The Dutch Structural Design Method for Jointed Plain Concrete
Pavements
Houben, L.J.M.
Delft University of Technology, Section Road and Railway Engineering,
P.O. Box 5048, 2600 GA Delft, the Netherlands, email: l.j.m.houben@tudelft.nl
Abstract
In the Netherlands the analytical structural design of jointed plain concrete pavements has developed
since the early eighties. The latest version of the design method was released early 2005 by CROW as
the software package VENCON2.0. This package not only includes jointed plain concrete pavements but
also continuously reinforced concrete pavements.
This paper describes the backgrounds of VENCON2.0 as far as it concerns jointed plain concrete
pavements. First the inputs are briefly outlined: traffic loadings, temperature gradients, substructure and
concrete properties. The thickness design of jointed plain concrete pavements is based on Miner’s fatigue
damage analysis, applied for various critical locations of the pavement, taking into account the traffic load
stresses and the temperature gradient stresses. The traffic load stresses are calculated with the ‘new’
Westergaard equation for edge loading, including load transfer at the edge or joint. The temperature
gradient stresses are calculated with a modified Eisenmann method.
Finally, for a case study the design results according to VENCON2.0 are presented, illustrating the effects
of various input parameters. For jointed plain concrete pavements the only design result is the thickness
of the concrete slabs.
Keywords: Structural design, plain concrete pavements
1
Introduction
In this paper the backgrounds of the current Dutch method for the structural design of
jointed plain concrete pavements, subjected to normal road traffic, are explained (STET,
2004; HOUBEN et al., 2006; STET et al., 2006). The design method is available as a
software package called VENCON2.0 (CROW, 2005) that was released early 2005 by
CROW.
The structural design of plain concrete pavements is based on a fatigue strength
analysis, performed for various potentially critical locations on the pavement, i.e. the
free longitudinal edge, the longitudinal joint(s) and the transverse joint in the centre of
the wheel tracks. The analysis includes the traffic load stresses (calculated by means of
a Westergaard-equation, taking into account the load transfer in the joint or at the edge)
and the temperature gradient stresses (calculated by means of a modified Eisenmann
theory). Van Cauwelaert’s multi-layer slab model is used to calculate the traffic load
stresses in bound bases (VAN CAUWELAERT, 2003).
Figure 1 gives an overview of the input and calculation procedure of the VENCON2.0
design method.
1. TRAFFIC LOADINGS:
Axle loads
Directional factor
Design traffic lane
Traffic at joints
2. CLIMATE:
Temperature
gradients
3. SUBSTRUCTURE:
Modulus of substructure
reaction
4. CONCRETE:
Strength
Parameters
Elastic modulus
6. TEMPERATURE
GRADIENT STRESSES:
Eisenmann/Dutch method
5. TRAFFIC LOAD
STRESSES:
Load transfer at joints
Westergaard equation
7. THICKNESS PLAIN/REINFORCED PAVEMENT:
Miner fatigue analysis
9. REINFORCEMENT OF
REINFORCED PAVEMENTS:
Shrinkage and temperature
Tension bar model
Crack width criterion
8. ADDITIONAL CHECKS
PLAIN PAVEMENTS:
Robustness (NEN 6720)
Traffic-ability at opening
10. ADDITIONAL CHECKS
REINFORCED PAVEMENT:
Robustness (NEN 6720)
Traffic-ability at opening
Parameter studies
Figure 1 - Flow chart of the structural design of plain/reinforced concrete pavements
according to the VENCON2.0 design method (HOUBEN et al, 2006)
As can be seen in Figure 1 the VENCON2.0 design method covers the structural design
of both jointed plain concrete pavements and continuously reinforced concrete
pavements. This paper only deals with jointed plain concrete pavements, which means
that the items 1 to 7 from Figure 1 are subsequently discussed in the chapters 2 to 8. In
chapter 9 some calculation results of the VENCON2.0 design method are presented for
a jointed plain concrete pavement case study.
2
Traffic loadings
The traffic loading is calculated as the total number of axles per axle load group (> 20
kN) on the design traffic lane during the desired life of the concrete pavement. In the
calculation is included:
 the division of the heavy vehicles per direction; for roads having one carriageway the
directional factor depends on the width of the carriageway, for roads having two
carriageways the directional factor is taken as 0.5;
 in the case that there is more than 1 traffic lane per direction: the percentage of the
heavy vehicles on the most heavily loaded lane (the design traffic lane); this
percentage varies from 100% (1 lane per direction) till 80% (4 lanes per direction);
 the average number of axles per heavy vehicle (Table 1).
In the case that no real axle load data is available, for a certain type of road the default
axle (wheel) load frequency distribution, given in Table 1, can be used. These frequency
distributions are based on axle load measurements on a great number of provincial
roads in the Netherlands in the years 2000 and 2001. In the design method all the truck
axles are taken into account. Note that the highest axle load group in Table 1 is 200-220
kN!
Table 1 makes clear that also in the Netherlands there are quite some overloaded axles
and these really should be taken into account when designing a concrete pavement.
Table 1 - Default axle load frequency distributions for different types of road
Axle load
group
(kN)
Average
wheel load
P (kN)
20-40
15
40-60
25
60-80
35
80-100
45
100-120
55
120-140
65
140-160
75
160-180
85
180-200
95
200-220
105
Average number of
axles per heavy vehicle
heavily
loaded
motorway
20.16
30.56
26.06
12.54
6.51
2.71
1.00
0.31
0.12
0.03
3.5
Axle load frequency distribution (%) for different types of road
normally
heavily
normally
municipal rural
public
loaded
loaded
loaded
main
road
transport
motorway
provincial provincial road
bus lane
road
road
14.84
26.62
24.84
8.67
49.38
29.54
32.22
32.45
40.71
25.97
30.22
18.92
21.36
25.97
13.66
13.49
9.46
11.12
13.66
8.05
7.91
6.50
6.48
8.05
2.18
100
3.31
4.29
2.70
2.18
0.38
0.59
1.64
0.83
0.38
0.38
0.09
0.26
0.19
0.38
0.00
0.01
0.06
0.03
0.00
0.00
0.01
0.03
0.00
0.00
0.00
3.5
3.5
3.5
3.5
3.1
2.5
Different types of tire are included in the VENCON2.0 design method:
 single tires, that are mounted at front axles of heavy vehicles;
 dual tires, that are mounted at driven axles, and sometimes at trailer axles;
 wide base tires, that are mostly mounted at trailer axles;
 extra wide wide base tires, that in future will be allowed for driven axles.
Every tire contact area is assumed to be rectangular. In the Westergaard equation for
calculation of the traffic load stresses, however, a circular contact area is used. The
equivalent radius a of the circular contact area of the tire is calculated by:
a = b √(0.0028*P + 51)
(Equation 1)
where:
b = parameter dependent on the type of tire (Table 2)
P = average wheel load (N) of the axle load group
Some tire type default frequency distributions are included in the design method (Table
2).
Table 2 - Value of parameter b (equation 1) for different types of tire
Type of tire
Single tire
Dual tire
Wide base tire
Extra wide
wide base tire
3
Width of
rectangular
contact area(s)
(mm)
200
200-100-200
300
400
Value of
parameter b
of Equation 1
9.2
12.4
8.7
9.1
Frequency distribution (%)
roads
public transport bus
lanes
39
38
23
0
50
50
0
0
Climate
With respect to the climate especially the temperature gradients in the concrete
pavement are important. In the years 2000 and 2001 the temperature gradient has
continuously been measured on a stretch of the newly build motorway A12 near Utrecht
in the centre of the Netherlands. The (continuously reinforced) concrete pavement has a
thickness of 250 mm and the measurements were done before the porous asphalt
wearing course was constructed. Based on these measurements it was decided to
include the default temperature gradient frequency distribution shown in Table 3 in the
current design method.
Table 3 - Default temperature gradient frequency distribution
Temperature gradient class Average temperature
(ºC/mm)
gradient ΔT (ºC/mm)
0.000 – 0.005
0.0025
0.005 – 0.015
0.01
0.015 – 0.025
0.02
0.025 – 0.035
0.03
0.035 – 0.045
0.04
0.045 – 0.055
0.05
0.055 – 0.065
0.06
Frequency distribution
(%)
59
22
7.5
5.5
4.5
1.0
0.5
4
Substructure
The rate of support of the pavement by the substructure is an important parameter in
the structural design of concrete pavements. The substructure includes all the layers
beneath the concrete pavement, so the base, the sub-base and the subgrade. The rate
of support is represented by the modulus of substructure reaction k at the top of the
base.
Starting point for the calculation of the k-value is the modulus of subgrade reaction ko at
the top of the subgrade. Among other things Table 4 shows the k o-values that are used
in VENCON2.0.
Table 4 - Modulus of subgrade reaction ko of Dutch subgrades
Subgrade Cone resistance qc
(N/mm2)
Peat
0.1 - 0.3
Clay
0.2 - 2.5
Loam
1.0 - 3.0
Sand
3.0 - 25.0
Gravel10.0 - 30.0
sand
CBR-value
(%)
Dynamic modulus of
elasticity Esg (N/mm2)
Modulus of subgrade
reaction ko (N/mm3)
1- 2
3- 8
5 - 10
8 - 18
15 - 40
25
40
75
100
150
0.016
0.023
0.036
0.045
0.061
To obtain the modulus of substructure reaction k at the top of the base, equation 2 has
to be applied for each layer (first the sub-base, then the base):
k= 2.7145.10-4 (C1 + C2.eC3 + C4.eC5)
(Equation 2)
where:
C1 = 30 + 3360.ko
C2 = 0.3778 (hb – 43.2)
C3 = 0.5654 ln(ko) + 0.4139 ln(Eb)
C4 = -283
C5 = 0.5654 ln(ko)
ko = modulus of subgrade/substructure reaction at top of underlying layer (N/mm 3)
hb = thickness of layer under consideration (mm)
Eb = dynamic modulus of elasticity of layer under consideration (N/mm 2)
k = modulus of substructure reaction at top of layer under consideration (N/mm3)
The boundary conditions for Equation 2 are:
1. hb ≥ 150 mm (bound material) and hb ≥ 200 mm (unbound material)
2. every layer has an Eb-value that is greater than the Eb-value of the underlying layer
3. log k ≤ 0.73688 log(Eb) – 2.82055
4. k ≤ 0.16 N/mm3
5
Concrete
Various concrete grades are applied in the top layer of concrete pavements (Table 5). In
the old Dutch Standard NEN 6720 (1995), valid until July 1, 2004, the concrete grade
was denoted as a B-value where the value represented the characteristic (95%
probability of exceeding) cube compressive strength after 28 days for loading of short
duration* (f’ck in N/mm2). In the new Standard NEN-EN 206-1 (2001), or the Dutch
application Standard NEN 8005 that is valid since July 1, 2004, the concrete grade is
denoted as C-values where the last value represents the characteristic (95% probability
of exceeding) cube compressive strength after 28 days for loading of short duration and
the first value represents the characteristic cylinder compressive strength at the same
conditions (Table 5).
Table 5 - Dutch concrete grades used in road construction
Concrete grade
B-value C-values
B35
C28/35
B45
C35/45
Characteristic (95% probability of exceeding) cube compressive
strength after 28 days for loading of short duration, f’ck (N/mm2)
35
45
Generally on heavily loaded jointed plain concrete pavements, such as motorways and
airport platforms, the concrete grade C35/45 is used. On lightly loaded jointed plain
concrete pavements (bicycle tracks, rural roads, etc.) mostly concrete grade C28/35
and sometimes C35/45 is applied.
According to both CEB-FIP Model Code 1990 (1993) and Eurocode 2 (prEN 1992-1-1,
2002) the mean cube compressive strength after 28 days for loading of short duration
(f’cm) is:
f’cm = f’ck + 8
(N/mm2)
(Equation 3)
For the structural design of concrete pavements not primarily the compressive strength
but the flexural tensile strength is important. In accordance with both NEN 6720 (1995)
and the Eurocode 2 (prEN 1992-1-1, 2002), in the VENCON2.0 design method the
mean flexural tensile strength (fbrm) after 28 days for loading of short duration is defined
as a function of the thickness h (in mm) of the concrete slab:
fbrm = 1.3 [(1600 – h)/1000)] [1.05 + 0.05 (f’ck + 8)]/1.2 (N/mm2)
(Equation 4)
The mean flexural tensile strength (fbrm) is used in the fatigue analysis (see chapter 8).
___________
* loading of short duration: loading during a few minutes
loading of long duration: static loading during 103 to 106 hours, or
dynamic loading with about 2.106 load cycles
Except the strength also the stiffness (i.e. Young’s modulus of elasticity) of concrete is
important for the structural design of concrete pavements. The Young’s modulus of
elasticity of concrete depends to some extent on its strength. According to NEN 6720
(1995) the Young’s modulus of elasticity Ec can be calculated with the equation:
Ec = 22250 + 250 ∙ f’ck
(N/mm2)
with 15 ≤ f’ck ≤ 65
(Equation 5)
For the two concrete grades applied in concrete pavement engineering, Table 6 gives
some strength and stiffness values. Besides some other properties are given, such as
the Poisson’s ratio (that plays a role in the calculation of traffic load stresses, see
chapter 6) and the coefficient of linear thermal expansion (that plays a role in the
calculation of temperature gradient stresses, see chapter 7).
Table 6 - Mechanical properties of (Dutch) concrete grades for concrete pavement
structures
Property
Characteristic* cube compressive strength after 28 days for
loading of short duration, f’ck (N/mm2)
Mean cube compressive strength after 28 days for loading of
short duration, f’cm (N/mm2)
Mean tensile strength after 28 days for loading of short duration,
fbt (N/mm2)
Mean flexural tensile strength after 28 days for loading of short
duration, fbrm (N/mm2): concrete thickness h = 180 mm
h = 210 mm
h = 240 mm
h = 270 mm
2
Young’s modulus of elasticity, Ec (N/mm )
Density (kg/m3)
Poisson’s ratio ν
Coefficient of linear thermal expansion α (°C-1)
Concrete grade
C28/35 C35/45
(B35)
(B45)
35
45
43
53
3.47
4.01
4.92
5.69
4.82
5.57
4.71
5.45
4.61
5.33
31,000 33,500
2300 - 2400
0.15 – 0.20
1∙10-5 – 1.2∙10-5
* 95% probability of exceeding
6
Traffic load stresses
The tensile flexural stress due to a wheel load P at the bottom of the concrete slab
along a free edge, along a longitudinal joint or along a transverse joint of a jointed plain
concrete pavement is calculated by means of the ‘new’ Westergaard equation for a
circular tire contact area (IOANNIDES, 1987):
P 
3 1    Pcal
  3    h2
  Ec h3 

4
1
a

 1.84   
 1.18 1  2   
l n 
4 
3
2
l
  100 k a 


(Equation 6)
where:
P = flexural tensile stress (N/mm²)
Pcal = wheel load (N), taking into account the load transfer (Equation 7)
a = equivalent radius (mm) of circular contact area (Equation 1 and Table 2)
Ec = Young’s modulus of elasticity (N/mm²) of concrete (Equation 5 and Table 6)
 = Poisson’s ratio of concrete (usually taken as 0.15)
h = thickness (mm) of concrete slab
k = modulus of substructure reaction (N/mm3) (Equation 2)
l
=
4
Ec h3
= radius (mm) of relative stiffness of concrete slab
12(1   2 )k
The load transfer W at edges/joints is incorporated in the design of jointed plain
concrete pavement structures by means of a reduction of the actual wheel load P to the
wheel load Pcal (to be used in the Westergaard equation) according to:
W 

Pcal  1  0.5 W /100  P  1 
P
200 

(Equation 7)
The contribution of the base to the load transfer W has been determined by means of
the model for a slab on a Pasternak-foundation (VAN CAUWELAERT, 2003).
In the VENCON2.0 design method the following values for the load transfer W are
included:
 free edge of jointed plain concrete pavement (at the outside of the carriageway):
- W = 20% in the case that a unbound base is applied;
- W = 35% in the case that a bound base is applied;
 longitudinal joints in jointed plain concrete pavements:
- W = 20% and 35% respectively at non-profiled construction joints without tie bars in
jointed plain concrete pavements on a unbound and a bound base respectively;
- W = 50% and 60% respectively at non-profiled construction joints with tie bars and
dowel bars respectively in jointed plain concrete pavements;
- W = 35% at contraction joints without any load transfer devices in jointed plain
concrete pavements;
- W = 70% and 80% respectively at contraction joints with tie bars and dowel bars
respectively in jointed plain concrete pavements;
 transverse joints in jointed plain concrete pavements:
- W = 20% and 35% respectively at non-profiled construction joints without dowel
bars in jointed plain concrete pavements on a unbound and a bound base
respectively;
- W = 60% at construction joints with dowel bars in jointed plain concrete pavements;
- W = 80% at contraction joints with dowel bars in jointed plain concrete pavements;
- W according to Equation 8 at contraction joints without dowel bars in jointed plain
concrete pavements:
W = {5.log(k.l2)–0.0025.L–25}.logNeq–20 log(k.l2)+0.01.L+180
(Equation 8)
In Equation 8 is:
W = joint efficiency (%) at the end of the pavement life
L = length (mm) of concrete slab
k = modulus of substructure reaction (N/mm3)
l
= radius (mm) of relative stiffness of concrete slab
Neq = total number of equivalent 50 kN standard wheel loads in the centre of the
wheel track during the pavement life, calculated with a 4 th power, i.e. the load
equivalency factor leq = (P/50)4 with wheel load P in kN
7
Temperature gradient stresses
In VENCON2.0 the stresses due to positive temperature gradients are only calculated
along the edges of the concrete slab (as, from a structural point of view, the weakest
point of the pavement always is somewhere at an edge and never in the interior of the
concrete slab). Starting point for the calculation of the temperature gradient stresses is
a beam (of unit width) along an edge of the concrete slab (LEEWIS, 1992).
In the case of a small positive temperature gradient T the maximum upward
displacement due to curling of the beam is smaller than the downward displacement
due to the compression of the substructure (characterised by the modulus of
substructure reaction k) because of the deadweight of the beam. In this case the beam
remains fully supported over the whole length. The flexural tensile stress σ T at the
bottom of the concrete slab along the edge or joint is then equal to (Figure 2 – left):
Figure 2 - Effect of small (left) and great (right) positive temperature gradient on the
behavior of a concrete pavement
T 
hT
 Ec
2
(Equation 9)
where:
σT = flexural tensile stress (N/mm2) at the bottom of the concrete slab due to a small
positive temperature gradient ΔT (°C/mm)
h = thickness (mm) of the concrete slab
α = coefficient of linear thermal expansion of concrete (usually taken as 1.10-5 ºC-1)
Ec = Young’s modulus of elasticity (N/mm²) of concrete (Equation 5 and Table 6)
In the case of a large positive temperature gradient T the maximum upward
displacement due to curling of the beam is greater than the downward displacement
due to the compression of the substructure because of the deadweight of the beam. In
this case the beam is only supported over a certain length C at either end. The flexural
tensile stress σT at the bottom of the concrete slab along the edge or joint (assuming a
volume weight of the concrete of 24 kN/m3) is then equal to (Figure 2 – right):
longitudinal edge:
 T  1.8*105
transverse edge:
 T  1.8*105 W ' 2 / h
L' 2 / h
(Equation 10a)
(Equation 10b)
The slab span in the longitudinal direction (L’) and in the transverse direction (W’) is
equal to:
L'  L 
2
C
3
W' W 
(Equation 11a)
2
C
3
(Equation 11b)
where:
L = length (mm) of the concrete slab
W = width (mm) of the concrete slab
C = supporting length (mm), which is equal to (EISENMANN, 1979):
C = 4.5
h
k T
if
C << L
(Equation 12)
The actually occurring flexural tensile stress at the bottom of the concrete slab due to a
temperature gradient ΔT at a free edge or joint is the smallest value resulting from the
Equations 9 and 10a (free edge or longitudinal joint) or the smallest value resulting from
the Equations 9 and 10b (transverse joint.
8
Slab thickness of jointed plain concrete pavement
In the case of jointed plain concrete pavements on a 2-lane road the fatigue strength
analysis is carried out for the following locations of the design concrete slab:
 the wheel load just along the free edge of the slab;
 the wheel load just along the longitudinal joint between the traffic lanes;
 the wheel load just before the transverse joint.
In the case of a multi-lane road (e.g. a motorway) the strength analysis is also done for:
 the wheel load just along every longitudinal joint between the traffic lanes;
 the wheel load just along the longitudinal joint between the entry or exit lane and the
adjacent lane.
The flexural tensile stress (Pi) at the bottom of the concrete slab due to the wheel load
(Pi) in each of the mentioned locations is calculated by means of the Westergaard
equation (Equation 6), taking into account the appropriate load transfer (joint efficiency
W, Equations 7 and 8) in the respective edge/joints.
The flexural tensile stress (Ti) at the bottom of the concrete slab due to a positive
temperature gradient (ΔTi) in each of the mentioned locations is calculated by means of
the Equations 9 to 12.
In the case of jointed plain concrete pavements the horizontal slab dimensions (length
L, width W) are predefined.
The structural design is based on a fatigue analysis for all the mentioned locations of
the pavement. The following fatigue relationship is used (CROW, 1999):
log Ni 
12.903 (0.995   maxi / fbrm)
1.000  0.7525  mini / fbrm
with 0.5   max / fbrm  0.833
(Equation 13)
where:
Ni = allowable number of repetitions of wheel load Pi i.e. the traffic load stress Pi till
failure when a temperature gradient stress Ti is present
mini = minimum occurring flexural tensile stress (= Ti)
maxi = maximum occurring flexural tensile stress (= Pi + Ti)
fbrm = mean flexural tensile strength (N/mm2) after 28 days for loading of short duration
(Equation 4)
The design criterion (i.e. cracking occurs), applied on every of the above-mentioned
locations of the plain or reinforced concrete pavement, is the cumulative fatigue damage
rule of Palmgren-Miner:

i
ni
= 1.0
Ni
(Equation 14)
where:
ni = occurring number of repetitions of wheel load Pi, i.e. the traffic load stress Pi,
during the pavement life combined with a temperature gradient stress Ti due to
the temperature gradient ΔTi
Ni = allowable number of repetitions of wheel load Pi, i.e. the traffic load stress Pi, till
failure combined with a temperature gradient stress Ti due to the temperature
gradient ΔTi
Lateral wander within a traffic lane is taken into account when analyzing a transverse
joint or crack, with 50% to 100% of the traffic loads driving in the centre of the wheel
track.
When analyzing a longitudinal free edge or longitudinal joint the number of traffic loads
just along the edge or joint is limited to 1% to 3% (free edge) or 5% to 10% (every
longitudinal joint) of the occurring total number of traffic loads on the carriageway (so
not the design traffic lane).
9
Design examples for case study
In this chapter, design results obtained by means of the program VENCON2.0 for a
specific case will be presented. The case concerns a jointed plain concrete pavement
for a 7.5 m wide 2-lane provincial road.
Because the width of the pavement is more than 4.5 to 5 m a longitudinal contraction
joint is required in the road axis to prevent uncontrolled (‘wild’) longitudinal cracking. Tie
bars are applied in the longitudinal joint, yielding a load transfer W = 70% (see chapter
6).
The following jointed plain concrete pavement structure is taken into account:
 plain concrete slabs, width 3.75 m (equal to the lane width) and length 4.5 m (to limit
the ratio of length and width of the slabs); the transverse contraction joints are
provided with dowel bars, which means that the load transfer W = 80% (see chapter
6);
 250 mm thick cement-bound base (E = 6000 MPa), that is not bonded to the
concrete slabs (safe assumption); the bound base results in a load tranfer at the free
edge of the pavement W = 35% (see chapter 6);
 500 mm sand sub-base (E = 100 MPa);
 subgrade with E = 100 MPa which equals a modulus of subgrade reaction k o = 0.045
N/mm3.
The modulus of substructure reaction (k-value of subgrade, sub-base plus base) is
equal to the maximum value k = 0.16 N/mm3 (see chapter 4, Equation 2).
The default temperature gradient frequency distribution of VENCON2.0 is applied
(Table 3).
With respect to the traffic loading, it is assumed that heavy vehicles are driving on the
road on 300 days per year. The heavy traffic is equally divided over the 2 traffic lanes.
The traffic growth is 3% per year. On average a heavy vehicle has 3 axles. The default
frequency distribution of the types of tire of VENCON2.0 is used (see Table 2, one but
last column).
It is assumed that 50% of the heavy vehicles on a traffic lane drives exactly in the centre
of the wheel track. It is furthermore assumed that 2% of the heavy vehicles on the road
drives exactly along the edge of the pavement and that 10% of the heavy vehicles on
the road drives exactly along the longitudinal joint.
In the calculations the following parameters are varied:
 the concrete grade: C28/35 (B35) or C35/45 (B45) (see chapter 5);
 the axle load frequency distribution on the provincial road: heavily loaded provincial
road (Table 1, 5th column) or normally loaded provincial road (Table 1, 6th column);
 the number of heavy vehicles per day on a traffic lane in the 1st year: 10, 100 or
1000;
 the design life of the pavement: 20, 30 or 40 years.
The numerical calculation results (required thickness of the concrete slabs) for the
jointed plain concrete pavement are given in Table 7. The calculation results are
graphically presented in Figure 3 and Figure 4.
The mentioned thicknesses include 15 mm extra concrete on top of the minimum
thickness calculated by means of the VENCON2.0 program.
In this case study the centre of the free edge of the pavement is always governing the
thickness design of the jointed plain concrete pavement. The centre of the longitudinal
joint and the centre of the wheel track at the transverse joint are never decisive for the
design.
Table 7 – Design thickness (mm) of plain concrete pavement for 2-lane provincial road
according to VENCON2.0
Concrete grade
Axle load frequency
distribution on
provincial road
Number of heavy
vehicles per day on
traffic lane in 1st year
Design life 20 years
Design life 30 years
Design life 40 years
C28/35 (B35)
Heavy
C35/45 (B45)
Normal
Heavy
Normal
10
100
1000
10
100
1000
10
100
1000
10
100
1000
234
237
239
247
250
254
263
267
271
224
227
230
238
241
244
253
258
262
208
211
213
221
225
227
235
239
243
199
202
205
212
215
218
227
231
234
concrete slab thickness (mm)
plain concrete pavement, effects of concrete grade and axle load
frequency distribution
260
250
240
230
220
210
200
20
25
30
35
40
design life (years)
C28/35, heavy, 100
C28/35, normal, 100
C35/45, heavy, 100
C35/45, normal, 100
Figure 3 - Effect of concrete grade, axle load frequency distribution and design life on
the required thickness of a jointed plain concrete pavement; 100 heavy
vehicles on design traffic lane in 1st year
plain concrete pavement, effects of concrete grade and number of
heavy trucks per day
concrete slab thickness (mm)
280
270
260
250
240
230
220
210
200
20
25
30
35
40
design life (years)
C28/35, heavy, 10
C28/35, heavy, 100
C28/35, heavy, 1000
C35/45, heavy, 10
C35/45, heavy, 100
C35/45, heavy, 1000
Figure 4 - Effect of concrete grade, number of heavy vehicles on design traffic lane in 1st
year and design life on the required thickness of a jointed plain concrete
pavement; heavy axle load frequency distribution
It appears from Table 7, Figure 3 and Figure 4 that the most influencing factors on the
required jointed plain concrete pavement thickness are:
 the concrete grade: concrete C35/45 results in 25 to 30 mm thinner slabs compared
to concrete C28/35 (due to the better fatigue behaviour, see Table 6 and Equation
13);
 the heavy axle load frequency distribution (highest axle load group 200-220 kN, see
Table 1) requires about 10 mm thicker concrete slabs than the normal axle load
frequency distribution (highest axle load group 180-200 kN);
 the number of heavy vehicles: a 10 times greater number of heavy vehicles requires
about 15 mm thicker concrete slabs;
 the design life: a 2 times longer design life requires only 5 to 10 mm thicker concrete
slabs.
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