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Eighth Semester B.E. Degree Examina~~7-,~aY/~9,ie'2010Pavement Design '~<~' '; ':'

Note: 1. Answer any FIVE full questions, selecting at leastTwo questions from each part.

2. Use of specified charts and tables ispermitted.

1 ~ What are the types of pavements? Explain each two lines. (OSMarks)-h/ Draw a neat sketch,ofpavement cross section (flexible type) and mention the functions and

importance of each component. (06 Marks)

c. Determinate the thickness of pavement by single layer elastic theory so as to limit thedeflection on subgrade to 5 mm due toi) Wheel load of 50 kN and contact pressure 0.7 N/mm2 due to truck loadingii) Wheel load of 5 kN and contact pressure 5 kN/mm2 due to bullock eart loading. Use

chart in Fig. Ql(c). Assume E of subgrade = 10N/mm2 ; l.l = 0.5. (09 Marks)

FOJ 0... OJ 0.60.10.80.91.0

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lJ,~ 2.0.' 0.25.

INumbers oncurves indicate ria

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2 a., \\fnat are the various climatic factors that effect the design and performance of pavement?Explain briefly. (08 Marks)

b. A dual wheel load assembly has 50 kN load on each wheel with a contact pressure of 0.6 N/mm2.

If the clear gap between the two wheels is 300 mm, using the stress chart determine the verticalstress values at a depth of 0.60 m due to dual wheel loads at stress points 'as follows:i) Vertically below the centre of dual wheel load assemblyji) Vertically below the centre of left wheeliii) At radial distances of 0.60 m and 0.90 m from centre of left wheel towards other wheel.

Use chart in Fig. Q2(b). (12 Marks)

0.1o OJ' OJ.O,.l o.60JIJJ

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4

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curves indicate ,~.r/a

'or --'f I.

r, iL t .

I • •• r 1•Fig. Q2(b)

3 a. Distinguish between Boussinesque's single layer theory and Burmister's two layer theory.(08 Marks)

b. ,A plate lo~ test conducted with 300mm diameter plate on' 3ubgrade and on a pavement ofthickness 400mm sustained pressure of 0.10 N/mm2 and oAo N/mm2 respectively at 5mmdefle<-1ion'

7Desi.gn the paveI¥en~ ~~ction for 50~, whed!)oad and contact pressure of

0.7 N/mrrc foran allowable deflectIOn of 8mm usmg BumiIster's approach. If you want tomaintain the deflection of 6.5mm, what ~hould be the required thickness? Use chart in.Fig. 3(b). .~:-.. (12 Marks)

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Fig. 3 (b)

4 a. Define ESWL. How ESWL is determined for dual wheel load assembly using equal stresscriteriaand equal deflection criteria? Explainbriefly. (08 Marks)

b. Designthe pavement section by triaxial test method using the following data:Wheel load = 50 kN; Tyre pressure = 0.7 N/nun2; Traffic coefficient, x = 1.25; Rainfallcoefficient, y = 0.90; design deflection, ~ = 2.5 nun; E value of -subgrade soil,Es = 10 N/mm2

; E value of base course material, Eb = 40 N/rnm2; E _value of 70 nim thickbitumin~us concrete, surface course = 100N/rnm2• (12 Marks)

5 a. Explainbriefly how the following factors effectdesign of cement conCretepavements :i) Wheel load and its repetitionsii) Subgrade strength and its propertiesiii) Properties of concreteiv) Temperature variations. (08 Marks)

b. - Calculate the warpi~g stresses at interior, edge and comer ror aconctete pavement ofthickness 200 mm with transverse joint at 4.0 m spacing. The width' of slab is 3.7 m. For

,concrete E = 3 X 104N/mm2 and Jl= 0.15, k value for subgrade = 0.06 N/mm3• Temperature

differential is 0.9°C per cm. Assume thermal coefficient of concrete as -10 x 10-6 pero C.Assumeradius ofloaded area as 150 Ill..'l1. Use chart in Fig. Q5(b). (12 Marks).



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Values of Lx / f and Ly if·

6 a.' Explain step by step procedure for design orC.C ..pavement by IRC : 58-2002 for given axleload spectmm. (08 Marks)

b. Design the size and spacing of dowel bars at the expansion joints of C. C pavement ofthickness.2&Q mm with a radius of relative stiffness 900 mm for a wheel load of 60 k.i"l'.Assume: the load capacity of dowel system as 40% of the design wheel load. Joint width is 20

.mm. Permissible shear and flexmal stresses in dowel bars are 100 N/mm2 aIld140 N!mm.2 respectively and permissible bearing stresses in C.C as 10 Nhnm2• (12 M~rks)

7 a. . Briefly explain structural evaluation and functional evaluation of pavements.b. Explain briefly with neat sketches, folloiring type of flexible pavement

.mentioning causes and remedial or maintenance measures.i) Alligator or map crackingii) Pot lwlesiii) Edge ~ackingiv) Reflectio.n cracking.

(OSM~rifailures' 0)

8 Write'shm IJDteson:a. RigicLpavem'el1t failuresb. DesiID1'factOJisfor runway pavementsc. Equivalent. wheel load factor (EWLF)d.. Flexible-pavement design by IRe 3y - 2001.:



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