This document summarizes an experimental study on the behaviour and analysis of stress in rigid pavements. It begins with an introduction on rigid pavements and their load carrying capacity. The methodology section outlines the concrete mix designs that will be tested, including conventional concrete and mixes replacing cement with silica fume and steel slag. The literature review summarizes previous studies on the effects of silica fume and pavement boundary depth. The objectives and scope are then provided. The document outlines the materials and experimental works conducted, including tests on flexural strength, modulus of elasticity, Poisson's ratio, bond strength, split tensile strength, coefficient of thermal expansion, and model tests on rigid pavement slabs. The results of these tests are presented

1. EXPERIMENTAL BEHAVIOUR AND
ANALYSIS OF STRESS IN RIGID
PAVEMENT
Presented by
M. VIVEK LOYOLA
09MK14
II ME INFRASTRUCTURE ENGINEERING
Guided by
Mrs.A.THILAGAM.,D.Arch,B.E,M.Plan,M.Sc
ASSOCIATE PROFESSOR IN CIVIL ENGINEERING
DEPARTMENT OF CIVIL ENGINEERING
PSG COLLEGE OF TECHNOLOGY
COIMBATORE .
1

2. INTRODUCTION
Rigid pavements do not flex much under loading like flexible
pavements. They are constructed using cement concrete. In this case,
the load carrying capacity is mainly due to the rigidity and high
modulus of elasticity of the slab (slab action).
H. M. Westergaard is considered the pioneer in providing the
rational treatment of the rigid pavement analysis.
.
2

3. METHODOLOGY
3

4. LITERATURE REVIEW
 Yin - Wen Chan*, Shu - Hsien Chu, EFFECT OF
SILICA FUME ON STEEL FIBER BOND
CHARACTERISTICS IN REACTIVE POWDER
CONCRETE, Cement and Concrete Research 34
(2004) 1167–1172
In this paper, the effect of silica fume on the
bond characteristics of steel fiber in matrix of
Reactive powder concrete (RPC), including bond
strength, pullout energy, etc., are presented. The
experimental results on steel fiber pullout test of
different conditions are reported. Various silica fume
contents ranging from 0% to 40% are used in the mix
proportions. Fiber pullout tests are conducted to
measure the bond characteristics of steel fiber from
RPC matrix.
4

5. It is found that the incorporation of silica fume
can effectively enhance the fiber–matrix interfacial
properties, especially in fiber pullout energy. It is
also concluded that in terms of the bond
characteristics, the optimal silica fume content is
between 20% and 30%, given the conditions of the
experimental program. The microstructural
observation confirms the findings on the interfacial-
toughening mechanism drawn from the fiber pullout
test results
5

6.  M. Khabiri Mohammed and R. Kargaran Bafqi
Mohammed, EFFECT OF PAVEMENT
BOUNDARIES DEPTHS ON THE
STRUCTURAL STRENGTH OF ROADWAY,
journals of applied sciences research, 4(1) : 103 –
109, 2008
Pavement thickness is highly variable in country
roadways. The main objective of pavement engineers is to
insure that these stresses do not exceed the strength of
materials used in different pavement layers. The main
objectives of this study were to examine the effect of pavement
shoulders on the structural strength of highways. The finite
element analysis and the kenlayer computer program were
used in the structural analysis of pavement shoulders. The
analysis indicated that shoulder width would result in a slight
reduction of vertical stresses.
6

7. OBJECTIVE & SCOPE
 To analysis the stresses in the rigid pavement using Westergaard’s & Bradbury's
analysis.
 To determine mechanical property of silica fume concrete.
 To evaluate the life cycle cost of the pavement.
 To conduct model tests on rigid pavement slab using various mixes C0,C1 &
C2.
 To study the increase in flexural and compressive strength of concrete, this
improves the pavement performance.
7

8. ADMIXTURES & ITS PROPERTIES:
Silica fume
It is also known as microsilica, is a byproduct of
the reduction of high-purity quartz with coal in
electric furnaces in the production of silicon and
ferrosilicon alloys.
Silica Fume is also collected as a byproduct in
the production of other silicon alloys such as
ferrochromium, ferromanganese, ferromagnesian,
and calcium silicon.
8

9. Physical Properties of Silica Fume:
 Particle size (typical): < 1 μm
 Bulk density:
 (as-produced): 130 to 430 kg/m3
 (densified): 480 to 720 kg/m3
 Specific gravity: 2.2
9
Silica fume affects both the fresh and hardened
properties of concrete. The effects on concrete are a
result of the physical and chemical properties of silica
fume.

10. Chemical Properties of Silica Fume
 Amorphous
 Silicon dioxide > 85%
 Trace elements depending upon type of fume.
In concrete, cement is replaced with silica fume at 3%.
10

11.  Steel slag is produced as a by-product during the oxidation of steel pellets in an
electric arc furnace.
 This by-product that mainly consists of calcium carbonate is broken down to
smaller sizes to be used as aggregates in asphalt and concrete.
 They are particularly useful in areas where good-quality aggregate is scarce.
11
Steel slag:

12. EXPERIMENTAL WORKSEXPERIMENTAL WORKS
CARRIED OUTCARRIED OUT
12

13. EXPERIMENTAL
MATERIALS
 53 – Grade Portland Cement
 Silica Fume (SF) @ 3%
 Steel slag 50% replacement
for fine aggregate
 Fine Aggregate: Grade II –Sand
 Coarse Aggregate: 20mm
Powder content Aggregate Content
13

14. EXPERIMENTAL WORKS
 Cement concrete mix design (M40 grade) as per IS 10262 -
2009.
 Mix Ratio:
14
Water Cement
Fine
aggregate
Coarse
aggregate
186 450 652.21 1193.84
0.40 1 1.44 2.65

15. 15
TRIAL DESCRIPTION
POWDER
CONTENT
AGGREGATE
CONTENT
W/C
Cement Fine Steel slag Coarse
C0
Conventional
concrete
450
652.21 - 1193.84 186
C1
(Silica fume
&
Steel slag 50%)
SF ( 3%), 13.5
652.21 401.50 596.92 186
Cement (97%) 436.5
C2
(Steel slag 50%)
Cement (100%) 450 652.21 401.50 596.92 186
C3
(Silica fume)
SF ( 3%) 13.5
652.21 - 1193.84 186
Cement (97%) 436.5

16. 16
EXPERIMENTALEXPERIMENTAL
INVESTIGATIONINVESTIGATION

17. TEST ON FLEXURAL STRENGTH
Flexural Strength Of Concrete
Trial Description 7 14 28
C0 conventional 4.97 5.40 8.88
C1 50% Slag + 3% SF 5.30 6.80 8.06
C2 50% Slag 5.58 8.64 8.79
C3 3% SF 5.34 6.08 6.91
17

18. TEST ON MODULUS OF ELASTICITY
18
YOUNG'S MODULUS OF CONCRETE IN MPa
Trial Mix 7 days 14 days 28 days
C0 conventional 18214.41 25600.85 31454.67
C1 50% Slag + 3% SF 22863.05 22205.30 30620.10
C2 50% Slag 23808.05 30642.09 34493.67
C3 3% SF 22846.62 26669.30 32327.43

19. 19
Graph on C2 28days Young’s Modulus of concrete

20. TEST ON POISSON'S RATIO OF
CONCRETE
20
POISSION'S RATIO OF CONCRETE
Trial Description 7days 14days 28days
C0 conventional 0.13 0.17 0.20
C1 50% Slag + 3% SF 0.16 0.16 0.21
C2 50% Sla0g 0.14 0.18 0.27
C3 3% SF 0.15 0.17 0.25

21. TEST ON BOND STRENGTH
BOND STRENGTH OF CONCRETE IN MPa
Trial Description 7 days 14days 28days
C0 Conventional 5.50 6.65 9.14
C1 50% Slag + 3% SF 6.86 7.52 9.84
C2 50% Slag 7.23 8.97 11.28
C3 3% SF 6.07 6.94 10.02
21

22. TEST ON SPLIT TENSILE STRENGTH
SPLIT TENSILE STRENGTH OF CONCRETE IN MPa
Trial Description 7days 14days 28days
C0 conventional 2.01 2.84 3.92
C1 50% Slag + 3% SF 1.70 2.81 3.88
C2 50% Slag 1.52 2.81 3.43
C3 3% SF 1.66 2.84 3.48
22

23. TEST ON COEFFICIENT OF
THERMAL EXPANSION
23
COEFFICIENT OF THERMAL EXPANSION OF CONCRETE X 10-5
Trial Description 7 days 14 days 28 days
C0 conventional 0.475 1.901 3.153
C1 50% Slag + 3% SF 0.261 3.380 4.307
C2 50% Slag 0.188 1.474 -
C3 3% SF 0.020 2.912 4.162

24. MODEL TEST ON RIGID PAVEMENT
 By conducting some model tests on rigid pavements made
of various mixes C0, C1 & C2
 The slab is resisting on sub grade (sand), with the modulus
of subgrade reaction is 5.74 kg/cm3
 The slab of size 0.6m x 0.75m x 0.05m were cast and cured
for 7, 14 & 28days.
 The slab is placed over the wooden box of size 0.8m x 0.8m
x 0.4m filled with sandy soil, that was acting as a sub
grade.
24

25. CBR TEST ON SAND (SUBGRADE)
I conducted test on sand, to determine the modulus of subgrade
reaction.
Trail I:
for CBR2.5 = 10%
for CBR5 = 11.5%
As per IRC : 58 – 2002,
The modulus of subgrade reaction corresponding to
CBR 11.5% = 5.74 kg/cm3
25

26. TEST ON RIGID PAVEMENT SLAB

26

27. For 28days test result for C2 slab
load at failure, P = 2.79 tonnes.
Young’s modulus, E = 34493.67
MPa.
Thickness of slab, h = 50mm.
Poisson's ratio, µ = 0.15.
Corner load stress = 3.96 MPa
27
Failure Pattern
Loading Set up

28. 28
ANALYSIS AND DESIGNANALYSIS AND DESIGN

29. TYPE OF
SLAB DAYS
SIZE OF
SLAB
(M)
LOAD
(CORNER)
AT FAILURE
IN
DIVISIONS
CORNER
LOAD
STRESS
(MPA)
BASE
COURSE
USED AND
TYPE OF
LOAD
C0
7
0.75 X 0.6 X
0.05
25 11250
Sandy soil and
corner load.
14 38 17100
28 62 27900
C1
7
0.75 X 0.6 X
0.05
30 13500
Sandy soil and
corner load.
14 48 21600
28 52 23400
C2
7
0.75 X 0.6 X
0.05
20 9000
Sandy soil and
corner load.
14 45 20250
28 60 27000 29

30. RIGID PAVEMENT DESIGN
The design procedure is explained for mix C2.
INPUT DATA
Design life : 20 years
Commercial vehicles per day : 2000cv
Flexural strength : 8.79 MPa
Modulus of subgrade reaction : 60MN/m3
Modulus of elasticity of concrete : 34493.67MPa
Poisson’s ratio : 0.27
Coefficient of thermal expansion : 0.0000336/c
Tyre pressure : 0.6MPa
Rate of increase of traffic intensity : 7.5%
Spacing of contraction joints : 4.5m
Width of slab : 3.5m
30

31. STEP 1:
The cumulative number of repetitions of axles during the design period may
be computed from the following formula
Cumulative traffic, C = A * 365 * { (1+r)n
– 1} / r
Where
A = initial number of axles per day in the year when the road is operational.
r = annual rate of growth of commercial traffic.
n = design period in years.
Design traffic:
25% of total repetitions of commercial vehicles are expected to use the edge
of the pavement.
STEP 2:
Assuming that midpoint of the axle load class represents the group, the total
repetitions of single axle and tandem axle loads are follows. 31

32. SINGLE AXLE TANDEM AXLE
Load in tonnes Expected repetition Load in tonnes Expected repetition
20 39516 36 15806
18 102740 32 15806
16 395155 28 39516
14 885148 24 126450
12 1722877 20 110643
10 1857229 16 39516
10 less 2426253 16 less 126450
32
STEP 3:
Assume trial thickness, say 24cm
Calculate stress from charts in IRC: 58 – 2002
Calculate fatigue life (N) as follows
N = unlimited for stress ratio < 0.45
N = {4.2577 / (SR – 0.4325) }3.268
, when 0.45 ≤ SR ≤ 0.55
Log10N = (0.9718 – SR ) / 0.0828 , when SR > 0.55

33. Axle load,
al (tonnes)
AL * 1.2
Stress
kg/cm2
(from
charts)
Stress ratio
Expected
repetition
Fatigue life
n
Fatigue life
consumed
1 2 3 4 5 6 5/6
Single axle
20 24 40 0.46 39516 14335235 0.00275
18 21.6 36 0.143 102740 ∞ 0
16 19.2 34 0.390 395155 ∞ 0
Tandem axle
36 43.2 32 0.36 15806 ∞ 0
33

34. 34

35. DESIGN OF TIE BAR
Design of tie bar as per IRC: 58 – 2002
For concrete mix for C2 28days.
INPUT DATA:
Slab thickness = 30cm
Lane width = 3.5m
Coefficient of friction, f = 1.5
Density of concrete = 2400 kg/m3
Allowable tensile stress in deformed bars = 2000 kg/m2
Allowable bond stress in deformed tie bars = 50.3
Diameter of tie bar, d = 12mm.
STEP 1: (Spacing And Length Of Diameter Of Tie Bar)
Area of steel bar per meter width of joint to resist the frictional force at slab
bottom.
As = (b x f x w) / s
= (3.5 x 1.5 x 0.3 x 2400) / 2000
= 1.89 cm2
/m
35

36. Diameter of tie bar is 12mm, the cross sectional area
A = d2
/4
= 1.131 cm2
Perimeter of tie bar, P = d
= 3.769 cm.
Spacing of bars = A/As
= (100 x 1.131) / 1.89
= 59.84 cm
Provide at a spacing of 60 cm c/c
Length of tie bar, L = (2 x S x A) / (B x P)
= (2 x 2000 x 1.131) / ( 50.3 x 3.77)
= 23.85 cm
Increase length by 10cm for loss of bond due to painting and another 5cm for
tolerance in placement. Therefore, the length is
= 23.85 + 10 + 5
= 38.85cm, say 40cm.
36

37. FINITE ELEMENT ANALYSIS:
 It can represent both linear and non-linear
analysis.
 The linear stage, the concrete is assumed to be
isotropic material upto cracking.
 The non-linear stage, the concrete may undergo
plasticity and/or creep.
37

38.  It is used in all types of application to calculate a
field quantity.
 For a stress analysis, it could be displacement
or stress.
 For a thermal analysis, it could be
temperature or heat flux.
 For a fluid flow analysis, it could be velocity
potential.
 FEA is a way getting a numerical solution to a
specific problem.
38

39. ABOUT ANSYS 12 PACKAGE
The ansys id the software package developed
by ANSYS Group Engineering that was used to
perform the finite element analysis in this study.
Inputs:
 The geometrics of the problem.
 Material properties.
 Loading conditions.
 Boundary conditions.
Outputs:
 Load and deflection behaviour.
 Stress and strain behaviour.
 Cracking pattern of the slabs.
39

40. NUMERICAL EXAMPLE:
For concrete mix C2, the Material properties are;
Elastic modulus of concrete = 34493.67 MPa
Poisson’s ratio = 0.27
Size of Slab = 0.60m x 0.75m
Thickness of Pavement Slab = 0.15m
40

41. 41
Fig : Model of Pavement slab with corner loadings.

42. 42Fig : Stress along X direction of the Slab.

43. 43Fig : Stress along Y direction of the Slab.

44. 44Fig : Deformation of the Slab.

45. 45
Fig : Moment of the Slab.

46. 46

47. CONCLUSIONS
 The earlier stage flexural strength is obtained by C2 mix. This leads
to increase the performance of pavement.
 From the various mix replacements, the earlier stage flexural
strength is obtained. This leads to increase the performance of
pavement at various temperature conditions.

 Using experimental results, 3D modeling is created using Ansys 12.
These results are been compared and analyzed.

 Using mat lab program, the rigid pavement design of IRC: 58 –
2002 is to be executed.
47

48. REFERENCES
 F. Tahmasebinia, Investigating Failure Mode In
Concrete Pavements Subjected To Impact Loading,
the indian concrete journal, july 2010.
 Mohammed N.S. Hadi, B.C. Budhinayake, Non-linear
Finite Element Analysis Of Flexible Pavements,
advance in engineering software 34(2008) 657 – 662.
 R. Y. Xiao, T. O’ Flaherty, Finite Element Analysis Of
Tested Concrete Connections, computer and structures
78(2000) 247 – 255.
 Neville A.M, ‘Properties of Concrete’, Prentice Hall, 4th
Edition, Pg: 666, 667,1995.
48

49.  Yin - Wen Chan, Shu - Hsien Chu, Effect Of Silica Fume
On Steel Fiber Bond Characteristics In Reactive
Powder Concrete, Cement and Concrete Research 34 (2004)
1167–1172
 Anonymous., IRC : 58 – 2002, “Guidelines For The Design
Of Plain Jointed Rigid Pavements For Highways” India
Road Congress, New Delhi.
 ACI Committee 226. 1987b. Silica fume in concrete:
Preliminary report. ACI Materials Journal March-April: 158-
66.
 E Kohler, R Alvarado, “Coefficient of Thermal Expansion
of Concrete Pavements”, University of California
Pavement Research Centre, April 2007
49

50. THANK YOUTHANK YOU
50