lab report highway boleh tiru

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)


Marshall Flow vs Binder Content


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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(%)


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


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


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.

lab report highway boleh tiru

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