The document discusses hot mix asphalt design and different mix design methods. It focuses on the Marshall mix design method. The key steps in the Marshall method include aggregate evaluation, determining mixing and compaction temperatures, compacting specimens, and analyzing specimens for stability, flow, density and void content to determine the optimum asphalt content. Specimens are compacted using a Marshall hammer and tested for properties like stability, flow and air voids to identify the asphalt content that meets the design requirements.

1. 1
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.

2. 2
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.

3. 3
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

4. 4
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

5. 5
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

6. 6
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

7. 7
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
Marshall Samples Volumetrics








b
b
se
s
mm
G
P
G
P
100
G







mm
mb
G
G
1100Va








b
b
mm
s
se
G
P
G
100
P
G









sb
s
bm
G
P
G001VMA
Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
26