1 Rijkswaterstaat Design method
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1 Rijkswaterstaat
Design method
2 Rijkswaterstaat
Design method
• Dutch design method has been adapted to the harmonised European Standards for asphalt
• these allow the fundamental approach (specification of stiffness, fatigue resistance, resistance to permanent deformation, water resistance) for asphalt concrete; the Netherlands has chosen this option
• the design parameters obtained from the type testing according to the European standards (stiffness, fatigue resistance) are translated to characteristic (85% reliable) values
• these are used in combination with partial factors of safety according to NEN-EN 1990 Eurocode 0 to incorporate design reliability
3 Rijkswaterstaat
Design method
verplaatsingsopnemer
krachtopnemer
0
1000
2000
3000
4000
5000
6000
7000
8000
0 200000 400000 600000 800000 1000000 1200000 1400000
Lastherhalingen
sti
jfh
eid
sm
od
ulu
s (M
Pa
)
• Stiffness and fatigue testing
4 Rijkswaterstaat
Design method
• asphalt stiffness
100
1000
10000
100000
-4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 Temperature [ºC] o
E_
as
ph
alt
[M
Pa
]
1 Hz
2 Hz
4 Hz
8 Hz
16 Hz
32 Hz
5 Rijkswaterstaat
Design method
• asphalt strains and stiffness –> fatigue life N_f
0
2
4
6
8
10
12
14
16
18
3 4 5 6
ln(asphalt strain)
ln(f
ati
gu
e l
ife
N_
f)
6 Rijkswaterstaat
Design method
• Triaxial testing
7 Rijkswaterstaat
Design method
• Water resistance
8 Rijkswaterstaat
Design method
• Use of functional propertiesFunctional properties
E&C - contracts
D&C contracts
ITS
R
fcm
ax
Sm
in
6
ITS
R
fcm
ax
Sm
in
6
PA and SMA empirical empirical AC wearing courses T T T T T T O O AC binder courses T T T T T T O O AC base courses T T T T T T O O
T = fixed value, dependent on traffic and application O = no fixed value, actual value is used in the design
9 Rijkswaterstaat
Design method
• Use of functional properties
Property layer
Class (traffic related)
HRmin HRmax water-resistance
stiffness min*.
Stiffness max.
Creep resisance
Fatigue resistance*
OL-A 4500 Smax11000 fcmax1,4 6-100 OL-B 5500 fcmax0,8 6-80 OL-C 7000 fcmax0,4 6-90
Base layer
OL-IB
Vmin2,0 Vmax7 ITSR70
7000 Smax14000
fcmax0,2 6-90
10 Rijkswaterstaat
Design method
• horizontal asphalt strains in bottom of different asphalt layers -> fatigue failure of
asphalt layers
• asphalt strains (highly dependent on asphalt stiffness) are compared to fatigue resistance of asphalt
sub
top view of wheel loading
wheel loading
asphaltlayers
road base
subbase/subgrade
hbase
hsub = ∞
Ebase
base
Esub
12 Rijkswaterstaat
Design method
• tensile stresses in semi – bound road bases (slag bound bases or self – cementing bases) –> disintegration of
road base
• tensile stresses usually tested against standard max. tensile stress value of 130 kPa
top view of wheel loading
wheel loading
asphaltlayers
road base
subbase/subgrade
hbase
hsub = ∞
Ebase
base
Esubsub
13 Rijkswaterstaat
Design method
• tensile stresses in bottom of cement bound road bases at extreme loading -> instantaneous failure of
road base
• tensile stress under high wheel loading is compared to characteristic tensile strength of road base material
top view of wheel loading
wheel loading
asphaltlayers
road base
subbase/subgrade
hbase
hsub = ∞
Ebase
base
Esubsub
14 Rijkswaterstaat
Design method
• repeated tensile stresses in bottom of bound road bases-> fatigue failure of
road base
• tensile stresses are compared to characteristic fatigue strength of road base material
• however this fatigue life is extremely hard to determine for conventional cement bound materials
top view of wheel loading
wheel loading
asphaltlayers
road base
subbase/subgrade
hbase
hsub = ∞
Ebase
base
Esubsub
15 Rijkswaterstaat
Design method
• compressive stress at top of cement bound road base -> crushing of
road base
• compressive stresses are compared to characteristic compressive strength of base material
top view of wheel loading
wheel loading
asphaltlayers
road base
subbase/subgrade
hbase
hsub = ∞
Ebase
base
Esubsub
16 Rijkswaterstaat
Design method
top view of wheel loading
wheel loading
asphaltlayers
road base
subbase/subgrade
hbase
hsub = ∞
Ebase
base
Esubsub
• compressive strains at top of
subgrade-> permanent deformation
of subgrade
• compressive strains are compared to characteristic deformation resistance of subgrade
17 Rijkswaterstaat
Design method
• subgrade strain –> subgrade deformation resistance
• this resistance is defined as the number of strain repetitions until deformation reaches intervention level
• is derived from classical SPDM relation, which proved (in Lin-track ALT testing) applicable for standard Dutch subgrade sand
• not to be used for any material!
1E+04
1E+05
1E+06
1E+07
1E+08
1E+02 1E+03 1E+04
compressive subgrade strain (m/m)
su
bg
rad
e d
efo
rmati
on
resis
tan
ce (
cycle
s)
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