23a_IRC582015_RP_Design(1).pdf
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About This Presentation
IRC 58-2015 PPT
Slide Content
DESIGNOF DESIGN
OF
RIGID PAVEMENTS USING
IRC METHOD Dr. Venkaiah Chowdar
y
IRC:58
-
2015
y
IRC:58
2015
Guidelines for the Design of Plain Jointed
Ri idP f Hi h Ri
g
id
P
avements
f
or
Hi
g
h
ways
(
Fourth Revision
)
()
OF
RIGID PAVEMENTS USING
IRC METHOD Dr. Venkaiah Chowdar
y
IRC:58
-
2015
y
IRC:58
2015
Guidelines for the Design of Plain Jointed
Ri idP f Hi h Ri
g
id
P
avements
f
or
Hi
g
h
ways
(
Fourth Revision
)
()
Develo
p
ments in IRC:58
•First Published: 1974
•
FirstRevision:1988
p
First
Revision:
1988
oLegal axle load limit increased from 8160 kg to 10200 kg o
TrafficclassificationbasedonCVPD[A:0
15;B:15
45;C:45
o
Traffic
classification
based
on
CVPD
[A:
0
-
15;
B:
15
-
45;
C:
45
-
150; D: 150-450; E: 450-1500; F: 1500-4500; G: >4500].
•
SecondRevision:2002
•
Second
Revision:
2002
oFatigue damage concept introduced
Fl l d i l d d l l d
o
Fl
exura
l stresses
d
ue to s
ing
le an
d
tan
d
em ax
le
loa
d
s
•Third Revision: 2011 (CFD, TDC, BUC, tied shoulders,
bddDLCifl f l) b
on
d
e
d
DLC
,
in
fl
uence o
f
permanent cur
l)
•Fourth Revision: 2015 (more rational design)
p
ments in IRC:58
•First Published: 1974
•
FirstRevision:1988
p
First
Revision:
1988
oLegal axle load limit increased from 8160 kg to 10200 kg o
TrafficclassificationbasedonCVPD[A:0
15;B:15
45;C:45
o
Traffic
classification
based
on
CVPD
[A:
0
-
15;
B:
15
-
45;
C:
45
-
150; D: 150-450; E: 450-1500; F: 1500-4500; G: >4500].
•
SecondRevision:2002
•
Second
Revision:
2002
oFatigue damage concept introduced
Fl l d i l d d l l d
o
Fl
exura
l stresses
d
ue to s
ing
le an
d
tan
d
em ax
le
loa
d
s
•Third Revision: 2011 (CFD, TDC, BUC, tied shoulders,
bddDLCifl f l) b
on
d
e
d
DLC
,
in
fl
uence o
f
permanent cur
l)
•Fourth Revision: 2015 (more rational design)
IRC
(
58-2015
)
Method of RP Desi
g
n
•Covers design of JPCP with and without tied concrete
shou
lde
r
s
(
)g
shoudes
•
App
licable to roads with avera
g
e traffic > 450 CVPD
pp g
•For low volume roads: IRC:SP:62-2014 •Guidelines include: (i) procedure for design of widened
outer lane, (ii) tied concrete shoulder, (iii) CC slab bonded
to stabilized sub-base, (iv) design of longitudinal joints,
expansion, and contraction joints
(
58-2015
)
Method of RP Desi
g
n
•Covers design of JPCP with and without tied concrete
shou
lde
r
s
(
)g
shoudes
•
App
licable to roads with avera
g
e traffic > 450 CVPD
pp g
•For low volume roads: IRC:SP:62-2014 •Guidelines include: (i) procedure for design of widened
outer lane, (ii) tied concrete shoulder, (iii) CC slab bonded
to stabilized sub-base, (iv) design of longitudinal joints,
expansion, and contraction joints
Salient Features of IRC:58-2015
•Design considering flexural stress caused due to combined effect
of different categories of axle loads and temperature gradient
•CFD caused by single, tandem, tridem axles taking into account
TDC dBUC TDC
an
d
BUC
•
Considerationof permanentcurlincalculationof flexuralstresses Consideration
of
permanent
curl
in
calculation
of
flexural
stresses
•Desi
g
ns without concrete shoulders and with tied concrete
g
shoulders D i f CC l b b d d bili d b
b
•
D
es
igns
f
or
CC
s
la
b
s
b
on
d
e
d
to cement sta
bili
ze
d
su
b
-
b
ases
•
Designsforwidenedouterlanes
•
Designs
for
widened
outerlanes
•Design considering flexural stress caused due to combined effect
of different categories of axle loads and temperature gradient
•CFD caused by single, tandem, tridem axles taking into account
TDC dBUC TDC
an
d
BUC
•
Considerationof permanentcurlincalculationof flexuralstresses Consideration
of
permanent
curl
in
calculation
of
flexural
stresses
•Desi
g
ns without concrete shoulders and with tied concrete
g
shoulders D i f CC l b b d d bili d b
b
•
D
es
igns
f
or
CC
s
la
b
s
b
on
d
e
d
to cement sta
bili
ze
d
su
b
-
b
ases
•
Designsforwidenedouterlanes
•
Designs
for
widened
outerlanes
Concrete Pavement T
yp
es
yp
•When PQC is laid over bituminous surface during sunshine,
necessary to whitewash the bituminous surface to minimize heat
absorption absorption
•When subgrade CBR ≥ 8%, granular separation and drainage layers
can be re
p
laced with
g
eos
y
nthetics servin
g
the desired function
pgy g
yp
es
yp
•When PQC is laid over bituminous surface during sunshine,
necessary to whitewash the bituminous surface to minimize heat
absorption absorption
•When subgrade CBR ≥ 8%, granular separation and drainage layers
can be re
p
laced with
g
eos
y
nthetics servin
g
the desired function
pgy g
Ri
g
id Pavement
(
MORTH
,
2001
)
g(,)
g
id Pavement
(
MORTH
,
2001
)
g(,)
Ri
g
id Pavement
(
MORTH
,
2013
)
g(,)
g
id Pavement
(
MORTH
,
2013
)
g(,)
Factors Governin
g
Desi
g
n
•Design period •
Designcommercialtrafficvolume
gg
•
Design
commercial
traffic
volume
•Composition of commercial traffic (single, tandem, tridem, and
li
l)
mu
lt
i-ax
les
)
•Axle load spectrum •Tyre pressure •
Lateralplacementof wheelloads
•
Lateral
placement
of
wheel
loads
•Directional distribution •Strength of foundation
•
Climaticfactors Climatic
factors
g
Desi
g
n
•Design period •
Designcommercialtrafficvolume
gg
•
Design
commercial
traffic
volume
•Composition of commercial traffic (single, tandem, tridem, and
li
l)
mu
lt
i-ax
les
)
•Axle load spectrum •Tyre pressure •
Lateralplacementof wheelloads
•
Lateral
placement
of
wheel
loads
•Directional distribution •Strength of foundation
•
Climaticfactors Climatic
factors
Axle Load Characteristics
Axletype Legalaxle load
Axle load group interval
forfatiguedamageanalysis for
fatigue
damage
analysis
Single 10.2 t (100 kN) 10 kN
Td
190 (186
kN
)
20
kN
T
an
d
em
19
.0
t
(186
kN
)
20
kN
Tridem 24.0 t (235 kN) 30 kN
•Data on axle load spectrum from axle load survey
conducted for a continuous 48 hour
p
eriod
p
•Commercial vehicles to be weighed (min.):
o
10%fortrafficexceeding6000CVPD
o
10%
for
traffic
exceeding
6000
CVPD
o15% for traffic between 3000 to 6000 CVPD o
20%fortrafficlessthan3000CVPD
o
20%
for
traffic
less
than
3000
CVPD
Axletype Legalaxle load
Axle load group interval
forfatiguedamageanalysis for
fatigue
damage
analysis
Single 10.2 t (100 kN) 10 kN
Td
190 (186
kN
)
20
kN
T
an
d
em
19
.0
t
(186
kN
)
20
kN
Tridem 24.0 t (235 kN) 30 kN
•Data on axle load spectrum from axle load survey
conducted for a continuous 48 hour
p
eriod
p
•Commercial vehicles to be weighed (min.):
o
10%fortrafficexceeding6000CVPD
o
10%
for
traffic
exceeding
6000
CVPD
o15% for traffic between 3000 to 6000 CVPD o
20%fortrafficlessthan3000CVPD
o
20%
for
traffic
less
than
3000
CVPD
Axle Load Characteristics
•Vehicles to be surveyed shall be selected randomly to
avoid
bias
avoidbias
•If spacing of consecutive axles (wheel base) is more
than 2.4 m, each axle shall be considered as a single axle TifCV0710MP
•
T
yre pressure
in most o
f
CV
s:
0
.7
to
1
.0
MP
a
•
Variationof tyrepressurewillhavenegligibleinfluence Variation
of
tyre
pressure
will
have
negligible
influence
on CC pavements with thickness ≥200 mm
•Design tyre pressure is 0.8 MPa
•Vehicles to be surveyed shall be selected randomly to
avoid
bias
avoidbias
•If spacing of consecutive axles (wheel base) is more
than 2.4 m, each axle shall be considered as a single axle TifCV0710MP
•
T
yre pressure
in most o
f
CV
s:
0
.7
to
1
.0
MP
a
•
Variationof tyrepressurewillhavenegligibleinfluence Variation
of
tyre
pressure
will
have
negligible
influence
on CC pavements with thickness ≥200 mm
•Design tyre pressure is 0.8 MPa
Wheel Base Characteristics
•Wheel base spacing information is used to estimate top-
dow
n f
atigue
c
r
ac
k
in
g
caused
by
a
xl
e
l
oads
du
r
in
g
n
ight
dow atiguecac i gcausedbya e oadsdui g ight period
•Data on axle load spacing shall be collected during
traffic survey
•If spacing between any pair of axles is less than the
i ft jit h l dtb
spac
ing o
f
t
ransverse
jo
in
t
s, suc
h
ax
les nee
d
t
o
b
e
considered in design traffic for computing top-down
fti ki d f
a
ti
gue crac
ki
ng
d
amage
•
Wheelbasesof trucksrangefrom36to>50m Wheel
bases
of
trucks
range
from
3
.6
to
>
5
.0
m
•Wheel base spacing information is used to estimate top-
dow
n f
atigue
c
r
ac
k
in
g
caused
by
a
xl
e
l
oads
du
r
in
g
n
ight
dow atiguecac i gcausedbya e oadsdui g ight period
•Data on axle load spacing shall be collected during
traffic survey
•If spacing between any pair of axles is less than the
i ft jit h l dtb
spac
ing o
f
t
ransverse
jo
in
t
s, suc
h
ax
les nee
d
t
o
b
e
considered in design traffic for computing top-down
fti ki d f
a
ti
gue crac
ki
ng
d
amage
•
Wheelbasesof trucksrangefrom36to>50m Wheel
bases
of
trucks
range
from
3
.6
to
>
5
.0
m
Wheel Base Characteristics
•Commonly used spacing of transverse joints is 4.5 m •
A
xles with spacing > 4.5 m are not expected to
contribute to top-down fatigue cracking
•If spacing of transverse joints is different from 4.5 m,
d i ffi f i i f
dki
d
es
ign tra
ffi
c
f
or est
imat
ion o
f
top-
d
own crac
ki
ng
damage may be selected appropriately
•% of CVs with spacing between front and first rear axle
lessthantheproposedspacingof transversejointsin less
than
the
proposed
spacing
of
transverse
joints
in
CC slab shall be determined from axle load survey
•Commonly used spacing of transverse joints is 4.5 m •
A
xles with spacing > 4.5 m are not expected to
contribute to top-down fatigue cracking
•If spacing of transverse joints is different from 4.5 m,
d i ffi f i i f
dki
d
es
ign tra
ffi
c
f
or est
imat
ion o
f
top-
d
own crac
ki
ng
damage may be selected appropriately
•% of CVs with spacing between front and first rear axle
lessthantheproposedspacingof transversejointsin less
than
the
proposed
spacing
of
transverse
joints
in
CC slab shall be determined from axle load survey
Desi
g
n Period
•Life span ≥30 years
g
•May be suitable modified considering:
T ffi l
o
T
ra
ffi
c vo
lume
o
Uncertaintyof trafficgrowthrate
o
Uncertainty
of
traffic
growth
rate
oCa
p
acit
y
of the road
py
oAugmentation of capacity by widening
g
n Period
•Life span ≥30 years
g
•May be suitable modified considering:
T ffi l
o
T
ra
ffi
c vo
lume
o
Uncertaintyof trafficgrowthrate
o
Uncertainty
of
traffic
growth
rate
oCa
p
acit
y
of the road
py
oAugmentation of capacity by widening
Traffic Consideration
•Design Lane:
o
Lanecarryinghighestno of heavyCVs
o
Lane
carrying
highest
no
.
of
heavy
CVs
oEach lane of a 2-way 2-lane highway and outer lane of multi-
lhih lane
hi
g
h
ways
•Design Traffic:
oADT based on 7-day, 24-h traffic volume o
Actualgrowthrateshallbeconsidered
o
Actual
growth
rate
shall
be
considered
oAnnual growth rate of CVs shall be min. 5% oDay & night traffic trends shall be captured
(
day loading
leads to bottom-up cracking, night loading leads to top-
d n r kin
)
d
ow
n
c
r
ac
kin
g
)
•Design Lane:
o
Lanecarryinghighestno of heavyCVs
o
Lane
carrying
highest
no
.
of
heavy
CVs
oEach lane of a 2-way 2-lane highway and outer lane of multi-
lhih lane
hi
g
h
ways
•Design Traffic:
oADT based on 7-day, 24-h traffic volume o
Actualgrowthrateshallbeconsidered
o
Actual
growth
rate
shall
be
considered
oAnnual growth rate of CVs shall be min. 5% oDay & night traffic trends shall be captured
(
day loading
leads to bottom-up cracking, night loading leads to top-
d n r kin
)
d
ow
n
c
r
ac
kin
g
)
Traffic Consideration
•Design Traffic:
o
Edgeflexuralstresscausedbyaxleloads
forbottom
up
o
Edge
flexural
stress
caused
by
axle
loads
for
bottom
-
up
cracking
is max. when tyre imprint of outer wheel touches
the long
itudinal ed
g
e
gg
oStress in the edge region reduces substantially when the tyre
positionisawayfromthelongitudinaledge position
is
away
from
the
longitudinal
edge
oEdge flexural stress is small when wheel loads are close to the
transversejoints transverse
joints
oData obtained from Indian Highways on lateral distribution
of wheelpathsof CVsindicatesthatthetyreimprintsof of
wheel
paths
of
CVs
indicates
that
the
tyre
imprints
of
very few vehicles are tangential to longitudinal edge/joint on
2-lane 2-
w
a
y
roads and multi-lane hi
g
hwa
y
s
y
gy
•Design Traffic:
o
Edgeflexuralstresscausedbyaxleloads
forbottom
up
o
Edge
flexural
stress
caused
by
axle
loads
for
bottom
-
up
cracking
is max. when tyre imprint of outer wheel touches
the long
itudinal ed
g
e
gg
oStress in the edge region reduces substantially when the tyre
positionisawayfromthelongitudinaledge position
is
away
from
the
longitudinal
edge
oEdge flexural stress is small when wheel loads are close to the
transversejoints transverse
joints
oData obtained from Indian Highways on lateral distribution
of wheelpathsof CVsindicatesthatthetyreimprintsof of
wheel
paths
of
CVs
indicates
that
the
tyre
imprints
of
very few vehicles are tangential to longitudinal edge/joint on
2-lane 2-
w
a
y
roads and multi-lane hi
g
hwa
y
s
y
gy
Traffic Consideration
•Design Traffic:
o
Somemulti
lanedividedhighwayshave85to90mwide
o
Some
multi
-
lane
divided
highways
have
8
.5
to
9
.0
m
wide
carriageways with single longitudinal joint
o
Lnmrkin in h dnt inid ith
o
L
a
n
e
m
a
rkin
gs
in
suc
h
cases
d
o
n
o
t
co
in
c
id
e w
ith
longitudinal joints resulting in large proportion of wheel
pathsmoveclosertolongitudinaljoint paths
move
closer
to
longitudinal
joint
oRecommended to consider 25% of total 2-way CVs shall be
consideredasdesigntraffic
for2
-
lane2
-
wayroadsfor
considered
as
design
traffic
for
2
lane
2
way
roads
for
analysis of bottom-up cracking
o
Forfour
-
laneandmulti
-
lanedividedhighways
25%of traffic
o
For
four
-
lane
and
multi
-
lane
divided
highways
,
25%
of
traffic
in the predominant direction shall be considered as
desi
g
n trafficfor anal
y
sis of bottom-u
p
crackin
g
g
y
pg
•Design Traffic:
o
Somemulti
lanedividedhighwayshave85to90mwide
o
Some
multi
-
lane
divided
highways
have
8
.5
to
9
.0
m
wide
carriageways with single longitudinal joint
o
Lnmrkin in h dnt inid ith
o
L
a
n
e
m
a
rkin
gs
in
suc
h
cases
d
o
n
o
t
co
in
c
id
e w
ith
longitudinal joints resulting in large proportion of wheel
pathsmoveclosertolongitudinaljoint paths
move
closer
to
longitudinal
joint
oRecommended to consider 25% of total 2-way CVs shall be
consideredasdesigntraffic
for2
-
lane2
-
wayroadsfor
considered
as
design
traffic
for
2
lane
2
way
roads
for
analysis of bottom-up cracking
o
Forfour
-
laneandmulti
-
lanedividedhighways
25%of traffic
o
For
four
-
lane
and
multi
-
lane
divided
highways
,
25%
of
traffic
in the predominant direction shall be considered as
desi
g
n trafficfor anal
y
sis of bottom-u
p
crackin
g
g
y
pg
Traffic Consideration
•Design Traffic:
o
Designtraffic
fortop
-
downcracking
analysiswillbea
o
Design
traffic
for
top
down
cracking
analysis
will
be
a
portion of the design traffic considered for bottom-up
cracking analysis
oCVs with spacing between front axle and first rear axle
less than the spacing of transverse joints shall be
considered for top-down cracking analysis
oActual proportion shall be determined from traffic (or)
lld
ax
l
e
l
oa
d
surveys
oDefault value of 50% of design traffic used for bottom-up
cracking
anal sisma beconsidered
cracking
anal
y
sis
ma
y
be
considered
oFor new roads, data from roads of similar classification and
importanceshallbeusedtopredictdesigntraffic importance
shall
be
used
to
predict
design
traffic
•Design Traffic:
o
Designtraffic
fortop
-
downcracking
analysiswillbea
o
Design
traffic
for
top
down
cracking
analysis
will
be
a
portion of the design traffic considered for bottom-up
cracking analysis
oCVs with spacing between front axle and first rear axle
less than the spacing of transverse joints shall be
considered for top-down cracking analysis
oActual proportion shall be determined from traffic (or)
lld
ax
l
e
l
oa
d
surveys
oDefault value of 50% of design traffic used for bottom-up
cracking
anal sisma beconsidered
cracking
anal
y
sis
ma
y
be
considered
oFor new roads, data from roads of similar classification and
importanceshallbeusedtopredictdesigntraffic importance
shall
be
used
to
predict
design
traffic
Traffic Consideration
•Design Traffic:
o
Sincefrontaxles(steeringaxles)fittedwithsinglewheelson
o
Since
front
axles
(steering
axles)
fitted
with
single
wheels
on
either side cause negligible bottom-up fatigue damage,
rear axles only are considered in the axle load spectrum
(
)
{
}
r
r A
C
n
1 1 365− + ×
=
Where,
C = cumulative no. of CVs durin
g
desi
g
n
p
eriod
r
ggp
A = initial no. of CVs per day in the year when road is
opened to traffic
r = annual growth rate of CVs
n = desi
g
n
p
eriod in
y
ears
gp y
•Design Traffic:
o
Sincefrontaxles(steeringaxles)fittedwithsinglewheelson
o
Since
front
axles
(steering
axles)
fitted
with
single
wheels
on
either side cause negligible bottom-up fatigue damage,
rear axles only are considered in the axle load spectrum
(
)
{
}
r
r A
C
n
1 1 365− + ×
=
Where,
C = cumulative no. of CVs durin
g
desi
g
n
p
eriod
r
ggp
A = initial no. of CVs per day in the year when road is
opened to traffic
r = annual growth rate of CVs
n = desi
g
n
p
eriod in
y
ears
gp y
Tem
p
erature Consideration
•Temperature Differential ( ∆T):
p
oTemperature differential between top and bottom surfaces of
concrete slab make it to curl
inducing stresses
oTemperature differential = f(solar radiation received by
pavement surface, wind velocity, thermal diffusivity of
concrete, latitude, longitude, and elevation of the place)
oTemperature differential values shall be estimated from
geographicalparametersandmaterialcharacteristics geographical
parameters
and
material
characteristics
o
Intheabsenceof data pickvaluesfromthetable
o
In
the
absence
of
data
,
pick
values
from
the
table
p
erature Consideration
•Temperature Differential ( ∆T):
p
oTemperature differential between top and bottom surfaces of
concrete slab make it to curl
inducing stresses
oTemperature differential = f(solar radiation received by
pavement surface, wind velocity, thermal diffusivity of
concrete, latitude, longitude, and elevation of the place)
oTemperature differential values shall be estimated from
geographicalparametersandmaterialcharacteristics geographical
parameters
and
material
characteristics
o
Intheabsenceof data pickvaluesfromthetable
o
In
the
absence
of
data
,
pick
values
from
the
table
Tem
p
erature Consideration
•Temperature Differential ( ∆T):
Vii f ihd hi
li d i
p
o
V
ar
iat
ion o
f
temperature w
it
h
d
ept
h
is non-
li
near
d
ur
i
ng
day time and nearly linear during night time
oMax. temperature differential during night is nearly half of
the day time max. temperature differential
oTemperature differentials are positive when slab is convex
upwards during day time and negative when slab is concave
upwards during night time
o
Axl
e
l
oad
st
r
esses
s
h
a
ll
be
co
m
puted
f
o
r f
at
igue
a
n
a
lys
is
o
e oadst essess a beco puted o atguea ayss
when slab is in a curled state due to temperature
differential during day as well as night times
p
erature Consideration
•Temperature Differential ( ∆T):
Vii f ihd hi
li d i
p
o
V
ar
iat
ion o
f
temperature w
it
h
d
ept
h
is non-
li
near
d
ur
i
ng
day time and nearly linear during night time
oMax. temperature differential during night is nearly half of
the day time max. temperature differential
oTemperature differentials are positive when slab is convex
upwards during day time and negative when slab is concave
upwards during night time
o
Axl
e
l
oad
st
r
esses
s
h
a
ll
be
co
m
puted
f
o
r f
at
igue
a
n
a
lys
is
o
e oadst essess a beco puted o atguea ayss
when slab is in a curled state due to temperature
differential during day as well as night times
(CRRI 1974) (CRRI
,
1974) ; Telangana
,
1974) ; Telangana
Tem
p
erature Consideration
•Zero Stress Temperature Gradient:
o
CCslabslaidduringdaywillhavehigh+
∆
Tduetointense
p
o
CC
slabs
laid
during
day
will
have
high
+
∆
T
due
to
intense
solar radiation, high air temperature, and chemical reaction
oSlabs will not curl because of +
∆
T
and remain flat
during hardening stage because of its plastic stage
oSlab remains stress free
and corres
p
ondin
g
tem
p
erature
pgp
gradient is termed as zero stress temperature gradient
oExposure of fresh concrete to sun and high air temperature
during hardening stage causes development of
p
ermanent
curl (warping!!!)in CC slabs which is nearly equal to curl
db n ti tmprtr diffrntil(
∆
T) f 5
°
C
cause
d
b
y
n
ega
ti
ve
t
e
mp
e
r
a
t
u
r
e
diff
e
r
e
nti
a
l (
-
∆
T)
o
f
5
°
C
oEquivalent -∆T shall be added algebraically to actual
temperaturedifferentialprevailingatanytime temperature
differential
prevailing
at
any
time
p
erature Consideration
•Zero Stress Temperature Gradient:
o
CCslabslaidduringdaywillhavehigh+
∆
Tduetointense
p
o
CC
slabs
laid
during
day
will
have
high
+
∆
T
due
to
intense
solar radiation, high air temperature, and chemical reaction
oSlabs will not curl because of +
∆
T
and remain flat
during hardening stage because of its plastic stage
oSlab remains stress free
and corres
p
ondin
g
tem
p
erature
pgp
gradient is termed as zero stress temperature gradient
oExposure of fresh concrete to sun and high air temperature
during hardening stage causes development of
p
ermanent
curl (warping!!!)in CC slabs which is nearly equal to curl
db n ti tmprtr diffrntil(
∆
T) f 5
°
C
cause
d
b
y
n
ega
ti
ve
t
e
mp
e
r
a
t
u
r
e
diff
e
r
e
nti
a
l (
-
∆
T)
o
f
5
°
C
oEquivalent -∆T shall be added algebraically to actual
temperaturedifferentialprevailingatanytime temperature
differential
prevailing
at
any
time
Tem
p
erature Consideration
Difference between curling and warping:
p
•Curlingis the deformation of the slab due to a
difference in tem
p
erature between the surface and
p
bottom of the slab ( temperature gradient)
•Warpingis the deformation of the slab surface profile
due to difference in moisture between the surface and
bottom of the slab ( moisture gradient)
•If a slab surface is allowed to dry and bottom is moist,
the edges of slab will warp upward ( permanent curl!!!)
p
erature Consideration
Difference between curling and warping:
p
•Curlingis the deformation of the slab due to a
difference in tem
p
erature between the surface and
p
bottom of the slab ( temperature gradient)
•Warpingis the deformation of the slab surface profile
due to difference in moisture between the surface and
bottom of the slab ( moisture gradient)
•If a slab surface is allowed to dry and bottom is moist,
the edges of slab will warp upward ( permanent curl!!!)
Tem
p
erature Consideration
•Zero Stress Temperature Gradient:
If
∆
Td i d i 20
°
C
∆
Tf i
p
o
If
max. +
∆
T
d
ur
ing
d
ay
is
20
°
C
,
∆
T
f
or stress computat
ion
can be taken as 15 °C
oHowever, 5 °C reduction in
∆
T is not made
so that design
for bottom-up cracking remains conservative
oIf max. -∆T during night is 10 °C, total effective - ∆T shall be
taken as 15 °C (=10 °C + 5 °C)
oSafer to consider effective negative temperature gradient for
c
h
ec
kin
g
t
h
e
s
lab
f
o
r
top
-
dow
n
c
r
ac
kin
g
caused
by
cec gtesabotop
dow c ac gcausedby
combined effects of traffic loads and night time - ∆T
p
erature Consideration
•Zero Stress Temperature Gradient:
If
∆
Td i d i 20
°
C
∆
Tf i
p
o
If
max. +
∆
T
d
ur
ing
d
ay
is
20
°
C
,
∆
T
f
or stress computat
ion
can be taken as 15 °C
oHowever, 5 °C reduction in
∆
T is not made
so that design
for bottom-up cracking remains conservative
oIf max. -∆T during night is 10 °C, total effective - ∆T shall be
taken as 15 °C (=10 °C + 5 °C)
oSafer to consider effective negative temperature gradient for
c
h
ec
kin
g
t
h
e
s
lab
f
o
r
top
-
dow
n
c
r
ac
kin
g
caused
by
cec gtesabotop
dow c ac gcausedby
combined effects of traffic loads and night time - ∆T
Tem
p
erature Consideration
•Zero Stress Temperature Gradient:
Cb hl lifi dp
o
C
um
b
ersome to carry out
h
our
ly cumu
lat
ive
f
at
igue
d
amage
analysis
oAssume max. +
∆
T to be constant for six hour period during
day time (10 a.m. to 4 p.m.) and max. -∆T to be constant for
ih iddi ihi (
06
)
s
ix
h
our per
io
d
d
ur
ing n
ig
h
t t
ime
(
0
a.m. to
6
a.m.
)
[morning and evening traffic peak hours???
]
oSlab shall be assumed to be free of warping stresses for
remaining 12 hours for fatigue damage analysis as the fatigue
ddbbidtiflddtt d
amage cause
d
b
y com
bi
ne
d
ac
ti
on o
f
loa
d
an
d
t
empera
t
ure
differential will be insignificant during this period
p
erature Consideration
•Zero Stress Temperature Gradient:
Cb hl lifi dp
o
C
um
b
ersome to carry out
h
our
ly cumu
lat
ive
f
at
igue
d
amage
analysis
oAssume max. +
∆
T to be constant for six hour period during
day time (10 a.m. to 4 p.m.) and max. -∆T to be constant for
ih iddi ihi (
06
)
s
ix
h
our per
io
d
d
ur
ing n
ig
h
t t
ime
(
0
a.m. to
6
a.m.
)
[morning and evening traffic peak hours???
]
oSlab shall be assumed to be free of warping stresses for
remaining 12 hours for fatigue damage analysis as the fatigue
ddbbidtiflddtt d
amage cause
d
b
y com
bi
ne
d
ac
ti
on o
f
loa
d
an
d
t
empera
t
ure
differential will be insignificant during this period
Embankment Soi
l
•CBR of embankment (500 mm below formation level) shall be
determined for estimating effective CBR of subgradeand
modulus of subgrade reaction (k)for CC pavement design
•Ex
p
ansi
v
e soil strata ma
y
b
e re
p
lace
d
w
ith non-ex
p
ansi
v
e soil
, if
pv ybpdw
pv ,
economically feasible.
•
Soilswellcanbecontrolledbysurchargeloads(placingswelling
•
Soil
swell
can
be
controlled
by
surcharge
loads
(placing
swelling
soils in lower part of the embankment)
bd
•Geosynthetics may
b
e use
d
to arrest tension cracks
•Ex
p
ansive soils shall be com
p
acted 1-3% above OMC
pp
•Expansive soils may be modified using lime (or) cement
l
•CBR of embankment (500 mm below formation level) shall be
determined for estimating effective CBR of subgradeand
modulus of subgrade reaction (k)for CC pavement design
•Ex
p
ansi
v
e soil strata ma
y
b
e re
p
lace
d
w
ith non-ex
p
ansi
v
e soil
, if
pv ybpdw
pv ,
economically feasible.
•
Soilswellcanbecontrolledbysurchargeloads(placingswelling
•
Soil
swell
can
be
controlled
by
surcharge
loads
(placing
swelling
soils in lower part of the embankment)
bd
•Geosynthetics may
b
e use
d
to arrest tension cracks
•Ex
p
ansive soils shall be com
p
acted 1-3% above OMC
pp
•Expansive soils may be modified using lime (or) cement
Characteristics of Sub
g
rade
•Subgrade is considered as a Winkler (dense liquid) foundation •
Strengthof s bgradeise pressedintermsof
modulusof
g
•
Strength
of
s
u
bgrade
is
e
x
pressed
in
terms
of
modulus
of
subgrade reaction (k)determined using a 75 cm dia. plate.
•One test per kilometre per lane.
•Additional tests shall be
p
erformed with chan
g
e in sub
g
rade soil
,
pgg,
sub-base, nature of formation (cut or fill).
[
]
078
0
21
1
+
=
φ
k
k
where, φis the plate diameter (in m), k
φ
and k
75
are modulus of
bd i(iMP/)ihldi
φ
d75
[
]
078
.
0
21
.
1
75
+
=
φ
φ
k
k
su
b
gra
d
e react
ion
(i
n
MP
a
/
m
)
w
it
h
p
late
di
ameter
φ
an
d
75
cm,
respectively
g
rade
•Subgrade is considered as a Winkler (dense liquid) foundation •
Strengthof s bgradeise pressedintermsof
modulusof
g
•
Strength
of
s
u
bgrade
is
e
x
pressed
in
terms
of
modulus
of
subgrade reaction (k)determined using a 75 cm dia. plate.
•One test per kilometre per lane.
•Additional tests shall be
p
erformed with chan
g
e in sub
g
rade soil
,
pgg,
sub-base, nature of formation (cut or fill).
[
]
078
0
21
1
+
=
φ
k
k
where, φis the plate diameter (in m), k
φ
and k
75
are modulus of
bd i(iMP/)ihldi
φ
d75
[
]
078
.
0
21
.
1
75
+
=
φ
φ
k
k
su
b
gra
d
e react
ion
(i
n
MP
a
/
m
)
w
it
h
p
late
di
ameter
φ
an
d
75
cm,
respectively
Characteristics of Sub
g
rade
•Strength of subgrade is affected by its moisture content •
Diffic lt(
timeconsumingandexpensive
)todetermine
k
g
•
Diffic
u
lt
(
time
consuming
and
expensive
)
to
determine
k
-
value at different densities and moisture contents
•k-
v
alue estimated from soaked CBR value:
Soaked k-value, Soaked k-value, CBR, % MPa/m CBR, % MPa/m
2211055
3281562 4352069 54250140 7 48 100 220
g
rade
•Strength of subgrade is affected by its moisture content •
Diffic lt(
timeconsumingandexpensive
)todetermine
k
g
•
Diffic
u
lt
(
time
consuming
and
expensive
)
to
determine
k
-
value at different densities and moisture contents
•k-
v
alue estimated from soaked CBR value:
Soaked k-value, Soaked k-value, CBR, % MPa/m CBR, % MPa/m
2211055
3281562 4352069 54250140 7 48 100 220
Characteristics of Sub
g
rade
•If CBR of 500 mm thick compacted subgrade is significantly
greater than the embankment, effective CBR shall be estimated
g
g
rade
•If CBR of 500 mm thick compacted subgrade is significantly
greater than the embankment, effective CBR shall be estimated
g
Characteristics of Sub
g
rade
•Min. recommended design CBR of subgrade is 8% •
In
sit CBRof s bgradecanalsobedeterminedfromD namic
g
•
In
-
sit
u
CBR
of
s
u
bgrade
can
also
be
determined
from
D
y
namic
Cone Penetrometer (DCP) using 60 °cone [ASTM D 6951]:
(
)
(
)
N
l
12
1
465
2
CBR
l
Where
, N
DCP
is the rate of cone
p
enetration
(
mm
/
blow
)
(
)
(
)
DCP 10 10
N
l
og
12
.
1
465
.
2
CBR
l
og
−
=
,
DCP
p(/)
•k-value can also be determined from Falling Weight
Deflectometer(FWD)tests Deflectometer
(FWD)
tests
•k-value of subgrade back-calculated from FWD test data is the
dik
l
d
ynam
ic
k
-
v
a
lue
•Static k-value is 50% of dynamic k-value
g
rade
•Min. recommended design CBR of subgrade is 8% •
In
sit CBRof s bgradecanalsobedeterminedfromD namic
g
•
In
-
sit
u
CBR
of
s
u
bgrade
can
also
be
determined
from
D
y
namic
Cone Penetrometer (DCP) using 60 °cone [ASTM D 6951]:
(
)
(
)
N
l
12
1
465
2
CBR
l
Where
, N
DCP
is the rate of cone
p
enetration
(
mm
/
blow
)
(
)
(
)
DCP 10 10
N
l
og
12
.
1
465
.
2
CBR
l
og
−
=
,
DCP
p(/)
•k-value can also be determined from Falling Weight
Deflectometer(FWD)tests Deflectometer
(FWD)
tests
•k-value of subgrade back-calculated from FWD test data is the
dik
l
d
ynam
ic
k
-
v
a
lue
•Static k-value is 50% of dynamic k-value
Characteristics of Sub
g
rade
•Filter and drainage layers shall be provided above the subgrade
for drainage of water to prevent:
g
i.Excessive softeningof subgrade and sub-base, and ii.Erosionof subgrade and sub-base under adverse moisture
conditions and heavy dynamic loads
•Geosynthetics may be used at the interface of subgrade and
granular sub-base layer for effective filtration (geotextiles, and
dd d
geocomposites
)
an
d
d
rainage (geotextiles, geonets, an
d
geocomposites)
•Geosynthetics will not allow migration of subgrade soil fines into
the granular sub-base layer
g
rade
•Filter and drainage layers shall be provided above the subgrade
for drainage of water to prevent:
g
i.Excessive softeningof subgrade and sub-base, and ii.Erosionof subgrade and sub-base under adverse moisture
conditions and heavy dynamic loads
•Geosynthetics may be used at the interface of subgrade and
granular sub-base layer for effective filtration (geotextiles, and
dd d
geocomposites
)
an
d
d
rainage (geotextiles, geonets, an
d
geocomposites)
•Geosynthetics will not allow migration of subgrade soil fines into
the granular sub-base layer
Characteristics of Sub-base
dfbld lb
•Provi
d
es a uni
f
orm, sta
bl
e, an
d
permanent support to CC s
la
b
•
Shallhave
sufficientstrength
topreventitsdisintegrationand
Shall
have
sufficient
strength
to
prevent
its
disintegration
and
erosion under heavy traffic and adverse environmental conditions
(excessive moisture, freezing and thawing)
•Recommended to use a Dry Lean Concrete (DLC) as sub-base
overGSBwith
7
-
dayavg compressivestrengthof 7MPa
(10
over
GSB
with
7
-
day
avg
.
compressive
strength
of
7
MPa
(10
MPa in IRC:58:2012)
•For PQC bonded to DLC, avg. 7-day strength of DLC > 10MPa
dfbld lb
•Provi
d
es a uni
f
orm, sta
bl
e, an
d
permanent support to CC s
la
b
•
Shallhave
sufficientstrength
topreventitsdisintegrationand
Shall
have
sufficient
strength
to
prevent
its
disintegration
and
erosion under heavy traffic and adverse environmental conditions
(excessive moisture, freezing and thawing)
•Recommended to use a Dry Lean Concrete (DLC) as sub-base
overGSBwith
7
-
dayavg compressivestrengthof 7MPa
(10
over
GSB
with
7
-
day
avg
.
compressive
strength
of
7
MPa
(10
MPa in IRC:58:2012)
•For PQC bonded to DLC, avg. 7-day strength of DLC > 10MPa
Characteristics of Sub-base
ff hllb hdhbhh
•Sur
f
ace o
f
DLC s
h
a
ll
b
e roug
h
ene
d
wit
h
wire
b
rus
h
wit
h
in 3 to 6
hours of laying
•Min. recommended thickness of DLC for major roads is 150 mm
C d( ) bili d b
blbd
•
C
emente
d
(
or
)
sta
bili
ze
d
su
b
-
b
ase may a
lso
b
e use
d
•
Cementtreatedsub
-
basewhenusedshallhaveamin28
-
day
Cement
treated
sub
base
when
used
shall
have
a
min
28
day
characteristic compressive strength of 7 MPa and loss of weight
shall not exceed 14% after 12 cycles of freeze-thaw simulation
ff hllb hdhbhh
•Sur
f
ace o
f
DLC s
h
a
ll
b
e roug
h
ene
d
wit
h
wire
b
rus
h
wit
h
in 3 to 6
hours of laying
•Min. recommended thickness of DLC for major roads is 150 mm
C d( ) bili d b
blbd
•
C
emente
d
(
or
)
sta
bili
ze
d
su
b
-
b
ase may a
lso
b
e use
d
•
Cementtreatedsub
-
basewhenusedshallhaveamin28
-
day
Cement
treated
sub
base
when
used
shall
have
a
min
28
day
characteristic compressive strength of 7 MPa and loss of weight
shall not exceed 14% after 12 cycles of freeze-thaw simulation
Characteristics of Sub-base
•Appropriate blanket course shall be used in addition to sub-
baseon problematic subgrade soils (clayey and expansive soils)
•k-values of granular and cement treated sub-base: •
ForCCslabslaidoverabituminoussub
-
base,k
-
valueshall
For
CC
slabs
laid
over
a
bituminous
sub
base,
k
value
shall
be adopted from IRC:SP:76
•Appropriate blanket course shall be used in addition to sub-
baseon problematic subgrade soils (clayey and expansive soils)
•k-values of granular and cement treated sub-base: •
ForCCslabslaidoverabituminoussub
-
base,k
-
valueshall
For
CC
slabs
laid
over
a
bituminous
sub
base,
k
value
shall
be adopted from IRC:SP:76
Characteristics of Sub-base
•k-values of DLC sub-base laid over granular sub-base consisting
of filter and drainage layers:
•An upper limit of 300 MPa/m is recommended considering the
loss of subgrade support expected by heavy traffic
•Contribution of granular sub-base placed below DLC layer can
be i
g
nored for estimatin
g
effective kof the foundation
gg
•k-values of DLC sub-base laid over granular sub-base consisting
of filter and drainage layers:
•An upper limit of 300 MPa/m is recommended considering the
loss of subgrade support expected by heavy traffic
•Contribution of granular sub-base placed below DLC layer can
be i
g
nored for estimatin
g
effective kof the foundation
gg
Se
p
aration La
y
er b
/
w DLC and CC Slab
•Interface between (b/w) DLC and CC slab shall be smooth to
reduce inter layer friction and to permit relative movements
py/
•Debonding layer of min. 125 µm polythene sheet used in India •
Waxbasedcompoundinplaceof plasticsheetmaybeused(used
•
Wax
based
compound
in
place
of
plastic
sheet
may
be
used
(used
in one of the National Highways projects in India)
•
Chokestone(NMAS95mm;smallsizeof uniformlygraded
•
Choke
stone
(NMAS
9
.5
mm;
small
size
of
uniformly
graded
stone layer of 13 to 25 mm thickness) used in USA
•
Srf dr inm b d
•
S
u
rf
ace
dr
ess
in
g
m
ay
b
e use
d
•Debonding layer is not necessary if CC slab is placed over BC
lill id iflb layer as
it a
ll
ows expans
ion an
d
contract
ion o
f
s
la
b
•Non-woven geotextile of 5-6 mm thickness ca be used
p
aration La
y
er b
/
w DLC and CC Slab
•Interface between (b/w) DLC and CC slab shall be smooth to
reduce inter layer friction and to permit relative movements
py/
•Debonding layer of min. 125 µm polythene sheet used in India •
Waxbasedcompoundinplaceof plasticsheetmaybeused(used
•
Wax
based
compound
in
place
of
plastic
sheet
may
be
used
(used
in one of the National Highways projects in India)
•
Chokestone(NMAS95mm;smallsizeof uniformlygraded
•
Choke
stone
(NMAS
9
.5
mm;
small
size
of
uniformly
graded
stone layer of 13 to 25 mm thickness) used in USA
•
Srf dr inm b d
•
S
u
rf
ace
dr
ess
in
g
m
ay
b
e use
d
•Debonding layer is not necessary if CC slab is placed over BC
lill id iflb layer as
it a
ll
ows expans
ion an
d
contract
ion o
f
s
la
b
•Non-woven geotextile of 5-6 mm thickness ca be used
Concrete Stren
g
th
•Flexural strength of CC is required for design of CC slabs
•
CanbeobtainedfromlaboratorytestsonCCbeam
g
Can
be
obtained
from
laboratory
tests
on
CC
beam
•Otherwise, use:
h
f
ifl l h( dl f )iMP d
f
ck cr
f f7.0=
wh
ere,
f
cr
is
fl
exura
l strengt
h
(
mo
d
u
lus o
f
rupture
)
in
MP
a, an
d
f
ck
is characteristic compressive cube strength of CC in MPa Fl l h f P Q li C (PQC)
hll
•
Fl
exura
l strengt
h
o
f
P
avement
Q
ua
li
ty
C
oncrete
(PQC)
s
h
a
ll
not
be less than 4.5 MPa
dbdddb
•90
d
ays strength shall
b
e permitte
d
(instea
d
of 28
d
ays)
b
ecause
no. of load repetitions is less during initial 90 days and also has
negligibleeffectoncumulativefatiguedamageof CC negligible
effect
on
cumulative
fatigue
damage
of
CC
•90 days strength of CC can be obtained by increasing 28 days
strength
byafactorof 110
strength
by
a
factor
of
1
.
10
g
th
•Flexural strength of CC is required for design of CC slabs
•
CanbeobtainedfromlaboratorytestsonCCbeam
g
Can
be
obtained
from
laboratory
tests
on
CC
beam
•Otherwise, use:
h
f
ifl l h( dl f )iMP d
f
ck cr
f f7.0=
wh
ere,
f
cr
is
fl
exura
l strengt
h
(
mo
d
u
lus o
f
rupture
)
in
MP
a, an
d
f
ck
is characteristic compressive cube strength of CC in MPa Fl l h f P Q li C (PQC)
hll
•
Fl
exura
l strengt
h
o
f
P
avement
Q
ua
li
ty
C
oncrete
(PQC)
s
h
a
ll
not
be less than 4.5 MPa
dbdddb
•90
d
ays strength shall
b
e permitte
d
(instea
d
of 28
d
ays)
b
ecause
no. of load repetitions is less during initial 90 days and also has
negligibleeffectoncumulativefatiguedamageof CC negligible
effect
on
cumulative
fatigue
damage
of
CC
•90 days strength of CC can be obtained by increasing 28 days
strength
byafactorof 110
strength
by
a
factor
of
1
.
10
Concrete Stren
g
th
•Target mean flexural strength while designing the mix shall be
such that there is 95% probability that the characteristic strength
g
w
ould be achieved when the mix is produced in the field
•Tar
g
et mean flexural stren
g
th at 28
d
a
y
s
(
in MPa
)
:
ggdy()
σ
a cr cr
Z f f
+ =
'
Where,
f
ischaracteristicflexuralstrengthat28days MPa
f
cr
is
characteristic
flexural
strength
at
28
days
,
MPa
Z
a
is a factor corresponding to desired confidence
ll(196f5%l ll) leve
l (1
.96
f
or
5%
to
lerance
leve
l)
σ
is standard deviation of field test samples, MPa
g
th
•Target mean flexural strength while designing the mix shall be
such that there is 95% probability that the characteristic strength
g
w
ould be achieved when the mix is produced in the field
•Tar
g
et mean flexural stren
g
th at 28
d
a
y
s
(
in MPa
)
:
ggdy()
σ
a cr cr
Z f f
+ =
'
Where,
f
ischaracteristicflexuralstrengthat28days MPa
f
cr
is
characteristic
flexural
strength
at
28
days
,
MPa
Z
a
is a factor corresponding to desired confidence
ll(196f5%l ll) leve
l (1
.96
f
or
5%
to
lerance
leve
l)
σ
is standard deviation of field test samples, MPa
Concrete Stren
g
th
•Modulus of elasticity (E) and Poisson’s ratio ( µ) of CC vary with
concrete materials and affects CC strength
g
•E increases and µdecreases with increase in CC strength •E and µmay be determined experimentall
y
•25% variation in these values will have ne
g
li
g
ible influenceof
gg
the flexural strength of CC
•
Forstressanalysisof CCslabwith28
-
dayflexuralstrengthof 45
For
stress
analysis
of
CC
slab
with
28
-
day
flexural
strength
of
4
.5
MPa (4.95 MPa for 90 days), E is 30,000 MPa and µis 0.15
C ffi i f h l i f (
)
dd
•
C
oe
ffi
c
ient o
f
t
h
erma
l expans
ion o
f
concrete
(
α
)
d
epen
d
s on
type of aggregateused in CC and for design purpose, αshall be
takenas10
×
10
-6
per
°
C
taken
as
10
×
10
per
C
g
th
•Modulus of elasticity (E) and Poisson’s ratio ( µ) of CC vary with
concrete materials and affects CC strength
g
•E increases and µdecreases with increase in CC strength •E and µmay be determined experimentall
y
•25% variation in these values will have ne
g
li
g
ible influenceof
gg
the flexural strength of CC
•
Forstressanalysisof CCslabwith28
-
dayflexuralstrengthof 45
For
stress
analysis
of
CC
slab
with
28
-
day
flexural
strength
of
4
.5
MPa (4.95 MPa for 90 days), E is 30,000 MPa and µis 0.15
C ffi i f h l i f (
)
dd
•
C
oe
ffi
c
ient o
f
t
h
erma
l expans
ion o
f
concrete
(
α
)
d
epen
d
s on
type of aggregateused in CC and for design purpose, αshall be
takenas10
×
10
-6
per
°
C
taken
as
10
×
10
per
C
Fati
g
ue Behaviour of CC
•Repeated application of flexural stresses due to wheel loads
causes progressive fatigue damage in CC slab in the form of
g
gradual development of micro-cracks especially when stress ratio (SR) is high.
•SR is defined as the ratio between applied flexural stress due to
wheel load and flexural strength (modulus of rupture) of CC
2577
4
45.0 for
268.3
⎤
⎡
<
∞=SR
N
55.0 45.0 when
4325 .0
2577 .
4
≤
≤
⎥
⎦
⎤
⎢ ⎣⎡
−
=SR
SR
N
55.0 for
0828 .0
9718 .0
log
10
>
−
=SR
SR
N
g
ue Behaviour of CC
•Repeated application of flexural stresses due to wheel loads
causes progressive fatigue damage in CC slab in the form of
g
gradual development of micro-cracks especially when stress ratio (SR) is high.
•SR is defined as the ratio between applied flexural stress due to
wheel load and flexural strength (modulus of rupture) of CC
2577
4
45.0 for
268.3
⎤
⎡
<
∞=SR
N
55.0 45.0 when
4325 .0
2577 .
4
≤
≤
⎥
⎦
⎤
⎢ ⎣⎡
−
=SR
SR
N
55.0 for
0828 .0
9718 .0
log
10
>
−
=SR
SR
N
Fati
g
ue Behaviour of CC
•With increase in SR, no. of load repetitions to cause cracking
decreases
g
•N value is used for checking the adequacy of pavement slab
bd
ihhi
b
ase
d
on M
i
ner’s
h
ypot
h
es
i
s
•
Fatigueresistancenotconsumedbyrepetitionsof aparticular
•
Fatigue
resistance
not
consumed
by
repetitions
of
a
particular
wheel load is available for repetitions of other wheel loads
•Above fatigue criteria developed by Portland Cement
A
ssociation (PCA, 1980) are very conservative and can be used
for analysis of bottom-up and top-down cracking
g
ue Behaviour of CC
•With increase in SR, no. of load repetitions to cause cracking
decreases
g
•N value is used for checking the adequacy of pavement slab
bd
ihhi
b
ase
d
on M
i
ner’s
h
ypot
h
es
i
s
•
Fatigueresistancenotconsumedbyrepetitionsof aparticular
•
Fatigue
resistance
not
consumed
by
repetitions
of
a
particular
wheel load is available for repetitions of other wheel loads
•Above fatigue criteria developed by Portland Cement
A
ssociation (PCA, 1980) are very conservative and can be used
for analysis of bottom-up and top-down cracking
Fati
g
ue Behaviour of CC
•New fatigue model for CC pavement was developed by American
Concrete Pavement Association
g
•This model is same as PCA model for a reliability of 90%
{
}
217.0
24.10
log
⎤
⎡
−
−
R
SR
{
}
10
10
0112 .0
log
log
⎥
⎦
⎤
⎢ ⎣⎡
−
=
R
SR
N
r
r
N
r
is fatigue life at load level r
SR
r
is stress ratio at load level r = (stress caused at load level r/ modulus of rupture) R is reliabilit
y
taken as 0.90 for 90% reliabilit
y
where 10% of CC
yy
slab is expected to undergo fatigue cracking at the end of design
period
g
ue Behaviour of CC
•New fatigue model for CC pavement was developed by American
Concrete Pavement Association
g
•This model is same as PCA model for a reliability of 90%
{
}
217.0
24.10
log
⎤
⎡
−
−
R
SR
{
}
10
10
0112 .0
log
log
⎥
⎦
⎤
⎢ ⎣⎡
−
=
R
SR
N
r
r
N
r
is fatigue life at load level r
SR
r
is stress ratio at load level r = (stress caused at load level r/ modulus of rupture) R is reliabilit
y
taken as 0.90 for 90% reliabilit
y
where 10% of CC
yy
slab is expected to undergo fatigue cracking at the end of design
period
Fati
g
ue Behaviour of CC
Reliabilityvaluesfordifferentcategoriesof roads:
g
Reliability
values
for
different
categories
of
roads:
•
V
illage roads: 60%
•District roads: 70%
•State highways: 80%
•
Nationalhighways:
90%
National
highways:
90%
•Expressways: 90%
g
ue Behaviour of CC
Reliabilityvaluesfordifferentcategoriesof roads:
g
Reliability
values
for
different
categories
of
roads:
•
V
illage roads: 60%
•District roads: 70%
•State highways: 80%
•
Nationalhighways:
90%
National
highways:
90%
•Expressways: 90%
Critical Stress Condition
•Severest combination of various factors that induce max.
stress in the CC slab is the critical stress condition
•Flexural stress due to combined action of wheel loads and
tem
p
erature differentia
l
b
et
w
een to
p
an
d
b
ottom faces of CC
p
bw p db
slab is considered for design of pavement thickness
•
Effectof moistureisoppositetothatof temperature
andis
•
Effect
of
moisture
is
opposite
to
that
of
temperature
and
is
not considered critical
bbd
•Flexural stress at
b
ottom face of the CC sla
b
is maximum
d
uring
day time when axle loads act at the middle of the CC slab when
temperaturegradientispositiveandleadstobottom
upcracking
temperature
gradient
is
positive
and
leads
to
bottom
-
up
cracking
(BUC)
•Severest combination of various factors that induce max.
stress in the CC slab is the critical stress condition
•Flexural stress due to combined action of wheel loads and
tem
p
erature differentia
l
b
et
w
een to
p
an
d
b
ottom faces of CC
p
bw p db
slab is considered for design of pavement thickness
•
Effectof moistureisoppositetothatof temperature
andis
•
Effect
of
moisture
is
opposite
to
that
of
temperature
and
is
not considered critical
bbd
•Flexural stress at
b
ottom face of the CC sla
b
is maximum
d
uring
day time when axle loads act at the middle of the CC slab when
temperaturegradientispositiveandleadstobottom
upcracking
temperature
gradient
is
positive
and
leads
to
bottom
-
up
cracking
(BUC)
Critical Stress Condition
Day time →positive temperature gradient →axle load acting at the
centre of slab →maximum flexural stress at bottom face of cement
concreteslab
→
bottom
upcracking
concrete
slab
→
bottom
-
up
cracking
Day time →positive temperature gradient →axle load acting at the
centre of slab →maximum flexural stress at bottom face of cement
concreteslab
→
bottom
upcracking
concrete
slab
→
bottom
-
up
cracking
Critical Stress Condition
Placement of axles for maximum edge flexural stress at bottom
of slab without tied concrete shoulders
Stresscausedbysingleaxle>tandemaxle>tridemaxle Stress
caused
by
single
axle
>
tandem
axle
>
tridem
axle
Max. stress occurs at same locations for tied concrete shoulders
Placement of axles for maximum edge flexural stress at bottom
of slab without tied concrete shoulders
Stresscausedbysingleaxle>tandemaxle>tridemaxle Stress
caused
by
single
axle
>
tandem
axle
>
tridem
axle
Max. stress occurs at same locations for tied concrete shoulders
Critical Stress Condition
Ni h i
→
idi
→
lld i l
Ni
g
h
t t
ime
→
negat
ive temperature gra
di
ent
→
ax
le
loa
d
act
ing c
lose
to transverse joints →maximum flexural stress at top face of the
cementconcreteslab
→
top
-
downcracking(TDC)
cement
concrete
slab
→
top
down
cracking
(TDC)
Ni h i
→
idi
→
lld i l
Ni
g
h
t t
ime
→
negat
ive temperature gra
di
ent
→
ax
le
loa
d
act
ing c
lose
to transverse joints →maximum flexural stress at top face of the
cementconcreteslab
→
top
-
downcracking(TDC)
cement
concrete
slab
→
top
down
cracking
(TDC)
Critical Stress Condition
Different axle load positions causing tensile stress at top face of
the CC slab with tied concrete shoulder
Built-in permanent curl induced during CC slab curing further aggravatestheproblem aggravates
the
problem
Different axle load positions causing tensile stress at top face of
the CC slab with tied concrete shoulder
Built-in permanent curl induced during CC slab curing further aggravatestheproblem aggravates
the
problem
Calculation of Flexural Stress
•For an axle load of 200 kN and ∆T = 0 °C with tied CC
shoulder, flexural stress decrease with increase in k-values for all
thicknesses
•For an axle load of 200 kN and ∆T = 0 °C with tied CC
shoulder, flexural stress decrease with increase in k-values for all
thicknesses
Calculation of Flexural Stress
•For an axle load of 200 kN and ∆T = 17 °C with tied CC
shoulder, warping stresses are higher for thicker slabs and results
in higher flexural stresses in slabs for higher k-
v
alues while
flexural stresses are lower for higher k-values for thinner slabs
No effect of k-value on flexural stress (
h = 270 mm
)
() Increasing k-value does not help in thickness design due to higher curling stresses caused by a stiffer support
•For an axle load of 200 kN and ∆T = 17 °C with tied CC
shoulder, warping stresses are higher for thicker slabs and results
in higher flexural stresses in slabs for higher k-
v
alues while
flexural stresses are lower for higher k-values for thinner slabs
No effect of k-value on flexural stress (
h = 270 mm
)
() Increasing k-value does not help in thickness design due to higher curling stresses caused by a stiffer support
Calculation of Flexural Stress
•For BUC, combination of load and nonlinear positive
temperature differentialis considered
•For TDC, combination of load and linear temperature
differentia
l
is consi
d
ere
d
dd
•In BUC case, single axle load causes largest edge stress followed
bytandemandtridemaxles by
tandem
and
tridem
axles
•Tridem axles are not considered for BUC analysisbecause of
dd bd
the lower flexural stresses in
d
uce
d
in CC sla
b
s
d
ue to these axles
•In TDC case, onl
y
one axle of sin
g
le/tandem/tridem axle units is
yg
considered for analysis in combination with front axle
•
Frontaxleloadisassumedtobe50%of weightof oneaxle Front
axle
load
is
assumed
to
be
50%
of
weight
of
one
axle
of the rear axle unit (single/tandem/tridem) for analysis
•For BUC, combination of load and nonlinear positive
temperature differentialis considered
•For TDC, combination of load and linear temperature
differentia
l
is consi
d
ere
d
dd
•In BUC case, single axle load causes largest edge stress followed
bytandemandtridemaxles by
tandem
and
tridem
axles
•Tridem axles are not considered for BUC analysisbecause of
dd bd
the lower flexural stresses in
d
uce
d
in CC sla
b
s
d
ue to these axles
•In TDC case, onl
y
one axle of sin
g
le/tandem/tridem axle units is
yg
considered for analysis in combination with front axle
•
Frontaxleloadisassumedtobe50%of weightof oneaxle Front
axle
load
is
assumed
to
be
50%
of
weight
of
one
axle
of the rear axle unit (single/tandem/tridem) for analysis
Calculation of Flexural Stress
Following cases are considered for the analysis:
•
Bottom
-
upcracking
Bottom
up
cracking
oPavement with tied concrete shoulders for single rear axle oPavement without concrete shoulders for single rear axle
oPavement with tied concrete shoulders for tandem rear axle
oPavement without concrete shoulders for tandem rear axle
•
Top
-
downcracking
Top
-
down
cracking
oPavements with and without dowel bars having front
(steering)axlewithsingletyresandthefirstaxleof therear (steering)
axle
with
single
tyres
and
the
first
axle
of
the
rear
axle unit (single/tandem/tridem) placed on the same panel
Following cases are considered for the analysis:
•
Bottom
-
upcracking
Bottom
up
cracking
oPavement with tied concrete shoulders for single rear axle oPavement without concrete shoulders for single rear axle
oPavement with tied concrete shoulders for tandem rear axle
oPavement without concrete shoulders for tandem rear axle
•
Top
-
downcracking
Top
-
down
cracking
oPavements with and without dowel bars having front
(steering)axlewithsingletyresandthefirstaxleof therear (steering)
axle
with
single
tyres
and
the
first
axle
of
the
rear
axle unit (single/tandem/tridem) placed on the same panel
Calculation of Flexural Stress
•For heavy traffic conditions, dowel bars are provided across
transverse joints for load transfer
•Tied concrete shoulders are necessary for high volume roads •Tied concrete shoulders and dowel bars are not warranted for
traffic volumes less than 450 CVPD
•Terminal load transfer efficiency (LTE) for dowelled
transverse joints is taken as 50% for stress computation
•Terminal LTE for tied joints between the slab and concrete
shoulder is taken as 40% for stress com
p
utation
p
•MEPDG recommends LTE of 60% and 50% respectively for
dowelledandtiedjoints dowelled
and
tied
joints
•For heavy traffic conditions, dowel bars are provided across
transverse joints for load transfer
•Tied concrete shoulders are necessary for high volume roads •Tied concrete shoulders and dowel bars are not warranted for
traffic volumes less than 450 CVPD
•Terminal load transfer efficiency (LTE) for dowelled
transverse joints is taken as 50% for stress computation
•Terminal LTE for tied joints between the slab and concrete
shoulder is taken as 40% for stress com
p
utation
p
•MEPDG recommends LTE of 60% and 50% respectively for
dowelledandtiedjoints dowelled
and
tied
joints
Calculation of Flexural Stress
•Considering a slab size as 3.5 m x 4.5 m, charts are available to
compute flexural stresses for combinations of (i) slab thickness,
(ii) modulus of subgrade reaction, (iii) axle load, (iv) axle type (single, tandem), (v) temperature differential, (vi) with and
ith tti d t h ld
with
ou
t
ti
e
d
concre
t
e s
h
ou
ld
er
•Linear interpolation is permitted between the charts
•Regression equations are available for computation of flexural
stresses for BUC and TDC cases
•Single regression equation for TDC case, and separate regression
equationsforBUCcasefordifferentpavementtypesand equations
for
BUC
case
for
different
pavement
types
and
foundation strengths
P d lfil il bl l ihIRC582015
•
P
rogramme
d
exce
l fil
e ava
il
a
bl
e a
long w
it
h
IRC
:58
:2015
•Considering a slab size as 3.5 m x 4.5 m, charts are available to
compute flexural stresses for combinations of (i) slab thickness,
(ii) modulus of subgrade reaction, (iii) axle load, (iv) axle type (single, tandem), (v) temperature differential, (vi) with and
ith tti d t h ld
with
ou
t
ti
e
d
concre
t
e s
h
ou
ld
er
•Linear interpolation is permitted between the charts
•Regression equations are available for computation of flexural
stresses for BUC and TDC cases
•Single regression equation for TDC case, and separate regression
equationsforBUCcasefordifferentpavementtypesand equations
for
BUC
case
for
different
pavement
types
and
foundation strengths
P d lfil il bl l ihIRC582015
•
P
rogramme
d
exce
l fil
e ava
il
a
bl
e a
long w
it
h
IRC
:58
:2015
Re
g
ression E
q
uations for Flexural Stress
BUC Case (single axle with tied concrete shoulder):
gq
g
ression E
q
uations for Flexural Stress
BUC Case (single axle with tied concrete shoulder):
gq
Re
g
ression E
q
uations for Flexural Stress
BUC Case (single axle without tied concrete shoulder):
gq
g
ression E
q
uations for Flexural Stress
BUC Case (single axle without tied concrete shoulder):
gq
Re
g
ression E
q
uations for Flexural Stress
BUC Case (tandem axle with tied concrete shoulder):
gq
g
ression E
q
uations for Flexural Stress
BUC Case (tandem axle with tied concrete shoulder):
gq
Re
g
ression E
q
uations for Flexural Stress
BUC Case (tandem axle without tied concrete shoulder):
gq
g
ression E
q
uations for Flexural Stress
BUC Case (tandem axle without tied concrete shoulder):
gq
Re
g
ression E
q
uations for Flexural Stress
TDC Case:
gq
g
ression E
q
uations for Flexural Stress
TDC Case:
gq
Re
g
ression E
q
uations for Flexural Stress
gq
g
ression E
q
uations for Flexural Stress
gq
Cumulative Fati
g
ue Dama
g
e
(
CFD
)
:
•Pavement should be checked for cumulative bottom-up and top-
down fatigue damage.
gg()
•For BUC analysis, flexural stress at the edge due to the combined
action of single or tandem rear axle load and positive temperature
differential cycles is considered and determined from either
stress charts or regression equations .
•For TDC analysis, flexural stre ss due to axle loads and negative
differential can be determined from equation.
•CC slab undergoes fatigue damage through crack growth induced
by repeated cycles of loading.
•Cumulative fatigue damage caused to the slab during its service
life should be equal to or less than one.
g
ue Dama
g
e
(
CFD
)
:
•Pavement should be checked for cumulative bottom-up and top-
down fatigue damage.
gg()
•For BUC analysis, flexural stress at the edge due to the combined
action of single or tandem rear axle load and positive temperature
differential cycles is considered and determined from either
stress charts or regression equations .
•For TDC analysis, flexural stre ss due to axle loads and negative
differential can be determined from equation.
•CC slab undergoes fatigue damage through crack growth induced
by repeated cycles of loading.
•Cumulative fatigue damage caused to the slab during its service
life should be equal to or less than one.
Cumulative Fati
g
ue Dama
g
e
(
CFD
)
:
gg()
g
ue Dama
g
e
(
CFD
)
:
gg()
Desi
g
n Criterion:
•If CFD (BUC) + CFD (TDC) ≤1, pavement will be safe from
cracking
g
•Pavement is deemed to have failed if sum of cumulative damages
is greater than 1
•In India, 6 h traffic for fatigue analysis for day and night hours
may not be valid for all regions
•Designers are recommended to carry out hourly or 2 hourly
fatigue damage analysis for all 24 h to examine pavement safety
MlldidCC dilkihih
•
M
any we
ll
d
es
igne
d
CC
pavements
di
sp
lay crac
k
s w
it
hi
n a s
h
ort
period of 5 years due to loss of support caused by permanent
deformationanderosionof GSBandsubgradeinpresenceof deformation
and
erosion
of
GSB
and
subgrade
in
presence
of
water and heavy loads, locked dowel bars, shrinkage cracks etc
rather than fati
g
ue cracks caused b
y
structural deficienc
y
gy y
g
n Criterion:
•If CFD (BUC) + CFD (TDC) ≤1, pavement will be safe from
cracking
g
•Pavement is deemed to have failed if sum of cumulative damages
is greater than 1
•In India, 6 h traffic for fatigue analysis for day and night hours
may not be valid for all regions
•Designers are recommended to carry out hourly or 2 hourly
fatigue damage analysis for all 24 h to examine pavement safety
MlldidCC dilkihih
•
M
any we
ll
d
es
igne
d
CC
pavements
di
sp
lay crac
k
s w
it
hi
n a s
h
ort
period of 5 years due to loss of support caused by permanent
deformationanderosionof GSBandsubgradeinpresenceof deformation
and
erosion
of
GSB
and
subgrade
in
presence
of
water and heavy loads, locked dowel bars, shrinkage cracks etc
rather than fati
g
ue cracks caused b
y
structural deficienc
y
gy y
Erosion Consideration:
•Important mode of failure in rigid pavements.
•
Erosioniscausedbytandemandmulti
-
axlevehiclesandsingle
Erosion
is
caused
by
tandem
and
multi
axle
vehicles
and
single
axles are responsible for fatigue cracking of slabs.
•
Tandem,tridem,andmulti
-
axlevehiclesformalargepercentage
Tandem,
tridem,
and
multi
axle
vehicles
form
a
large
percentage
of total CVs on Highways in India.
•
ErosiondataisnotavailableinIndiaanditisverymuchessential Erosion
data
is
not
available
in
India
and
it
is
very
much
essential
to collect this data for revision of future guidelines.
•
Erosionoccurswhenuntreatedsub
-
baseandsubgradematerials
Erosion
occurs
when
untreated
sub
base
and
subgrade
materials
are used.
•
Erosiondependsonqualityof subgrade sub
-
base climatic
Erosion
depends
on
quality
of
subgrade
,
sub
base
,
climatic
conditions, and gross weight of the vehicles.
•
GPRorFWDcanindicateextentof voidsbelowDLClayer GPR
or
FWD
can
indicate
extent
of
voids
below
DLC
layer
•Important mode of failure in rigid pavements.
•
Erosioniscausedbytandemandmulti
-
axlevehiclesandsingle
Erosion
is
caused
by
tandem
and
multi
axle
vehicles
and
single
axles are responsible for fatigue cracking of slabs.
•
Tandem,tridem,andmulti
-
axlevehiclesformalargepercentage
Tandem,
tridem,
and
multi
axle
vehicles
form
a
large
percentage
of total CVs on Highways in India.
•
ErosiondataisnotavailableinIndiaanditisverymuchessential Erosion
data
is
not
available
in
India
and
it
is
very
much
essential
to collect this data for revision of future guidelines.
•
Erosionoccurswhenuntreatedsub
-
baseandsubgradematerials
Erosion
occurs
when
untreated
sub
base
and
subgrade
materials
are used.
•
Erosiondependsonqualityof subgrade sub
-
base climatic
Erosion
depends
on
quality
of
subgrade
,
sub
base
,
climatic
conditions, and gross weight of the vehicles.
•
GPRorFWDcanindicateextentof voidsbelowDLClayer GPR
or
FWD
can
indicate
extent
of
voids
below
DLC
layer
Draina
g
e La
y
er:
•New pavements are impermeable but with passage of time,
joints, median and cracks allow water to infiltrate into pavement
gy
•Entrapped water (due to infiltration of moisture or thawing in
snow bound areas) in the unbound layers causes erosion of the
foundation material because pore water pressure caused by tandem and tridem axle loads is substantially high Pdflidhddidl
•
P
avement
d
e
fl
ect
ion
d
ue to
h
eavy tan
d
em an
d
tr
id
em ax
les can
be up to 1.0 mm and results in formation of voids spaces below
CCslabduetopermanentdeformationof foundationmaterial CC
slab
due
to
permanent
deformation
of
foundation
material
•Essential to provide a drainage layer together with a filter/
se
p
aration la
y
er beneath the sub-base throu
g
hout the road width
py
g
•Filter/separation layer prevents fines from pumping up from
sub
g
rade to the draina
g
e la
y
er
ggy
g
e La
y
er:
•New pavements are impermeable but with passage of time,
joints, median and cracks allow water to infiltrate into pavement
gy
•Entrapped water (due to infiltration of moisture or thawing in
snow bound areas) in the unbound layers causes erosion of the
foundation material because pore water pressure caused by tandem and tridem axle loads is substantially high Pdflidhddidl
•
P
avement
d
e
fl
ect
ion
d
ue to
h
eavy tan
d
em an
d
tr
id
em ax
les can
be up to 1.0 mm and results in formation of voids spaces below
CCslabduetopermanentdeformationof foundationmaterial CC
slab
due
to
permanent
deformation
of
foundation
material
•Essential to provide a drainage layer together with a filter/
se
p
aration la
y
er beneath the sub-base throu
g
hout the road width
py
g
•Filter/separation layer prevents fines from pumping up from
sub
g
rade to the draina
g
e la
y
er
ggy
Draina
g
e La
y
er:
•Amount of water infiltrating into the pavement should be
assessed and a drainage layer having required permeability need
gy
to be designed
•Min. permeability of ≥300 m/day is recommended •Drainage layer is very crucial for highways in areas having annual
rainfall ≥1000 mm
•Drainage layer can be treated with 2 to 2.5% bitumen/cement or
2.5 to 3% bitumen emulsion to obtain a stable platform to permit
movementof constructiontrafficwithoutanydisplacementor movement
of
construction
traffic
without
any
displacement
or
shoving of open graded aggregates
•
If granularlayersarenotrequiredbecauseof highsubgrade If
granular
layers
are
not
required
because
of
high
subgrade
strength, geosynthetics can be used for separation and drainage
w
ith reduced thickness of
g
ranular la
y
er over sub
g
rade
gy g
g
e La
y
er:
•Amount of water infiltrating into the pavement should be
assessed and a drainage layer having required permeability need
gy
to be designed
•Min. permeability of ≥300 m/day is recommended •Drainage layer is very crucial for highways in areas having annual
rainfall ≥1000 mm
•Drainage layer can be treated with 2 to 2.5% bitumen/cement or
2.5 to 3% bitumen emulsion to obtain a stable platform to permit
movementof constructiontrafficwithoutanydisplacementor movement
of
construction
traffic
without
any
displacement
or
shoving of open graded aggregates
•
If granularlayersarenotrequiredbecauseof highsubgrade If
granular
layers
are
not
required
because
of
high
subgrade
strength, geosynthetics can be used for separation and drainage
w
ith reduced thickness of
g
ranular la
y
er over sub
g
rade
gy g
Draina
g
e La
y
er:
•Laboratory tests on GSB gradations shown in MORTH (2013)
resulted in permeability less than 12 m/day (considered poor for
gy
drainage layer)
•Drainage layer shall have good permeability and stability •However, more permeable materials will have low stability
•
Properbalanceof permeabilityandstabilityisdesirable Proper
balance
of
permeability
and
stability
is
desirable
•Stabilization is necessary for stability of open graded aggregates
Cidifdili d
•
C
onservat
ive
d
es
ign
f
or
d
ra
inage
layer
is necessary to guar
d
against pavement failure observed in India within 5 years of
constructionduetodeformationinGSBandsubgradedueto construction
due
to
deformation
in
GSB
and
subgrade
due
to
heavy loads and moisture
•
VariousgradationsareinuseinUSAfordrainagelayer Various
gradations
are
in
use
in
USA
for
drainage
layer
g
e La
y
er:
•Laboratory tests on GSB gradations shown in MORTH (2013)
resulted in permeability less than 12 m/day (considered poor for
gy
drainage layer)
•Drainage layer shall have good permeability and stability •However, more permeable materials will have low stability
•
Properbalanceof permeabilityandstabilityisdesirable Proper
balance
of
permeability
and
stability
is
desirable
•Stabilization is necessary for stability of open graded aggregates
Cidifdili d
•
C
onservat
ive
d
es
ign
f
or
d
ra
inage
layer
is necessary to guar
d
against pavement failure observed in India within 5 years of
constructionduetodeformationinGSBandsubgradedueto construction
due
to
deformation
in
GSB
and
subgrade
due
to
heavy loads and moisture
•
VariousgradationsareinuseinUSAfordrainagelayer Various
gradations
are
in
use
in
USA
for
drainage
layer
Draina
g
e La
y
er:
•In US, CC slab is directly laid over cement treated drainage layer
known as permeable base where stability of drainage layer is
gy
crucial for good performance of pavemen
t
•Open graded cement treated permeable base is also required to
allow the construction traffic
•In India, DLC layer bears the construction traffic and also
provides a strong support to CC slab
•Grading 4, 6, 7 (see Table in next slide) containing higher fines
can be used without stabilization and can provide a good balance
between permeability and stability
•For other gradations (1, 2, 3, 5, 8), stabilization is necessary to
impart stability
g
e La
y
er:
•In US, CC slab is directly laid over cement treated drainage layer
known as permeable base where stability of drainage layer is
gy
crucial for good performance of pavemen
t
•Open graded cement treated permeable base is also required to
allow the construction traffic
•In India, DLC layer bears the construction traffic and also
provides a strong support to CC slab
•Grading 4, 6, 7 (see Table in next slide) containing higher fines
can be used without stabilization and can provide a good balance
between permeability and stability
•For other gradations (1, 2, 3, 5, 8), stabilization is necessary to
impart stability
Draina
g
e La
y
er:
gy
Sieve
size, mm
AASHTO57
cement/
bitumen
California
bitumen
treated
Wisconsin
cement
treated
New Jersey
bitumen
treated
Virginia
cement
treated
AASHTO93
grading
45and6
bitumen
treated
treated
treated
treated
treated
4
,
5
,
and
6
(unstabilized)
12345678
37.5 100 - - - - - - -
25.4 95-100 100 100 100 100 - - -
19 5
-
96
-
100
90
-
100
95
-
100
-
100
100
100
19
.5
96
100
90
100
95
100
100
100
100
12.5 25-60 35-65 - 85-100 25-60 81.5 79.5 75
9.5 - 20-45 20-55 60-90 - 72.5 69.5 63
4.75 0-10 0-10 0-10 15-25 0-10 49 43.5 32
2.36 0-5 0-5 0-5 2-10 0-5 29.5 22 5.8
1.18 - - - - - 16 5 0
0.3 - - - - - 0 0 0
0 075
0
2
0
2
0
5
2
5
0
0
0
0
.075
0
-
2
0
-
2
0
-
5
2
-
5
-
0
0
0
Permeability,
m/day
6600 5000 3000 300 3000 350 850 950
g
e La
y
er:
gy
Sieve
size, mm
AASHTO57
cement/
bitumen
California
bitumen
treated
Wisconsin
cement
treated
New Jersey
bitumen
treated
Virginia
cement
treated
AASHTO93
grading
45and6
bitumen
treated
treated
treated
treated
treated
4
,
5
,
and
6
(unstabilized)
12345678
37.5 100 - - - - - - -
25.4 95-100 100 100 100 100 - - -
19 5
-
96
-
100
90
-
100
95
-
100
-
100
100
100
19
.5
96
100
90
100
95
100
100
100
100
12.5 25-60 35-65 - 85-100 25-60 81.5 79.5 75
9.5 - 20-45 20-55 60-90 - 72.5 69.5 63
4.75 0-10 0-10 0-10 15-25 0-10 49 43.5 32
2.36 0-5 0-5 0-5 2-10 0-5 29.5 22 5.8
1.18 - - - - - 16 5 0
0.3 - - - - - 0 0 0
0 075
0
2
0
2
0
5
2
5
0
0
0
0
.075
0
-
2
0
-
2
0
-
5
2
-
5
-
0
0
0
Permeability,
m/day
6600 5000 3000 300 3000 350 850 950
Draina
g
e La
y
er:
•Aggregates used in highly permeable drainage layers are
predominantly coarser than 4.75 mm
gy
•Filter/separation layer placed above subgrade must prevent
intermixing of subgrade soil and drainage layer (refer to IRC:37)
•Effect of bitumen treatment on permeability (cement treatment
will have similar effect):
Aggregate
size, mm
Permeability, m/day
Untreated
T
reated with 2% bitumen
38 to 25.4 mm 46000 40000
20 to 9.5 mm 33000 31600
4.75 to 2.36 mm 2600 2000
g
e La
y
er:
•Aggregates used in highly permeable drainage layers are
predominantly coarser than 4.75 mm
gy
•Filter/separation layer placed above subgrade must prevent
intermixing of subgrade soil and drainage layer (refer to IRC:37)
•Effect of bitumen treatment on permeability (cement treatment
will have similar effect):
Aggregate
size, mm
Permeability, m/day
Untreated
T
reated with 2% bitumen
38 to 25.4 mm 46000 40000
20 to 9.5 mm 33000 31600
4.75 to 2.36 mm 2600 2000
Draina
g
e La
y
er:
•It may not always be possible to determine permeability of
drainage layer
gy
•Permeability of a drainage layer depends on effective aggregate
size (D
10
) and uniformity coefficient (C
u
)
•C
u
= D
60
/D
10
; D
60
is sieve size through which 60% passes; C
u
is
an indicator of the spread of particle sizes between 10 and 60%
•Greater the value of D
10
, greater is the permeability
•
D
10
>2mmisadoptedforhighlypermeableaggregates
D
10
>
2
mm
is
adopted
for
highly
permeable
aggregates
•C
u
= 1 for single size aggregates
C
40f d d d
•
C
u
=
40
f
or
d
ense gra
d
e
d
aggregates
•Lower the value of C
u
, greater is the permeability (lower
bili !)
sta
bili
ty
!)
g
e La
y
er:
•It may not always be possible to determine permeability of
drainage layer
gy
•Permeability of a drainage layer depends on effective aggregate
size (D
10
) and uniformity coefficient (C
u
)
•C
u
= D
60
/D
10
; D
60
is sieve size through which 60% passes; C
u
is
an indicator of the spread of particle sizes between 10 and 60%
•Greater the value of D
10
, greater is the permeability
•
D
10
>2mmisadoptedforhighlypermeableaggregates
D
10
>
2
mm
is
adopted
for
highly
permeable
aggregates
•C
u
= 1 for single size aggregates
C
40f d d d
•
C
u
=
40
f
or
d
ense gra
d
e
d
aggregates
•Lower the value of C
u
, greater is the permeability (lower
bili !)
sta
bili
ty
!)
Draina
g
e La
y
er:
•C
u
should be between 2 and 8 for a good drainage layer
•
If C
<
4,drainagelayerhashighpermeabilitybutlayerwouldbe gy
If
C
u
4,
drainage
layer
has
high
permeability
but
layer
would
be
unstable which must be stabilized with either cement or bitumen
for heavy traffic pavements
•L.A. abrasion value of aggregates used for drainage layer must be
less than 40% to limit degradation during compaction.
•Thickness of drainage layer will depend on permeability and
quantity of water infiltrating into the pavement
•Duration of rainfall is critical instead of rainfall intensity for
infiltration of water into the pavement
•Infiltration rate (I
c
) through joints or cracks is 0.223 m
3
/day/m
and can be used for design of the drainage layer
g
e La
y
er:
•C
u
should be between 2 and 8 for a good drainage layer
•
If C
<
4,drainagelayerhashighpermeabilitybutlayerwouldbe gy
If
C
u
4,
drainage
layer
has
high
permeability
but
layer
would
be
unstable which must be stabilized with either cement or bitumen
for heavy traffic pavements
•L.A. abrasion value of aggregates used for drainage layer must be
less than 40% to limit degradation during compaction.
•Thickness of drainage layer will depend on permeability and
quantity of water infiltrating into the pavement
•Duration of rainfall is critical instead of rainfall intensity for
infiltration of water into the pavement
•Infiltration rate (I
c
) through joints or cracks is 0.223 m
3
/day/m
and can be used for design of the drainage layer
Draina
g
e La
y
er:
•Permeability shall be selected such that total outflow capacity of
the drainage layer is greater than the inflow of rainwater into the
gy
pavemen
t
•
Infiltrationrateperunitarea(q
):
•
Infiltration
rate
per
unit
area
(q
i):
g
e La
y
er:
•Permeability shall be selected such that total outflow capacity of
the drainage layer is greater than the inflow of rainwater into the
gy
pavemen
t
•
Infiltrationrateperunitarea(q
):
•
Infiltration
rate
per
unit
area
(q
i):
Draina
g
e La
y
er:
•Water entering into the pavement from earthen median can
damage the pavement if care is not taken to prevent entry of
gy
w
ater along with fines into the drainage layer
•
Usageof filterornonwovengeotextilelayercanminimize
•
Usage
of
filter
or
nonwoven
geotextile
layer
can
minimize
choking of drainage layer with soils entering into the drainage
la
y
er near the median
y
•Exposed drainage layer along embankment slope shall not be
r d ith rth p i ll hil r tif in r i n f id
cove
r
e
d
w
ith
ea
rth
es
p
ec
ia
ll
y w
hil
e
r
ec
tif
y
in
g e
r
os
io
n
o
f
s
id
e
slopes after rain
•Blockage of a drainage layer may cause a much serious problem
than with no drainage layer
g
e La
y
er:
•Water entering into the pavement from earthen median can
damage the pavement if care is not taken to prevent entry of
gy
w
ater along with fines into the drainage layer
•
Usageof filterornonwovengeotextilelayercanminimize
•
Usage
of
filter
or
nonwoven
geotextile
layer
can
minimize
choking of drainage layer with soils entering into the drainage
la
y
er near the median
y
•Exposed drainage layer along embankment slope shall not be
r d ith rth p i ll hil r tif in r i n f id
cove
r
e
d
w
ith
ea
rth
es
p
ec
ia
ll
y w
hil
e
r
ec
tif
y
in
g e
r
os
io
n
o
f
s
id
e
slopes after rain
•Blockage of a drainage layer may cause a much serious problem
than with no drainage layer
Draina
g
e La
y
er:
A four-lane divided CC pavement will be constructed for a high traffic
volume road in an area having an annual rainfall of 1500 mm/year.
gy
The width of each carriageway will be 7.0 m with 2.5 m (1.5 m CC +
1.0 m unpaved) width shoulders will be provided. Transverse joint
p i illb 45 Th hi h h l it di l di t f 3%
s
p
ac
ing w
ill
b
e
4
.5
m.
Th
e
hi
g
h
way
h
as a
long
it
u
di
na
l gra
di
en
t
o
f
3%
and a camber of 2.5%. Side slopes of embankment are 2:1 (horizontal
:vertical).Thepavementhasa300mmthickCCslabplacedover150 : vertical).
The
pavement
has
a
300
mm
thick
CC
slab
placed
over
150
mm thick DLC layer. Estimate the requirement of permeability of the
drainage layer material to be used if the layer thickness is 150 mm.
•Combined thickness of slab & DLC layer = 300+150 = 450 mm
•
DrainagelayerwillbeprovidedbelowDLClayeratadepthof Drainage
layer
will
be
provided
below
DLC
layer
at
a
depth
of
450 mm from the pavement surface
•
Drainagelayerwillbeextendedtofullwidthof embankment Drainage
layer
will
be
extended
to
full
width
of
embankment
g
e La
y
er:
A four-lane divided CC pavement will be constructed for a high traffic
volume road in an area having an annual rainfall of 1500 mm/year.
gy
The width of each carriageway will be 7.0 m with 2.5 m (1.5 m CC +
1.0 m unpaved) width shoulders will be provided. Transverse joint
p i illb 45 Th hi h h l it di l di t f 3%
s
p
ac
ing w
ill
b
e
4
.5
m.
Th
e
hi
g
h
way
h
as a
long
it
u
di
na
l gra
di
en
t
o
f
3%
and a camber of 2.5%. Side slopes of embankment are 2:1 (horizontal
:vertical).Thepavementhasa300mmthickCCslabplacedover150 : vertical).
The
pavement
has
a
300
mm
thick
CC
slab
placed
over
150
mm thick DLC layer. Estimate the requirement of permeability of the
drainage layer material to be used if the layer thickness is 150 mm.
•Combined thickness of slab & DLC layer = 300+150 = 450 mm
•
DrainagelayerwillbeprovidedbelowDLClayeratadepthof Drainage
layer
will
be
provided
below
DLC
layer
at
a
depth
of
450 mm from the pavement surface
•
Drainagelayerwillbeextendedtofullwidthof embankment Drainage
layer
will
be
extended
to
full
width
of
embankment
Draina
g
e La
y
er:
•Width of drainage layer = 7 m (pavement) + 2.5 m (shoulder) +
2 x 0.45 m = 10.4 m.
gy
•Direction of flow of water along AD (diagonal)
•AB = 10.4 m; AC = 10.4x(0.03/0.025) = 12.48 m; AD = 16.24 m
•Drop of elevation along AC = 12.48 x 0.03 = 0.374 m
•Dro
p
of elevation alon
g
CD = 10.4 x 0.025 = 0.26 m
pg
g
e La
y
er:
•Width of drainage layer = 7 m (pavement) + 2.5 m (shoulder) +
2 x 0.45 m = 10.4 m.
gy
•Direction of flow of water along AD (diagonal)
•AB = 10.4 m; AC = 10.4x(0.03/0.025) = 12.48 m; AD = 16.24 m
•Drop of elevation along AC = 12.48 x 0.03 = 0.374 m
•Dro
p
of elevation alon
g
CD = 10.4 x 0.025 = 0.26 m
pg
Draina
g
e La
y
er:
Drop of elevation along AD = 0.374 + 0.260 = 0.634 m
Gradient alon
g
AD = I = dro
p
alon
g
AD
/
len
g
th of AD =
gy
gpg/g
0.634/16.24 = 0.039
I
c
= crack infiltration rate = 0.223 m
3
/day/m
N
c
= no. of longitudinal joints/cracks = 3 (one joint between lanes +
one joint between lane and shoulder + one joint between paved
shoulder and edge)
W
p
= width of pavement subjected. to infiltration = 7 + 2.5 = 9.5 m W
c
= length of transverse cracks or
joints = 7 + 1.5 = 8.5 m
C
s
= spacing of transverse joints = 4.5 m
K
p
= rate of infiltration through un-cracked pavement surface = 0
q
i
= rate of infiltration of water into pavement = 0.115 m
3
/day/m
2
g
e La
y
er:
Drop of elevation along AD = 0.374 + 0.260 = 0.634 m
Gradient alon
g
AD = I = dro
p
alon
g
AD
/
len
g
th of AD =
gy
gpg/g
0.634/16.24 = 0.039
I
c
= crack infiltration rate = 0.223 m
3
/day/m
N
c
= no. of longitudinal joints/cracks = 3 (one joint between lanes +
one joint between lane and shoulder + one joint between paved
shoulder and edge)
W
p
= width of pavement subjected. to infiltration = 7 + 2.5 = 9.5 m W
c
= length of transverse cracks or
joints = 7 + 1.5 = 8.5 m
C
s
= spacing of transverse joints = 4.5 m
K
p
= rate of infiltration through un-cracked pavement surface = 0
q
i
= rate of infiltration of water into pavement = 0.115 m
3
/day/m
2
Draina
g
e La
y
er:
Amount of water infiltrated per metre length flowing along the path
AD of the drainage layer = 16.24 x 0.115 = 1.868 m
3
/day/m
gy
Rate of flow through drainage layer, Q = KIA I = 0.039; KA = Q/I = 1.868/0.039 = 47.89 A1015015
2
(i150dil)
A
=
1
x
0
.15
=
0
.15
m
2
(
assum
ing
150
mm
d
ra
inage
layer
)
K
=
requiredcoefficientof permeability
=
47.89/0.15
=
319m/day
K
required
coefficient
of
permeability
47.89/0.15
319
m/day
If thickness of drainage layer is 300 mm, K4789/030160/d K
=
47
.89/0
.30
=
160
m
/d
a
y
g
e La
y
er:
Amount of water infiltrated per metre length flowing along the path
AD of the drainage layer = 16.24 x 0.115 = 1.868 m
3
/day/m
gy
Rate of flow through drainage layer, Q = KIA I = 0.039; KA = Q/I = 1.868/0.039 = 47.89 A1015015
2
(i150dil)
A
=
1
x
0
.15
=
0
.15
m
2
(
assum
ing
150
mm
d
ra
inage
layer
)
K
=
requiredcoefficientof permeability
=
47.89/0.15
=
319m/day
K
required
coefficient
of
permeability
47.89/0.15
319
m/day
If thickness of drainage layer is 300 mm, K4789/030160/d K
=
47
.89/0
.30
=
160
m
/d
a
y
Tied Concrete Shoulder and
•Used to
p
rotect the ed
g
e of hi
g
h volume hi
g
hwa
y
p
avements
Widened Outer Lane:
pgggyp
•Outer lanes of CC pavements are widened by 0.5 to 0.6 mfor
2-lane 2-way roads to reduce flexural stresses in the wheel path
•Widened outer lane functions as a monolithic CC shoulder
reduces edge flexural stress by 20 to 30%
Rlidi f hik
•
R
esu
l
ts
i
n re
d
uct
i
on o
f
pavement t
hi
c
k
ness
•Total quantity of CC remains nearly the same as that without
shoulder shoulder
•Rough texture to the widened portions improves safety of
v
ehicles es
p
eciall
y
durin
g
ni
g
ht hours
py gg
•Thickness of CC slab with widened outer lane and tied CC
shoulder are nearly the same
•Used to
p
rotect the ed
g
e of hi
g
h volume hi
g
hwa
y
p
avements
Widened Outer Lane:
pgggyp
•Outer lanes of CC pavements are widened by 0.5 to 0.6 mfor
2-lane 2-way roads to reduce flexural stresses in the wheel path
•Widened outer lane functions as a monolithic CC shoulder
reduces edge flexural stress by 20 to 30%
Rlidi f hik
•
R
esu
l
ts
i
n re
d
uct
i
on o
f
pavement t
hi
c
k
ness
•Total quantity of CC remains nearly the same as that without
shoulder shoulder
•Rough texture to the widened portions improves safety of
v
ehicles es
p
eciall
y
durin
g
ni
g
ht hours
py gg
•Thickness of CC slab with widened outer lane and tied CC
shoulder are nearly the same
Bonded Ri
g
id Pavement:
•CC pavement laid over a sustained slope on ghat sections may
slip if a debonding layer of polythene membrane is provided
g
between CC slab and DLC layer
•Eliminating polythene separation membrane between CC slab
dDLC b
bl li
li hi i
fb h
an
d
DLC
su
b
-
b
ase
layer resu
lts
in mono
li
t
hi
c act
i
ono
f
b
ot
h
the layers which in turn reduces the pavement thickness
•
DLClayershallbemaderoughwithwirebrushwithin3to6h
•
DLC
layer
shall
be
made
rough
with
wire
brush
within
3
to
6
h
of placement and a bonding agent of water and cement slurry
shall be a
pp
lied over the surface before la
y
in
g
of P
Q
C
pp y g Q
•For monolithic slab, transverse joints shall be made in DLC by
cutting grooves up to 1/3
rd
of its depth at same locations where
transverse
joints are to be provided in PQC layer to prevent
random reflection cracking of PQC layer due to cracks in un-
jointedDLClayer jointed
DLC
layer
g
id Pavement:
•CC pavement laid over a sustained slope on ghat sections may
slip if a debonding layer of polythene membrane is provided
g
between CC slab and DLC layer
•Eliminating polythene separation membrane between CC slab
dDLC b
bl li
li hi i
fb h
an
d
DLC
su
b
-
b
ase
layer resu
lts
in mono
li
t
hi
c act
i
ono
f
b
ot
h
the layers which in turn reduces the pavement thickness
•
DLClayershallbemaderoughwithwirebrushwithin3to6h
•
DLC
layer
shall
be
made
rough
with
wire
brush
within
3
to
6
h
of placement and a bonding agent of water and cement slurry
shall be a
pp
lied over the surface before la
y
in
g
of P
Q
C
pp y g Q
•For monolithic slab, transverse joints shall be made in DLC by
cutting grooves up to 1/3
rd
of its depth at same locations where
transverse
joints are to be provided in PQC layer to prevent
random reflection cracking of PQC layer due to cracks in un-
jointedDLClayer jointed
DLC
layer
Bonded Ri
g
id Pavement:
•7 day compressive strength of DLC layer in bonded rigid
pavement shall not be less than 10 MPa
g
•Method of equivalent flexural stiffness is used for design of
bonded pavement
•GSBof 200 to 250 mm shall be provided below DLC layer for
bonded CC pavement for filtration and drainage and estimate
ff i
k
lfbd
GSB bi i
e
ff
ect
ive
k
-
v
a
lue o
f
su
b
gra
d
e-
GSB
com
bi
nat
ion
•Total slab thickness (h) over GSB layer is determined for given
trafficandotherdesignparameters traffic
and
other
design
parameters
•Part of PQC thickness (h) shall be replaced by 150 mm DLC
suchthatcombinedflexuralstiffnessof pavementslablayer(h
)
such
that
combined
flexural
stiffness
of
pavement
slab
layer
(h
1
)
and DLC layer (h
2
) is ≥PQC slab (h) flexural stiffness over GSB
g
id Pavement:
•7 day compressive strength of DLC layer in bonded rigid
pavement shall not be less than 10 MPa
g
•Method of equivalent flexural stiffness is used for design of
bonded pavement
•GSBof 200 to 250 mm shall be provided below DLC layer for
bonded CC pavement for filtration and drainage and estimate
ff i
k
lfbd
GSB bi i
e
ff
ect
ive
k
-
v
a
lue o
f
su
b
gra
d
e-
GSB
com
bi
nat
ion
•Total slab thickness (h) over GSB layer is determined for given
trafficandotherdesignparameters traffic
and
other
design
parameters
•Part of PQC thickness (h) shall be replaced by 150 mm DLC
suchthatcombinedflexuralstiffnessof pavementslablayer(h
)
such
that
combined
flexural
stiffness
of
pavement
slab
layer
(h
1
)
and DLC layer (h
2
) is ≥PQC slab (h) flexural stiffness over GSB
Bonded Ri
g
id Pavement:
g
•If the design slab thickness over GSB + Subgrade foundation is
“h’, and if it is proposed to provide DLC of thickness ‘h
2
’
bonded to CC slab of thickness ‘h
1
’, then “h
1
” can be obtained
by equating the flexural stiffness of design slab to the
bi d iff f DLCl dCC l b
com
bi
ne
d
st
iff
ness o
f
DLC
l
ayer an
d
CC
s
l
a
b
g
id Pavement:
g
•If the design slab thickness over GSB + Subgrade foundation is
“h’, and if it is proposed to provide DLC of thickness ‘h
2
’
bonded to CC slab of thickness ‘h
1
’, then “h
1
” can be obtained
by equating the flexural stiffness of design slab to the
bi d iff f DLCl dCC l b
com
bi
ne
d
st
iff
ness o
f
DLC
l
ayer an
d
CC
s
l
a
b
Bonded Ri
g
id Pavement:
•Recall the equation discussed in KENSLABS
g
(
)
2 2
5
0
5
0
h
h
h
E
h
+
⎞
⎜⎛
+
•Neutral axis depth:
(
)
2
2 1 2
1
1
5.
0
5.
0
E
h
h
h
E
h
d
⎞
⎜⎛
+
⎠
⎜⎝
+
=
2
1
2
1
h
E
E
h
⎠
⎞
⎜⎝⎛
+
g
id Pavement:
•Recall the equation discussed in KENSLABS
g
(
)
2 2
5
0
5
0
h
h
h
E
h
+
⎞
⎜⎛
+
•Neutral axis depth:
(
)
2
2 1 2
1
1
5.
0
5.
0
E
h
h
h
E
h
d
⎞
⎜⎛
+
⎠
⎜⎝
+
=
2
1
2
1
h
E
E
h
⎠
⎞
⎜⎝⎛
+
Bonded Ri
g
id Pavement:
g
•Flexural stiffness of P
Q
C:
Q
•Flexural stiffness of DLC: •28-day compressive strength of DLC having 7-day compressive
stren
g
th of 10 MPa is 13.6 MPa
g
•E of DLC = 5000(f
ck
)
0.5
= 18439 MPa
•
T
hin
D
L
C
l
aye
r m
ay
c
r
ac
k
due
to
s
hrink
age,
co
n
t
r
act
io
n
&
t
r
a
ffi
c
T D C aye ayc ac duetos age,co t acto &t a c
•Effective E of DLC = 1000f
ck
= 13600 MPa [Reduced E!!!]
•
Poisson
’sratioof DLC
=
0.2
Poissons
ratio
of
DLC
0.2
g
id Pavement:
g
•Flexural stiffness of P
Q
C:
Q
•Flexural stiffness of DLC: •28-day compressive strength of DLC having 7-day compressive
stren
g
th of 10 MPa is 13.6 MPa
g
•E of DLC = 5000(f
ck
)
0.5
= 18439 MPa
•
T
hin
D
L
C
l
aye
r m
ay
c
r
ac
k
due
to
s
hrink
age,
co
n
t
r
act
io
n
&
t
r
a
ffi
c
T D C aye ayc ac duetos age,co t acto &t a c
•Effective E of DLC = 1000f
ck
= 13600 MPa [Reduced E!!!]
•
Poisson
’sratioof DLC
=
0.2
Poissons
ratio
of
DLC
0.2
CC Slab Desi
g
n Procedure:
1)Specify design values for various parameters (n, r, A, lanes, etc.)
2
)
Select trial desi
g
n thickness of CC slab
g
)
g
3)Compute repetition of axle loads of different magnitudes and
categories during design life
4)Find proportion of axle load repetitions operating during day and
night times
5)Estimate axle load repetitions in 6-h period during day time (max.
+∆T is assumed to remain constant during 6-h for BUC analysis)
6)Estimate axle load repetitions in 6-h period during night time
(max. -∆T is taken as half of + ∆T; to take into account
tl
∆
Tf5
°
C
hll
bdddt
∆
Tf TDC
permanen
t
cur
l, -
∆
T
o
f
5
°
C
s
h
a
ll
b
e a
dd
e
d
t
o
∆
T
f
or
TDC
analysis; vehicles with spacing b/w steering axle and first rear axle
<
transversejointspacingshallbeconsideredforTDCanalysis) transverse
joint
spacing
shall
be
considered
for
TDC
analysis)
g
n Procedure:
1)Specify design values for various parameters (n, r, A, lanes, etc.)
2
)
Select trial desi
g
n thickness of CC slab
g
)
g
3)Compute repetition of axle loads of different magnitudes and
categories during design life
4)Find proportion of axle load repetitions operating during day and
night times
5)Estimate axle load repetitions in 6-h period during day time (max.
+∆T is assumed to remain constant during 6-h for BUC analysis)
6)Estimate axle load repetitions in 6-h period during night time
(max. -∆T is taken as half of + ∆T; to take into account
tl
∆
Tf5
°
C
hll
bdddt
∆
Tf TDC
permanen
t
cur
l, -
∆
T
o
f
5
°
C
s
h
a
ll
b
e a
dd
e
d
t
o
∆
T
f
or
TDC
analysis; vehicles with spacing b/w steering axle and first rear axle
<
transversejointspacingshallbeconsideredforTDCanalysis) transverse
joint
spacing
shall
be
considered
for
TDC
analysis)
CC Slab Desi
g
n Procedure:
7)Compute flexural stresses at edge due to single and tandem axle
loads for combined effect of axle loads and + ∆T during day time
g
(determine SR and evaluate CFD for single and tandem loads)
8)Compute flexural stress in the central area of the CC slab with
front axle near to approaching transverse joint and front rear axle
lfllijiih ld
∆
T(d i
c
lose to
f
o
ll
ow
ing
jo
int
in t
h
e same pane
l un
d
er -
∆
T
(d
eterm
ine
SR and evaluate CFD for different axle loads for TDC)
9)Sum of CFD for BUC and TDC shall be less than 1.0
g
n Procedure:
7)Compute flexural stresses at edge due to single and tandem axle
loads for combined effect of axle loads and + ∆T during day time
g
(determine SR and evaluate CFD for single and tandem loads)
8)Compute flexural stress in the central area of the CC slab with
front axle near to approaching transverse joint and front rear axle
lfllijiih ld
∆
T(d i
c
lose to
f
o
ll
ow
ing
jo
int
in t
h
e same pane
l un
d
er -
∆
T
(d
eterm
ine
SR and evaluate CFD for different axle loads for TDC)
9)Sum of CFD for BUC and TDC shall be less than 1.0
Desi
g
n Exam
p
le-1:
A CC pavement is to be designed for a 4-lane divided NH with 2
lanes in each direction in Bihar. Design the pavement for 30 years
gp
w
ith 3.5 m lane width and 4.5 m transverse
joint spacing. It is
expected that the road will carry, in the year of completion
t ti b t3000CVPDi hdi ti A l l d
cons
t
ruc
ti
on, a
b
ou
t
3000
CVPD
in eac
h
di
rec
ti
on.
A
x
le
loa
d
survey
of CVs indicated that the proportion of front single axle, rear single
axle,reartandemaxle,andreartridemaxleare45%,15%,25%,and axle,
rear
tandem
axle,
and
rear
tridem
axle
are
45%,
15%,
25%,
and
15%, respectively. The proportion of CVs with spacing between front
axle and first rear axle less than 4.5 m is 55%. Traffic count indicates
that 60% of CVs travel during night time (6 p.m. to 6 a.m.). The avg.
no. of axles per CV is 2.35 (due to the presence of multi-axle
ehicles) Effecti eCBRof compacteds bgradeis8% DesignaCC
vehicles)
.
Effecti
v
e
CBR
of
compacted
s
u
bgrade
is
8%
.
Design
a
CC
pavement for the following: (i) with tied CC shoulder with doweled
trans
v
erse
joint
, (
ii
)
w
ithout tie
d
CC shoul
d
er an
d
w
ithout
d
o
w
ele
d
vj,()w d ddw dwd
transverse joint, (iii) with widened outer lane, (iv) bonded case.
g
n Exam
p
le-1:
A CC pavement is to be designed for a 4-lane divided NH with 2
lanes in each direction in Bihar. Design the pavement for 30 years
gp
w
ith 3.5 m lane width and 4.5 m transverse
joint spacing. It is
expected that the road will carry, in the year of completion
t ti b t3000CVPDi hdi ti A l l d
cons
t
ruc
ti
on, a
b
ou
t
3000
CVPD
in eac
h
di
rec
ti
on.
A
x
le
loa
d
survey
of CVs indicated that the proportion of front single axle, rear single
axle,reartandemaxle,andreartridemaxleare45%,15%,25%,and axle,
rear
tandem
axle,
and
rear
tridem
axle
are
45%,
15%,
25%,
and
15%, respectively. The proportion of CVs with spacing between front
axle and first rear axle less than 4.5 m is 55%. Traffic count indicates
that 60% of CVs travel during night time (6 p.m. to 6 a.m.). The avg.
no. of axles per CV is 2.35 (due to the presence of multi-axle
ehicles) Effecti eCBRof compacteds bgradeis8% DesignaCC
vehicles)
.
Effecti
v
e
CBR
of
compacted
s
u
bgrade
is
8%
.
Design
a
CC
pavement for the following: (i) with tied CC shoulder with doweled
trans
v
erse
joint
, (
ii
)
w
ithout tie
d
CC shoul
d
er an
d
w
ithout
d
o
w
ele
d
vj,()w d ddw dwd
transverse joint, (iii) with widened outer lane, (iv) bonded case.
Desi
g
n Exam
p
le-1:
gp
Axle Load Spectrum:
g
n Exam
p
le-1:
gp
Axle Load Spectrum:
Desi
g
n Exam
p
le-1:
gp
Typical Cross-section of a CC Pavement:
g
n Exam
p
le-1:
gp
Typical Cross-section of a CC Pavement:
Desi
g
n Exam
p
le-1:
gp
Selection of Modulus of Subgrade Reaction:
•Effective CBR of compacted subgrade = 8%
•Modulus of subgrade reaction = 50.3 MPa/m •Provide 150 mm GSB
•Provide 150 mm DLC sub-base with min. 7-da
y
com
p
ressive
yp
strength of 7 MPa
•
Effectivemodulusof subgradereactionof combinedfoundation
•
Effective
modulus
of
subgrade
reaction
of
combined
foundation
(subgrade + GSB + DLC sub-base) = 285 MPa/m
Pid125
db di l f lh h b CC
•
P
rov
id
e
125
µ
m
d
e
b
on
di
ng
layer o
f
po
lyt
h
ene s
h
eet
b
etween
CC
slab and DLC sub-base
g
n Exam
p
le-1:
gp
Selection of Modulus of Subgrade Reaction:
•Effective CBR of compacted subgrade = 8%
•Modulus of subgrade reaction = 50.3 MPa/m •Provide 150 mm GSB
•Provide 150 mm DLC sub-base with min. 7-da
y
com
p
ressive
yp
strength of 7 MPa
•
Effectivemodulusof subgradereactionof combinedfoundation
•
Effective
modulus
of
subgrade
reaction
of
combined
foundation
(subgrade + GSB + DLC sub-base) = 285 MPa/m
Pid125
db di l f lh h b CC
•
P
rov
id
e
125
µ
m
d
e
b
on
di
ng
layer o
f
po
lyt
h
ene s
h
eet
b
etween
CC
slab and DLC sub-base
Desi
g
n Exam
p
le-1:
gp
Selection of Flexural Strength of CC:
•28-day compressive strength of CC = 40 MPa
•28-day flexural strength of CC = 4.5 MPa •90-day flexural strength of CC = 1.10*4.5 = 4.95 MPa
g
n Exam
p
le-1:
gp
Selection of Flexural Strength of CC:
•28-day compressive strength of CC = 40 MPa
•28-day flexural strength of CC = 4.5 MPa •90-day flexural strength of CC = 1.10*4.5 = 4.95 MPa
Desi
g
n Exam
p
le-1:
gp
Selection of Design Traffic for Fatigue Analysis:
•Design period = 30 years
•Annual growth rate of CVs = 0.075 •Traffic in the predominant direction = 3000 CVPD
•2-
w
a
y
traffic = 2*3000 = 6000 CVPD
y
•Total 2-way traffic during design period is 226,444,692 CVs
()
{
}
()
{
}
075
0
1 075.01 6000 365 1 1 365
30
− + ×
=
− + ×
=
r
r A
C
n
075
.
0
r
g
n Exam
p
le-1:
gp
Selection of Design Traffic for Fatigue Analysis:
•Design period = 30 years
•Annual growth rate of CVs = 0.075 •Traffic in the predominant direction = 3000 CVPD
•2-
w
a
y
traffic = 2*3000 = 6000 CVPD
y
•Total 2-way traffic during design period is 226,444,692 CVs
()
{
}
()
{
}
075
0
1 075.01 6000 365 1 1 365
30
− + ×
=
− + ×
=
r
r A
C
n
075
.
0
r
Desi
g
n Exam
p
le-1:
gp
Selection of Design Traffic for Fatigue Analysis:
•Avg. no. of axles (steering/single/tandem/tridem) per CV is 2.35
•Total 2-way axle load repetitions during design period =
226,444,692
*
2.35
=
532,145,025axles
226,444,692 2.35
532,145,025
axles
•No. of axles in predominant direction (50%) = 266,072,513 •Design traffic (25%) = 66,518,128 •
Nighttime(12
h)designaxlerepetitions(60%)=39910877
•
Night
time
(12
-
h)
design
axle
repetitions
(60%)
=
39
,910
,877
•Day time (12-h) design axle load repetitions (40%) = 26,607,251 •Day time 6-h axle load repetitions (design no. of axle load
repetitions for BUC analysis) = 13,303,626
g
n Exam
p
le-1:
gp
Selection of Design Traffic for Fatigue Analysis:
•Avg. no. of axles (steering/single/tandem/tridem) per CV is 2.35
•Total 2-way axle load repetitions during design period =
226,444,692
*
2.35
=
532,145,025axles
226,444,692 2.35
532,145,025
axles
•No. of axles in predominant direction (50%) = 266,072,513 •Design traffic (25%) = 66,518,128 •
Nighttime(12
h)designaxlerepetitions(60%)=39910877
•
Night
time
(12
-
h)
design
axle
repetitions
(60%)
=
39
,910
,877
•Day time (12-h) design axle load repetitions (40%) = 26,607,251 •Day time 6-h axle load repetitions (design no. of axle load
repetitions for BUC analysis) = 13,303,626
Desi
g
n Exam
p
le-1:
gp
Selection of Design Traffic for Fatigue Analysis:
•Night time 6-h axle load repetitions = 19,955,439
•Proportion of CVs with spacing between front axle and first rear
axle less than transverse joint spacing is 55%)
•Design no. of axle load repetitions (TDC analysis) = 10,975,492
Axle Proportion Category-wise Category-wise
categor
y
of the axle
category
axle repetitions
for BUC analysis
axle repetitions
for TDC analysis
Front
single
045
5986632
4938971
Front
single
0
.45
5
,986
,632
4
,938
,971
Rear single 0.15 1,995,544 1,646,324
Tandem 0.25 3
,325
,906 2
,743
,873
,,
,,
Tridem 0.15 1,995,544 1,646,324
Total 1.00 13,303,626 10,975,492
g
n Exam
p
le-1:
gp
Selection of Design Traffic for Fatigue Analysis:
•Night time 6-h axle load repetitions = 19,955,439
•Proportion of CVs with spacing between front axle and first rear
axle less than transverse joint spacing is 55%)
•Design no. of axle load repetitions (TDC analysis) = 10,975,492
Axle Proportion Category-wise Category-wise
categor
y
of the axle
category
axle repetitions
for BUC analysis
axle repetitions
for TDC analysis
Front
single
045
5986632
4938971
Front
single
0
.45
5
,986
,632
4
,938
,971
Rear single 0.15 1,995,544 1,646,324
Tandem 0.25 3
,325
,906 2
,743
,873
,,
,,
Tridem 0.15 1,995,544 1,646,324
Total 1.00 13,303,626 10,975,492
Desi
g
n Exam
p
le-1:
gp
CFD for BUC and TDC, and Selection of Slab Thickness:
•Effective k-value of foundation = 285 MPa/m
•E of CC = 30,000 MPa •µof CC = 0.15
/
3
•Unit weight of CC = 24 kN
/
m
3
•
Designflexuralstrengthof CC
=
4.95MPa
Design
flexural
strength
of
CC
4.95
MPa
•Max. day-time ∆T in slab for BUC for Bihar = 16.8 °C •Max. night-time ∆T in slab for TDC = (16.8/2) + 5 = 13.4 °C
g
n Exam
p
le-1:
gp
CFD for BUC and TDC, and Selection of Slab Thickness:
•Effective k-value of foundation = 285 MPa/m
•E of CC = 30,000 MPa •µof CC = 0.15
/
3
•Unit weight of CC = 24 kN
/
m
3
•
Designflexuralstrengthof CC
=
4.95MPa
Design
flexural
strength
of
CC
4.95
MPa
•Max. day-time ∆T in slab for BUC for Bihar = 16.8 °C •Max. night-time ∆T in slab for TDC = (16.8/2) + 5 = 13.4 °C
Desi
g
n Exam
p
le-1:
gp
Option-1 (with tied CC shoulder, with dowel bars):
•Trial thickness of slab = 0.28 m
•Radius of relative stiffness = 0.66621 m
•Beta factor in stress equations for doweled transverse joints for
TDC analysis is 0.66
•Fatigue damage for BUC = 0.976 + 0.274 = 0.976
F i d f TDC 0274+0445+0036 0755
•
F
at
igue
d
amage
f
or
TDC
=
0
.274
+
0
.445
+
0
.036
=
0
.755
•CFD for BUC and TDC = 0.976 + 0.755 = 1.731 •
The
trialthicknessof 028mis
notadeq ate
•
The
trial
thickness
of
0
.28
m
is
not
adeq
u
ate
•Increase thickness to 290 mm •
CFDforBUandTDC=0527(OK)
•
CFD
for
BU
and
TDC
=
0
.527
(OK)
•If retexturing is considered in 30 years, thickness of 300 mm will
be ade
q
uate
q
g
n Exam
p
le-1:
gp
Option-1 (with tied CC shoulder, with dowel bars):
•Trial thickness of slab = 0.28 m
•Radius of relative stiffness = 0.66621 m
•Beta factor in stress equations for doweled transverse joints for
TDC analysis is 0.66
•Fatigue damage for BUC = 0.976 + 0.274 = 0.976
F i d f TDC 0274+0445+0036 0755
•
F
at
igue
d
amage
f
or
TDC
=
0
.274
+
0
.445
+
0
.036
=
0
.755
•CFD for BUC and TDC = 0.976 + 0.755 = 1.731 •
The
trialthicknessof 028mis
notadeq ate
•
The
trial
thickness
of
0
.28
m
is
not
adeq
u
ate
•Increase thickness to 290 mm •
CFDforBUandTDC=0527(OK)
•
CFD
for
BU
and
TDC
=
0
.527
(OK)
•If retexturing is considered in 30 years, thickness of 300 mm will
be ade
q
uate
q
Desi
g
n Exam
p
le-1:
gp
Option-2 (without tied CC shoulder, without dowel bars):
•Trial thickness of slab = 0.33 m
•Radius of relative stiffness = 0.75358 m •Beta factor in stress equations for transverse joints without dowel
bars for TDC analysis is 0.90
•Fatigue damage for BUC = 0.935 + 0 = 0.935 •Fatigue damage for TDC = 0.233 + 0.390 + 0.030 = 0.654
C Df C dTDC 0935 0654 5 9
•
C
F
D
f
or BU
C
an
d
TDC
=
0
.935
+
0
.654
= 1.
5
8
9
•
Thetrialthicknessof 0.33mis
notadequate
The
trial
thickness
of
0.33
m
is
not
adequate
•Trial thickness of 340 mm would be adequate
g
n Exam
p
le-1:
gp
Option-2 (without tied CC shoulder, without dowel bars):
•Trial thickness of slab = 0.33 m
•Radius of relative stiffness = 0.75358 m •Beta factor in stress equations for transverse joints without dowel
bars for TDC analysis is 0.90
•Fatigue damage for BUC = 0.935 + 0 = 0.935 •Fatigue damage for TDC = 0.233 + 0.390 + 0.030 = 0.654
C Df C dTDC 0935 0654 5 9
•
C
F
D
f
or BU
C
an
d
TDC
=
0
.935
+
0
.654
= 1.
5
8
9
•
Thetrialthicknessof 0.33mis
notadequate
The
trial
thickness
of
0.33
m
is
not
adequate
•Trial thickness of 340 mm would be adequate
Desi
g
n Exam
p
le-1:
gp
Option-3 (with widened outer lanes):
•
Reductioninflexuralstressduetowideningof outerlaneby05 Reduction
in
flexural
stress
due
to
widening
of
outer
lane
by
0
.5
to 0.6 m is the same as that of providing tied concrete shoulder
•
Thicknessof thepavementissameasthatobtainedforOption
-
1
Thickness
of
the
pavement
is
same
as
that
obtained
for
Option
1
(with tied CC shoulder and with dowel bars)
•
Designthicknessof CCslab
=
0.29
m
Design
thickness
of
CC
slab
0.29
m
g
n Exam
p
le-1:
gp
Option-3 (with widened outer lanes):
•
Reductioninflexuralstressduetowideningof outerlaneby05 Reduction
in
flexural
stress
due
to
widening
of
outer
lane
by
0
.5
to 0.6 m is the same as that of providing tied concrete shoulder
•
Thicknessof thepavementissameasthatobtainedforOption
-
1
Thickness
of
the
pavement
is
same
as
that
obtained
for
Option
1
(with tied CC shoulder and with dowel bars)
•
Designthicknessof CCslab
=
0.29
m
Design
thickness
of
CC
slab
0.29
m
Desi
g
n Exam
p
le-1:
gp
Option-4 (CC slab bonded to DLC):
•Provide 250 mm GSB above the subgrade
•Effective modulus of subgrade reaction of foundation consisting
of subgrade(8%CBR)andGSB=72MPa/m of
subgrade
(8%
CBR)
and
GSB
=
72
MPa/m
•Assuming that doweled transverse joints and tied CC shoulders,
thickness of slab = 0.30 m
•
E
=30000MPa E
=13600MPa
µ
=015and
µ
=020
•
E
1
=
30
,000
MPa
,
E
2
=
13600
MPa
,
µ
1
=
0
.15
,
and
µ
2
=
0
.20
•Provide 150 mm DLC •Depth of neutral axis = 0.16 m
g
n Exam
p
le-1:
gp
Option-4 (CC slab bonded to DLC):
•Provide 250 mm GSB above the subgrade
•Effective modulus of subgrade reaction of foundation consisting
of subgrade(8%CBR)andGSB=72MPa/m of
subgrade
(8%
CBR)
and
GSB
=
72
MPa/m
•Assuming that doweled transverse joints and tied CC shoulders,
thickness of slab = 0.30 m
•
E
=30000MPa E
=13600MPa
µ
=015and
µ
=020
•
E
1
=
30
,000
MPa
,
E
2
=
13600
MPa
,
µ
1
=
0
.15
,
and
µ
2
=
0
.20
•Provide 150 mm DLC •Depth of neutral axis = 0.16 m
Desi
g
n Exam
p
le-1:
gp
Option-4 (CC slab bonded to DLC):
•Assume a trial slab thickness (to be bonded to 0.150 m thick
DLC layer) = 0.235 m
•
Stiffnessof slabtobeplacedoverDLC=4665MN
m
•
Stiffness
of
slab
to
be
placed
over
DLC
=
46
.65
MN
-
m
•Stiffness of DLC layer = 23.28 MN-m •Combined stiffness of CC slab and DLC = 46.65 + 23.28 =
6993MN
m
69
.93
MN
-
m
•Stiffness of the design slab of 0.30 m thickness = 69.06 MN-m •Combined stiffness is greater than the design stiffness
requirement(OK) requirement
(OK)
g
n Exam
p
le-1:
gp
Option-4 (CC slab bonded to DLC):
•Assume a trial slab thickness (to be bonded to 0.150 m thick
DLC layer) = 0.235 m
•
Stiffnessof slabtobeplacedoverDLC=4665MN
m
•
Stiffness
of
slab
to
be
placed
over
DLC
=
46
.65
MN
-
m
•Stiffness of DLC layer = 23.28 MN-m •Combined stiffness of CC slab and DLC = 46.65 + 23.28 =
6993MN
m
69
.93
MN
-
m
•Stiffness of the design slab of 0.30 m thickness = 69.06 MN-m •Combined stiffness is greater than the design stiffness
requirement(OK) requirement
(OK)
Thank You
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