1. UNIVERSITY OF NAIROBI MASTERS OF SCIENCE IN CIVIL ENGINEERING
(TRANSPORTATION)
CE 462
SUPERPAVE HOT MIX ASPHALT DESIGN
Presenter
OTWANI J. A
F56/67543/2013
NOVEMBER 2013

2. 1.0 INTRODUCTION 1.1 Background :
Superpave stands for SUperior PERforming asphalt PAVEments. (FHWA:US-DoT)
Developed in the US (1987 – 1993) through the Strategic Highway Research Programme (SHRP)
Adopted in SA in 2001 – blend of Marshall and Superpave.

3. 1.0 INTRODUCTION 1.2 Problem statement
Increasing traffic loads, traffic volumes and tyre contact stresses have resulted in increased incidences of premature distress (rutting, ravelling, cracking and potholes)
Marshall method does not satisfactorily address secondary compaction.

4. 1.0 INTRODUCTION 1.3 Research Questions
What are the inherent deficiencies in the Marshall method of mix design?
How does the superpave design method address the deficiencies in the Marshall method?

5. 1.0 INTRODUCTION 1.3. Study objectives
To outline inherent deficiencies in the Marshall method of HMA design.
To illustrate how the superpave method addresses inherent deficiencies in the Marshall method of HMA design.

6. 1.0 INTRODUCTION
1.4. Scope and Limitations of Study The study covers the superpave method of HMA design adopted from SA.

7. 2.0 LITERATURE REVIEW 2.1 Overseas Road Note 19
Details the types of HMA
Materials specifications for HMA
Marshall design method
Superpave design method
Mix design specifications.

8. 2.0 LITERATURE REVIEW
2.2 Strategic Highway Research Programme (FHWA, 1998)
Initiated in 1987 by the US Congress
5-year, $150 million applied research program
Aimed at improving the performance, durability, safety, and efficiency of the US highway system.

9. 2.0 LITERATURE REVIEW
2.2 Strategic Highway Research Programme (FHWA, 1998)- cont……
Three primary objectives:
Investigate why some pavements perform well, while others do not.
Develop tests and specifications for materials 
Work with highway agencies and industry to have the new specifications put to use.

10. 2.0 LITERATURE REVIEW
2.2 Strategic Highway Research Programme (FHWA, 1998) – cont…..
Results of SHRP:
Superpave HMA design method.
Three levels of design for low, intermediate and high traffic volumes (ESA).
Complexity of mix design increases from level 1 to 3
Performance based criteria used to select mix design.

11. 4.0 SUPERPAVE HMA DESIGN METHOD 4.1 FLOW CHART

12. 4. 0 SUPERPAVE HMA DESIGN METHOD CONT’D 4
4.0 SUPERPAVE HMA DESIGN METHOD CONT’D 4.1 Selection of bitumen and source of aggregates
Bitumen grade selected to suit temperature conditions and traffic loading.(Pen, Softening point)
Aggregates tested to confirm compliance with specs (LAAV, SSS, FI, ACV)

13. 4.0 SUPERPAVE HMA DESIGN METHOD CONT’D 4.1 Grading of aggregates

14. 4.0 SUPERPAVE HMA DESIGN METHOD CONT’D 4.1 Grading of aggregates cont

15. 4.0 SUPERPAVE HMA DESIGN METHOD CONT’D 4.1 Grading of aggregates cont
Aggregate single size and combined grading
Agg size
14-30mm
6-14mm
3-6mm
0-3mm
Filler
GRADING
Proportions
Theoretical
Actual
Control points
Sieve 39 20 12 29
grading
sieve
min
max
37.5
100 28 99 25 90 64 86 88 19 14 72 73
2.36 45
6.3
0.5 4 42 43
0.075 1 7 2 75 22 21
Caution zone 47 13
0.3
4.75
39.5 11
3.2 3
26.8
30.8
1.18
18.1
24.1
0.6
13.6
17.6
Flakiness Index
18.6
17.5
11.4

16. 4.0 SUPERPAVE HMA DESIGN METHOD CONT’D 4.1 Grading of aggregates cont

17. 4. 0 SUPERPAVE HMA DESIGN METHOD CONT’D 4
4.0 SUPERPAVE HMA DESIGN METHOD CONT’D 4.1 Compaction of superpave mix design

18. Constant pressure of 600 kPa on compacting ram.
4.0 SUPERPAVE HMA DESIGN METHOD CONT’D 4.1 Compaction of superpave mix design cont’d
Constant pressure of 600 kPa on compacting ram.
Constant rate of rotation of the mould at 30 gyrations per minute
Mould positioned at compaction angle of 1.25 degrees.
Compaction effort depends on design traffic loading

19. 4. 0 SUPERPAVE HMA DESIGN METHOD CONT’D 4
4.0 SUPERPAVE HMA DESIGN METHOD CONT’D 4.1 Compaction of superpave mix design cont’d

20. 4. 0 SUPERPAVE HMA DESIGN METHOD CONT’D 4
4.0 SUPERPAVE HMA DESIGN METHOD CONT’D 4.1 Compaction of superpave mix design cont’d

21. 4. 0 SUPERPAVE HMA DESIGN METHOD CONT’D 4
4.0 SUPERPAVE HMA DESIGN METHOD CONT’D 4.2 Refusal density determination

22. 4. 0 SUPERPAVE HMA DESIGN METHOD CONT’D 4. 2
4.0 SUPERPAVE HMA DESIGN METHOD CONT’D Mix properties at refusal density
Refusal density Test by Vibrating Hammer Method
Binder content
3.5
4.0
4.5
Refusal density
2.225
2.249
2.26
Maximum specific gravity
2.380
2.364
2.348
Refusal voids in mix
6.5
4.9
3.7
Voids in mineral aggregates
13.4
12.9
13.0
Voids filled with Binder
51.5
62.5
71.2

23. 4. 0 SUPERPAVE HMA DESIGN METHOD CONT’D 4. 2
4.0 SUPERPAVE HMA DESIGN METHOD CONT’D Refusal density property curves

24. 4. 0 SUPERPAVE HMA DESIGN METHOD CONT’D 4. 2
4.0 SUPERPAVE HMA DESIGN METHOD CONT’D Determination of optimum bitumen content
Parameter BC
1. At 4.0% Refusal voids
4.4
2. A 13.0 %Voids in Mineral Aggregates
3.9
3. At 65% Voids Filled With Binder
4.1
Total
12.4
Average
Design binder content from vibrating hammer test %

25. 4. 0 SUPERPAVE HMA DESIGN METHOD CONT’D 4. 2
4.0 SUPERPAVE HMA DESIGN METHOD CONT’D Mix properties at design binder content
Summary of DBM mix properties at the design binder content (4.1%)
Parameter
Unit
Result
Specifications
Min
Max
Marshall 60°C   KN
12.8 5
Flow
(mm)
3.4 2
Voids in Mix from marshall test
(%)
6.9 4 10
Voids in Mix from V.H test
4.7 3
Voids in mineral aggregates
12.9 12
Voids filled with bitumen 65 75

26. 4.3 MARSHALL HMA DESIGN METHOD 4.3.1 Marshall test data
Binder Content (%) 3
3.5
4.0
4.5
5.0
Theoretical Max. Relative Density
2.397
2.381
2.365
2.348
2.333
Bulk Relative Density
2.172
2.191
2.193
2.209
2.203
Voids in mix(%)
9.4
8.0
7.3
5.9
5.6
Voids in mineral aggregates(%)
15.0
14.7
15.1
14.9
15.6
Voids filled with Binder(%)
37.5
45.9
52.0
60.2
64.4
Stability (KN)
12.65
13.09
12.51
12.15
10.59
Flow(mm)
2.7
3.3
3.9

27. 4.3 MARSHALL HMA DESIGN METHOD 4.3.2 Marshall design curves

28. 4.3 MARSHALL HMA DESIGN METHOD 4.3.2 Marshall design curves cont…

29. 4. 3 MARSHALL HMA DESIGN METHOD 4. 3
4.3 MARSHALL HMA DESIGN METHOD Determination of optimum bitumen content.
From the Marshall design curves: 
Parameter BC
At maximum Density
4.6
2. At maximum Stability
3.5
3. At 7% VIM
4.0
4. At 3.5 mm Flow
4.3
5. At 14.9% VMA
6. At 65% VFB 5
TOTAL
24.9
Average =
4.2
Therefore, the Optimum Binder Content from the Marshall test is, 4.2% 

30. 4. 3 MARSHALL HMA DESIGN METHOD 4. 3
4.3 MARSHALL HMA DESIGN METHOD Calculation of Voids In Mineral Aggregates (VMA).

31. 4. 3 MARSHALL HMA DESIGN METHOD 4. 3
4.3 MARSHALL HMA DESIGN METHOD Calculation of Voids In Mix (VIM).

32. 4. 3 MARSHALL HMA DESIGN METHOD 4. 3
4.3 MARSHALL HMA DESIGN METHOD Calculation of Voids Filled with Bitumen (VFB).

33. QUESTIONS, COMMENTS AND SUGGESTIONS
THANK YOU
QUESTIONS, COMMENTS AND SUGGESTIONS