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Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Hot Mix Asphalt Design
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Hot Mix Asphalt Concrete (HMA)
Mix Designs
• Objective:
• Develop an economical blend of aggregates and
asphalt binders that meet design requirements
• Historical mix design methods
• Marshall
• Hveem
• New
• Superpave gyratory
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Requirements in Common
• Sufficient asphalt binder to ensure a durable pavement
• Sufficient stability under traffic loads
• Sufficient air voids
• Upper limit to prevent excessive environmental damage
• Lower limit to allow room for initial densification due to traffic
• Sufficient workability
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Low binder contents can lead to raveling, stripping,
Fatigue Cracking, and premature aging.
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Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
High binder contents can lead to flushing, or bleeding,
and Rutting.
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Marshall Mix Design
• Aggregate evaluation
• Binder evaluation • Establish mixing and compaction temperatures
• Specimen preparation • Heat and mix asphalt binder and aggregates
• Compact specimen (100 mm diameter)
• Marshall stability and flow
• Density and void analysis
• Determine asphalt content
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
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Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Specimen preparation
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
HMA Mix Designs 10
Specimen preparation
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
HMA Mix Designs 11 Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Automatic Marshall Hammer
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Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Extrude Sample from the mold
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
HMA Mix Designs 14
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
HMA Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Measure
stability and
Flow
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Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
HMA Mix Designs 17
Marshall Stability and Flow
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Correction Factors for Marshall Stability
Values
Volume of
specimen
(cm)
Thickness
of specimen
(mm)
Correction
Factor
457 - 470 57.1 1.19
471 - 482 68.7 1.14
483 - 495 60.3 1.09
496 - 508 61.9 1.04
509 - 522 63.5 1.00
523 - 535 65.1 0.96
536 - 546 66.7 0.93
547 - 559 68.3 0.89
560 - 573 69.9 0.86
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Marshall Design Criteria
Light Traffic Medium Traffic Heavy Traffic
ESAL < 104 10 4 < ESAL< 10 ESAL > 106
Compaction 35 50 75
Stability N (lb.) 3336 (750) 5338 (1200) 8006 (1800)
Flow, 0.25 mm 8 to 18 8 to 16 8 to 14
Air Voids, % 3 to 5 3 to 5 3 to 5
Voids in Mineral Agg.
(VMA) Varies with aggregate size
(see the following table)
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Minimum VMA
Nominal Max. Size
(mm)
Minimum VMA, %
Design Air Voids, %
3.0 4.0 5.0
2.36 19 20 21
4.75 16 17 18
9.5 14 15 16
12.5 13 14 15
19.0 12 13 14
25.0 11 12 13
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Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Marshall Mix Design Tests
• Heights
• Used to correct stability measurements
• Bulk specific gravity of compacted sample
• Maximum specific gravity of loose mix
• Stability and flow
• 60oC water bath (30 to 40 minutes)
• 50 mm/min loading rate
• Max. load = uncorrected stability
• Corresponding vertical deformation = flow
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Marshall Design Use of Data
Asphalt Institute Procedure
Air Voids,
%
Asphalt Binder
Content, %
Stability Unit Wt.
Target optimum asphalt binder content = average
4%
Asphalt Binder
Content, %
Asphalt Binder
Content, %
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Marshall Design Use of Data
Asphalt Institute Procedure
Flow VMA, %
Use target optimum asphalt binder
content to check if these criteria are met
UL
Min
OK OK
Asphalt Binder
Content, % Asphalt Binder
Content, %
LL
VFA, %
Asphalt Binder
Content, %
UL
LL
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Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Marshall Samples Volumetrics
b
b
se
s
mm
G
P
G
P
100G
mm
mb
G
G1100Va
b
b
mm
sse
G
P
G
100
PG
sb
sbm
G
PG001VMA
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
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