Rigid Pavement Design - IES Previous Year Questions
11. Consider the following factors:Â
- Period of construction, winter/summer
- Degree of foundation roughness
- Slab thickness
- Reinforced/unreinforced
Which of these factors are considered as per IRC for obtaining the maximum expansion joint spacing in rigid pavements ?
[IES 2002]
- 2, 3 and 4
- 2 and 3
- 1 and 4
- 1, 2 and 3
Explanation:
The spacing of expansion joints in rigid pavements depends on roughness of foundation surface, thickness of pavement slab and period of construction (i.e., summer or winter).
12. Which one of the following criteria is used for obtaining the value of modulus of subgrade reaction from the plate bearing test data ?
[IES 2007]
- Pressure corresponding to the settlement of 1.25 mm.
- Pressure corresponding to a pressure of 1.25 kg/cm2.
- Pressure corresponding to the settlement of 1.50 mm.
- Slope of pressure settlement graph.
Explanation:
Modulus of subgrade reaction is the pressure corresponding to the settlement of 1.25 mm.
13.  Which of the following factors are used for calculating temperature stress at the critical edge region in rigid pavement design ?
- Coefficient of thermal expansion of concrete
- Slab lengthÂ
- Slab width
- Maximum temperature difference between summer and winter
Select the correct answer using the codes given below:
[IES 2007]
- 2, 3 and 4
- 1 and 2 only
- 1 and 3 only
- 1, 2 and 3
Explanation:
The temperature stress at critical edge region, obtained as per Westergaard’s analysis is given by,
σte =
Where,
σte - Temperature stress in edge region
E - Young’s modulus of concrete
α - Coefficient of thermal expansion of concrete
Δt - Maximum temperature difference during the day between top and bottom of the slab
C - Bradbury’s coefficient which depends upon
14.  Radius of relative stiffness of cement concrete pavement does not depend upon which one of the following ?
[IES 2009]
- Wheel load
- Modulus of elasticity of cement concrete
- Poisson’s ratio of concrete
- Modulus of subgrade reaction
Explanation:
The radius of relative stiffness, l = {
Where,
E - Young’s modulus of cement concrete
h - Thickness of cement concrete slab
K - modulus of subgrade reaction
μ - Poisson’s ratio for concrete
15.  Which one of the following methods is used in the design of rigid pavements ?
[IES 2009]
- Group Index method
- Westergaard’s method
- McLeod’s method
- CBR method
Explanation:
Group Index method, McLeod method and CBR method are some of the methods of designing flexible pavements.
16.  For conditions prevailing in India, at which location in a cement concrete pavement will the combined stresses due to traffic wheel load and temperature have to be critically checked during design ?
[IES 2009]
- Corner and interior
- Corner and edge
- Corner, edge and interior
- Corner
Explanation:
The critical combination of stresses are,
- During summer mid-day = load stress + warping stress - frictional stress, at edge region
- During winter mid-day = load stress + warping stress + frictional stress, at edge region
- During mid-night = load stress + warping stress, at corner region
17.  Which one of the following sets of factors is related to the design of thickness rigid pavement by Westergaard method ?
[IES 2009]
- Deflection factor and traffic index
- Swelling index and bulk modulus
- Radius of relative stiffness and modulus of subgrade reaction
- CBR value and stiffness index of soil
Explanation:
The thickness of rigid pavement depends on the stress due to wheel load and the temperature change. The wheel load stress and temperature stress depends on few parameters like concrete properties (Poisson’s ratio, Young’s modulus, coefficient of thermal expansion), modulus of subgrade reaction, radius of relative stiffness, slab dimensions, etc.,
18.  Assertion (A): Dowel bars are provided at expansion joints and sometimes also at contraction joints in cement concrete slabs.
Reason (R): Longitudinal joints in cement concrete pavements are constructed with tie bars.
[IES 2009]
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not a correct explanation of A.
- A is true but R is false.Â
- A is false but R is true.
Explanation:
- Dowel bars are provided along transverse joints in cement concrete slabs.
- Tie bars are provided along the longitudinal joints in cement concrete pavements.
19.  Assertion (A): Tie bars are used in cement concrete slabs across the longitudinal joints.
Reason (R): Tie bars are designed to act as load transfer devices.
[IES 2010]
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not a correct explanation of A.
- A is true but R is false.Â
- A is false but R is true.
Explanation:
- Tie bars are provided along the longitudinal joints in cement concrete pavements.
- Tie bars are not designed for transferring the load between the slabs. These are designed to withstand the tensile stresses. Tie bars are provided to overcome the frictional force between the bottom of the adjoining pavement slab and the soil subgrade.
20.  In a concrete pavement, during summer at and soon after mid-day, the combined stress at the interior of the slab is equal to _____ .
[IES 2011]
- Wheel load stress + temperature warping stress – Subgrade resistant stress
- Wheel load stress – temperature warping stress + Subgrade resistant stress
- Wheel load stress – temperature warping stress – Subgrade resistant stress
- Wheel load stress + temperature warping stress + Subgrade resistant stress
Explanation:
At the interior of concrete pavement, during summer mid-day, the combined stress = load stress + warping stress - frictional stress (subgrade resistant stress)