/JN) EC COMPRfSS-IVE ST·RAJ:N AT THE TOP Of LA'tERf-fN'/JN)
STRUCTURAL RESPONSES RESP -- - - --- - - - - - - - -- -- - __ .,.. ___ --- - - - - - - - - - - - - - -- - -- - - - -TYPE H - H --: · H· -oz o. 732£-01 o-. 751£-0t o. 74-4£-0l Et O. t23E-02- O. f·:r.!E-02 0. tt-9£-02 EC 0.282£-02 0.226E-02 O_.t98£-'02 DZ 0.695E-01 0. 709£-01 0.699£-0·t ET 0·.129£-02' O. 127£-02 0. 123£-02 Ec-0.29t£-02 0.2·24£-02 0.191£-02 oz 0.673£·-01 0.689£-01 0.681£-0t f·T 0. 118£-02 O. 1 t7E-02 0, 1 t-3£-02 EC 0.269E-02 0.212£-02 0.183E-02 DZ 0.637£-01 0.656£-0t 0.651£-01 ET 0.101£-02 O. tO!E-02- 0·.98-tE-03 EC 0.234£-02 O. t92E-02 0.170£-02 DZ 0·.533£-01 0.553£-01 0.552£-01 ET 0.607£-03 0.616£-03 0.604£-03 EC O. 150£-02 0. 134E-02 0.124£-02 oz 0.510£-01 0.529£-01 0.529£-0-f ET 0.534£-03 0.544£-03 0.534£-03 EC 0·.134£.-02 .o .. 1·22E-O:! 0. t1-4E-02: DZ 0.46tE-01 0.478£-0f 0.479£·-01 E'f<0.,403£.-03 0~41.1£--03 0.404£-03,. EC O.tOGE-07 0.986E-Oa0.930E-03 DZ 0.211£-01 0.219E-Ot 0.2f8E-Ot ET o·.25tE-03 0.254£-03 0.249£-03 EC- 0.613£-03 0.544£-03 0.502£-03 DZ 0.151£-01 0.156£-0-1 0.155£-01 ET 0.234E-03 0.234£-03 0.228E-03 EC 0.545£-03 0.450E-03 0.400£-03 oz 0.673E-Ot 0.695£-0t 0.699£-01 ET 0.464£-03 0.476£-03 0.-468£-03 EC 0. 129£-02 0.123E'-02- 0.118£-02 DZ 0.683E-01 0.708£-01 0.708£-01 ET 0.635£-03 0.649£•03 0.637£-03 EC 0.164£-02 0.152£-02 0. 143£-02 OZ 0\735£-01 0.76-IE-01-''0.7S.7£.,.-01 Cl o.100E--02 0.101£-02 o._988E--O:J, EC 0.:..!39E·0-2 0.205£-02 O.J86E:..02-
MONTHLY DAMAGE'S
H-- H- H-
0.01855 0.01819' 0.01648 2.83665- 1.05083 0.5754"1
O.Ot880 0.01791 0·.01'5-99 3-.26531 L00205 0.49095
0.01603 0.01555 0.014-0-1 2~26603 o. 78088 0.4f00f
0.01209 0.01204 0.01098 1.22115 0.500-1'-t 0.28946
0.00448 0.00472 0.00442 o. 1"6607 o.1oo9a 0.01153
&.00-34-7 o.00368 0-.0034& 0.10203 0.0664t ' 0.04854
0~00193, 0.00208 0.00196' o.03466 0-.02544 , 0.01964
0.00051 0.00053 0.00049 o.00304 0.00111 0-.00124
0.00035 0.00035 0.00032 0.00179 o,00076 0.00045
0:00309 0.00335 0.00319 0.08462 0.06911 0.056-74
o.00567 o.00608 o.-OOS73 0.24995 -0.17664 . -o. 13401
0.01343 -0-.01'378 0:0121& 1 .33686 0.-67339 0.43490
·••••• DAMA-GE .SUM FOR 12 -MOHTHS
LAYER 0.098402 0.09825'4 0.089604
LAYER 2 t 1 .668159 4. 448·379 2. 532855
'1:'.·
..... "' 00
•••••••••• DESIGN LIFIE OF PAVEMENT **********
LAYER
2
DAMAGE TYPE
FATIGUE
. RUTTING
CU MULA TI VIE DAMAGE
1.000
2.837
ANALYSIS 1 ... NS-1 FAILURE REPETITION ANALYSIS
LAYER MAT'L THICK
A. C. 4.00
SR
1.00
TOTAL TAE
DESIGN REPETITIONS BY MS-1
. 12943E 04
REPETITION RATIO (OAMA) ( NF RUTTING/NF FATIGUE )
LAVER 1 0.008
REPETITION RATIO (MS-1) ( NF DAMA CRITICAL/NF BY MS-1
0.773
lAE(l)
4.00
4.00
ANALYSIS 2 ... MS-1 THICKNESS ANALYSIS(lNCli)
REQUIRED TA(MS-1)
3.71
ACTUAL TAE(DAMA)
4.00
DIFFERENCE (TA-TAE)
co.29
CRITICAL POSITION
DESIGN LIFE( YEARS)
10.2
0.1
DESIGN REPETITIONS
O. 1219E 06
O. IOOOE 04
**********LAYER 2 CONTROLS DESIGN LIFE
.... V1
"'