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1 Simulation of compaction of asphalt concrete
Alieh Alipour
Simulation of compaction of asphalt concrete
Alieh Alipour Delft University of Technology
Section of Pavement Engineering
2 Simulation of compaction of asphalt concrete
Alieh Alipour
Simulation
No-Tension
characteristics
of aggregates
Simulation
Compaction
of asphalt
concrete layer
3 Simulation of compaction of asphalt concrete
Alieh Alipour
Compaction
Reduction of air voids in hot mix asphalt by applying force
Desired Density
4 Simulation of compaction of asphalt concrete
Alieh Alipour
Increase stability and strength
Decrease moisture damage
Decrease rutting and consolidation by traffic
Effect of compaction on pavement performance
Low level of compaction
high level of compaction
5 Simulation of compaction of asphalt concrete
Alieh Alipour
Important parameters in compaction
Composition of asphalt mixture
Mixture with high volume of natural sand and soft
bitumen
Mixture with high volume of crushed aggregates and
stiff bitumen
6 Simulation of compaction of asphalt concrete
Alieh Alipour
Important parameters affecting compaction
Temperature
Initial mixture temperature
Base temperature
Air temperature
Wind speed
Layer thickness
Co
mp
acti
on
eff
ort
Mix temperature in ⁰C
End of Compaction
Favourable Compaction
Temperature
Start of Compaction
40 60 80 100 120 140 160 180 200
7 Simulation of compaction of asphalt concrete
Alieh Alipour
Important parameters in compaction
Type and magnitude of applied load
Static compaction
Tandem rollers
Pneumatic tired rollers
Vibratory compaction
8 Simulation of compaction of asphalt concrete
Alieh Alipour
Level of compaction
Void content (%)
Density (kg/m3 )
Specific volume (%)
volume of voids in mixture100%
volume of total mixture including airaV
3
weight of the material kg
volume of the material [m ]
total volume of mixture 100%
volume of solid part of the mixturev
9 Simulation of compaction of asphalt concrete
Alieh Alipour
Methods of compaction
Laboratory
compaction
method
Field
compaction
method
Marshal Superpave
10 Simulation of compaction of asphalt concrete
Alieh Alipour
Methods of measuring compaction
Laboratory
compaction
method
Field
compaction
method
Modelling
compaction
(FEM) Aggregate
properties
Bitumen
properties
Environment
information
Type of roller
Number of
passes
Suitable mix
design
11 Simulation of compaction of asphalt concrete
Alieh Alipour
Constitutive Model
Phase 1 : Aggregates matrix (Elasto-Plastic)
Effect of Pressure on tangent moduli
Effect of void reduction
12 Simulation of compaction of asphalt concrete
Alieh Alipour
Constitutive Model
Phase 2 : Bitumen (Visco-Elastic)
Vis
co
sit
y
Temperature in ⁰C
13 Simulation of compaction of asphalt concrete
Alieh Alipour
Pressure dependent elasticity
p
p
p
p
p
Bulk Modulus (K) Pressure dependent
force
Shear Modulus (G) Constant
14 Simulation of compaction of asphalt concrete
Alieh Alipour
Loading-unloading curve
lnv
ln( )p
Normal consolidation line
Swelling line
Plastic volume
changing
Elastic volume
changing
Nonlinear elastic law
Triaxial test
device
2p1p
15 Simulation of compaction of asphalt concrete
Alieh Alipour
2J
1I
Yield surface for aggregates matrix
2 2 2
2 1 2 2 3 3 1
1( ) ( ) ( )
6J
1
2
3
2
1
Invariants of stress tensor
1 1 2 3
1( )
3I Yield surface
(growth) 1 1I I
16 Simulation of compaction of asphalt concrete
Alieh Alipour
Hardening rule based on experimental data
lnv
ln( )p
2J
1I
Hardening Law Loading-unloading
curve
Yield surface
17 Simulation of compaction of asphalt concrete
Alieh Alipour
Results
Stress-Strain curve for hydrostatic test
P
P P
18 Simulation of compaction of asphalt concrete
Alieh Alipour
Results
Equivalent Plastic Strain development
for hydrostatic test
P
P P
19 Simulation of compaction of asphalt concrete
Alieh Alipour
Conclusions and future plans
Develop a model to simulate no-tension characteristics of unbound
aggregates in base and subbase layer
Develop a model to simulate compaction of aggregates (elasto-plasticity)
Consider the effect of viscosity and temperature to simulate compaction
of asphalt mixture (elasto-visco-plasticity)
Evaluate the model with experimental data
Develop CST (Compaction Simulation Tool)
