Pavement Design - Book Spar

Eighth Semester B.E. Degree Examination, June/July 2011 "T

Pavement Design

Note: 1. Allswer FIVEfull questions selectingat least TWO questions from each part.

2. Missing data if any, may suitably be assumed.

1 I-tC Draw a neat sketch of flexible pavement section and show the component parts. Brieflyexplain each component. (06 Marks)

¥/Bring out the points of difference between highway and airport pavements. (06 Marks)e:' Briefly explain the desirable characteristics of the pavement. (08 Marks)

2 a. Explain frost action. What are the measures adopted to reduce its effects? (06 Marks)b. State the assumptions and limitations ofBoussinesq's theory. (06 Marks)c. A plate bearing test conducted with 3D cm diameter plate on sub grade yielded a pressure of

2.26 kg/cm2 at 0.25 cm deflection. The test when conducted on a base course of 22.5 cm,yielded a pressure of 7.53 kg/cm2 at 0.25 cm deflection. Design the pavement section byBurmi.ster's approach for a contact pressure of 8.85 kglcm2 having radius of contact area of15 cm. (Chart enclosed). (08 Marks)

3 a. Write a brief note on "contact pressure". (06 Marks)b. Explain the concept of ESWL. How is it determined graphically for tandem dual wheel

assembly? (06 Marks)c. Calculate the design repetitions for 20 years period for various wheel loads equivalent to

22.68 kN wheel load using the following data on a four-lane load:

Load, kNVol per day

22.68 27.22 31.7530 25 20

4 a. Explain Mcleod method of highway pavement design. (06 Marks)b. Design the flexible pavement by triaxial method using the following data:

E-value of sub grade soil = 100 kg/cm2

E-value of base course = 400 kg/cm2

E-value of8 cm thick bituminous surface = 1000 kg/cm2

Design wheel load = 6000 kgRadius of contact area = 15 cmTraffic coefficient = 1.5Rainfall coefficient = 0.6Design deflection = 0.25 cm (06 Marks)

c. Write the equation recommended by IRC : 37 - 2001 for the computation of design traffic.Explain each term. How are the values obtained?.

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5 a. Explain: i) Radius of relative stiffness; ii) Equivalent radius of resisting sectioniii) Critical load positions. (06 Marks)

b. Write a brief note on "reinforcement in cement concrete pavement". (06 Marks)c. A cement concrete pavement slab of thickness 25 cm is constructed over a granular sub base

having modulus of reaction of 12 kg/cm3. The temperature differential during summer is15°C. The spacing of transverse joints is 4.5 m and that of longitudinal is 3.5 m. The designwheel load is 6000 kg, radius of contact area is 15 cm, E-value of cement concrete is 3 x 105

kg/cm2, Poisson's ratio is 0.25, coefficient of thermal expansion is 10 x 1O-6tC,unit weight

of concrete is 2400 kg/m3 and the frictional coefficient is 1.5. Find the worst combination ofstresses at edge, based on Westergaard's equations. (chart enclosed).

6 a. Explain the design steps for slab thickness of cement concrete pavement, recommended bylRC : 58 - 2002. (06 Marks)

b. Explain the design procedure for tie bar system in concrete pavement. (06 Marks)c. Check the adequacy of dowel bar system for a concrete pavement using the following data:

Slab thicknessJoint widthRadius of relative stiffnessDesign wheel loadPercentage of load transferGrade of concrete to be used

. Diameter of dowel barSpacing of dowelModulus of dowel/concrete interactionE for steel

=33cm=2cm= 103.53 cm= 8000 kg=40=M40=32mm=32cm= 41500 kg/cm2/cm= 2 x 106 kg/cm2

7 a. Explain any six types of flexible pavement failures. (06 Marks).b. Briefly explain the various maintenance works of bituminous surfaces. (06 Marks)c. What is the principle involved in overlay design by Benkelman deflection studies? What

steps are to be carried out in the study after marking deflection observation points?(08 Marks)

8 a. Briefly explain the mud pumping phenomenon in concrete roads. (06 Marks)b. List the methods available for functional evaluation of pavement. Briefly explain anyone

method. (06 Marks)c. What are the factors considered in thickness determination of airport pavement? Briefly

explain LCN method of rigid airport pavement design. (08 Marks)



Pavement Design - Book Spar

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