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8/10/2019 lab report Highway boleh tiru
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8/10/2019 lab report Highway boleh tiru
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GRAPH
1. Binder content vs corrected Marshall Stability
2. Binder content vs Marshall flow
8
9
10
11
12
13
14
15
4.00 4.50 5.00 5.50 6.00 6.50 7.00
MarshallStability(kN)
% AC BY WEIGHT OF MIX
Corrected Marshall Stability vs Binder content
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
4.00 4.50 5.00 5.50 6.00 6.50 7.00
MarshallFlow
(mm)
% AC BY WEIGHT OF MIX
Marshall Flow vs Binder Content
8/10/2019 lab report Highway boleh tiru
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3. Binder content vs percentage of void (VIM) in the total mix
4.
Binder content vs percentage of void in compacted mineral aggregates (VMA)
0
2
4
6
8
10
12
14
16
4.5 4.7 4.9 5.1 5.3 5.5 5.7 5.9 6.1 6.3 6.5
VIM(%)
% AC BY WEIGHT OF MIX
Percentage of Void (VIM) vs Binder content
20
20.5
21
21.5
22
22.5
23
23.5
24
24.5
4.00 4.50 5.00 5.50 6.00 6.50 7.00
VMA
% AC BY WEIGHT OF MIX
VMA vs Binder Content
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5. Binder content vs unit weight or bulk specific gravity (Gm)
From the following graphs above, the binder content that corresponding to maximum stability,
maximum unit weight and specified percent air voids in the total mix were obtained:
Binder content corresponding to maximum stability, B1= 5.58
Binder content corresponding to maximum bulk specific gravity, B2 = 6.5
Binder content corresponding to the median of designed limits of percent air voids, B3 = 5.22
The optimum bitumen content is given by : B0 = B1 + B2 + B3
3
Therefore, B0 = (5.58+6.5+5.22)/3 = 5.77% bitumen content
2.1
2.12
2.14
2.16
2.18
2.2
2.22
2.24
2.26
2.28
4.00 4.50 5.00 5.50 6.00 6.50 7.00
UnitWeight
% AC BY WEIGHT OF MIX
Unit weight vs Binder Content
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DISCUSSION
The objectives of this experiment is to determine the stability, flow, air voids percentage and
aggregate voids filled with binder percentage (VFA) of specimen which usually were used as
pavement.
Stability of pavement is the ability of the mixture to resist shoving and rutting under loads. A strong
and stable pavement can resist any change in shape and can maintain it smoothness when subjected
to repeated loading. Whereas Marshall flow indicate the ability of the specimen to behave like
plastic. A high flow values indicate that the specimen has potential for permanent deformation such
as rutting or shoving, under loading. However, low flow values indicate the specimen may have
insufficient bitumen which may lead to durability problems with the pavement.
Percent Voids in the mineral aggregate (VMA) is the volume of intergranular void space between the
aggregate particles of a compacted paving mixture that includes the air voids and the effective
bitumen content which expressed as a percent of the total volume of the specimen. As VMA is low,
there is not enough room in the mixture to add sufficient bitumen to adequately coat the individual
aggregate particles. Meanwhile, excessive VMA will lead to low stability of the specimen.
Percent Voids filled with asphalt (VFA) are the void spaces that exist between the aggregate particles
in the compacted paving HMA that are filled with binder. VFA is inversely related to air voids. VFA
will increases as air void decreases. The main effect of the VFA is to limit maximum levels of VMA
and subsequently maximum levels of binder content.
The result from the experiment is compared with the Marshall Mix Design Criteria for Medium
Traffic Surface and Base.
Marshall Mix Design Criteria for Medium Traffic Surface & Base
Marshall Method Mix Criteria Medium Traffic Surface & BaseMin Max
Number of blows each end of
specimen
50 -
Stability 5338 -
Flow 8 16
Percent Air Voids 3 5
Percent Voids in the Mineral
Aggregate
14 16
Result Marshall Mix Design from Experiment
Marshall Method Mix Criteria Medium Traffic Surface & Base
Min Max
Number of blows each end of
specimen
50 -
Stability 10200 13000
Flow 3.15 4.2
Percent Air Voids 6.4 14.8
Percent Voids in the Mineral
Aggregate
20.73 23.95
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The Marshall Mix Design traffic type where classified based on the number of blows (compaction) as
it indicate the loads that expected to be applied to the specimens. Heavy type traffic surface and
base tend to have higher stability so that it can withstand any applied load without having any
unacceptable distortion and displacement.
As we can see, the result for all tests does not satisfy the requirement that stated by Marshall Mix
Design Criteria. Most of the values in the experiment are bigger than the values from Marshall Mix
Design Method except for percent air voids. The specimen from the experiment has high stability
which is good as high stability can prevent any unacceptable distortion and displacement when
traffic load is applied. However, the amount void is too much and this is critical as it can cause
bleeding and loss of stability when traffic load is applied. Adequate amount of voids is essential as it
permit a small amount of compaction when traffic load is applied without bleeding and loss of
stability. The amount of voids can be reduced by adding more mineral filler in the mix.
There are some errors that occur during the experiment which lead to inaccurate result. First, some
of the specimens have been heated beyond the temperature limit and this could effects thestructure and durability of the aggregates and fillers. Besides, during flow value test, there are some
specimen having total time between removing the specimen from the bath and completion of the
test exceeding 30 second. The total time should not exceed 30 seconds as stated in lab manual thus
causing the specimen to have wrong result. In addition, during this test, the flow test machine that
was used to test the specimens was not in good condition and this causes the data to be inaccurate.
Other than that, the surrounding temperature during the experiment is not constant and most of
the time the surrounding temperature is low which effect the specimen during the compaction
process. Besides that, the compaction is carried out manually and this may affect the consistency of
the compaction process. Furthermore, it is difficult to measure the weight of bitumen accurately
when pouring the binder to the aggregates. The result of the experiment can be improved if all these
errors were minimized or even prevented.
CONCLUSION
The objectives of the experiment were achieved. However the result does not satisfy the values from
Marshall Mix Design Criteria. The optimum bitumen content that we obtained from the experiment
is 5.77%. This mean that this percentage are the best to be used as it provides a good stability,
marshall flow, percent air voids and percent voids in the mineral aggregate.