Complete Guide to Job Mix Formula (JMF) and Marshall Stability Test for HMA Layers

JOB MIX FORMULA (JMF)
PRSENTED BY: NISSAR AHMED
2

INTRODUCTION
 Basically, its just a recipe for
making hot mix.
That would be the asphalt
cement.
That would be the aggregate.
3

ASPHALT CONCRETE
Asphaltic concrete is a mixture of
Coarse Aggregate
Fine aggregate
Mineral filler and
Bitumen

ASPHALT BINDER
 The main purpose of the binder is to completely coat the surface
area of the aggregate. This will waterproof the aggregate.
 Too little AC in the mix can leave portions of the aggregate
uncoated. This results in a lack of durability and strength, and can
lead to raveling or stripping.
 Too much AC in the mix results in a needlessly expensive mix, rich
spots or bleeding, lowered skid resistance, and rutting or shoving of
the pavement. In other words, the performance of the pavement
depends on how much asphalt binder is in the mix. 5

BITUMEN
The residue of crude oil in a distillation
process is called bitumen.
6
It is brown and black in
color.
 It is uses as a binder
material.

Tests on Asphalt Cement
Test/Property ASTM Designation
AASHTO
Designation
Penetration D 5 T 49
Absolute Viscosity D 2171 T 202
Kinematic Viscosity D 2170 T 201
Flash Point D 92 T 48
Thin Film Oven Test D 1754 T 179
Rolling Thin Film Oven Test D 2872 T 240
Ductility D 113 T 51
Solubility D 2042 T 44
Absolute viscosity is the
measurement of the fluid's
internal resistance to flow
kinematic viscosity refers to the
ratio of dynamic viscosity to
density.

AGGREGATES
 “aggregate”, is a broad category of coarse particulate
material used in construction, including sand, gravel,
crushed stone, slag, recycled concrete and
geosynthetic aggregates. ...
 Aggregates are also used as base material under
foundations,
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 The basic property of the aggregate
is its grain size distribution or
gradation

Tests on Mineral Aggregates
Test/Property ASTM Designation AASHTO Designation
Los Angeles Abrasion C 131 or C 535 T 96
Unit Weight C 29 T 19
Sieve Analysis (Aggregates) C 136 T 27
Sieve Analysis (Filler) D 546 T 37
Specific Gravity (Coarse) C 127 T 85
Specific Gravity (Fine) C 128 T 84
Specific Gravity (Filler) D 854 or C188 T 100 or T 133
Sulphate Soundness C 88 T 104
Sand Equivalent D 2419 T 176
Particle Shape D 4791 -

JOB MIX Formula (JMF)
JOB MIX IS PRODUCED BY THE COMBINATION OF
AGGREGATE BLENDING AND BITUMEN%

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AGGREGATE BLENDING
Basic Formula
P = Aa + Bb + Cc
P = the percentage of material passing a given sieve for
the combined aggregates A, B, C, etc.;
A, B, C, etc. = percentages of material passing a given
sieve for aggregates A, B, C, etc
a, b, c, etc. = proportions of aggregates, A, B, C, etc. used
in the combination and where the total =1.00.

AGGREGATE BLENDING
P = Aa + Bb + Cc
a = –
𝑷 𝑩/ –
𝑨 𝑩
b = –
𝑷 𝑨/ –
𝑩 𝑨
a + b + c= 1
b + c = 1 – a

AGGREGATE BLENDING
Sieve analysis

GRADING SPECIFICATION AND GRADATIONS
(No.8), a = P-B/A-B
= 42.5 – 82/3.2 – 82 = 0.50
(No. 200), P=Aa+Bb+Cc
7 =0.50+9.2b+82c
b +c =1 - 0.50 = 0.50
b = 0.50 - c
7 = 0.5+9.2 (0.50 - c) + 82c
c = 0.03 b = 0.50 - 0.03 = 0.47

1
6
Grading specification and gradations
Trail and Error Method

Optimum Asphalt content determination
Marshal Testing
Procedure
1. Preparation of aggregates
2. Preparation of Trial Specimen
3. mixing and Compacting Temperatures
4. Preparation of Mixtures
5. Compaction of Specimen
6. Density and Void Analysis
7. Stability and Flow test

OPTIMUM ASPHALT CONTENT DETERMINATION
Preparation of aggregates
Sieve Sizes 1 to
¾ in
¾ in
to ½
inch
½ inch
to 3/8
in
3/8 in
to
No.4
No.
4 to
No.
8
No.8
to
No.16
No.16
to
No.30
No.30
to
No.50
No.50
to
No.100
No.100
to
No.200
Total
Weight
Weight
Retained g
153 224 223 170 97 106 89 65 49 24 1200
Dry aggregates to constant weight at 105
to 110 0
C and separate the aggregates to
dry sieving into the desired size fraction.

 Prepare19 specimen, these specimens are
prepared by half percent increment.
 First specimen is prepared to find out the time
required it is then discarded.
 Prepared the specimen starting with 3.0% then
3.5%, 4. 0%, 4.5 %, and 5.0 % asphalt
respectively.
Preparation of Trial Specimen

Determination of mixing and Compacting Temperatures
1. The temperature to which asphalt cement must be
heated to produce a viscosity of 170 ± 20 CST shall
be the mixing temperature.(170/1000= 0.17 P s)
2. The temperature to which asphalt cement must be
heated to produce a viscosity of 280 ± 30 CST shall be
the compacting temperature.(280/1000 = 0.28 P s)

 Weigh into separate pans for each specimen
 Place the pans on the hot plate or in an oven
and heat to a temperature not exceeding the
mixing temperature.
 Charge the mixing bowls with heated
aggregates and dry mix thoroughly.
 Form a crater in the dry blended aggregate,
place it on the balance, note the weight and
start pouring Asphalt.
 Mix the aggregate and bituminous material
rapidly until thoroughly coated.

Compaction of Specimen
1. Thoroughly clean the specimen mold assembly and the face compaction
hammer and heat them on the hot pate to a temperature between 93.3
and 148.9.
2. Place a piece of filter paper or paper toweling cut to size in the
bottom of the mold before the mixture is introduced.
3. Place the entire batch in the mold, spade the mixture vigorously
with a heated spatula or trowel 15 times around the perimeter
and 10 times over the interior.

Compaction of Specimen
5. place the mold assembly on compaction pedestal, in the mold holder
and unless otherwise specified
6. Apply required blows (check with Specification) with the compaction
hammer with a free fall of 18 inch.
7. Remove the base plate and collar, and reverse and reassemble the mold
8. Apply the same number of compaction blows to the face of the reversed
specimen
9.After compaction, remove the base plate and place the sample extractor
on the end of the specimen
10. Carefully transfer the specimen to a smooth, flat surface and allow it to
stand overnight at room temperature.

Density and Void Analysis
After the specimen has cooled to Room
temperature, measure the height of specimen
from three sides and take average.
Weigh and record the mass of specimen in air,
water and saturated surface dry conditions

Stability and Flow test
1. Bring the specimens prepared with asphalt
cement to the specified temperature of 60o
C by
immersing in the water bath 30 to 40 minutes.
2. Remove the specimen from the water bath, and place in
the lower segment of the breaking head.
3. Place the complete assembly in position over on of the guide
rods and adjust the flow meter to zero.
4. Apply the load to the specimen, 2inch/minute till the maximum
load is reached, and the load decreases as indicated by the dial

Stability and Flow test
5. Record the maximum load noted on the testing machine or converted
from the maximum meter dial reading.
6. Note and record the indicated flow value or equivalent units in
hundredths of an inch (25 hun dredths of a millimeter) if a micrometer
dial is used to measure the flow.
7. The elapsed time for the test from removal of the test specimen from
the water bath to the maximum load determination shall not exceed 30
seconds.
8. The stability values are made equivalent by applying correlation
factors, if the height of specimen is not 2.5 inch.
9. The compaction does not simulate with actual field condition because
we are giving impact load but in field there is instantaneous movement,
so the test results may not be very curate.

Data analysis
1. Draw the graphs for: % AC vs. Percentage air voids, %
AC vs. Stability, % AC vs. Flow, % AC vs. Unit weight
and % AC vs. Voids in Mineral Aggregate
2. Check for the minimum and maximum values as required
by Marshall criteria in Table.
3. Summarize all the values calculated in step 2 above in the
form, as illustrated below.
4. Draw a perpendicular line that will satisfy all the criteria

Design Criteria for Marshall Method

3
0
1A 1B 1C Averag
AC Content (%) a w.r.t aggregate weight
AC Content (%) b a/(100+a)
Specimen Height c
Weight (gr)
In Air d
In Water e
Volume (cm3) f d-e
Specific gravity
Mixture g d/(d-e)
Mixture(theoretic) h
Volume w.r.t
total %
Asphalt i b*g/(SGasp)
Aggregate j (100-b)*g/SGagg
Air Void k 100-i-j
Void
percentages (%)
Aggregate l 100-j
Fill with asphalt m i/l
Total mixture n 100-100g/h

% AC by
Wt of mix
Unit
Wt.
(pcf)
% Air
voids
Flow in
1/100
inch
Stability,
Lbs. %
VMA
2.5 137.5 15.2 6 1000 20
3 142 10 7 2350 16.7
3.5 145.5 7.6 8 2700 15.6
3.9 147.5 5.5 11 2750 14.9
4.6 148 3.7 16.5 2000 15.3
5.5 147.5 2.8 30 1250 16.1
7 146 2 44 400 17.6
Example

% AC by Unit
Wt of mix Wt. (pcf)
2.5 137.5
3 142
3.5 145.5
3.9 147.5
4.6 148
5.5 147.5
7 146 2 3 4 5 6 7 8
132
134
136
138
140
142
144
146
148
150
AC VS UNIT wt
%AC
UNIT
wt

%AC
% AC by % Air
Wt of mix voids
2.5 15.2
3 10
3.5 7.6
3.9 5.5
4.6 3.7
5.5 2.8
7 2 2.5 3 3.5 3.9 4.6 5.5 7
0
2
4
6
8
10
12
14
16
Chart Title

%AC
% AC
by
Flow in
Wt of
mix
1/100
inch
2.5 6
3 7
3.5 8
3.9 11
4.6 16.5
5.5 30
7 44
2 3 4 5 6 7 8
0
5
10
15
20
25
30
35
40
45
50
AC% VS FLOW

%AC
% AC
by
Stability
,
Wt. of
mix
Lbs.
2.5 1000
3 2350
3.5 2700
3.9 2750
4.6 2000
5.5 1250
7 400
2 3 4 5 6 7 8
0
500
1000
1500
2000
2500
3000
%AC vs Stability

%AC vs
% AC by
% VMA
Wt of mix
2.5 20
3 16.7
3.5 15.6
3.9 14.9
4.6 15.3
5.5 16.1
7 17.6 2 3 4 5 6 7 8
0
5
10
15
20
25
% AC vs %VMA

CONCLUSION
4.6% Asphalt is selected as optimum
asphalt content.
 4.6 percent of 1200g is 55.2g
So we will use 55.2g of Bitumen for
each sample.

Complete Guide to Job Mix Formula (JMF) and Marshall Stability Test for HMA Layers

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