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Amardeep Singh
Marshall Stability Test

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Marshall Stability Test
• Marshall stability test is mix design method to find out optimum binder content
of given mix. In this test we find out the stability of the mix ( strength ) for
desired flow ( workability ) on different binder contents in worst conditions.
Worst condition may be understood as,
• “When in summer season a highly rainfall occurs and most of the bituminous
road surface become water logged and water penetrates or tend to penetrate
the bituminous surfacing………… After the rain fall stops and again the sun shines
the environment becomes hot and moist.”
At this condition the bituminous bonding between road aggregates starts to
break down thus damage to road starts.
• This condition is considered the worst condition for a bituminous pavement and
Marshall stability test is performed equaling to this condition as the prepared
specimens are kept for 30-40 mins in water bath at 60o C temp. at which
stability and flow is measured.

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Marshall Stability Test
Hammer
Marshall Stability test Apparatus
Mould

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Marshall Stability Test
This test was invented in America by Bruce Marshall, Mississippi Highway
Department to design the roads pavements made up of Bitumen.
Apparatus consists of cylindrical moulds of 10.16 cm dia and 7.62 cm in height with
base plate and collar. The hammer consists of 4.54 kg with fall of 45.7 cm.
Other apparatus are Pedestals, Breaking heads, Loading jack to provide uniform
loading of 5.08 cm per minute, Oven or hot plate, Mixing apparatus, water bath
15.24 cm deep, thermostat 60.0oc +-5.0oc
In Marshall Stability of the mix is defined as the maximum load carried by a
compacted specimen at a standard test temp. at 60oc
The flow value is the deflection in mm. The deformation of the Marshall test
specimen during loading upto maximum load, measured in 0.25mm units.
Mixes with very high Stability and very low flow are not such required as this type of
mix can be brittle enough to make cracks in the pavement under heavy traffic.

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Marshall Stability Test
Volume of Specimen in cc Approx. Thickness of specimen
in mm
Correction factors
457-470 57.1 1.19
471-482 58.7 1.14
483-495 60.3 1.09
496-508 61.9 1.04
509-522 63.5 1.00
523-535 65.1 0.96
536-546 66.7 0.93
547-559 68.3 0.89
560-573 69.9 0.86
Correction factors for height and volume basis

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Marshall Stability Test
• Example : Adding the % (Ps) age of aggregate and binder to make mix for
prepare the one specimen mould. The blending %ages of diff. aggregates are A =
75%,B = 5%,C = 23%and D = 2% respectively and %age of bitumen is 5%
Eg. Weight of sample taken 1210 gms to fill the mould at 5% of Bitumen.
Binder = 5% of 1210 gms = 60.5 gms
The total aggregates becomes
1210 – 60.5 = 1149.5 gms
Then A,75% of 1149.5gm = 805 gms
B,5% of 1149.5 gms = 58 gms
C,23% of 1149.5 gms = 264 gms
D,2% of 1149.5 gms = 23 gms

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Marshall Stability Test
JOB MIX FORMULAE (JMF) for DBM 50 mm Thick
IS
SIEVES
BY WEIGHT % PASSING OF COARSE & FINE
AGGREGATE
Percentage required
JMF
SPECIFIED
LIMIT
MIDDLE
LIMIT
40% 23% 35% 2%
P1 P2 P3 P4
(mm)
A
(20.0 mm)
B
(10.0 mm)
C
(fine agg.)
D
(lime)
A) B) C) D) A+B+C+ D
37.50 100.00 100.00 100.00 100.00 40.00 23.00 35.00 2.00 100.0 100.00 100.00
26.50 98.20 100.00 100.00 100.00 39.28 23.00 35.00 2.00 99.3 90-100 95.00
19.00 81.30 100.00 100.00 100.00 32.52 23.00 35.00 2.00 92.5 71-95 82.50
13.20 42.20 100.00 100.00 100.00 16.88 23.00 35.00 2.00 76.9 56-80 68.00
4.75 6.20 15.80 99.50 100.00 2.48 3.63 34.83 2.00 42.9 38-54 46.00
2.36 0.80 2.90 91.80 100.00 0.32 0.67 32.13 2.00 35.1 28-42 35.00
0.30 0.00 0.00 46.30 99.40 0.00 0.00 16.21 1.99 18.2 7-21 14.00
0.075 0.00 0.00 16.90 93.80 0.00 0.00 5.92 1.88 7.8 2-8 5.50
JOB MIX FORMULAE (JMF) for DBM 50 mm Thick Pavement
Step 1 Set the percentages of different aggregates for given mix

8. 8
Marshall Stability Test
S.no Material Specific Gravity Apparent Specific
Gravity
Water
Absorption
1. 20 mm 2.644 2.674 0.428
2. 10 mm 2.636 2.669 0.479
3. Sand 2.604 2.690 1.23
4. Lime 2.625
Step 2 Find specific gravity and apparent specific gravity
S.no Material Gsb Gse
1. 20 mm,10mm, sand, lime 2.628 2.647
Step 3 Find Gsb, Gse of mixed aggregates
When the aggregates and lime mixed in decided ratios then it has its own specific gravity and
apparent specific gravities. Gsb is specific gravity and Gse is apparent specific gravity of
mixed aggregates.
Specific gravity of bitumen Gb is generally a constant value for different grades of bitumen,
i.e. 1.02

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Marshall Stability Test
Bulk Specific Gravity of total aggregates, Gsb
P1 20 mm = 40 % G1 = 2.644 Ga1 = 2.647
P2 10 mm = 23 % G2 = 2.636 Ga2 = 2.669
P3 fine agg. = 35 % G3 = 2.604 Ga3 = 2.690
P4 lime = 2 % G4 = 2.625 Ga4 = 2.625
= P1+ P2+ P3 + P4
Gsb P1 + P2 + P3 + P4
G1 G2 G3 G4
where
P1+P2+P3+P4 = Individual percentages by weight of aggregates
G1+G2+G3+G4 = Individual Bulk Specific Gravity of aggregates
Gsb =
Bulk Specific Gravity of total aggregates
40 + 23 + 35 + 2
= 40 + 23 + 35 + 2
2.644 2.636 2.604 2.6
= 100
15.13 + 8.73 + 13.44 + 0.8
= 100
38.06
Gsb = 2.628
Bulk Apparent Specific Gravity of total aggregates, Gse
Gse
=
0.5 x (Gsb + Bulk apparent specific
gravity of mix)
P1+ P2+ P3 + P4
P1 + P2 + P3 + P4
Ga1 Ga2 Ga3 Ga4
wher
e
P1+P2+P3+P4 = Individual percentages by weight of aggregates
Ga1+Ga2+Ga3+Ga4 =
Individual Apparent Specific Gravity of
aggregates
Gse =
Effective Bulk Apparent Specific Gravity of total
aggregates
40 + 23 + 35 + 2
= 40 + 23 + 35 + 2
2.647
2.66
9 2.690 2.6
= 100
15.11 + 8.62 + 13.01 + 0.8
= 100 = 2.667
37.50
Gse = 2.647

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Marshall Stability Test
Step 4 Preparation of specimens
• After completion of JMF the blending of diff aggregates used, Put the
aggregate in oven and make them as hot as they will used while the execution of
work, generally aggregates at 150oc to 170oc and Binder at 150oc (softening
point + 90oc), the temp of bitumen and aggregate shall be within limit (diff 14oc
specified), after the constitutes become hot mix them & hot them again in oven
at 160oc, if required, the assembly should also have to warm up at about 100oc
in oven or in water bath. Put the gloves up. During compaction the hammer
should be vertical.
• Test should be scheduled on the basis of 0.5 % increments of bitumen
content and at least 6 no of samples should prepared. Each sample generally
requires 1200 gms of mix. The compacted thickness of the specimen should be
63.5mm. The mix is placed and compacted both sides by Hammer with 75 blows.
If the process is by modified marshall the weight of rammer will be 10.2 kg dia of mould will
be 150 mm.The mix is placed and compacted both sides by Hammer with 113 blows. The
stability will be 2.25 times of ordinary method as written in MORT&H.

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Marshall Stability Test
Step 5 Find Gmm specific gravity of mix at different % age of binder
*Max Theoritical Density ASTM D - 2041
S.no % of bitumen in mix Gmm
1. 4.5 2.470
2. 4.75 2.461
3. 5.0 2.452
4. 5.25 2.443
5. 5.5 2.434
Let bitumen content 5.5%
Wt of Flask (A) = 1050
Wt of Flask filled with water (B) = 2003.5
Wt of flask + Full water + Mix (C) = 2610
Wt of Sample in air (D) = 1029.5
D/
Gmm = (D+B)-C = 2.434 gm/cc
Example (its same as finding specific gravity in pycnomenter):

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Marshall Stability Test
• After 24 hours the specimens are removed from moulds and Density (Gmb) is
measured by water bucket immersion method. After measuring its Density
specimen are kept immersed in water at temp 60oc for 30-40 mins and the
Stability (max load carried in kg) and Flow (the deformation of the specimen in
mm until max loading in 0.25 mm units) is recorded in machine, the height of
the specimen should be 63.5 mm, if not the correction factors ( as given above )
are applied to meet the results.
Graphs are plotted with the values of bitumen content against the values of
• Density (Gmb), gm/cc
• Marshall Stability, S in kg
• Voids in total mix, Va %
To find out Optimum Binder Content required for the mix.

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Marshall Stability Test
Marshall Test Results of individual sample
a Bitumen CRMB
b % age 4.5%
c Specific Gravity of Bitumen 1.02
d % age aggregates 95.5%
e Aggregates 20 10 Fine agg. Lime
f % age 40 23 35 2
g Sp. Gravity 2.644 2.636 2.604 2.625
h App. Sp. Gravity 2.647 2.669 2.690 2.625
1
Density
Wt. in air = 1183.5gm
Wt. in water = 668gm
SSD wt. = 1206.5gm
Density = 2.198gm/cc
2
Average Specific Gravity of mix
(without Binder)
Gsb = 2.628
3
Effective specific Gravity of mix
(without Binder)
Gse = 2.647
4
Absorbed bitumen %
Pba = 0.29
5
Max Theoritical Density
Gmm = 2.470
6
Bulk Density on Basis of Max Theoretical
Density = 88.99%
7
Air Voids
Va = 11.01%
8
Effective bitumen
Pbe = 4.23%
9
Vol of Bitumen
Vbe = 9.11%
10
Voids in Mineral Aggregates
VMA = 20.12%
11
Voids Filled with
Bitumen/Asphalt
VFA = 45.26%
12
Reading of Proving ring = 305
correction for ring factor = 3.55
Correction for height = 0.9
Stability = 974.475 kg
13 Flow(mm) = 3.3 mm

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Marshall Stability Test
1 2 3 4 5 6 7 8 9
S. no.
% Bitumen by wt
of total mix
Weight in air
(gms)
Weight in water
( gms)
S.S.D. in air
(gms)
Bulk volume
Unit weight of
compacted mix
(Gmb)
Bulk Specific
gravity of comb.
Aggregates (Gsb)
Effective specific
gravity of
aggregate (Gse)
a b c d e f g h
1 4.50 1240.2 712.6 1248.3 535.7 2.315 2.628 2.647
2 4.75 1244.3 722.7 1251.5 528.8 2.353 2.628 2.647
3 5.00 1238.8 723.1 1244.9 521.8 2.374 2.628 2.647
4 5.25 1250.2 730.5 1255.8 525.3 2.380 2.628 2.647
5 5.50 1248.5 728.8 1253.2 524.4 2.381 2.628 2.647
10 11 12 13 14 15 16 17
S. no.
Aggregate
content % by mix
(Ps)
Sp. Gravity of
bitumen ( Gb)
Absorbrd
Bitumen % Pba
Max Sp.Gravity
of Bitumenous
mix (Gmm)
ASTM D - 2041
Effective
bitumen content
% Pbe
Voids in mix %
Va
% VMA % VFA
i j k l m n o p
1 95.50 1.02 0.28 2.470 4.23 6.3 15.9 60.5
2 95.25 1.02 0.28 2.461 4.48 4.4 14.7 70.3
3 95.00 1.02 0.28 2.452 4.73 3.2 14.2 77.7
4 94.75 1.02 0.28 2.443 4.98 2.6 14.2 81.9
5 94.50 1.02 0.28 2.434 5.23 2.2 14.4 84.9
Stability and Flow value has to recorded from dial gauges of apparatus

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Marshall Stability Test
2.25
2.26
2.27
2.28
2.29
2.3
2.31
2.32
4 4.25 4.5 4.75 5 5.25 5.5
BulkDensity(gm/cc)
Bitumen %

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Marshall Stability Test
3.00
4.00
5.00
6.00
7.00
4.30 4.40 4.50 4.60 4.70 4.80 4.90 5.00 5.10 5.20 5.30
Airvoids(%)
Bitumen (%)

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Marshall Stability Test
900
950
1000
1050
1100
1150
1200
1250
4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5 5.1 5.2 5.3 5.4
Stability(Kg.)
Bitumen ( % )

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Marshall Stability Test
Calculations :
Density, Gmb : wt of specimen in air/wt of SSD specimen in air- wt of specimen in
water
Gsb : as in step 3, 2.628
Gse : as in step 3, 2.647
Aggregate Content %,Ps : 1-percentage of bitumen in mix
Specific gravity of bitumen, Gb : 1.02 ( standard value/given in MTC/can be find
out)
Absorbed bitumen %, Pba : (Gse-Gsb)/(Gse x Gsb) x Gb x 100
Max sp gravity of bitumen mix, Gmm : as in step 5, for different %age of bitumen or
theoretically
100/(%age of bitumen in mix/Gb) + (Ps/Gse)

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Marshall Stability Test
Effective Bitumen content %,Pbe : % of bitumen in mix – ((Ps x Pba)/100)
Voids in mix %, Va : (1-Gmb/Gmm) x 100
Voids in mineral aggregates VMA,% : (Pbe x Gmb/Gb)+Va
Voids filled with Asphalt VFA,% : ((Gmb x Pbe/Gb)/VMA) x 100
Some of text books gives different formulas for same calculations. However the results are
same in every cases. Asphalt Institute MS-2 may be refer for details.

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Marshall Stability Test
FINAL DESIGN PARAMETERS AS PER JMF
Sr no GRAPH TYPE
Optimum Binder content from graphical
representation
1 Bitumen Content v/s Bulk density of mix 5.00%
2 Bitumen Content v/s 4 % Air voids in Mix 5.00%
5 Bitumen Content v/s stability 5.00%
Avrage 5.00%
DESIGN PARAMETERS AS PER JMF SPECIFIED LIMITS
1 Bitumen 5.00% MIN 5 %
2 Bulk density 2.374 gm/cc ----
3 Air Void in Mix 3.20% 3% - 5%
4 Voids in Mineral aggregate 14.2% MIN 15 %
5 Voids filled with bitumen 77.7% 65% - 78%
6 Stability 1227 kg MIN 1200 KG
7 Flow 3.3mm 2.5 - 4 MM

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Marshall Stability Test
Ways to Increase VMA
1. Reduce the dust content
2. Open the aggregate gradation
3. Gap-grade the aggregate blend
4. Increase manufactured sand
5. Reduce flaky-and-elongated particles

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