UNIVERSITI PUTRA MALAYSIA43400 SERDANG, SELANGOR DARUL EHSAN

FACULTY OF ENGINEERING

DEPARTMENT OF CIVIL ENGINEERING

TITLE OF LAB REPORT: LAB 13: MIX DESIGN ANALYSIS

NO. GROUP MEMBERS MATRIC NO.

1. MOHAMAD ASRAF MAT SADAN 152129

2.NOOR MUNIRAH BINTI RAJA AHMAD

151925

3. NURUL AYUNIE BINTI AZMAN 154697

4.NOR SUHAIZA BINTI ABD RAHMAN

152191

NAME : NOR HARYANTI BINTI ARIFINMATRIC NO : 152427GROUP NO. : 2LECTURER : PROF DR RATNASAMY MUNIANDYTEACHING ASSISTANCE: MR DANIAL

MOAZAMIDEMONSTRATOR: EN AZRY TAMBERDATE OF SUBMISSION: 21 MAY 2012

TABLE OF CONTENT:

NO. TITLE PAGE

1.

ASPHALT MIX DESIGN ANALYSIS INTRODUCTION OBJECTIVE APPARATUS PROCEDURE RESULTS

3

2.

RESILIENT MODULUS TEST (ASTM D4123)• INTRODUCTION• OBJECTIVE• APPARATUS• PROCEDURE RESULTS

13

3.

MARSHALL STABILITY & FLOW TEST (ASTM D1559) INTRODUCTION OBJECTIVE APPARATUS PROCEDURE RESULTS

18

4. DISCUSSION 23

5. RECOMMENDATION 27

6. CONCLUSION 29

7. REFERENCES 30

8. APPENDICES 31

2

1.0 ASPHALT MIX DESIGN ANALYSIS

1.1 INTRODUCTION

Asphalt mix design is a complex issue with a lot of variables involved. However

two methods of a mix design have become popular worldwide. They are the Marshall

Mix Design and the Hveem Mix Design Method. In Malaysia, the Marshall Method of

mix design has become the norm in the road industry.

Before any asphalt mixes can be placed and laid on the road, the aggregate and

the binder types are generally screened for quality and requirement. Approximately 15

samples are required to be prepared to determine the required Optimum Asphalt

Content (OAC). The prepared case samples are to be analyzed for bulk density, air

void and stability. By using the Asphalt Institute Method, the Optimum Asphalt

Content is determined from the individual plots of bulk density, voids in total mix and

stability versus percent asphalt content. The average of the 3 OAC values is taken for

further sample preparation and analysis.

Another procedure developed in UPM is the inclusion of Resilient Modulus,

which is considered as the important parameter in the performance of pavement. As

the previous analysis, a graph of Resilient Modulus versus percentage of asphalt

content is to be plotted. From the graph the percentage of asphalt at the optimum

resilient modulus will be determined.

The Optimum Asphalt Content, using UPM’s method, was adopted from

Asphalt Institute by averaging the percentage of asphalt at optimum value for

Resilient Modulus, Marshall Stability, Bulk Density and 4% VTM.

3

Some of the requirements of an asphalt concrete paving mix are:

Stability

Durability

Flexibility

Fatigue Resistance: Thick Layers; Thin Layers

Fracture Strength: Overload Conditions; Thermal Conditions.

Skid Resistance

Impermeability

Workability

The binder type and content govern most of these properties and to some extend

the degree of compaction, aggregate gradation and shape. It is clearly impossible for

one single test to cover all these factors but the Marshall Test gives the engineer

considerable help. The complete test reveals:

Stability

Flow

Density

Voids in Total Mix (VTM)

Voids in the Mineral Aggregate (VMA)

Voids filled with binder (VFB)

Resilient Modulus (MR)

These parameters plotted against the binder content enable the optimum to be

obtained for specific applications of the asphalt concrete or provide guidance for a

change in the aggregate composition.

4

1.2 OBJECTIVES

The main objective of this experiment is to prepare standard specimens of

asphaltic concrete for the determination of stability and flow in the Marshall apparatus

and to determine density, percentage air voids and percent of aggregate voids filled

with binder.

1.3 APPARATUS

In conducting this analysis, the apparatus below are used:

1. Oven

2. Mould

3. Base plate

4. Marshall compacted pedestal

5. Filter paper

5

1.4 PROCEDURE

1. The aggregate graded according to the ASTM or BS standard are over-

dried at 170-180oC and a sufficient amount is weighed about 1200g for

sample preparation that may give a height of 63.5mm when compacted

in the mould.

2. The required quantity of asphalt is weighed out and heated to a

temperature of about 160-165oC.

3. The aggregate is heated in the oven to a temperature not higher than 28 oC above the binder temperature.

4. A crater is formed in the aggregates, the binder poured in and mixing

carried out until all the aggregate are coated. The mixing temperature

shall be within the limit set for the binder temperature. The thoroughly

cleaned mould is heated on a hot plate or in an oven to a temperature

between 140-170 oC. The mould is 101.6mm diameter by 76.2 mm high

and provided with a base plate and extension collar.

5. A pieced of filter paper is fitted in the bottom of the mould and the

whole mix poured in three layers. The mix is then vigorously trowelled

15 times round the perimeter and 10 times in the centre leaving a

slightly rounded surface.

6. The mould is placed on the Marshall Compaction pedestal and is given

50 blows.

7. The specimen is then carefully removed from the mould, transferred to

a smooth flat surface and allowed to cool at room temperature.

8. Finally, the specimen is measured and weighed in air and water (for

volume determination). If the asphalt mix has an open (porous) texture,

the weighing in water will lead to error in the volume and so the

specimen is then marked and stored for stability and flow

measurements.

6

1.5 RESULTS

Table 1.5(a): Sieve Results

Percentage combination gradation (%)

Sieve size (mm) Weight of retained (g)

14.0 19.0 492.0

10.0 12.5 492.0

Quarry Dust 9.5 108.0

Filler - 108.0

Total: 1200

Table 1.5(b): Percentage of Asphalt

Percentage of Asphalt (%)

Weight of Asphalt (x)GroupFor 1

sampleFor 4

sample

4.0 50.0 200.0 G5

4.5 56.5 226.0 G1

5.0 63.2 252.8 G2

5.5 69.8 279.2 G3

6.0 76.6 306.4 G4

Percent of asphalt =X

X+weight of aggregate

For 4.0% asphalt binder:

0.040 = X

X+1200

0.040X + 48 = X

X = 50.0 g

7

For 4.5% asphalt binder:

0.045 = X

X+1200

0.045X + 54 = X

X = 56.5 g

For 5.0% asphalt binder:

0.05 = X

X+1200

0.05X + 60 = X

X = 63.2 g

For 5.5% asphalt binder:

0.055 = X

X+1200

0.055X + 66 = X

X = 69.8 g

For 6.0% asphalt binder:

0.060 = X

X+1200

0.060X + 72 = X

X = 76.6 g

8

9

Asphalt (%)

SampleWeight in air (kg)

Weight in water (kg)

Weight in SSD

Bulk Density (g/mm3)

TMD (g/mm3)

VTM (%) VMA (%) VFA (%)

4.0

1 1232.0 700.8 1234.3 2.31

2.46

6.10 15.03 59.44

2 1234.5 706.4 1253.4 2.26 8.13 16.87 51.823 1232.7 701.5 1256.1 2.22 9.76 18.34 46.82

Average 2.26 7.99 15.95 52.69

4.5

1 1229.6 698.4 1242.3 2.26

2.43

6.70 17.31 59.58

2 1230.0 717.3 1258.7 2.27 6.58 16.94 61.133 1234.9 700.3 1245.4 2.27 6.58 16.94 61.13

Average 2.27 6.72 17.06 60.61

5.0

1 1243.5 704.5 1256.30 2.25

2.42

7.02 18.10 61.20

2 1225.6 699.6 1243.90 2.25 7.02 18.10 61.203 1243.9 702.2 1259.60 2.23 7.85 18.83 58.31

Average 2.24 7.30 18.35 60.23

5.5

1 1236.6 692.9 1248.0 2.23

2.39

6.69 19.26 65.24

2 1229.9 693.9 1240.8 2.25 5.86 18.53 68.40

3 1250.2 695.6 1259.4 2.22 7.11 19.62 63.75Average 2.23 6.56 19.14 65.79

6.0

1 1242.5 671.5 1251.6 2.14

2.39

10.46 22.93 54.38

2 1226.1 671.3 1229.9 2.20 7.95 20.77 61.723 1250.6 687.1 1254.9 2.20 7.95 20.77 61.72

Average 2.18 8.79 21.49 59.27

Table 1.5(c): Results on density and void analysis (ASTM D2726)

11

Example calculation:

For 5% asphalt binder:

Bulk Density, d

Gmb =Weight∈air

Weight∈SSD−Weight∈Water

=1243.5

1256.30−704.5

= 2.25

Bulk density, d = Gmb x ρw

= 2.25 (1g/mm3)

Theoretical Maximum Density, (TMD)

Gmm =

11−PbGse

+PbGb

; Gse = 2.60 , Gb = 1.03

=1

1−0.052.60

+0.051.03

= 2.42

Void in Total Mix (VTM)

VTM = (1 - dTMD

) × 100

= (1 - 2.252.42

) × 100

= 7.02%

Void in Mineral Aggregate (VMA)

VMA = 1 - ( Gmb(1−Pb)

G sb

) × 100 ; Gsb = 2.61

= 1 - ( 2.25(1−0.05)

2.61) × 100

= 18.10%

Void Filled with Asphalt (VFA)

VFA = ( VMA−VTMVMA

) × 100

= ( 18.10−7.02

18.10) × 100

= 61.2

3.5 4 4.5 5 5.5 6 6.52.13

2.15

2.17

2.19

2.21

2.23

2.25

2.27

Bulk Density vs % of binder

% binder

Bulk

Den

sity

(g/m

m3)

From chart, OAC = 4.30% at maximum bulk density = 2.26

13

3 3.5 4 4.5 5 5.5 6 6.53

4

5

6

7

8

9

Voids in total mix vs % of binder

% binder

VTM

(%)

3.5 4 4.5 5 5.5 6 6.510

15

20

25

Voids in mineral aggregate vs % binder

% binder

VMA

(%)

14

3.5 4 4.5 5 5.5 6 6.550

52

54

56

58

60

62

64

66

Void filled with asphalt vs % of binder

% Binder

VFA

(%)

2.0 RESILIENT MODULUS TEST (ASTM D4123)

2.1 INTRODUCTION

The Resilient Modulus Test is carried out to measure the stiffness modulus of asphalt

mixes. It is carried out using the Material Testing Apparatus (MATTA). The

procedure is as described in ASTM D4123 (46).

The Resilient Modulus is the equivalent “elastic modulus” of the materials in

the pavement structure. It is well known that most materials that comprise flexible

pavement are not elastic and exhibit inelastic behaviors such as permanent

deformation and time dependency. If the stress exerted on the materials is small

compared to its strength, however, and the exertion is repeated many times, the strain

under each load application is nearly the same and is proportional to the stress; thus it

can be considered elastic. The latest version of the AASHTO design method and the

15

Asphalt Institute design method have used the resilient modulus as the material

property input for the subgrade soil.

The Resilient Modulus (MR) is a subgrade material stiffness test.  A material's

resilient modulus is actually an estimate of its modulus of elasticity (E).  While the

modulus of elasticity is stress divided by strain for a slowly applied load, resilient

modulus is stress divided by strain for rapidly applied loads – like those experienced

by pavements.

Mr is a fundamental material property used to characterize unbound pavement

materials. It is a measure of material stiffness and provides a mean to analyze stiffness

of materials under different conditions, such as moisture, density and stress level. It is

also a required input parameter to mechanistic-empirical pavement design method. Mr

is typically determined through laboratory tests by measuring stiffness of a cylinder

specimen subject to a cyclic axle load. Mr is defined as a ratio of applied axle deviator

stress and axle recoverable strain.

2.2 OBJECTIVE

The main objective for this experiment is to measure the stiffness modulus of asphalt

mixes. It is carried out using the Material Testing Apparatus (MATTA). The

procedure is as described in ASTM D4123 (46).

2.3 APPARATUS

The main apparatus for this experiment is the Resilient Modulus Equipment.

16

2.4 PROCEDURE

1. Specimens are to be kept in the MATTA machine at a temperature of 25°C for at

least two hours and the pressure adjusted to 750kPa. A direct compressive

load is to be applied through a 12mm wide loading strip along the vertical

diameter of the specimens. The linear variable differential transducers (LVDTs)

are used to monitor the resultant indirect tensile stress and strain along the

horizontal diameter.

2. Prior to the actual test, an initial conditioning of five load pulses with a

17

three second interval between pulses, is applied to assess the strength and the

load that should be applied in the subsequent test period to

generate sufficient horizontal deformation is determined without damaging the

specimens. These pulses also serve to bed the loading strips on to the specimens.

3. The rise and the rest times in between the initial application and the peak value

of the load is arbitrarily specified at 100 milliseconds. The rise time gives a

load-time relationship with a clearly defined peak at

20°C for all the specimens tested was observed. The test conditions as

described above are essentially maintained throughout the test, as the elastic

stiffness depends on these conditions.

4. For each specimen, the test is repeated after rotating the specimen through

approximately 90°. Provided the difference is about 10% or less, the mean of the

two test results is taken as the elastic stiffness of the specimen.

18

2.5 RESULTS

% Binder

Sample Diameter (mm) Average Average Height (mm)Averag

eResilient Modulus

(MPa)

4.01 102.2 101.66 101.78 101.89 76.2 76.68 76.88 76.6 5576.32 101.58 101.2 101.28 101.29 75.94 75.56 75.6 75.7 5701.53 102.04 102.02 101.84 101.97 76.8 76.86 77.10 76.92 6171.9

Average 101.72 76.41 5816.6

4.51 101.70 101.50 101.60 101.60 75.20 75.10 75.72 75.34 6721.42 102.94 101.63 101.58 102.05 76.48 76.50 76.28 76.42 5614.03 102.80 102.80 102.78 102.79 76.18 75.50 75.70 75.79 5426.3

Average 102.15 75.85 5920.6

5.01 101.54 101.92 101.90 101.79 78.34 78.30 78.70 78.45 4680.72 101.78 101.88 102.00 101.89 79.22 79.12 79.46 79.27 4188.03 101.90 102.06 101.92 101.96 77.70 77.20 77.50 77.47 5247.5

Average 101.88 78.40 4705.4

5.51 102.3 102.1 102.6 102.33 76.26 76.68 76.80 76.58 9366.02 102.16 102.46 102.30 102.31 76.00 76.10 75.80 75.97 1383.33 103.2 102.1 103.40 102.90 77.46 76.78 76.36 76.87 4775.3

Average 102.51 76.47 5174.9

6.01 104.02 103.26 103.26 103.51 75.4 76.8 74.8 75.67 4566.62 102.5 102.76 103.16 102.81 75.33 74.2 74.1 74.54 3794.53 103.32 102.16 101.18 102.22 75.7 76.38 76.50 76.19 3794.6

Average 102.85 75.47 4051.9

Example calculation:

For 5% asphalt binder:

To calculate the average diameter:

= 101.79 + 101.89 + 101.96

= 101.88

To calculate the average height:

= 78.45 + 79.27 + 77.47

= 78.40

To calculate the average Resilient Modulus:

= 4680.7 + 4188.0 + 5247.5

= 4705.4

3.5 4 4.5 5 5.5 6 6.50

1000

2000

3000

4000

5000

6000

Y-Values

From graph, OAC = 3.86% at maximum resilient modulus of 5640 MPa.

3.0 MARSHALL STABILITY & FLOW TEST (ASTM D1559)

3.1 INTRODUCTION

The most widely used method of asphaltic mix design is the Marshall method

developed by the U.S. Corps of Engineers. Stability and flow, together with density,

voids and voids filled with binder are determined at varying binder contents to

determine an optimum for stability, durability, flexibility, fatigue resistance, etc.

The mechanism of failure in the Marshall Test apparatus is complex but it is

essentially a type of unconfined compression test. This being so, it can only have

limited correlation with deformation in a pavement where the material is confined by

the tire, the base and the surrounding surfacing. Wheel tracking tests have shown

that resistance to plastic flow increases with reducing binder content whereas

Marshall Stability has an optimum, below which stability decreases. Improvement

on the assessment, based on stability, is possible by considering flow and most

agencies (e.g. Asphalt Institute, Malaysia s JKR)(43, 44) set minimum for stability

and maximum for flow for various purposes (roads, airports, etc.). In addition to the

binder content, stability and flow being the prime variables in the performance of an

asphalt sample, the type of binder, grading of aggregates, the particle shape,

geological nature of parent rock (most importantly, porosity), degree of compaction,

etc (45) also pray an important role.

Marshall Stability measures the maximum load sustained by the bituminous

material at a loading rate of 50.8 mm/minute. The test load is increased until it

reaches a maximum. Beyond that, when the load just starts to decrease, the loading is

ended and the maximum load (i.e. Marshall Stability) is recorded. During the loading

test, dial gauge is attached which measures the specimen’s plastic flow owing to the

applied load. The flow value refers to the vertical deformation when the maximum

load is reached. Marshall Stability is related to the resistance of bituminous materials

to distortion, displacement, rutting and shearing stresses. The stability is derived

mainly from internal friction and cohesion. Cohesion is the binding force of binder

material while internal friction is the interlocking and frictional resistance of

aggregates. As bituminous pavement is subjected to severe traffic loads from time to

time, it is necessary to adopt bituminous material with good stability and flow.

21

3.2 OBJECTIVE

To measure the resistance to plastic flow of cylindrical specimens of an

asphaltic paving mixture loaded on the lateral surface by means of the

Marshall apparatus. The method is suitable for mixtures containing aggregates

up to 25mm maximum size.

3.3 PROCEDURE

The dimension and specifications of the Marshall apparatus are explained in

ASTM D1559. The diameter of the specimen is 101.6 mm and the nominal

thickness is 63.5 mm. Table 3.1, taken from ASTM D1559, gives a correlation

ratio for stability of specimens which are not 63.5 mm thick.

1. Three specimens, prepared according to the Standard, are immersed in a

water bath for 30 to 40 minutes or in an oven for 2 hours at 60 ± 1.0°C.

2. The testing heads and guide rods are thoroughly cleaned, guide rods lubri-

cated and head maintained at a temperature between 21.1 and 37.8°C.

3. A specimen is removed from the water bath or oven, placed in the lower

jaw and the upper jaw placed in position (Fig. 3.2). The complete assembly

is then placed in the compression-testing machine and the flow meter ad-

justed to zero.

4. The load is applied to the specimen at a constant strain rate of 50.8 mm/min

until the maximum load is reached. The maximum force and flow at that

force are read and recorded. The maximum time that s allowed between

removal of the specimens from the water bath and maximum load is 30 s.

22

3.4 RESULTS

%Asphalt SampleAverage Height (mm)

In (time) Out (time)Correlation

ratio (x)

Marshall Stability

(kN)Flow (mm)

Marshall Stability (kN) x X

4.0

1 76.59 7.30 pm 8.00 pm 0.76 6.09 2.78 4.628

2 75.7 7.35 pm 8.05 pm 0.77 7.22 4.81 5.559

3 76.92 7.40 pm 8.10 pm 0.75 6.18 5.16 4.635

Average 76.4 0.76 6.50 4.25 4.94

4.5

1 75.34 6.15 pm 6.30 pm 0.77 7.94 0.19 6.11

2 76.42 6.20 pm 6.35 pm 0.76 9.00 1.97 6.84

3 75.79 6.25 pm 6.40 pm 0.77 7.49 0.21 5.77

Average 75.85 0.77 8.14 0.79 6.24

5.0

1 78.45 5.05 pm 5.35 pm 0.75 5.75 0.23 4.31

2 79.27 5.15 pm 5.45 pm 0.75 6.07 0.78 4.55

3 77.47 5.10 pm 5.40 pm 0.76 5.87 2.28 4.46

Average 78.39 0.75 5.90 1.10 4.44

5.5

1 76.58 5.34 pm 6.04 pm 0.76 5.51 1.75 4.19

2 75.97 5.39 pm 6.09 pm 0.77 4.90 1.32 3.77

3 76.87 5.44 pm 6.14 pm 0.78 5.01 2.95 3.91

Average 76.47 0.77 5.14 2.01 3.96

6.0

1 77.2 5.12 pm 5.42 pm 0.77 6.45 2.45 4.97

2 74.54 5.17 pm 5.47 pm 0.78 5.05 2.64 3.94

3 76.19 5.22 pm 5.52 pm 0.76 5.05 2.64 3.84

Average 75.98 0.77 5.52 2.58 4.25

Example calculation:

For 5% asphalt binder:

To calculate the average height:

= 76.58 + 75.97 + 76.87

= 76.47 mm

To determine the correlation ratio, refer table of stability correlation ratio ASTM

D1559

In order to calculate the Correlation Ratio, we need to calculate by using interpolation

method.

The corrected Marshall Stability can be calculated as follow:

= Marshall Stability x Height Correlation Ratio

= 5.51 x 0.76

= 4.19 kN

The optimum Asphalt Content using UPM’s method which was adopted from Asphalt

Institute by averaging the percentage of asphalt of optimum values for Resilient

Modulus, Marshall Stability, Bulk Density and 4% VTM.

3.5 4 4.5 5 5.5 6 6.50

1

2

3

4

5

6

7

Marshall Stability vs % of Binder

From chart, OAC = 4.06 % at Maximum Marshall Stability = 5.06kN

25

4.0 DISCUSSION

For the first experiment, we have prepared prepare standard specimens of

asphaltic concrete for the determination of stability and flow in the Marshall apparatus

and to determine density, percentage air voids and percent of aggregate voids filled

with binder. The sample was prepared; 492 g of 14mm and 10mm aggregates was

sieved. Quarry dust and filler was prepared for about 108 g. Other than that, the

percent of asphalt binder was assigned to every group. Every group was using

different percent of asphalt binder. For our group, we need to use 5% of asphalt

binder for our mix.

During preparation of specimen for Marshall Analysis in the laboratory, there

are some errors occurred and will affect the results of optimum asphalt content.

Firstly, the temperature is hard to control during the mixing as there will be lost of

heat to the surrounding. 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 asphalt accurately when pouring the binder to the aggregate.

In this laboratory experiment, we follow the JKR standard for SMA 20 in mixing the

aggregate. The maximum size of SMA 20 is 19 mm. During the mix design, we

should consider a few criteria. Firstly, the traffic flow of the design roadway should

be considered. Asphalt concrete mixes should be designed to meet the necessary

criteria based on type of roadway and traffic volume. Besides that, the types of

aggregate and asphalt binder used are also important because it will affect the

appearance and quality of the design.

There are some errors occurred while the experiment was carried out that

affect the accuracy of the result. They include the specimen is not well mixed, the

specimen is not fully compacted, too much grease applied at the mould and the

compaction is done at temperature below than 140˚C.

26

The weight of asphalt for 1 sample for our group will be 63.2g. The weight

should be as accurate as possible to get good results. Every group need to prepare 3

samples. In the void and density analysis, we need to determine the bulk density,

voids in total mix (VTM), voids in mineral aggregate (VMA), and voids filled with

asphalt (VFA). For the bulk density, for 4.0% and 4.5% asphalt, the result is 2.26

g/mm3. For 5% is 2.24 g/mm3, 5.5% is 2.23 g/mm3, and lastly 6% is 2.18 g/mm3.

Other than that, Theoretical Maximum Density was also determined. For 4% asphalt,

TMD is 2.46, 4.5% is 2.432, 5% is 2.42, 5.5% is 2.39 and lastly 6% is 2.386.

The density and void analysis is important in the mix design because it can

directly affect the strength of the pavement. Air voids are small air spaces or pockets

of air that occur between the coated aggregate particles in the final compacted SMA.

A certain percentage of air voids is necessary in all dense-graded mixes to prevent the

pavement from flushing, shoving, and rutting. Air voids may be increased or

decreased by lowering or raising the binder content. The more fines added to the

SMA generally the lower the air voids. The air voids may be changed by varying the

aggregate gradation in the SMA.

From the graph bulk density vs percentage binder, the bulk density

increase with increasing asphalt content. When it reaches a maximum, it will start

decreasing. This happened due to the asphalt in the mixture acts like a lubricant. It

allows the aggregate particles to be more tightly compacted up to a certain point after

which the asphalt films become so thick that they in effect cause a separation of the

aggregate particles. Since there are fewer coarse particles within any given volume,

the result is a decrease in density. From the graph, the maximum bulk density is 2.260

g/mm³ with 4.30 % of asphalt content.

VTM calculate for 4% is 7.99%, 4.5% is 6.72, 5% is 7.30%, 5.5% is 2.39%

and lastly VTM for 6% is 8.79%. The highest VTM is at 6% asphalt, which is 8.79%.

For VMA results, the highest VMA is 21.49% and the lowest is 15.95% for 4.0%

asphalt binder. Lastly, for VFA, the highest VFA is for 5.5% asphalt, which is

65.79%, and the lowest is 52.69%.

27

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

asphalt content, expressed as a percent of the total volume of the specimen. When

VMA is too low, there is not enough room in the mixture to add sufficient asphalt

binder to adequately coat the individual aggregate particles. Also, mixes with a low

VMA are more sensitive to small changes in asphalt binder content. Excessive VMA

will cause unacceptably low mixture stability. From the graph, percent of VMA

should decrease with increasing asphalt content; reach a minimum then start to

increase again.

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. As air voids decrease, VFA will increase. The main effect of the VFA is to

limit maximum levels of VMA and subsequently maximum levels of binder content.

Percent of VFA increase with increasing asphalt binder content from the graph

plotted.

From the Resilient Modulus test, the diameter and the height of the sample

need to be determined. The average diameter for all groups is approximately the

same. The range is about 101mm to 103mm. It goes the same for the height of the

sample. The average height of the sample is in the range of 75mm to 78mm. By using

the equipment for Resilient Modulus test, the test was done and the results were taken

from the computer. The results that we got need to be deducted by 1000, due to some

error.

In this experiment, we measured the stiffness modulus of asphalt mixes. It is

carried out using the Material Testing Apparatus (MATTA). The procedure is as

described in ASTM D4123 (46). Mr for 4% asphalts is 5816.6MPa while the resilient

modulus for 4.5% asphalt is 5920.6Mpa, which is the highest Mr compared to the

others. For 5%, Mr is 4705.4Mpa, for 5.5%, Mr is 5174.9Mpa and lastly for 6%, Mr is

5174.9Mpa. The lowest Mr is 4705.4MPa.

28

The next test is the Marshall Stability and Flow Test (ASTM D1559). For this

test, we measured the resistance to plastic flow of cylindrical specimens of an

asphaltic paving mixture loaded on the lateral surface by means of the Marshall

apparatus.

The method is suitable for mixtures containing aggregates up to 25mm

maximum size. In this test, some control need to be considered. For example, the time

in and out of the sample from the water bath should be controlled. The gap between

the first and second sample should be 5 minutes. Other than that, the sample should be

taken out after 15minutes, and quickly run the Marshall test. The faster we can run the

Marshall test, the better it will be. The correlation ratio can be calculated by referring

to the table of the stability correlation ratio. The results for the Marshall stability need

to be corrected, by using the correlation ratio that we get. The corrected Marshall

stability can be calculated by multiplying the Marshall stability with the correlation

ratio. The highest Marshall stability calculated is 6.24kN, and the lowest one is

3.96kN.

Stability of a pavement is the ability of the mixture to resist shoving and

rutting under loads (traffic). A stable pavement will maintain the shape and

smoothness required under repeated loading. From the graph of Marshall Stability vs

percentage binder, stability increases with increasing asphalt binder content. When it

reaches a peak, it will start to decrease. From the graph, the maximum Marshall

stability is 5.06 kN with asphalt content of 4.06 %. For Marshall Flow, a high flow

values indicate an asphalt mixture that has plastic behavior and has the potential for

permanent deformation, such as rutting or shoving, under loading. However, low flow

values indicate a mixture that may have insufficient asphalt binder, which may lead to

durability problems with the pavement. Low flow values may also indicate a mixture

with a binder so stiff, that the pavement experiences low temperature or fatigue

cracking.

29

5.0 RECOMMANDATION

In order to obtain accurate results, there are several precautions that need to be

consider during the test was done. For the asphalt mix design analysis, the precautions

are as follow:

1. We must make sure all the mixing and compaction process are done at the

required temperature.

2. Other than that, we must apply grease on the surface of whole inner mould so

that the asphaltic specimen would not stick on the mould.

3. Assure aggregate and asphalt is well mixed. Make sure there is no any filler

stick on the wall of mixing blow.

4. Make sure all the equipment that will be use the mix design was always kept in

the oven when it not uses.

5. Try to control the temperature of asphalt and aggregate, so that in can be

maintained at its mixing temperature.

6. Make sure the compaction effort occur at best condition and similar to what

happened if use the machine. Do not rush to finish the compaction; the

compaction must be suitable periodic sequence.

For the density and void analysis, the precautions that need to be considered are as

follow:

1. During measured the weight of sample in water, make sure all the part of

specimens was completely submerged in the water before take a reading, if not

the reading is not exact weight of specimen in water.

2. Let the specimens submerged in the water at certain period that considerably

enough time to let water going inside. The objective is to make sure all the void

in the specimens was replaced by water.

3. Make sure cloth is used to dry the specimen but not paper towels because it

may absorb the water in the pores of the specimen.

4. The sample should be immersed to a depth sufficient to cover it during mass

determination.

30

The Resilient Modulus test was conducted by the MATTA. By using this equipment,

the test can be done easily, and the results that we obtain should be correct enough if

we did the test well by considered these precautions:

1. The specimens should be kept in the machine at temperature of 25˚C for at

least two hours.

2. Make sure that the specimen is placed at the centre when it was tested.

3. Make sure the specimens are tested again if the readings are unacceptable.

4. Adjust or tighten the lock at the two corners of the sample properly before

experiment.

5. We have to look at the computer whether the sample is really in stable

condition for testing when making adjustment during the test.

For the Marshall Stability and Flow Test, the precautions that need to be considered

are as follow:

1. Make sure the specimens are tested within 30 seconds after removing from the

water bath.

2. Make sure the time is set before immersed the specimens in the water bath.

3. The testing head and guide rods must be thoroughly cleaned before the test.

4. Each specimen shall be place inside the water bath at interval of 5 minutes or

more such that all specimens can be tested after immersed for exactly 30

minutes.

31

6.0 CONCLUSION

Most of the objectives for this experiment were successfully achieved. For the first

test, we are able to prepare the standard specimens of asphaltic concrete for determination of

stability and flow in the Marshall apparatus and to determined density, percentage air voids

and percent of aggregate voids filled with binder. Specimens with 4.5%, 5%, 5.5%, 6% and

6.5 % asphalt content are prepared successfully.

For the density and void analysis, we also successfully determine the density and void

analysis in the mix design specimens. The graphs of bulk density, VTM, VMA and VFA

versus percentage of binder are plotted. The proportion of void in the mix design can affect

the strength of the pavement thus it should be design in such a way that is fulfilling the

requirements of the asphalt mix design.

The third test, which is the Resilient Modulus test, was successfully conducted and

the results were successfully obtained. We are able to determine the resilient modulus or the

stiffness modulus of asphalt mixes using MATTA machine. Graph of resilient modulus

versus percentage of binder is plotted. There are three parameters that are needed to control in

the Resilient Modulus Test, which is the temperature, load duration and strain level achieve

in the test sample.

For the Marshall Stability and flow test, the objective of the experiment is achieved.

We are able to measure the resistance to flow of cylindrical specimens of an asphaltic paving

mixture loaded on the lateral surface by means of the Marshall Apparatus. Marshall Stability

test is the performance prediction measure conducted on the bituminous mix. The procedure

consists of determination of properties of mix, Marshal Stability and flow analysis and finally

determination of optimum asphalt content.

32

7.0 REFERENCES

1. Ratnasamy Muniandy, Radin Umar Radin Sohaidi, Highway Materials A guide

Book for Engineers, Universiti Putra Malaysia.(2001).

2. Fred L. Mannering, Walter P. Kilareski, Principle of Highway Engineering and

Traffic Analysis, 2nd Edition.

3. Paul H. Wright, Karen K.Dixon, Highway Engineering,7th edition, United State,

(2004).

4. Testing of Asphalt Mixtures. Retrieved May 19, 2012,from

http://www.virginiadot.org/business/resources/Materials/MCS_Study_Guides/bu-

mat-Chapt7AP.pdf

33

8.0 APPENDIX

34

Figure 8(a):Three samples that being prepared

Figure 8(b):The forth sample

Figure 8(c):Wire basket for void analysis

Figure 8(e):MATTA for Resilient Modulus

Analysis

Figure 8(d):Resilient Modulus Analysis

Figure 8(f):Marshall Stability test

35

Figure 8(g):Sample’s condition after the Marshall

Stability test

Figure 8(h):Sample’s condition before the

Marshall Stability test

Figure 8(h):Sample’s condition before the

Marshall Stability test

Figure 8(i):Reading show for the Marshall

Stability test

Figure 8(j):Sample before the water bath

Figure 8(k):Setting before the test done