Highway Materials

Chapter Four

Mix Design

Introduction

Bituminous mixes are used in the surface layer of road and airfield pavements. The mix is composed
usually of aggregate and asphalt cements. Some types of bituminous mixes are also used in base coarse.
There are several methods to design the Asphalt Mix, the common methods are Marshall Stability,
Hveem Stabilometer and Supper Pave tests.

The desirable properties of Asphalt mixes are:

1. Resistance to permanent deformation: The mix should not be displaced when subjected to traffic
loads. The resistance to permanent deformation is more important at high temperatures.
2. Fatigue resistance: the mix should not crack when subjected to repeated loads over a period of time.
3. Resistance to low temperature cracking: This mix property is important in cold regions.
4. Durability: the mix should contain sufficient asphalt cement to ensure an adequate film thickness around
the aggregate particles. The compacted mix should not have very high air voids, which accelerates the aging
process.
5. Resistance to moisture-induced damage.
6. Skid resistance.
7. Workability: the mix must be capable of being placed and compacted with reasonable effort.
8. Low noise and good drainage properties: If the mix is to be used for the surface (wearing) layer of
the pavement structure.

Marshall Mix Design Method

In Marshall Mix Design method, the resistance to plastic deformation of a compacted cylindrical specimen
of bituminous mixture is measured when the specimen is loaded diametrically at a deformation rate of 50
mm per minute.
The Marshall stability of the mix is defined as the maximum load carried by the specimen at a standard test
temperature of 60C. The flow value is the deformation that the test specimen undergoes during loading up
to the maximum load. Flow is measured in 0.25 mm units. In this test, an attempt is made to obtain optimum
binder content for the type of aggregate mix used and the expected traffic intensity.

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Objective

1. To prepare standard specimens of asphalt concrete for measurement of stability and flow in the
Marshall apparatus.
2. To determine density, percentage air voids, and percentage of aggregate voids filled with binder.
3. To find the optimum binder content in the mix.
Apparatus

1. Specimen mold 101.6 mm diameter and 76.2 mm height with extension collar and base plate
2. Specimen extractor
3. Compaction hammer 4.536 kg weight, 457.2 mm drop
4. Specimen mold holder
5. Breaking head
6. Ring dynamometer assembly
7. Flow meter
8. Oven or hot plate
9. Mixing bowls
10. Water bath
11. Water tank balance
12. Thermometers Marshall Sample Water tank balance
13. Miscellaneous apparatus
Materials:

1. Coarse Aggregate
2. Fine Aggregate
3. Filler
4. Bitumen

Preparation of Material

1. The aggregate, graded according to Iraqi Specification road mix (see Table 1 and Figure 1), is dried at
105-110 oC and sufficient amount is weighed (about 1200 g) to give a height of 63.5 + 1.3 mm when
compacted in the mould.

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2. The required quantity of bitumen is weighed out and heated to a temperature which will give a
viscosity of 170 + 20 mm 2/s.
3. The aggregate is heated in the oven to a temperature not higher than 28⁰ C above the binder
temperature.
Preparation of specimens:

1. The compaction mould assembly and rammer are cleaned and kept pre-heated to a
temperature of 100C to 145C.
2. The heated aggregates and bitumen are thoroughly mixed at a temperature of 154 – 160Co.
3. Place the mixture in a preheated Marshall mould with a collar and base. Place filter paper on
top and bottom of the sample.
4. Place the mould in a Marshall Compaction pedestal and compact the materials with a
specified number of blows by the rammer on either side at temperature of 138 to 149Co.
5. After compaction, invert the mould. With the collar on the bottom, remove the base and
extract the sample by pushing it out by the extractor.
6. Allow the sample to cool. Obtain the sample’s mass in air and submerged to measure density
of specimen.
7. Preferably, five specimens are required with two specimens having bitumen content above
and two below the expected optimum content.
8. Specimens are heated to 60±1 Co, either in a water bath for 30 – 40 min or in an oven for 2
hours.

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Figure4-1: Preparation of specimen

Testing of specimens:

1. Remove the specimen from the water bath and place in the lower segment of the breaking head
on the specimen and place the complete assembly in position on the testing machine.
2. Place the flow meter over one of the post and adjust it to read zero.
3. Apply the load at a rate of 50 mm/min until the maximum load reading is obtained.

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4. Record the maximum load reading in Newton and obtain the flow as recorded on the flow meter
in units of 0.25 mm.

Figure 4-2: Testing of specimen

Calculation

The binder content is determined with Marshall Stability, flow, void content, voids filled with binder and
density requirements for the mix being investigated.

Steps of Design

1. Select aggregate grading to be used.

2. Determine the proportion of each aggregate size required to produce the design grading.
3. Determine the specific gravity of the aggregate combination and asphalt cement.
4. Prepare the trial specimens with varying asphalt contents.
5. Determine the specific gravity of each compacted specimen.
6. Perform stability tests on the specimens.
7. Calculate the percentage of voids, and percent voids filled with Bitumen in each specimen.
8. Select the optimum binder content from the data obtained.

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9. Evaluate the design with the design requirements.

1. Aggregate gradation and blending
Distribution of particle sizes expressed as percent of total weight, Determined by sieve analysis. Gradation
is a key property of aggregate. It affects the workability of Portland cement concrete, the stability and
durability of bituminous concrete and the stability, drainage and frost resistance of base courses.
Types of Gradations:

Uniformly Graded Aggregate

1. Narrow range of sizes

2. Grain-to-grain contact
3. High void content
4. High permeability
5. Low stability
6. Difficult to compact Uniformly Graded Aggregate
Open-Graded Aggregate

1. Few fine particles

2. Grain-to-grain contact
3. High void content
4. High permeability
5. High stability
6. Difficult to compact Open-Graded Aggregate
Gap-Graded Aggregate

1. Missing middle sizes

2. No grain-to-grain contact
3. Moderate void content
4. Moderate permeability
5. Low stability
6. Easy to compact Gap-Graded Aggregate
Dense-Graded Aggregate

1. Wide range of sizes

2. Grain-to-grain contact
3. Low void content

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4. Low permeability
5. High stability
6. Difficult to compact

Dense-Graded Aggregate

Densest aggregate gradations give greatest durability and minimize air voids in bituminous materials.
According to the Iraqi specification (SCRB, 2007, R9), the asphalt concrete mixtures for base course
(type I), binder course (type II) and surface course (type IIIA or IIIB) shall be composed basically of
coarse aggregate, fine aggregate, mineral filler (if needed), and asphalt cement.

Table 4-1: Asphalt Mixture

Type I Type II Type IIIA Type IIIB
Binder or
Base Surface of Wearing
Sieve Size mm Lcvcling
Course Course
Course
% passing by Weight of Total Aggregate + Filler
1 ½ in 37.5 100
1 25.0 90-100 100
¾ 19.0 76-90 90-100 100
½ 12.5 56-80 76-90 90-100 100
3/8 9.5 48-74 56-80 76-90 90-100
No. 4 4.75 29-59 35-65 44-74 55-85
No. 8 2.36 19-45 23-49 28-58 32-67
No. 50 0.300 5-17 5-19 5-21 7-23
No. 200 0.750 2-8 3-9 4-10 4-10
Asphalt Cement
3-5.5 4-6 4-6 4-6
(% weight of total mix)

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Figure 4-3: Type of Aggregate Gradation

The Iraqi SCRB (2009, R9) stated that contractor will be allowed the tolerances from the approved job-
mix formula shown in Table 2.

Table 4-2: Job-Mix Formula Tolerances

Tolerance
Aggregate passing sieve 4.75mm (No. 4) or larger ± 6%
Aggregate passing sieve 2.36 (No. 8) to 0.3mm (No. 50) ± 4%
Filler passing sieve 0.075mm (No. 200) ± 2%
Asphalt cement ± 0.3%
Mix temperature ± 15 oC

Blending of Aggregates

1. Numerical method
2. Trial and error
3. Basic formula
4. Graphical

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Apparatus

1. A set of sieves.
2. Laboratory oven
3. Riffle box
4. Balance
Procedure

1. Place the aggregate under test in a heap. Divide it into four parts by quartering (passing vertical sections
the two being at right angles to each other). This can also be done using a Riffle box. Divide it further
into parts so as to obtain finally about 1.5 Kg of the aggregate sample.

2. Dry the aggregate in the oven at approximately 105 co for about 4 hours.

3. Clean and dry the set of sieves as desired. Find the weights of ovary sieves (empty) individually.

4. Place the sieves one above the other in a manner that the max. Aperture size will be at the top and the
minimum aperture size will be at the bottom which will be just above the pan.

5. Place 1000 gm of the dried aggregate in the top sieves.

6. Shake the sieves (preferably by mechanical source) for a period not less than 2 minutes and not
exceeding 7 minutes.

7. Remove the sieves from the shaker and find the weights of every sieve (containing aggregate particles)
individually.

8. Enter all the above readings in the observation chart, and calculate the cumulative percentage passing
for every sieve separately.

9. Plot a graph in a semi log paper. The aperture size will be plotted in the x axis which will be in
logarithmic scale while the corresponding passing percentage will be plotted on the Y axis in ordinary
scale. Draw the gradation curve.

10. Repeat the whole above procedure for the second and subsequent aggregate samples and plot the
corresponding gradation curves.

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Blending of Aggregate

A. determine the desired blending percentage by curve:

1. The size distributions of the fractions to be mixed (A, B, C and D in Table 1) are plotted on this scale
of sieve size giving lines EFO (fraction A), GHI (fraction B), JKL (fraction C) and OPQ (fraction D)
in Figure 2.
2. The nearest straight lines to these size distributions are drawn with the aid of a transparent straight-
edge, by the 'minimum balanced areas' method. They are the broken lines RO, TS, VU and OW.
3. The opposite ends of these lines are joined giving the chain lines RS, TU and VW.
4. The points where these lines cross the required distribution line (diagonal) are marked by the circles
1, 2 and 3, or specification is plotted on the chart (desired gradation) see Figure 3.
5. The proportions in which the four fractions should be mixed are obtained from the difference between
the ordinates of these points and are shown on the right-hand side of Figure 1 (sections A, B, C and D).
6. The theoretical particle-size distribution which will result from mixing the fractions in these
proportions is given in Table 2.

Table 4-3: Particle Size Distribution of Components

Sieve
Hot-bin. or cold feed samples Design
size
of spec.
mm grading
A B C D
19.0 100 100 100 100 100
13.2 85 100 100 100 90
6.7 30 90 100 100 78
4.75 0 70 100 100 61
2.38 0 25 95 100 45
1.18 0 10 70 100 30
0.600 0 0 50 100 22
0.300 0 0 30 95 16
0.150 0 0 10 80 12
0.075 0 0 0 50 6

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Figure 4-4: Aggregate Blending Chart RothFuchs’s Method

Figure 4-5: Aggregate Blending Chart by plotting specification (desired gradation)

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2. Determine the proportion of each aggregate size

Table 4-4: Theoretical Blend Resulting from RothFuchs’s Method

Percentage of Design of
22% of 45% of 25 % of 8% of Cumulative
spec.
each fraction A B C D grading
grading
19.0 22 45 25 8 100.0 100
13.2 18.7 45 25 8 96.7 90
6.7 6.6 40.5 25 8 80.1 78
4.75 0 31.5 25 8 64.5 61
2.38 0 11.25 23.75 8 43.0 45
1.18 0 4.5 17.5 8 30.0 30
0.600 0 0 12.5 8 20.5 22
0.300 0 0 7.5 7.6 15.1 16
0.150 0 0 2.5 6.4 8.9 12
0.075 0 0 0 4 4.0 6

B. Determine the desired blending percentage by trial and error:

Trial and error procedure: Vary the proportion of materials until the required aggregate gradation is

achieved.

A trial percentage of each aggregate source is assumed and is multiplied by the percentage passing each

sieve. These gradations are added to get the composite percentage passing each sieve for the blend. The

gradation of the blend is compared to the specification range to determine if the blend is acceptable. With

practice, blends of four aggregates can readily be resolved.

The basic equation for blending is:

Pi = Aa + Bb + Cc + …

Where:
Pi = blend material passing sieve size i.
A, B, C, … = Percent of aggregates A, B, C, passing sieve i.
a, b, c, … = decimal fractions by weight of aggregates A, B, and C used in the blend, where the total is
1.00.

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1. Aggregate Gradation

Table 4-5: Aggregate Gradation Analysis

Sieve size
(19-9) mm (9-4) mm (4-0) mm Filler Specification Limits
(mm)
19.1 100 100 100 100 100
12.7 73 100 100 100 90-100
9.5 35 100 100 100 70-90
4.75 0 58 100 100 35-65
2.36 0 38 75 100 23-49
0.300 0 0 35 100 5-19
0.075 0 0 0 85 3-9

2. Proportion of each aggregate size

First Trial:
The proportion of each aggregate size is as follows:
A = 31, B = 46, C = 16, D = 7
Table 4-6: Blend gradation Results

Sieve size (19-9) mm (9-4) mm (4-0) mm Filler Desired blend Mid Specification
(mm) P = 31 P = 46 P = 16 P=7 gradation Limits
19.1 31 46 16 7 100 100
12.7 23 46 16 7 92 95
9.5 11 46 16 7 80 80
4.75 0 27 16 7 50 50
2.36 0 17 12 7 36 36
0.300 0 0 6 7 13 12
0.075 0 0 0 6 6 6

Second Trial:
The proportion of each aggregate size is as follows:
A = 31, B = 53, C = 9, D = 7

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Table 4-7: Blend gradation Results

Sieve size (19-9) mm (9-4) mm (4-0) mm Filler Desired blend Mid Specification
(mm) P = 31 P = 53 P=9 P=7 gradation Limits
19.1 31 53 9 7 100 100
12.7 23 53 9 7 92 95
9.5 11 53 9 7 80 80
4.75 0 31 9 7 47 50
2.36 0 20 7 7 34 36
0.300 0 0 3 7 10 12
0.075 0 0 0 6 6 6

Third Trial:
The proportion of each aggregate size is as follows:
A = 39, B = 39, C = 15, D = 7
Table 4-8: Blend gradation Results

Sieve size (19-9) mm (9-4) mm (4-0) mm Filler Desired blend Mid Specification
(mm) P = 39 P = 39 P = 15 P=7 gradation Limits
19.1 39 39 15 7 100 100
12.7 28 39 15 7 89 95
9.5 14 39 15 7 75 80
4.75 0 23 15 7 45 50
2.36 0 15 11 7 33 36
0.300 0 0 5 7 12 12
0.075 0 0 0 6 6 6

The first trial is the best proportion for blending aggregate, the proportion of each aggregate size is as
follows:
A = 31, B = 46, C = 16, D = 7
3. Determine the specific gravity of the aggregate combination and asphalt cement:

Sieve size (mm) (19-9) mm (9-4) mm (4-0) mm Filler

% Blending of Aggregates 31 46 16 7

Specific Gravity (Gsb) 2.606 2.626 2.618 2.580

Specific Gravity (Gb) 1.03

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100
Sp. Gr. of total Aggregate =
%Agg. 1 %Agg. 2 %Agg. 3 %Agg. 4 %Agg. 5 %filler Cement
Spgr. 1 + Spgr. 2 + Spgr. 3 + Spgr. 4 + Spgr. 5 + Spgr + Spgr

100
Gsb = 31 46 16 7 = 2.615
+ + +
2.606 2.626 2.618 2.580

3. Prepare the trial specimens with varying asphalt contents:

Suppose, AC = 3.5% by total mix, total Aggregate = 96.5% total mix

Fractions blending% Calculation required weight (gm)
19-9 31% 0.31*0.965*1200 358.98
9-4 46% 0.46*0.965*1200 532.68
4-0 16% 0.16*0.965*1200 185.28
Filler 7% 0.07*0.965*1200 81.06
Asphalt %3.5 first trail 0.035*1200 42

Suppose, AC = 4% by total mix, total Aggregate = 96% total mix

Fractions blending% Calculation required weight (gm)
19-9 31% 0.31*0.96*1200 357.12
9-4 46% 0.46*0.96*1200 529.92
4-0 16% 0.16*0.96*1200 184.32
Filler 7% 0.07*0.96*1200 80.64
Asphalt %4 first trail 0.04*1200 48

Suppose, AC = 4.5% by total mix, total Aggregate = 95.5% total mix

Fractions blending% Calculation required weight (gm)
19-9 31% 0.31*0.955*1200 355.26
9-4 46% 0.46*0.955*1200 527.16
4-0 16% 0.16*0.955*1200 183.36
Filler 7% 0.07*0.955*1200 80.22
Asphalt %4.5 first trail 0.045*1200 54

Suppose, AC = 5% by total mix, total Aggregate = 95% total mix

Fractions blending% Calculation required weight (gm)
19-9 31% 0.31*0.95*1200 353.4
9-4 46% 0.46*0.95*1200 524.4
4-0 16% 0.16*0.95*1200 182.4
Filler 7% 0.07*0.95*1200 79.8
Asphalt %5 first trail 0.05*1200 60

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Suppose, AC = 5.5% by total mix, total Aggregate = 94.5% total mix

Fractions blending% Calculation required weight (gm)
19-9 31% 0.31*0.945*1200 351.54
9-4 46% 0.46*0.945*1200 521.64
4-0 16% 0.16*0.945*1200 181.44
Filler 7% 0.07*0.945*1200 79.38
Asphalt %5.5 first trail 0.055*1200 66

5. Determine the specific gravity of each compacted specimen.

% A.C by
Wt. in air Wt.in Water Wt. SSD Vol. Cc = Bulk-Gmb Sp.Gr. Unit Weight
weight of
A C B (B-C) A/(B-C) = ρw ∗ Gmb
mix
3.5 1220 731 1244 513 2.378 2.378
4 1223 734 1245 511 2.393 2.393
4.5 1227 739 1251 512 2.396 2.396
5 1228 739 1250 511 2.403 2.403
5.5 1229 738 1250 512 2.400 2.400

6. Perform stability tests on the specimens.

AC% Marshall Marshall

by weight Satbility Flow
of Mix KN mm
3.5 13.2 2.2
4 14.0 2.7
4.5 13.3 3.6
5 12.4 4.4
5.5 11.4 6.1

Effect Specific Gravity for Asphalt Mix Design (Loose HMA (Not Compacted))
Wt. of Wt. of Wt. of Wt. of
% Wt. of Wt. of
sample sample + bowl sample Volume Gmm=
Asphalt bowl in sample in
+ bowl bowl in in in water C= A-B A/C
Content air air (A)
in air water water (B)
3.5 2785.6 1565 1220.6 4481.7 3745.5 736.2 484.4 2.520
4 2798.9 1565 1233.9 4486.3 3745.5 740.8 493.1 2.502
4.5 2783 1565 1218 4473 3745.5 727.5 490.5 2.483
5 2775.2 1565 1210.2 4464.8 3745.5 719.3 490.9 2.465
5.5 2761.9 1565 1196.9 4453.2 3745.5 707.7 489.2 2.447

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Effective Specific Gravity of Aggregate, Gse:

Gse = Pmm − Pb
Pmm Pb
Gmm − Gb

100 − 3.5
Gse = 100 3.5 = 2.659 %AC = 3.5%
−
2.52 1.03

100 − 4.0
Gse = 100 4.0 = 2.66 %AC = 4%
2.502 − 1.03

100 − 4.5
Gse = 100 4.5 = 2.659 %AC = 4.5%
−
2.483 1.03

100 − 5.0
Gse = = 2.66 %AC = 5%
100 5.0
−
2.465 1.03

100 − 5.5
Gse = = 2.659 %AC = 5.5%
100 − 5.5
2.447 1.03

2.659 + 2.66 + 2.659 + 2.66 + 2.659

𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝐺𝑠𝑒 = = 2.659
5

❖ Theoretical Maximum Specific Gravity of Asphalt Mix, Gmm:

Gmm = Pmm
Ps Pb
+
Gse Gb

100
Gmm = 96.5 3.5 = 2.520 %AC = 3.5%
2.66 + 1.03
100
Gmm = 96 4 = 2.502 %AC = 4%
+
2.66 1.03
100
Gmm = 95.5 4.5 = 2.483 %AC = 4.5%
+
2.66 1.03
100
Gmm = 95 5 = 2.465 %AC = 5%
+
2.66 1.03
100
Gmm = = 2.447 %AC = 5.5%
94.5 + 5.5
2.66 1.03
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7. Calculate the percentage of voids, and percent voids filled with Bitumen in each
specimen:
Asphalt concrete primarily consists of three different components or phases: aggregate,
asphalt binder, and air, see the figure 4.

Figure 4: Asphalt Concrete

Air can exist in pores on the aggregate surface, pockets within aggregate particles, or voids with
in the asphalt binder or between the binder and aggregate particles. Only the last type of air is
included in the air void content of asphalt concrete mixtures.

Figure 5: Types of Air Voids

Effective asphalt includes asphalt binder

Figure 6: Effective Asphalt Content

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Voids in the mineral aggregate (VMA) refers to the space between aggregate particles in an asphalt
concrete mixture VMA is also often used to characterize loose aggregate. Voids in
mineral aggregate (VMA) is composed of asphalt binder and air voids.

Figure 7: Voids in mineral aggregate

Asphalt Absorption:
Gse − Gsb
Pba = (100) Gb
Gsbx Gse

2.66 − 2.615
Pba = (100) x 1.03 = 0.666
2.615 x 2.66

Percent Effective Asphalt Content

Pba
Pbe = Pb − Ps
100

0.666
Pbe = 3.5 − x 96.5 = 2.857 %AC = 3.5%
100

0.666
Pbe = 4 − x 96 = 3.361 %AC = 4%
100

0.666
Pbe = 4.5 − x 95.5 = 3.864 %AC = 4.5%
100

0.666
Pbe = 5 − x 95 = 4.367 %AC = 5%
100

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0.666
Pbe = 5.5 − 100 x 94.5 = 4. 871 %AC = 5.5%

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Percent Voids in Mineral aggregate:

Gmb x Ps
VMA = 100 −
Gsb

2.378 x 96.5
VMA = 100 − = 12.2 %AC = 3.5%
2.615

2.393 x 96
VMA = 100 − = 12.1 %AC = 4%
2.615

2.396 x 95.5
VMA = 100 − = 12.4 %AC = 4.5%
2.615

2.403 x 95
VMA = 100 − = 12.7 %AC = 5%
2.615

2.400 x 94.5
VMA = 100 − = 13.3 %AC = 5.5%
2.615

Percent Air voids:

Gmm − Gmb
Va = 100 x
Gmm

2.520 − 2.378
Va = 100 x = 5.63 %AC = 3.5%
2.520

2.502 − 2.393
Va = 100 x = 4.36 %AC = 4%
2.502

2.483 − 2.396
Va = 100 x = 3.5 %AC = 4.5%
2.483

2.465 − 2.403
Va = 100 x = 2.52 %AC = 5%
2.465

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2.447 − 2.400
Va = 100 x = 1.92 %AC = 5.5%
2.447

Percent voids Filled with Asphalt:

VMA − Va
VFA = 100 x
VMA

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12.2 − 5.63
VFA = 100 x = 54% %AC = 3.5%
12.2

12.1 − 4.36
VFA = 100 x = 64% %AC = 3.5%
12.1

12.4 − 3.5
VFA = 100 x = 72% %AC = 3.5%
12.4

12.7 − 2.52
VFA = 100 x = 80% %AC = 3.5%
12.7

13.3 − 1.92
VFA = 100 x = 86% %AC = 3.5%
13.3

8. Select the optimum binder content from the data obtained.

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Stability + Unit weight + Air voids

%AC =
3

4.1 + 4.9 + 4.175

%AC = = 4.43
3

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Phase diagram approach to calculate the volumetric properties of HMA paving mixture:

Definition of volume terms used in volumetric analysis:

Ma Air Va

VMA
Mbe Asphalt binder Vbe
Mb Vb
Mba Absorbed asphalt Vba
Mmb Vmb

Ms
Aggregate Vsb
Mse Vse

Vmb: Bulk volume of compacted mix

VMA: Volume of voids in mineral aggregate
Vmm: Voidless volume of paving mix
VFA: Volume of voids filled with asphalt
Va: Volume of air voids
Vb: Volume of asphalt

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Vba: Volume of absorbed asphalt

Vbe: Volume of effective asphalt binder
Vsb: Volume of mineral aggregate
Vse: Volume of mineral aggregate
Mbe: Mass of effective asphalt binder
Mba: Mass of absorbed asphalt binder
Ms: Mass of aggregate, total
Mb: Mass of asphalt binder, total
Mse: Mass of aggregate, effective (excluding surface pores filled with asphalt)
Ma: Mass of air voids
Mmb: Mass of specimen, total

Example (volumetric analysis):

Pb = 5% , Gmb = 2.403 ,Gb = 1.030, Gsb = 2.615, Gmm = 2.465
Assume unit volume = 1cm 3
Mass of mix:
Mm = Vm Gmb ρm
Mm = 1cm3 x 2.403 x 1gm/cm3 = 2.403gm
Mass of Asphalt: Mb = Pb Mm
Mb = 5/100 x 2.403 = 0.120
Mass of Aggregate: Ms = Mm – Mb
Ms = 2.403 – 0.120 = 2.283
Mb
Volume of total Asphalt: Vb =
Gb ρm
Vb = 0.120/1.030 = 0.117

Pmm−Pb
Effective Specific Gravity of Aggreagte: Gse =
Pmm Pb
Gmm− Gb

100 − 5
Gse = = 2.66
100 5
−
2.465 1.03

Ms
Effective volume of Aggregate: Vse = G se ρm

Vse = 2.283/2.66 = 0.858

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Ms
Bulk volume of Aggregate: Vsb = G
sb ρm

Vsb = 2.283/2. 2.615 = 0.873

Volume of Absorbed Asphalt: Vba = Vsb – Vse

Vba = 0.873 – 0.858 = 0.015
Volume of Effective Asphalt: Vbe = Vb – Vba
Vbe= 0.117 – 0.015 = 0.102
Volume of Air Voids: Va = Vm – Vse – Vb
Va = 1 – 0.858 – 0.117 = 0.025
V𝑎
%of voids: Pa = x 100%
Vm

0.025
Pa = x 100 = 2.5
1

Va + Vbe
Voids in Mineral aggregate: VMA = x 100
Vm

0.025 + 0.102
VMA = x 100 = 12.7
1

Vbe
Voids filled with Asphalt: VFA = x 100
VMA

0.102
VFA = x 100 = 80.31
0.127

Mass of absorbed Asphalt: Mba = Vba Gb ρm

Mba = 0.015 x 1.030 = 0.0154
Mass of Effective Asphalt: M be= Vbe Gb ρm
Mbe = 0.102 x 1.030 = 0.1051
Mbe
Effective Asphalt Content (%Mass of mix): Pbe = x 100
Mm

0.1051
Pbe = x 100 = 4.37
2.403

Mba
AbsorbedAsphalt Content(%Mass of Aggregate): Pba = x 100
Ms

Pb a=

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 Highway Materials

0.0154
2.283 x 100
=
0.674

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