Bituminous Design 2-1 Chapter 2 Bituminous Design Bituminous design consists of selecting the bitumen and aggregate gradation, blending the aggregates to conform to the selected gradation, determining the optimum content, and calculating the job-mix formula (JMF). After determining the percentages of materials, calculate the total quantity of materials needed for the project. This chapter details the design of a typical high mix. Low mixes are designed by the same method, although many steps are often omitted because the allowable variations are great enough that accurate measurements are unnecessary. BITUMEN SELECTION 2-1. The selection of a particular bituminous material depends on the type of pavement, the range of temperatures, the amount of rainfall, the type and volume of traffic, and the type and availability of equipment. In general, hard- penetration grades of AC are used in warm climates and soft-penetration grades are used in cold climates. Heavy grades of asphalt cutback and tar are normally used in warm regions, and light grades are used in cool regions. AC is generally more suitable for high traffic volume than cutback. Asphalt and tar do not necessarily bond to each other; thus, bonding also becomes a consideration in bitumen selection. Tables 2-1 and 2-2, pages 2-2 through 2-4, list the characteristics and uses of bituminous materials. ASPHALT CEMENT 2-2. AC is usually used in hot-mix pavements and is solid at 77°F. To make AC fluid enough for mixing with aggregate or for spraying, heat it to a temperature of 250° to 350°F. A disadvantage of AC is that adequate heating equipment may not always be available. The various penetration grades of AC are suitable for plant mixes, penetration macadams, and surface treatments. ASPHALT CUTBACK 2-3. Different types and grades of asphalt cutback are used during various climatic conditions. When the cutter stock evaporates, it leaves AC as an active bonding and waterproofing agent. Consider the prevailing atmospheric temperature during construction when selecting the grade of asphalt cutback. Light grades are usually used in cool weather. If the preferred grade and type of asphalt cutback is unavailable, use a comparable grade of another type. For example, using RC-70 instead of MC-70 or using RC-300 instead of MC-300 will not seriously affect the finished structure. In the field, light grades of asphalt cutback can be made by adding solvents to AC or to heavier grades of asphalt cutback. (See Chapter 5 for more information on the field manufacture of asphalt cutbacks.)
Transcript
Bituminous Design 2-1
Chapter 2
Bituminous Design
Bituminous design consists of selecting the bitumen and aggregategradation, blending the aggregates to conform to the selected gradation,determining the optimum content, and calculating the job-mix formula(JMF). After determining the percentages of materials, calculate the totalquantity of materials needed for the project. This chapter details thedesign of a typical high mix. Low mixes are designed by the same method,although many steps are often omitted because the allowable variationsare great enough that accurate measurements are unnecessary.
BITUMEN SELECTION
2-1. The selection of a particular bituminous material depends on the type ofpavement, the range of temperatures, the amount of rainfall, the type andvolume of traffic, and the type and availability of equipment. In general, hard-penetration grades of AC are used in warm climates and soft-penetrationgrades are used in cold climates. Heavy grades of asphalt cutback and tar arenormally used in warm regions, and light grades are used in cool regions. ACis generally more suitable for high traffic volume than cutback. Asphalt andtar do not necessarily bond to each other; thus, bonding also becomes aconsideration in bitumen selection. Tables 2-1 and 2-2, pages 2-2 through 2-4,list the characteristics and uses of bituminous materials.
ASPHALT CEMENT
2-2. AC is usually used in hot-mix pavements and is solid at 77°F. To makeAC fluid enough for mixing with aggregate or for spraying, heat it to atemperature of 250° to 350°F. A disadvantage of AC is that adequate heatingequipment may not always be available. The various penetration grades of ACare suitable for plant mixes, penetration macadams, and surface treatments.
ASPHALT CUTBACK
2-3. Different types and grades of asphalt cutback are used during variousclimatic conditions. When the cutter stock evaporates, it leaves AC as anactive bonding and waterproofing agent. Consider the prevailing atmospherictemperature during construction when selecting the grade of asphalt cutback.Light grades are usually used in cool weather. If the preferred grade and typeof asphalt cutback is unavailable, use a comparable grade of another type. Forexample, using RC-70 instead of MC-70 or using RC-300 instead of MC-300will not seriously affect the finished structure. In the field, light grades ofasphalt cutback can be made by adding solvents to AC or to heavier grades ofasphalt cutback. (See Chapter 5 for more information on the field manufactureof asphalt cutbacks.)
FM 5-436
2-2 Bituminous Design
Tabl
e2-
1.C
hara
cter
istic
sof
Bitu
min
ous
Mat
eria
ls
Mat
eria
lF
orm
Gra
deD
esig
na-
tion
Tem
pera
ture
ofA
pplic
atio
nR
ange
sF
lash
Poi
ntR
emar
ksS
pray
ing
1M
ixin
g
°F°C
°F°C
°F°C
Pen
etra
tive
soil
bind
erLi
quid
130-
150
55-
6580
27C
onta
ins
naph
tha.
Cau
tion:
Hig
hly
flam
mab
le.
Cut
back
(RC
)
Liqu
id—
asph
alt
resi
dues
fluxe
dw
ithm
ore
vola
tile
petr
oleu
mdi
still
ate
RC
-70
RC
-250
RC
-800
RC
-3,0
00
105-
1752
145-
220
180-
255
215-
2902
41-7
92
63-1
04
82-1
242
102-
1432
95-1
3513
5-17
517
0-21
020
0-24
0
35-5
757
-79
77-9
993
-116
80 80 80
27 27 27
RC
cutb
acks
cont
ain
high
lyvo
latil
ena
phth
acu
tters
tock
.N
apht
haev
apor
ates
quic
kly,
leav
ing
anA
Cbi
nder
and
perm
ittin
gea
rlyus
eof
the
surf
ace.
Cau
tion:
Hig
hly
flam
mab
le.
Cut
back
(MC
)
Liqu
id—
asph
alt
resi
dues
fluxe
dw
ithm
ore
vola
tile
petr
oleu
mdi
still
ate
MC
-30
MC
-70
MC
-250
MC
-800
MC
-3,0
00
70-1
4010
5-17
514
5-22
018
0-25
521
5-29
0
21-6
041
-79
63-1
0482
-124
102-
143
55-9
595
-135
135-
175
170-
210
200-
240
13-3
535
-57
57-7
977
-99
93-1
16
100
100
150
150
150
37 37 65 65 65
MC
cutb
acks
cont
ain
less
vola
tile
kero
sene
cutte
rst
ock.
Ker
osen
eev
apor
ates
less
rapi
dly
than
naph
tha.
Cau
tion:
Fla
mm
able
.
Cut
back
(SC
)
Liqu
id—
asph
alt
resi
dues
fluxe
dw
ithm
ore
vola
tile
petr
oleu
mdi
still
ate
SC
-70
SC
-250
SC
-800
SC
-3,0
00
105-
175
145-
220
180-
225
215-
290
41-7
963
-104
82-1
2410
2-14
3
95-1
3513
5-17
517
0-21
020
0-24
0
35-5
757
-79
71-9
993
-116
150
175+
200+
225+
65 79+
93+
107+
SC
cutb
acks
cont
ain
slig
htly
vola
tile
dies
el-f
uelc
utte
rst
ock.
Die
self
uele
vapo
rate
ssl
owly
.C
autio
n:F
lam
mab
le.
AC
Sol
id
40-5
060
-70
85-1
0012
0-15
020
0-30
0
285-
350
285-
350
285-
350
260-
325
141-
177
141-
177
141-
177
127-
163
300-
350
275-
325
275-
325
275-
325
200-
275
149-
177
135-
163
135-
163
135-
163
93-1
35
Pen
etra
tions
40to
100
are
used
for
crac
kan
djo
int
fille
rs.P
enet
ratio
ns70
to30
0ar
eus
edfo
rpl
ant
mix
es,p
enet
ratio
nm
acad
am,a
ndsu
rfac
etr
eatm
ent.
Test
tode
term
ine
the
flash
poin
t.
Pow
dere
das
phal
tH
ard
and
solid
asph
altg
roun
dto
pow
der
Use
dw
ithS
Cto
prod
uce
extr
ato
ugh
road
surf
aces
.
1 Low
tem
pera
ture
isba
sed
ona
200-
cent
isto
keki
nem
atic
visc
osity
,and
the
high
tem
pera
ture
isba
sed
ona
50-c
entis
toke
visc
osity
.2 R
Ccu
tbac
ksar
ese
ldom
used
for
spra
ying
.
FM 5-436
Bituminous Design 2-3
Tabl
e2-
1.C
hara
cter
istic
sof
Bitu
min
ous
Mat
eria
ls(c
ontin
ued)
Mat
eria
lF
orm
Gra
deD
esig
-na
tion
Tem
pera
ture
ofA
pplic
atio
nR
ange
sF
lash
Poi
ntR
emar
ksS
pray
ing
1M
ixin
g
°F°C
°F°C
°F°C
Asp
halt
emul
sion
(RS
)
Liqu
id(a
spha
ltpa
rtic
les
held
inan
aque
ous
susp
ensi
onby
anem
ulsi
fyin
gag
ent)
RS
-1R
S-2
RS
-2K
RS
-3K
50-1
4050
-140
50-1
4050
-140
10-6
010
-60
10-6
010
-60
Non
mix
ing
50-1
4050
-140
50-1
40
10-6
010
-60
10-6
010
-60
Fre
ezin
gde
stro
ysem
ulsi
ons.
Use
dfo
rroa
dan
dpl
antm
ixes
with
CA
(SS
).A
llem
ulsi
ons
with
“K”
suffi
xar
eca
tioni
c.
Asp
halt
emul
sion
(MS
)
Liqu
id(a
spha
ltpa
rtic
les
held
inan
aque
ous
susp
ensi
onby
anem
ulsi
fyin
gag
ent)
MS
-2S
M-K
CM
-K
50-1
4050
-140
50-1
40
10-6
010
-60
10-6
0
50-1
4050
-140
50-1
40
10-6
010
-60
10-6
0
Asp
halt
emul
sion
(SS
)
Liqu
id(a
spha
ltpa
rtic
les
held
inan
aque
ous
susp
ensi
onby
anem
ulsi
fyin
gag
ent)
SS
-1S
S-1
HS
S-K
SS
-KH
50-1
4050
-140
50-1
4050
-140
10-6
010
-60
10-6
010
-60
50-1
4050
-140
50-1
4050
-140
10-6
010
-60
10-6
010
-60
RT
Liqu
idR
T-1
RT-
2R
T-3
60-1
2560
-125
60-1
25
15-5
215
-52
27-6
6
Prim
ing
oils
.RT-
4th
roug
hR
T-12
are
notg
ener
ally
used
.
RT
CB
Liqu
idR
TC
B-5
RT
CB
-660
-120
60-1
2016
-49
16-4
9P
atch
ing
mix
ture
s.C
autio
n:F
lam
mab
le.
Roc
kas
phal
tS
olid
Mix
edan
dus
edlo
cally
whe
refo
und.
Cut
back
may
bead
ded
ifne
cess
ary.
1 Low
tem
pera
ture
isba
sed
ona
200-
cent
isto
keki
nem
atic
visc
osity
,and
the
high
tem
pera
ture
isba
sed
ona
50-c
entis
toke
visc
osity
.2 R
Ccu
tbac
ksar
ese
ldom
used
for
spra
ying
.
FM 5-436
2-4 Bituminous Design
Table 2-2. Typical Uses of Bituminous Materials
Purpose or Use Grade or Designation 1 of Asphalt Cutback 2
RC MC SC
Dust palliative DCA-703 MC-30, -70, -250APSB
SC-70, -250
Prime coat:Tightly bonded surfacesLoosely bonded, fine-grained surfacesLoosely bonded, coarse-grained
surfaces
MC-30MC-70MC-250
SC-70SC-250
Tack coat RC-250, -800 MC-250, -800
Surface treatment and seal coat:Coarse sand coverClean CA coverGraded gravel aggregate coverGravel mulch
1Prevailing temperature during construction also affects selection of bitumen and may be thedetermining factor rather than size and gradation of aggregate.2Caution: Do not overheat aggregate when cutbacks are used to produce hot mixes.3DCA-70 is a water emulsion of a polyvinyl acetate containing chemical modifiers (formerly UCAR-131). Proprietary product of Union Carbide Corporation, New York, NY.
FM 5-436
Bituminous Design 2-5
ASPHALT EMULSION
2-4. The mixing grades of asphalt emulsion can be combined with dampaggregate with little or no heating. The recommended use depends on thesetting rate and the mixing ability. Use emulsions for surface treatments, roadand plant mixes, and crack and joint fillings.
TAR
2-5. Since tar does not dissolve in petroleum distillates, use it in areas whereasphalt is unsuitable, such as refueling aprons at airfields where petroleumdistillates are likely to be spilled. Because tar has greater penetratingqualities than asphalt, it is preferred when penetration is critical. Use hot tarfor plant mixes, surface treatments, penetration macadams, and crack fillers.Use RTCB for patch mixes, surface treatments, and road mixes. Do not useopen flames near storage tanks or drums of RTCB because it is highlyflammable. Tar is more susceptible to temperature changes than asphalt, andtar becomes soft at high temperatures and brittle at low temperatures.
AGGREGATE SELECTION
2-6. Before including specific aggregate in a mix design, conduct apreliminary investigation of the aggregate and ensure that its physicalproperties conform to those described in Chapter 1. In addition, perform acomplete analysis of the aggregate as described in FM 5-472 and determinethe quantity of aggregate available. Select the gradation specification usingthe criteria in Table 2-3, pages 2-6 through 2-9.
MIX GRADATION
2-7. Aggregates and mineral fillers can be combined to produce a dense-graded or an open-graded mix:
• Dense-graded mix. A dense-graded mix contains a continuousgradation of particle sizes that are coarse to very fine. Fine particlesfill the voids between large particles, thereby increasing the mix’sweight. A dense-graded mix is more impervious to water and providesmore protection to the base and the subgrade. It usually requires lessmaintenance, and the asphalt life is prolonged. However, a dense-graded mix requires precise determination and control of the bitumen-aggregate ratio.
• Open-graded mix. An open-graded mix also contains coarse and fineparticles in a continuous gradation. However, it does not containenough fine particles to fill the voids between large particles so it isless dense. Because of the increased voids in an open-graded mix, thebitumen-aggregate ratio is less critical.
FM 5-436
2-6 Bituminous Design
Tabl
e2-
3.G
rada
tion
Spe
cific
atio
nLi
mits
for
Bitu
min
ous
Con
stru
ctio
n
Sie
veD
esig
na-
tion
Per
cent
age
Pas
sing
byW
eigh
tM
axim
umP
artic
leS
ize
2In
ch1
1/2
Inch
1In
ch3/
4In
ch1/
2In
ch1/
4In
chP
avem
ents
,Pla
ntM
ixes
(Squ
are
Ope
ning
s)
Asp
halt
Mix
ture
,Sur
face
Cou
rse,
Low
-Pre
ssur
eTi
res
(100
psia
ndU
nder
)G
rada
tion
1G
rada
tion
2G
rada
tion
3G
rada
tion
4G
rada
tion
5A
BC
AB
CA
BC
AB
CA
BC
11/
2in
ch10
010
010
0--
---
---
---
---
---
---
---
---
---
---
---
-1
inch
79-9
583
-96
86-9
810
010
010
0--
---
---
---
---
---
---
---
---
-
3/4
inch
70-8
474
-86
78-9
080
-95
84-9
690
-98
100
100
100
---
---
---
---
---
---
1/2
inch
61-7
566
-79
71-8
468
-86
74-8
979
-93
80-9
584
-96
87-9
810
010
010
0--
---
---
-
3/8
inch
54-6
860
-72
65-7
860
-77
66-8
272
-87
72-8
676
-88
80-9
279
-94
81-9
585
-96
100
100
100
No.
442
-54
48-6
054
-66
45-6
052
-68
60-7
555
-70
61-7
467
-80
59-7
364
-80
72-8
575
-95
78-9
580
-95
No.
833
-45
39-5
145
-57
34-4
941
-57
49-6
443
-57
49-6
256
-68
46-6
053
-67
60-7
360
-79
63-8
366
-86
No.
1626
-37
31-4
237
-48
26-4
033
-47
40-5
434
-46
39-5
146
-57
39-4
942
-54
48-6
046
-65
49-6
852
-72
No.
3019
-29
23-3
329
-38
19-3
025
-37
30-4
326
-36
30-4
036
-46
28-3
832
-42
37-4
833
-51
36-5
438
-58
No.
5014
-22
17-2
521
-29
14-2
318
-28
21-3
218
-27
21-3
026
-34
19-2
822
-30
26-3
521
-37
24-4
026
-43
No.
100
8-14
10-1
613
-19
8-16
11-1
813
-21
10-1
713
-20
16-2
211
-18
13-2
016
-22
12-2
414
-26
16-2
8
No.
2001
3-6
3.5-
6.5
4-7
3-7
3.5-
7.6
4-8
3-7
3.5-
7.5
4-8
4-8
4-8
4-8
5-9
6-10
7-11
Asp
halt
Mix
ture
,Sur
face
Cou
rse,
Hig
h-P
ress
ure
Tire
s(O
ver
100
psi),
Opt
iona
lfor
Low
-Pre
ssur
eTi
res
Gra
datio
n6
Gra
datio
n7
AB
CA
BC
1in
ch10
0--
---
---
---
---
-
3/4
inch
86-9
7--
---
-10
0--
---
-
1/2
inch
76-9
0--
---
-82
-96
---
---
3/8
inch
69-8
3--
---
-79
-90
---
---
No.
455
-70
---
---
60-7
3--
---
-
No.
845
-59
---
---
46-6
0--
---
-
No.
1635
-48
---
---
34-4
8--
---
-
No.
3026
-38
---
---
24-3
8--
---
-
No.
5017
-29
---
---
15-2
8--
---
-N
o.10
010
-20
---
---
8-17
---
---
No.
2001
3-6
---
---
3-6
---
---
1 Fra
ctio
npa
ssin
gN
o.20
0si
eve
shal
lcon
form
toth
efo
llow
ing
grad
atio
nlim
its:0
.05-
in,7
0-10
0%fin
es;0
.02-
in,3
5-65
%fin
es;0
.005
,10-
22%
fines
.2 M
axim
umpa
rtic
lesi
zeis
21/
2in
ch.
3 Cle
ansa
ndor
sand
grav
elm
aybe
used
inst
ead
ofcr
ushe
dro
ck.
4 Max
imum
part
icle
size
will
pass
aN
o.4
siev
e.
FM 5-436
Bituminous Design 2-7
Tabl
e2-
3.G
rada
tion
Spe
cific
atio
nLi
mits
for
Bitu
min
ous
Con
stru
ctio
n(c
ontin
ued)
Sie
veD
esig
na-
tion
Per
cent
age
Pas
sing
byW
eigh
tM
axim
umP
artic
leS
ize
2In
ch1
1/2
Inch
1In
ch3/
4In
ch1/
2In
ch1/
4In
chP
avem
ents
,Pla
ntM
ixes
(Squ
are
Ope
ning
s)
Asp
halt
Mix
ture
,Bin
der
Cou
rse,
Hig
h-an
dLo
w-P
ress
ure
Tire
sG
rada
tion
8G
rada
tion
9G
rada
tion
10G
rada
tion
11G
rada
tion
12A
BC
AB
CA
BC
AB
CA
BC
2in
ch10
010
010
0--
---
---
---
---
---
---
---
---
---
---
---
-
11/
2in
ch79
-95
81-9
582
-96
100
100
100
---
---
---
---
---
---
---
---
---
1in
ch68
-84
70-8
671
-88
73-9
575
-95
79-9
510
010
010
0--
---
---
---
---
---
-
3/4
inch
60-7
562
-78
64-7
964
-83
67-8
570
-87
72-9
575
-95
81-9
610
010
010
0--
---
---
-
1/2
inch
52-6
754
-69
56-7
255
-73
59-7
762
-80
61-8
265
-85
69-8
970
-95
74-9
577
-95
100
100
100
3/8
inch
46-6
048
-63
50-6
648
-65
52-6
955
-73
53-7
258
-76
62-8
160
-80
64-8
468
-88
71-9
575
-95
78-9
5N
o.4
32-4
734
-49
37-5
235
-51
39-5
542
-58
38-5
443
-59
48-6
642
-60
47-6
552
-70
50-7
154
-75
59-8
0
No.
822
-37
24-3
927
-42
26-4
029
-45
33-4
928
-43
32-4
737
-53
30-4
936
-54
29-5
736
-56
40-6
045
-66
No.
1617
-30
18-3
120
-34
19-3
222
-36
25-3
920
-34
24-3
828
-43
23-3
927
-43
29-4
626
-44
29-4
834
-52
No.
3012
-23
14-2
415
-26
14-2
516
-27
18-3
015
-27
17-2
920
-33
17-3
019
-23
22-3
619
-34
22-3
725
-40
No.
508-
189-
1810
-19
10-1
811
-20
12-2
110
-20
11-2
214
-24
12-2
313
-24
15-2
613
-25
15-2
717
-29
No.
100
5-12
5-12
6-14
5-12
6-13
7-14
7-14
7-15
8-16
7-16
8-17
9-18
9-18
10-1
911
-19
No.
2001
3-7
3-7
3-7
3-7
3-7
3-7
3-7
3-7
3-7
3-7
3-7
3-7
4-9
4-9
4-9
Tar
Mix
ture
,Sur
face
Cou
rse,
Low
-Pre
ssur
eTi
res
(100
psia
ndun
der)
Gra
datio
n13
Gra
datio
n14
Gra
datio
n15
AB
CA
BC
AB
C1
inch
100
100
100
---
---
---
---
---
---
3/4
inch
78-9
580
-95
84-9
610
010
010
0--
---
---
-
1/2
inch
68-8
571
-88
75-9
076
-95
80-9
585
-96
100
100
100
3/8
inch
57-7
562
-82
66-8
567
-85
73-8
979
-93
75-9
580
-95
86-9
6
No.
440
-58
47-6
552
-70
50-6
658
-73
65-8
055
-70
63-8
070
-84
No.
828
-46
35-5
140
-58
38-5
343
-58
53-6
838
-54
48-6
754
-69
No.
1620
-35
26-4
030
-47
28-4
132
-46
41-5
527
-41
36-4
941
-55
No.
3013
-25
18-3
022
-36
19-3
023
-36
29-4
218
-29
24-3
628
-42
No.
508-
1712
-21
15-2
612
-21
15-2
518
-29
10-2
015
-25
18-2
9
No.
100
4-12
7-14
9-18
6-14
90-1
611
-18
6-13
9-17
11-1
9
No.
2001
2-8
4-10
4-10
4-10
4-10
6-10
4-10
7-10
6-10
1 Fra
ctio
npa
ssin
gN
o.20
0si
eve
shal
lcon
form
toth
efo
llow
ing
grad
atio
nlim
its:0
.05-
in,7
0-10
0%fin
es;0
.02-
in,3
5-65
%fin
es;0
.005
,10-
22%
fines
.2 M
axim
umpa
rtic
lesi
zeis
21/
2in
ch.
3 Cle
ansa
ndor
sand
grav
elm
aybe
used
inst
ead
ofcr
ushe
dro
ck.
4 Max
imum
part
icle
size
will
pass
aN
o.4
siev
e.
FM 5-436
2-8 Bituminous Design
Tabl
e2-
3.G
rada
tion
Spe
cific
atio
nLi
mits
for
Bitu
min
ous
Con
stru
ctio
n(c
ontin
ued)
Sie
veD
esig
na-
tion
Per
cent
age
Pas
sing
byW
eigh
t
Max
imum
Par
ticle
Siz
e
2In
ch1
1/2
Inch
1In
ch3/
4In
ch1/
2In
ch1/
4In
ch
Pav
emen
ts,P
lant
Mix
es
(Squ
are
Ope
ning
s)
Tar
Mix
ture
,Bin
der
Cou
rse,
Hig
h-an
dLo
w-P
ress
ure
Tire
s
Gra
datio
n16
AB
C
11/
2in
ch10
0--
---
-
1in
ch70
-95
---
---
3/4
inch
56-8
4--
---
-
1/2
inch
44-7
5--
---
-
3/8
inch
36-6
5--
---
-
No.
420
-95
---
---
No.
812
-23
---
---
No.
166-
23--
---
-
No.
302-
15--
---
-
No.
500-
8--
---
-
No.
100
0-4
---
---
Bitu
min
ous
Mix
ture
,Sur
face
Cou
rse
Gra
datio
n17
Gra
datio
n18
Gra
datio
n19
AB
CA
BC
AB
C
1in
ch10
0--
---
---
---
---
---
---
---
-
3/4
inch
85-1
00--
---
-10
0--
---
---
---
---
-
1/2
inch
72-9
5--
---
-82
-100
---
---
---
---
---
3/8
inch
61-9
0--
---
-68
-95
---
---
100
---
---
No.
443
-79
---
---
48-3
2--
---
-57
-88
---
---
No.
832
-68
---
---
35-7
1--
---
-41
-76
---
---
No.
1624
-56
---
---
26-6
0--
---
-30
-64
---
---
No.
3018
-44
---
---
20-4
8--
---
-22
-52
---
---
No.
5013
-32
---
---
14-3
8--
---
-15
-40
---
---
No.
100
9-21
---
---
10-2
5--
---
-10
-26
---
---
No.
2001
5-12
---
---
5-12
---
---
5-12
---
---
1 Fra
ctio
npa
ssin
gN
o.20
0si
eve
shal
lcon
form
toth
efo
llow
ing
grad
atio
nlim
its:0
.05-
in,7
0-10
0%fin
es;0
.02-
in,3
5-65
%fin
es;0
.005
,10-
22%
fines
.2 M
axim
umpa
rtic
lesi
zeis
21/
2in
ch.
3 Cle
ansa
ndor
sand
grav
elm
aybe
used
inst
ead
ofcr
ushe
dro
ck.
4 Max
imum
part
icle
size
will
pass
aN
o.4
siev
e.
FM 5-436
Bituminous Design 2-9
Tabl
e2-
3.G
rada
tion
Spe
cific
atio
nLi
mits
for
Bitu
min
ous
Con
stru
ctio
n(c
ontin
ued)
Sie
veD
esig
na-
tion
Per
cent
age
Pas
sing
byW
eigh
t
Max
imum
Par
ticle
Siz
e
2In
ch1
1/2
Inch
1In
ch3/
4In
ch1/
2In
ch1/
4In
ch
Pav
emen
ts,P
lant
Mix
es
(Squ
are
Ope
ning
s)
Tar
Mix
ture
,Bin
der
Cou
rse,
Hig
h-an
dLo
w-P
ress
ure
Tire
s
Gra
datio
n20
2G
rada
tion
21G
rada
tion
22
AB
CA
BC
AB
C
21/
2in
ch10
0--
---
---
---
---
---
---
---
-
2in
ch90
-100
---
---
---
---
---
---
---
---
11/
2in
ch35
-70
---
---
---
---
---
---
---
---
1in
ch0-
15--
---
-10
0--
---
---
---
---
-
3/4
inch
0-9
---
---
90-1
00--
---
---
-10
0--
-
1/2
inch
0-5
---
---
55-8
0--
---
---
-90
-100
---
3/8
inch
---
---
---
20-5
5--
---
---
-40
-75
---
No.
4--
---
---
-0-
10--
---
---
-5-
25--
-
No.
8--
---
---
-0-
5--
---
---
-0-
5--
-
Bitu
min
ous
Mix
ture
,Sur
face
Cou
rse
Gra
datio
n23
Gra
datio
n24
Gra
datio
n25
Gra
datio
n26
3G
rada
tion
273
AB
CA
BC
AB
CA
BC
AB
C4
11/
2in
ch10
0--
---
---
---
---
---
---
---
---
---
---
---
---
---
-
1in
ch90
-100
---
---
100
100
---
---
---
---
---
---
---
---
---
---
3/4
inch
40-7
5--
---
-90
-100
90-1
00--
-10
010
0--
---
---
---
---
---
---
-
1/2
inch
15-3
5--
---
-20
-55
45-7
5--
-90
-100
90-1
00--
-10
0--
---
---
---
---
-
3/8
inch
0-15
---
---
0-15
20-5
5--
-40
-70
40-7
5--
-85
-100
---
---
100
100
---
No.
40-
5--
---
-0-
50-
10--
-0-
155-
25--
-10
-30
---
---
85-1
0095
-100
100
No.
8--
---
---
---
-0-
5--
-0-
50-
5--
-0-
10--
---
-10
-40
70-9
250
-100
No.
16--
---
---
---
---
---
---
---
---
---
---
---
-0-
1045
-80
---
No.
30--
---
---
---
---
---
---
---
---
---
---
---
---
-26
-56
---
No.
50--
---
---
---
---
---
---
---
---
---
---
---
---
-5-
30--
-
No.
100
---
---
---
---
---
---
---
---
---
---
---
---
---
0-8
---
1 Fra
ctio
npa
ssin
gN
o.20
0si
eve
shal
lcon
form
toth
efo
llow
ing
grad
atio
nlim
its:0
.05-
in,7
0-10
0%fin
es;0
.02-
in,3
5-65
%fin
es;0
.005
,10-
22%
fines
.2 M
axim
umpa
rtic
lesi
zeis
21/
2in
ch.
3 Cle
ansa
ndor
sand
grav
elm
aybe
used
inst
ead
ofcr
ushe
dro
ck.
4 Max
imum
part
icle
size
will
pass
aN
o.4
siev
e.
FM 5-436
2-10 Bitu minou s Design
2-8. The allowable variation in gradation of some low and intermediate mixesis great enough that natural or man-made aggregates can be used without anyspecial preparation. High mixes and some intermediate mixes have such asmall allowable variation in gradation that two or more aggregates must beblended to obtain the desired gradation.
2-9. The following example shows how to determine specific requirements fora surface course:
Example: You are using an asphalt finisher to place a 2-inch surface courseon a main supply route (MSR). The maximum aggregate size available is 1inch, and a limited supply of limestone dust is available to use as a mineralfiller. The bitumen is AC, so an aggregate gradation must be selected.
Solution:
• Surface course thickness: 2 inches.• Bitumen: AC.• Tire pressure: Low (truck tires have <100 pounds per square inch
[psi]).• Maximum aggregate size available: 1 inch.• Method of placement: Machine (2 inches x 0.5 = 1 inch).• Gradation type: Open-graded (conserves limestone dust).
AGGREGATE BLENDING
2-10. Aggregate blending is proportionately mixing several aggregategradations to obtain one desired aggregate gradation. The normal procedureis to mix three or four aggregates from various sources. Record the results ofgradation tests for each source on Department of Defense (DD) Form 1207(Figure 2-1, pages 2-11 and 2-12) or present them in tabular form.
2-11. Use DD Form 1217 (Figure 2-2, pages 2-13 and 2-14) as a work sheet tocalculate the aggregate blend. There are several methods for determining thecorrect blend; however, use the test-strip method because other methodsrequire complicated graphs and formulas.
FM 5-436
Bituminous Design 2-11
SAMPLE
Fig
ure
2-1.
Sam
ple
DD
For
m12
07
FM 5-436
2-12 Bituminous Design
SAMPLE
Fig
ure
2-1.
Sam
ple
DD
For
m12
07(c
ontin
ued)
FM 5-436
Bituminous Design 2-13
SAMPLE
Fig
ure
2-2.
Sam
ple
DD
For
m12
17
FM 5-436
2-14 Bituminous Design
SAMPLE
Fig
ure
2-2.
Sam
ple
DD
For
m12
17(c
ontin
ued)
FM 5-436
Bituminous Design 2-15
EXAMPLE OF AGGREGATE BLENDING
2-12. This example shows how to determine aggregate blending. Usegradation 2A as the specification limit, and refer to Figure 2-1, page 2-11, forthe gradations of stockpile samples. Complete a DD Form 1217 (Figure 2-2,page 2-13) for a bituminous mix design.
Gradation of Material
2-13. Complete this section as follows:
• Record the sieve sizes and percents passing for all four aggregates.• Enter the specified gradation limits across the desired row of the
section for reference.• Enter 100 percent in all the blanks to the left of the 100 percent
passing for each aggregate. (When 100 percent passes any given sieve,it will also pass larger sieves.)
Combined Gradation for Blend—Trial Number 1
2-14. Complete this section as follows:
• Enter the mean of the specified gradation limits in the desired row.For example, the percentage of the specified gradation limits for a 3/4-inch sieve is 0.5 x (80 + 95) = 87.5 percent.
• Estimate the percent used. The first estimate should be the mineral-filler value. In this example, the mineral filler is limestone dust (LSD).Estimate the percent used by calculating the percent necessary tosatisfy the number 200 requirements. For example, 90 percent of theLSD passed the number 200 sieve at the stockpile. The desiredamount passing is 5 percent with a low limit of 3 percent, so use 4percent for trial number 1. The percent used is 0.04 x 90 = 3.6.
• Calculate the percent passing for each sieve size and gradation usingthe following formula: percent passing = percent used x gradation ofmaterial. For example, trial number 1 indicates that the mix designcontains 45 percent CA and the gradation test shows that 72 percentof the CA passed the 3/4-inch sieve at the stockpile. Therefore, thepercent passing is 0.45 x 72 = 32.4.
• Examine other gradations that contribute to the percent passing. Forexample, Figure 2-2 shows that only 3 percent of the fine river-barsand (FRBS) passed the number 200 sieve at the stockpile. Thus, anynormal FRBS value would affect the percent passing the number 200sieve by less than one. Four percent would be somewhat low, so use 5percent. The percent passing is 0.05 x 90 = 4.5.
• Add the columns for each sieve and compare the totals to the desiredgradation range. Ensure that the total of the percent-used column is100. When blending three aggregates, find the intermediate aggregatepercent-used column by subtracting the two predetermined percent-used figures from 100. If you are blending more than three aggregates,subtract the two predetermined percent-used figures from 100 anddivide this figure by the number of intermediate aggregates. Thisyields the trial percent used for each aggregate. For example, if the
FM 5-436
2-16 Bituminous Design
percent of CA used is 45, the percent of FA used is 5, and the twointermediate aggregates are FA and FRBS, the intermediateaggregate percent is 25 as shown in the following calculation:
Combined Gradation for Blend—Trial Number 2
2-15. Complete this block as follows:
• Use a series of calculations to obtain the percents used for the secondtrial.
• Calculate the average of the specified gradation range for the percentpassing the second largest sieve by using the following formula:
where—T = percent passing at the stockpileS = mean of the upper and lower limits of the specified gradation range for
the percent passing the second largest sieveC = percent passing the second largest sieve for the original gradation of
the aggregate
Example: In Figure 2-2, page 2-13, and the sample DD Form 1219 shown inFigure 2-3, the gradation range of the CA is 80 to 95 and 72 percent of the CApassed the 3/4-inch sieve at the stockpile.
Solution:
• Complete each block as explained in paragraph 2-14 for trial 1.
Succeeding Trials
2-16. Each succeeding trial is a refinement of the results from the precedingtrial. Even if the results of the first trial are within the limits of the specifiedgradation, try to get a blend that is as close as possible to the means of thegradation. This allows for a slightly greater deviation in the blend, whichlimits the frequency of adjustments to the central plant (see Figure 2-2).Conduct succeeding trials as follows:
• Inspect the preceding trial and note the sieve sizes whose blend is notwithin the specified gradation range.
• Consider changing the percent of intermediate aggregate used to yieldresults that are within the specified limits.
----------------------------- 44.7 or 45 percent===
FM 5-436
Bitumin ous Desig n 2-17
Figur e 2-3. Sampl e DD Form 1219
SAMPLE
FM 5-436
2-18 Bituminous Design
• Consider changing the original CA and FA figures since the originalfigures were only guides.
2-17. For example, in trial 1, the blend values between the number 4 and thenumber 200 sieves were high. Reduce the percent-passing value by reducingthe amount of the fine material in the blend. Try a trial gradation of 45/30/20/5 (CA/FA/FRBS/LSD) to correct the blend.
Final Trial
2-18. Conduct a final trial when the set of values are well within the specifiedlimits. Evaluation of the percent-used column shows that a relatively largerange of values yields results that are within the specification limits. Thepurpose of a final trial is to obtain a blend as close as possible to the mean ofthe specification limits. Compute the final trial the same as preceding trials,except ensure that the desired row contains the mean value (average of highand low values) of the specifications. In the sample, trial 2 is close enough tothe median that no further trials are necessary.
REPORTING
2-19. Allow an independent party to check the calculations completed for theaggregate blending and record the information on the following forms:
• DD Form 1217 (Figure 2-2, page 2-13). This is a reporting andcomputational form. Record the gradation of material and trialcomputations. Enter the contents of the final trial in the blockfollowing the last numbered trial.
• DD Form 1207 (Figure 2-1, page 2-11). This is a graphical record ofthe aggregate blend. Plot the upper and lower limits of the specifiedgradation, the mean of the specified gradation, and the calculatedfinal blend on the same graph (the mean is sometimes omitted).
OPTIMUM BITUMEN CONTENT
2-20. The Marshall test method is used to determine the optimum bitumencontent (OBC) of hot-mix pavements where stability and durability arerequired to withstand the action of high-pressure aircraft tires or heavy roadtraffic. A modified version of the Marshall test is used to determine the OBCfor cold mixes. (See FM 5-472 for complete details on the Marshall testmethod.)
REPORTING TEST RESULTS
2-21. Report the test results on one of the following forms:
• DD Form 1218 (Figure 2-4, pages 2-19 and 2-20). This form is thelaboratory work sheet for the Marshall test. If the form is used in lieuof bituminous mix curves, plot the curves to evaluate the data.
FM 5-436
Bituminous Design 2-19
SAMPLE
Fig
ure
2-4.
Sam
ple
DD
For
m12
18
FM 5-436
2-20 Bituminous Design
SAMPLE
Fig
ure
2-4.
Sam
ple
DD
For
m12
18(c
ontin
ued)
FM 5-436
Bituminous Design 2-21
• DD Form 1219 (Figure 2-3, page 2-17). This form presents theresults of the Marshall test in graphic form. Ensure that the curvesare smooth and without deviations, including extraneous values.
EVALUATING TEST RESULTS
2-22. Use the information in Table 2-4 to evaluate the results of the Marshalltest and to obtain an OBC.
2-23. Obtain the percent of bitumen for stability, the unit weight, the percentof voids in the total mix, and the percent of voids filled with bitumen fromTable 2-3, page 2-6, and Figure 2-3. Average the bitumen-content percentagesand note the result as the trial OBC.
Asphalt-concretebinder course Peak of curve2 Peak of curve2 ≥500 lb ≥1,800 lb
Sand asphalt Peak of curve --- ≥500 lb ---
Unit weight
Asphalt-concretesurface course
Peak of curve Peak of curve Not used Not used
Asphalt-concretebinder course
Not used Not used Not used Not used
Sand asphalt Peak of curve --- Not used Not used
Flow
Asphalt-concretesurface course
Not used Not used ≤20 lb ≤16 lb
Asphalt-concretebinder course
Not used Not used ≤20 lb ≤16 lb
Sand asphalt Not used Not used ≤20 lb ≤16 lb
Percent ofvoids in thetotal mix
Asphalt-concretesurface course
4 (3) 4 (3) 3-5 (2-4) 3-5 (2-4)
Asphalt-concretebinder course
5 (4) 6 (5) 4-5 (3-5) 5-7 (4-6)
Sand asphalt 6 (5) --- (-) 5-7 (4-6) --- (-)
Percent ofvoids filledwith bitumen
Asphalt-concretesurface course
80 (85) 75 (80) 75-85 (80-90) 70-80 (75-85)
Asphalt-concretebinder course
70 (75) 60 (65)2 65-75 (70-80) 70-80 (55-85)
Sand asphalt 70 (75) --- (-) 65-75 (70-80) --- (-)1Figures in parentheses are for use with bulk-impregnated specific gravity (water absorption by aggregategreater than 2.5 percent).2If the inclusion of the optimum asphalt content of these points (average) causes the voids in the total mix tofall outside the limits, adjust the optimum asphalt content so that the voids in the total mix are within the limits.
FM 5-436
2-22 Bituminous Design
Example: The bituminous mix curves shown in Figure 2-3, page 2-17, are foran airfield AC surface course (high-pressure tires). Determine the trial OBC.
Solution:
• Unit weight: 4.5.• Stability: 4.3.• Percent of voids in the total mix: 4.9.• Percent of voids filled with bitumen: 5.• Total: 18.7.• Average: 18.7 ÷ 4 = 4.7 percent AC (trial OBC).
2-24. Evaluate the curves for stability, flow, percent of voids in the total mix,and percent of voids filled with bitumen at the trial OBC. Compare thesevalues with the criteria in Table 2-3, page 2-6. If all the values meet thecriteria, the trial OBC becomes the final OBC. If one or more of the criteriafails to meet the specifications—
• Recheck computations.• Determine if any of the curves yields a bitumen that is out of line with
the others. If so, rerun the Marshall test.• Recheck the aggregate for conformance to the specified blend.• Rerun the Marshall test (check apparatus first).• Change the aggregate blend.
2-25. The test properties of the sample mix (Table 2-5) are within thespecification limits, so designate the trial OBC as the final OBC.
JOB-MIX FORMULA
2-26. After establishing the OBC and the aggregate blend, determine theactual percentages, by weight, of the components in the final mix. Thefollowing example shows how to determine the job-mix formula:
Example: The OBC is set at 5.5 percent, and the aggregate blend is 40/30/25/5 (CA/FA/FRBS/LSD). Determine the job-mix formula (see Table 2-6, page2-23).
Solution:
Table 2-5. Marshall-Test Results of the Sample Mix
Test Property Actual Value Desired Value
Stability (pounds) 2,020 >1,800
Flow (1/100 inch) 10.8 <16
Percent of voids in the total mix 4.2 3 to 5
Percent of voids filled with bitumen 72.3 70 to 80
100 OBC–100
---------------------------100 5.5–
100----------------------
94.5100---------- 0.945 percent of bitumen= = =
FM 5-436
Bituminous Design 2-23
2-27. In the field, check the mix for conformance to specifications using one ofthe following methods.
• Mix-percentage check. Compare the percentage of bitumen in thecompleted mix with the percentage set up in the design. Perform thischeck daily (minimum) at the plant or the construction site. (See FM5-472 for further details on this procedure.)
• Density check. Perform a density check on samples from thecompacted, cooled, and completed pavement. This test checks the mixand the construction methods used in placing and compacting the mix.(See Chapter 4 for further details on the density test.)
Table 2-6. Sample Job-Mix Formula
ComponentAggregate
BlendPercent ofBitumen
Percentof Mix
CA 40 x 0.945 = 37.8
FA 30 x 0.945 = 28.4
FRBS 25 x 0.945 = 23.6
LSD 5 x 0.945 = 4.7
AC 5.5
Total 100.0
NOTE: The total percent of the mix always equals100.
