1. SUPERPAVE MIX DESIGN
Superpave Mix Design

2. Superpave Gyratory Compaction and Mixture Requirements
Section objectives
Describe the Superpave gyratory compactor
Review the Superpave mixture requirements
Summarize the moisture sensitivity test
Final Result
Participant will know the principles of the SGC and what mix criteria are included in the Superpave system
Superpave Mix Design

3. Goals of Compaction Method
Simulate field densification
traffic
climate
Accommodate large aggregates
Measure of compactability
Conducive to QC
Superpave Mix Design

4. Superpave Gyratory Compactor?
Basis
Texas equipment
French operational characteristics
150 mm diameter
Up to 37.5 mm nominal size
Height recordation ? ?
Superpave Mix Design

5. height control and data measurement acquisition panel reaction frame
loading
ram
mold
tilt bar
rotating
base
Superpave Mix Design

6. ram pressure 600 kPa 1.25 degrees (external)
150 mm diameter mold
30 gyrations
per minute
1.25 degrees
(external)
Superpave Mix Design

7. Common SGC Types Troxler Pine Brovold Interlaken Rainhart 4140
AFGC125X
HM-293
GYR-001
144
4141
AFG1A
Superpave Mix Design

8. Professor Training Course
SGC Compaction Curve
% Gmm
The increase in density
(%Gmm) with each gyration
is used to graph this
compaction curve.
Log Gyrations
Superpave Mix Design

9. Gyratory Compaction
We will evaluate the density of the HMA at two points:
Ninitial
Ndesign
These N’s represent numbers of gyrations.
Superpave Mix Design

10. Current AASHTO Ndesign Table
Professor Training Course
Current AASHTO Ndesign Table
Traffic
Level N
initial
design 6 50
0.3 to < 3.0 7 75
3.0 to < 30.0 8
100 9
125
Compaction Level
< 0.3
> 30.0
The SGC requirements vary with traffic levels. The higher the traffic levels the higher the values of Ninitial, Ndesign and Nmaximum.
Some States use different Ndesign Tables
Superpave Mix Design

11. Gyratory Compaction
The density Ndesign is the most important. This is where we will calculate the volumetric properties.
Ninitial and Ndesign are points at which we use to check the compactability and densification of the HMA.
Superpave Mix Design

12. Four Steps for Superpave Mix Design
1. Materials Selection
2. Design Aggregate Structure
TSR
3. Design Binder Content
4. Moisture Sensitivity
Superpave Mix Design

13. Example Project Data- Project on I-43 Milwaukee, Wisconsin
18,000,000 ESAL Design
Asphalt Overlay - 88 mm total thickness
38 mm - wearing course (12.5 mm NMAS)
50 mm - intermediate course (19 mm NMAS)
Superpave Mix Design

14. 4 Steps of Superpave Mix Design
1. Materials Selection
2. Design Aggregate Structure
TSR
3. Design Binder Content
4. Moisture Sensitivity
Superpave Mix Design

15. Step 1. Materials Selection
Binder Selection
Binder grade is specified in nearly all cases
Selecting the supplier of the binder is most often based on cost.
Aggregates Selection
Choice of aggregates is usually limited to locally available materials
Superpave Mix Design

16. Project Weather Conditions
Professor Training Course
Project Weather Conditions 52 55
-32
-26
-40
-30
-20
-10 10 20 30 40 50 60 70
Pavement Temperature (°C), Milwaukee, Wisc.
Superpave Mix Design

17. Climate Based Selection
PG 58-34
PG 52-28
Asphalt Binder Grades
Milwaukee, Wisc.
Climate Based Selection
-40
-30
-20
-10 10 20 30 40 50 60 70
Pavement Temperature (°C), Milwaukee, Wisc
Superpave Mix Design

18. Binder Selection Milwaukee, Wisc
PG 52-28
PG 58-34
Reliability(%)
Selected PG 58-34
Superpave Mix Design

19. Temp-Vis Relationship
PG Binder 5
Mix Temp Range: °C
Comp Temp Range: °C 1
Viscosity, Pa-s
Compaction Range
Mixing Range
0.1
0.05
100
110
120
130
140
150
160
170
180
190
200
Temperature, C
Superpave Mix Design

20. Select Aggregates Available Stockpiles #1 stone 12.5 mm chip
Manufactured sand
Screen sand
Superpave Mix Design

21. Aggregate Properties
Superpave Mix Design

22. Coarse Aggregate Angularity
Test Results
Aggr Frac Faces Crit Frac Faces Crit.
#1 Stone % 88%
12.5 mm Chip % % min 94% % min
9.5 mm Chip % 95%
Superpave Mix Design

23. Fine Aggregate Angularity
Test Results
Aggregate % Air Voids Criterion
Manufactured Sand 52% % min
Screen Sand 40%
Superpave Mix Design

24. Flat & Elongated Particles
Test Results
Aggregate %Flat & Elongated Criterion
#1 Stone 0%
12.5mm Chip 0% % max. 9.5mm Chip 0%
Superpave Mix Design

25. Sand Equivalent Test Results Aggregate Sand Equivalent Criterion
Manufactured Sand min
Screen Sand 70
Superpave Mix Design

26. 4 Steps of Superpave Mix Design
1. Materials Selection
2. Design Aggregate Structure
TSR
3. Design Binder Content
4. Moisture Sensitivity
Superpave Mix Design

27. Selection of Design Aggregate Structure
Establish trial blends
Check aggregate consensus properties
Compact specimens
Evaluate trial blends
Select design aggregate structure
Superpave Mix Design

28. Gradation Percent Passing 100 max density line nom max size max size
control point
Sieve Size, mm (raised to 0.45 power)
Superpave Mix Design

29. IH-43 Trial Gradations % PASSING 19.0 mm Nominal Mixture 100.0 90.0
80.0
70.0
Trial Blend 3
Trial Blend 1
60.0
% PASSING
50.0
40.0
Trial Blend 2
30.0
20.0
10.0
0.0
0.075
2.36
19.0
Sieve Size (mm) raised to 0.45 power
Superpave Mix Design

30. Example Trial Blends Trail Blend 1 Trial Blend 2 Trial Blend 3
#1 Stone 25 30 10
½” Chip 15
3/8” Chip 22 13
Mfg Sand 18 17 31
Scr. Sand 20 14
Superpave Mix Design

31. Aggregate Consensus Properties
Blended aggregate properties are determined
Property Criteria Blend Blend Blend 3
Coarse Ang. 95%/90% min. 96%/92% 95%/92% 97%/93%
Fine Ang. 45% min % % 48%
Flat/Elongated 10% max % % 0%
Sand Equiv min
Combined Gsb n/a
Combined Gsa n/a
Superpave Mix Design

32. Compact Specimens (Trial Blends)
Establish trial asphalt binder content
Establish trial aggregate weight
Batch, mix, and compact specimens
Determine Nini and Ndes
Determine mixture properties
Superpave Mix Design

33. Professor Training Course
Specimen Preparation
Specimen height
Mix design mm (4700 g)
Moisture sensitivity - 95 mm (3500 g)
Loose specimen for Gmm (Rice)
Sample size varies with NMAS
19 mm (2000 g)
12.5 mm (1500 g)
150 mm
Superpave Mix Design

34. Batching Samples of Trial Blends
Superpave Mix Design

35. Superpave Mix Design

36. Short Term Aging Two hours at the compaction temperature
Superpave Mix Design

37. Superpave Mix Design

38. Superpave Mix Design

39. Superpave Mix Design

40. Measure Gmb, Gmm and calculate volumetric properties
Superpave Mix Design

41. Superpave Mixture Requirements
Professor Training Course
Superpave Mixture Requirements
Specimen height
Mixture volumetrics
Air voids
Voids in the mineral aggregate (VMA)
Voids filled with asphalt (VFA)
Dust proportion
Nini
Superpave Mix Design

42. Trial Blend Results Property 1 2 3 Trial Binder Content 4.4% 4.4% 4.4%
Ndes 96.2% 95.7% 95.2%
Nini 87.1% 85.6% 86.3%
%Air Voids 3.8% 4.3% 4.8%
%VMA 12.7% 13.0% 13.5%
%VFA 68.5% 69.2% 70.1%
Dust Proportion
Superpave Mix Design

43. Estimated Volumetric at 4% AV
Pbe = Pbi – 0.4 x (4-Va)
Pbe: estimated design asphalt content
Pbi: asphalt content used in trial blends
VMAe = VMAi + C x (4-Va)
VMAe: estimated VMA at design asphalt content
VMAi: initial VMA of trial blend
C= constant: 0.1 when air voids < 4% and 0.2 when air voids > 4%
Superpave Mix Design

44. Volumetric Design Criteria
Superpave Mix Design

45. Compare Trial Blends to Mixture Criteria
Blend Criteria
Binder Content 4.3% 4.5% 4.7%
Nini 86.9% 85.9% 87.1% < 89%
%Air Voids 4.0% 4.0% 4.0% 4.0%
%VMA 12.7% 13.0% 13.3%  13.0%
%VFA 68.5% 69.2% 70.1% 65-75%
Dust Proportion
Superpave Mix Design

46. Select Design Aggregate Structure
What to do if none of the 3 trial blends are acceptable?
Recombine aggregates to form further trial blends (i.e., Blend 4, Blend 5, etc.)
Obtain new materials (aggregates, asphalt binder, modifiers)
Superpave Mix Design

47. 4 Steps of Superpave Mix Design
1. Materials Selection
2. Design Aggregate Structure
TSR
3. Design Binder Content
4. Moisture Sensitivity
Superpave Mix Design

48. Determining the Design Asphalt Content
The selected trial blend becomes the design aggregate structure.
Batch, mix, and compact more samples with this gradation with four asphalt contents.
Determine volumetric properties
Select Pb at 4.0% air voids and check other volumetric properties.
Superpave Mix Design

49. Superpave Mix Design

50. Design Binder Content Samples
Nini 85.7% 87.1% 87.4% 88.6%
Ndes 94.6% 96.1% 97.1% 98.2%
%Air Voids 5.4% 3.9% 2.9% 1.8%
%VMA 13.3% 13.1% 13.3% 13.5%
%VFA 59.4% 70.2% 78.2% 86.7%
Dust Proportion
Superpave Mix Design

51. Densification Curves I-43, 19.0 mm NMAS, Blend 3 98.0 96.0
% MAX THEORETICAL DENSITY
89.0
4.2% AC
85.0
4.7% AC
5.2% AC
80.0
5.7% AC
75.0 1 10
100
1000
NUMBER OF GYRATIONS
Superpave Mix Design

52. Professor Training Course
air voids
Mix Air Voids Requirement
% binder
4% at Ndes Regardless of the Traffic Level
Regardless of the traffic levels the Air voids requirement is 4%.
Superpave Mix Design

53. Air Voids - Example Mix Design
I-43 Binder Course, Blend 3
8.0
6.0
Air Voids = 4%
4.0
2.0
0.0
3.7
4.2
4.7
5.2
5.7
6.2
% ASPHALT BINDER
Superpave Mix Design

54. Mix VMA Requirements Voids in the Mineral Aggregate
% binder
NMAS, mm
Minimum VMA, %
Superpave Mix Design

55. VMA – Example Mix Design
I-43 Binder Course, Blend 3
14.5
13.5
VMA = 13.2%
12.5
3.7
4.2
4.7
5.2
5.7
6.2
% ASPHALT BINDER
Superpave Mix Design

56. Mix VFA Requirements Voids Filled with Asphalt
% binder
Traffic
106 ESALs
Range of VFA, %
<
<
<
>
Superpave Mix Design

57. VFA – Example Mix Design
I-43 Binder Course, Blend 3
100.0
90.0
80.0
VFA = 70%
70.0
60.0
50.0
3.7
4.2
4.7
5.2
5.7
6.2
% ASPHALT BINDER
Superpave Mix Design

58. Mix Requirement for Dust Proportion
100 92 83 65 48 36 22 15 9 4
Mix Requirement for Dust Proportion
% weight of material
% weight of effective asphalt
0.6 <
< 1.2
Unabsorbed binder in mix
Superpave Mix Design

59. Dust Proportion – Example Mix Design
I-43 Binder Course, Blend 3
1.8
1.2
DP = 0.9
0.6
3.7
4.2
4.7
5.2
5.7
6.2
% ASPHALT BINDER
Superpave Mix Design

60. %Gmm @ Nini %Gmm @ Nini = 87.1% I-43 Binder Course, Blend 3 90.0 88.0
86.0
84.0
82.0
80.0
3.7
4.2
4.7
5.2
5.7
6.2
% ASPHALT BINDER
Superpave Mix Design

61. Select Design Asphalt Binder Content
Summary of Mixture 4.7% AC
Property Result Criteria
%Air Voids 4.0% 4.0%
%VMA 13.2% >13.0%
%VFA 70% 65-75%
D/A Ratio
Nini 87.1% <89%
Superpave Mix Design

62. 4 Steps of Superpave Mix Design
1. Materials Selection
2. Design Aggregate Structure
TSR
3. Design Binder Content
4. Moisture Sensitivity
Superpave Mix Design

63. Moisture Sensitivity AASHTO T 283
Measured on proposed aggregate blend and asphalt content
Tensile Strength Ratio
80 %
minimum
3 Conditioned Specimens
3 Dry Specimens
Superpave Mix Design

64. AASHTO T 283 Conditioning Short term aging Loose mix 16 hrs @ 60°C
Comp mix °C
Two subsets with equal voids
One “dry”
One saturated
Dry
6 to 8 % air
6 to 8 % air
55 to 80 % saturation
Superpave Mix Design

65. AASHTO T 283 Conditioning Optional freeze cycle Hot water soakoC
Optional freeze cycle
Hot water soak
24 60 oC
Superpave Mix Design

66. AASHTO T 283 Test Procedure
51 mm / 25 oC
Avg Dry Tensile Strength
Avg Wet Tensile Strength
TSR =  80 %
Wet
Dry
Superpave Mix Design

67. Calculate %TSR Wet Strength %TSR = 100* Dry Strength 721 kPa = 100*
= 82.6%
872 kPa
Criterion is 80% minimum. Design asphalt mixture exceeds the minimum requirement.
Superpave Mix Design

68. Design Asphalt Mixture
Aggregate Gradation:
25 mm 100%
19.0 mm 97%
12.5 mm 89%
9.5 mm 77%
4.75 mm 44%
2.36 mm 32%
1.18 mm 22%
0.6 mm 15%
0.3 mm 8%
0.15 mm 4%
0.075 mm %
Aggregate:
10% #1 Stone
15% 12.5mm Chip
30% 9.5mm Chip
31% Manuf. Sand
14% Screen Sand
Asphalt Binder:
4.7% PG 58-34
Superpave Mix Design

69. Questions – does it all make sense?
Superpave Mix Design