1. PACKING CHARACTERISTICS OF DIFFERENT
AGGREGATE GRADATIONS IN ASPHALTIC
MIXTURE FOR PAKISTAN
By
Engr. Muhammad Aakif Ishaq

2. INTRODUCTION
OBJECTIVES OF THE STUDY
METHODOLOGY
EXPERIMENTAL WORK
RESULTS AND DISCUSSION
CONCLUSIONS
Contents

3. • Premature Failure of Flexible
pavements is common in Pakistan.
• Factors contributing towards failures;
like loading, temperature variation,
construction practices, material
specifications, and designs (Pavement
and asphalt mix design).
Introduction
• Asphalt mix design Practices;
• Lack of knowledge about aggregate
packing characteristics.
• We blend aggregate closer to mid
line of aggregate gradation.

4. Conventional Field Mix Design
• Materials Properties
•Flakiness and elongation ratio
• %age absorption, Gsb
• LAAV
• Soundness Value, PI Value
Values should
be within
Specifications
Drawbacks
• Shape, texture effects
;
• Packing;
• Volumetric Control
• Performance of Mix
TRIAL BLEND
SIEVE
Sizes
Fraction#
01, 02, 03
(Passing
%)
Batch
Percent
Final
Blend
J.M.F
LIMITS Spec.

5. Bailey Method
• Originally developed in 1980’s by Robert D.
Bailey (IDOT).
• Focus is aggregate PACKING!
• Determine “COARSE” and “FINE”
• Evaluate individual agg’s and combined blend
by VOLUME as well as by WEIGHT.
• Estimate HMA Volumetric especially VMA.

6. Bailey Method
The Bailey Method is a;
• systematic approach to blending aggregates
• provides aggregate interlock as the backbone of
the structure and,
• a balanced continuous gradation to complete the
mixture.
• set of tools that allows the evaluation of
aggregate blends.
• These tools provide a better understanding in the
relationship between aggregate gradation and
mixture voids.

7. Bailey Method
Large aggregate particles that when placed in unit
volume creates voids.
Aggregate particles that can fill the voids
created by the coarse aggregate in the mixture.
Definition of coarse and fine depends on the NMAS of the mixture.
Sieve that define coarse and fine aggregate is known as Primary Control Sieve (PCS)

8. Coarse versus Fine Aggregate
Example: Break b/w coarse and fine aggregate for 19.0mm
NMAS mixture.
PCS= NMASX0.22
Mix.
NMAS
NMASX0.22 PCS
Sieve
37.5mm 8.25mm 9.5mm
25.0mm 5.5mm 4.75mm
19.0mm 4.18mm 4.75mm
12.5mm 2.75mm 2.36mm
9.5mm 2.09mm 2.36mm
4.75mm 1.045mm 1.18mm
is “0.22” a
magical
number?

9. Primary Control Sieve
Particle
Shape
PCS
Factor
All Round
0.15
2 Round
1Flate
0.20
1Round
2Flate
0.24
All Flate 0.29
Average 0.22
Round
face of
particle
Flate face
of particle
Particle
dia (d)
2-D & 3-D analysis of the packing of different shape particles

10. Primary Control Sieve
Primary Control Sieve
≈ 0.22 x NMAS
NMAS
Secondary Control Sieve
≈ 0.22 x NMAS

11. K J I H G F E D C B AK J I H G F E D C B A
Sieve Size (mm) Raised to 0.45 PowerSieve Size (mm) Raised to 0.45 Power
100100
00
%Passing%Passing Combined Blend GradationCombined Blend Gradation
5050
2020
8080
Sieve % Passing
A 100
B 97
C 76
D 63
E 39
F 25
G 17
H 11
I 7
J 5
K 4.2
1010
3030
4040
6060
7070
9090
CoarseFine
1
2
3
4
Coarse agg. Ratio (CA) relates to
the coarse & intermediate fractions
Fine agg. Coarse ratio (Fac) relates to
the amount of large sand in the mix.
Primary Control Sieve (PCS)
defines what is coarse and fine
Fine agg. Fine ratio
(FAf) relates to the
amount of fine sand
in the mix.
SCS
TCS

12. Combined Blend Evaluation
Coarse-Graded Mixes
Half Sieve = 0.5 x NMAS
PCS = 0.22 x NMAS
Coarse
Fraction
Fine
Fraction
SCS = 0.22 x PCS
TCS = 0.22 x SCS
1
CA CUW (% PCS)
CA Ratio =
% Half Sieve - % PCS
100 - % Half Sieve
FAf Ratio = % TCS
% SCS
2
3
4
FAc Ratio = % SCS
% PCS

13. CA= 0.84
FAc
FAf

14. Typical Values (Bailey Method)

15. Unit Weight
Loose Unit Weight Rodded Unit Weight
• No compactive efforts
• Start of particle-
particle contact
• Volume of voids
• With compactive
efforts
• 3-layers, 25-temping
• Increased p-to-p
contact
• Volume of voids

16. Chosen Unit Weight ~ VMA
Lower limit of aggregate interlock
Upper limit of aggregate interlock
Less than LUW≈ Fine agg. skeleton
More than RUW≈ Dense graded mix

17. Combined Blend Evaluation
Coarse-Graded Mixes
3. FAc Ratio increase = VMA decrease
 0.05 change ≅ 1% change in VMA or Voids
 Range 0.025 – 0.075
1. CA CUW increase = VMA increase
 4% change in PCS ≅ 1% change in VMA or Voids
 Range 3 – 5%
2. CA Ratio increase = VMA increase
 0.20 change ≅ 1% change in VMA or Voids
 Range 0.10 – 0.30
4. FAf Ratio increase = VMA decrease
 0.05 change ≅ 1% change in VMA or Voids
 Range 0.025 – 0.075
Has the
most
influence on
VMA or
Voids

18. Estimating VMA or Voids
Coarse-Graded Mix (Example)
 Trial #1 (% Passing)
25.0mm 100.0
19.0mm 97.4
12.5mm 76.2
9.5mm 63.5
4.75mm 38.2
2.36mm 23.6
1.18mm 18.8
0.60mm 13.1
0.30mm 7.4
0.15mm 5.7
0.075mm 4.0
 Trial #2 (% Passing)
25.0mm 100.0
19.0mm 98.0
12.5mm 76.5
9.5mm 63.6
4.75mm 37.2
2.36mm 22.1
1.18mm 16.5
0.60mm 11.8
0.30mm 6.8
0.15mm 5.2
0.075mm 3.5
NMAS
HALF
PCS
SCS
TCS

19. Estimating VMA or Voids
Trial #2 vs. Trial #1
Controls Difference VMA or
Voids
Variation in
VMA
PCS 37.2%-38.2%= -1.0 Increases 1.0/4.0 = +0.25%
CA Ratio 0.725-0.693= +0.032 Increases 0.032/0.2= +0.16%
FAc 0.444-0.492= -0.048 Increases 0.048/0.05= +0.96%
FAf 0.412-0.394= +0.018 Decreases 0.018/0.05= -0.36%
Total Estimate Change (approx.) 1.0%

20. Sieve analysis of each
aggregate fraction
Selecting % of Coarse
Fractions
Defining %age Coarse
aggregate Loose unit weight
Specific gravity
determinations
Loose & Rodded Dry Unit
Weight
%age absorption
Weight/volume contributed
Coarse aggregate
Voids in Coarse Aggregates
Weight per volume contributed
by the Fine aggregate
%age Coarse and Fine Aggregate
by weight
Defining Control Sieves
(PCS, SCS, TCS)
Defining CA Ratio, FAc &
FAf Ratio
Define Coarse and Fine
aggregate
Final aggregate gradation
Amount of fine in each Coarse
and amount of coarse in fine
aggregate
Correction to Fine and Coarse
aggregate
Amount of minus 0.075mm
material (filler)
Collection of aggregate
from each stockpile
Hierarchy of Bailey Method
1
2
3
4
5
6
7
8
9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8

21. Ratio’s Ratio
CA 0.652
FAc 0.453
FAf 0.461
Final Percentages by
WEIGHT
#1-CA 33.3 %
#2-CA 30.9 %
#3-CA 0.0 %
#4-CA 0.0 %
#1-FA 35.8 %
#2-FA 0.0 %
#3-FA 0.0 %
#4-FA 0.0 %
MF 0.0 %
Hyd Lime 0.0 %
Total = 100.0 %
Work Sheet (Bailey Method)
Gsb VCA
2.641 51.32

22. To investigate the possible relationship between the Voids in
Coarse aggregate (VCA) and maximum achievable
packing (density) using the local aggregates.
To establish limiting values of voids in Coarse aggregate
(VCA) against achievable packing (density) at different nominal
maximum aggregate sizes using the Bailey Method.
To investigate the effect of packing characteristic on
asphalt mixture performance.
Objectives

23. EXPERIMENTAL PROGRAM

24. Conclusion

25. Sr.
No.
Title Test Designation
Output Parameters/ Test
Details and units
Tests Results
1 Fractured Particles ASTM D 5821 100 %
2 Flat and Elongated Particles BS 812-105.1:1989 Flakiness Index, Elongation Index 12.05, 16.5
3 Loss Angeles Abrasion test ASTM C 131 % Weight Loss 22
4 Soundness & Durability ASTM C 88 % Weight Loss (Coarse, Fine) 0.18, 2.48
5 Deleterious Materials ASTM C 142 % Loss 0.94
6 Water Absorption ASTM C 127
% (25-38 mm, 12-25 mm, 5-12
mm, 0-5 mm)
0.35, 0.59, 0.70, 1.65
7 Bulk Specific Gravity ASTM C 127
(25-38 mm, 12-25 mm, 5-12 mm,
0-5 mm)
2.656, 2.640, 2.619, 2.700
8 Apparent Specific Gravity ASTM C 127
(25-38 mm, 12-25 mm, 5-12 mm,
0-5 mm)
2.686, 2.690, 2.691, 2.741
9 Effective Specific Gravity ASTM C 127
(25-38 mm, 12-25 mm, 5-12 mm,
0-5 mm)
2.667, 2.659, 2.646, 2.709
10 Gradation Test ASTM C 136
11 Unit Weight (Loose) ASTM C 29
(25-38 mm, 12-25 mm, 5-12 mm,
0-5 mm) in kg/m3 1368, 1409, 1347, 1625
12 Unit Weight (Rodded) ASTM C 29
(25-38 mm, 12-25 mm, 5-12 mm,
0-5 mm) in kg/m3
1487, 1529, 1471, 1790
13 Uncompacted Voids (Fine Aggregates only) ASTM C 1252 % (0-5 mm) 40
14 Sand Equivalent (Fine Aggregates only) ASTM D 2419 % 81.25
15 Plasticity Index (Fine Aggregates only) ASTM D 4318 Non-plastic ---
Qualitative Testing of Ubhan Shah aggregates

26. Trials Using Bailey Method

27. Schematic diagram of Trials
CA#01 (20-30%)
CA#02 (40-50%)
CA#03 (20-30%)
FA#01 (By Volume of
voids)
+
+
+
Gsb
VCA
CA CUW
95-105 %
CA (0.8-0.95)
Fac (0.35-0.5)
FAf (0.35-0.5)
NMAS = 37.5mm
25.4,19.5,12.5,9.5
BAILEY
TRIALS

28. CLUW Gsb VCA CA Fac Faf
95 2.653 51.697 0.908 0.42 0.38
100 2.655 49.1382 0.878 0.41 0.38
105 2.657 46.5770 0.879 0.40 0.38
CLUW Gsb VCA CA Fac Faf
105
2.658 46.594 0.936 0.38 0.38
2.657 46.585 0.906 0.39 0.38
2.657 46.577 0.879 0.40 0.38
2.656 46.569 0.855 0.41 0.38
2.656 46.560 0.829 0.42 0.38
2.655 46.552 0.806 0.44 0.38
CLUW Gsb VCA CA Fac Faf
100
2.655 49.140 0.803 0.41 0.38
2.655 49.139 0.828 0.41 0.38
2.653 49.105 0.828 0.45 0.38
2.653 49.113 0.852 0.44 0.38
2.655 49.139 0.853 0.41 0.38
2.654 49.121 0.878 0.43 0.38
2.655 49.138 0.878 0.41 0.38
2.655 49.138 0.905 0.41 0.38
2.655 49.137 0.935 0.41 0.38
CLU
W
Gsb VCA
CA
(0.8-0.95)
Fac
(0.35-0.5)
Faf
(0.35-0.5)
95
2.651 51.667 0.803 0.46 0.38
2.652 51.674 0.828 0.45 0.38
2.652 51.682 0.853 0.44 0.38
2.652 51.689 0.880 0.43 0.38
2.653 51.697 0.908 0.42 0.38
2.653 51.706 0.854 0.41 0.38
2.653 51.706 0.881 0.41 0.38
2.653 51.707 0.827 0.41 0.38
2.653 51.705 0.909 0.41 0.38
2.653 51.705 0.938 0.41 0.38
Typical Trial (37.5mm)

29. Summary of Trial
25.0 mm
LUW Gsb VCA CA Fac Faf
95 2.641 51.674 0.73 0.4383 0.4839
100 2.643 49.147 0.77 0.4343 0.4844
105 2.646 46.587 0.73 0.4335 0.4850
19 .5 mm
LUW Gsb VCA CA Fac Faf
95 2.644 52.00 0.71 0.42 0.48
100 2.647 49.40 0.68 0.41 0.48
105 2.649 46.90 0.68 0.41 0.49
12.5 mm
LUW Gsb VCA CA Fac Faf
95.00 2.622 51.60 0.58 0.38 0.47
100.00 2.623 49.10 0.58 0.38 0.47
105.00 2.627 46.50 0.51 0.39 0.48
9.5 mm
LUW Gsb VCA CA Fac Faf
95 2.632 52.30 0.47 0.38 0.47
100 2.635 49.80 0.44 0.38 0.47
105 2.638 47.30 0.42 0.38 0.47

31. Summary of Plots

32. NMAS
Coarse Graded Mix
Gsb VCA
37.5 2.651-2.660 46.55-51.71
25.4 2.641-2.646 46.58-51.71
19.5 2.643-2.649 45.8-52.0
12.5 2.621-2.627 46.5-51.7
9.5 2.632-2.638 47.3-52.3
NMAS
Fine Graded Mix
Gsb VCA
37.5 2.64-2.65 54.14-59.34
25.4 2.637-2.640 54.32-56.93
19.5 2.633-2.644 54.29-62.2
12.5 2.613-2.622 54.12-61.81
9.5 2.60-2.61 54.78-62.33
Packing Characteristics

33. Mix Design Practice

34. Selected Aggregate Gradation
Sieve Size
(mm)
Bailey Method
(19.5mm NMAS)
NHA-Class B
(19.5 mm NMAS)
NHA-B Wearing
Course Envelope
19
100.0 100.00
100-90
12.5
76.9 82.50
75-90
9.5
63.4 70.00
60-80
4.75
39.1 50.00
40-60
2.36
27.1 30.00
20-40
1.18
16.3 19.75
12-27
0.60
10.3 13.51
8-19
0.30
8.0 10.00
5-15
0.15
5.7 7.40
4-11
0.075
4.1 5.50
3-8

36. Asphalt Binder

37. Asphalt Mix Design
Design
Parameters
Bailey Mix
NHA-B Mix
Gsb 2.646 2.631
AC% 4.61 4.65
Gmb 2.4 2.398
Va 4.2 4.0
VMA 13.9 13.1
VFA 69.89 69.41
Marshall Method of Mix Design

38. Compaction characteristics
App. 20% more efforts in Bailey mix
App. 3% effort per change of VA
92% = approx. 7% va
98% = approx. 2% va

39. Passes = 10,000
Frequency = 26.5 rpm
Load = 720 N
Test Temp. = 40, 50°C
Test Standard = EN12697-22
Specimen Dim. =305x305x50mm
Va = 5.5± 0.5
Loading Wave = Sinusoidal
Frequency = 25,10,5,1,0.5,01 Hz
Stress Levels = 150, 75, 35, 7.5 psi
Test Temp. = 4.4, 21, 38, 54.4°C
Test Standard = AASHTO TP 62
Specimen Dim. = 100x 150mm dia.
Va = 5.5± 0.5
Wheel Tracker Test Dynamic Modulus Test
Performance Testing
RutRut
depthdepth E*E*

40. Test Results

41. NHA (B) Versus Bailey @40˚C
Comparison

42. NHA (B) Versus Bailey @50˚C
Comparison

43. Comparison

44. Comparison

45. Dynamic Modulus Test

46. Complex Modulus Testing
(AASHTO TP62-03)
 Complex modulus (E*) defines the relationship between stress and strain for
a linear viscoelastic material under sinusoidal loading (δO/εo).
• Useful test for comparative
study of mixtures.
• Results can be used to develop
master curves
│E*│=

47. Development of Master Curve
γ = affects the steepness of the function (rate of change
between minimum and maximum) and
β = the horizontal position of the turning point.
δ and α rely on aggregate gradation, binder amount
air void content.
β and γ, on the other hand, rely on the characteristics of
the asphalt binder and the magnitude of δ and α
[2002 Design Guide, (2004)].
|E*| = dynamic modulus
tr
= time of loading at the reference
temperature (reduced time)
δ = minimum modulus value
δ + α = maximum modulus value
β, γ = parameters describing the shape of
the sigmoidal function

48. Development of Master Curve

49. Development of Master Curve

50. Development of Master Curve
Bailey Mix
NHA-b Mix

51. Development of Master Curve

52. Statistical Analysis
Two-way ANOVA: Bailey versus temp, freq
Source Df SS MS F P
Temp 3 27452372 9150791 83.1 0
freq 5 2408720 481744 4.38 0.012
Error 15 1651570 110105
Total 23 31512662
S=331.8 R-Square=94.76 % R-Sqaure(Adj)=91.96 %
Two-way ANOVA: NHAB versus temp, freq
Source Df
SS
MS F P
Temp 3 24254934 8084978 56.44 0
freq 5 2532825 506565 3.54 0.026
Error 15 2418821 143255
Total 23 28936579
S=378.5 R-Square=92.57 % R-Sqaure(Adj)=88.61 %

53. Main Effect Plot for E*

54. Direct relationship exist between VCA and
Gsb.
Conclusion
Limiting values of Packing parameters can
be used for different aggregate gradation.
1
2
3
Optimum criteria based on VCA & Gsb
provide general solution for blending the
aggregate gradation for all NMAS.

55. Conclusion
Mix with Bailey gradation showed lesser rut potential.
Mix with Bailey method showed less temperature
sensitivity and yield higher stiffness.
Mix with Bailey gradation showed more resistance to post
compaction.
Bailey method works well with the aggregate properties in
Pakistan.
4
5
6
7

56. Q&A