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)