28 Pavement Design (1).ppt

7/24/2019 28 Pavement Design (1).ppt

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Pavement Design

CE 453 Lecture 28



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Objectives

Understand and complete E!Lcalculation

"no# variables involved in and beable to calculate re$uired t%ic&nesso' rigid and 'le(ible pavements



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!!)*O Pavement Design+et%od Considerations

Pavement Per'ormance *ra''ic

,oadbed oil +aterials o' Construction Environment Drainage ,eliabilit- Li'e.C-cle Costs %oulder Design



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*#o Categories o' ,oad#a- Pavements

,igid Pavement /le(ible Pavement

,igid Pavement *-pical !pplications )ig% volume tra''ic lanes /ree#a- to 'ree#a- connections E(it ramps #it% %eav- tra''ic



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!dvantages o' ,igid Pavement

0ood durabilit-

Long service li'e 1it%stand repeated 'looding and

subsur'ace #ater #it%out deterioration



Disadvantages o' ,igid Pavement

+a- lose non.s&id sur'ace #it% time

eeds even sub.grade #it% uni'ormsettling +a- 'ault at transverse joints



Flexible Pavement TypicalApplications

*ra''ic lanes !u(iliar- lanes ,amps Par&ing areas

/rontage roads %oulders



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!dvantages to /le(ible Pavement

!djusts to limited di''erentialsettlement

Easil- repaired !dditional t%ic&ness added an- time on.s&id properties do not deteriorate

uieter and smoot%er *olerates a greater range o'

temperatures



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Disadvantages o' /le(ible Pavement

Loses some 'le(ibilit- and co%esion #it%time

eeds resur'acing sooner t%an PCconcrete

ot normall- c%osen #%ere #ater ise(pected



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Basic AASHTO FlexiblePavement Design Method

Determine t%e desired terminalserviceabilit-9 pt

Convert tra''ic volumes to number o'e$uivalent 78.&ip single a(le loads :E!L;

Determine t%e structural number9

Determine t%e la-er coe''icients9 ai olve la-er t%ic&ness e$uations 'or

individual la-er t%ic&ness



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Basic AASHTO Rigid PavementDesign Method

elect terminal serviceabilit- Determine number o' E!Ls Determine t%e modulus o' sub.grade

reaction Determine t%e slab t%ic&ness



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Vaiables incl!ded in"omogaphs

,eliabilit-9 ,< =ncorporates a degree o' certaint- into

design process< Ensures various design alternatives #ill

last t%e anal-sis period ,esilient +odulus 'or ,oadbed oil9

+,< 0enerall- obtained 'rom laborator-

testing



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Vaiables incl!ded in"omogaphs

E''ective +odulus o' ub.0rade ,eaction9&< Considers>

7? ub.base t-pe2? ub.base t%ic&ness3? Loss o' support4? Dept% to rigid 'oundation

Drainage Coe''icient9 mi< Use in la-er t%ic&ness determination

< !pplies onl- to base and sub.base< ee *ables 2?75 :'le(ible; and 27?6 :rigid;



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/le(ible Pavement Design

Pavement structure is a multi.la-ered elastics-stem9 material is c%aracteri@ed b- certainproperties +odulus o' elasticit- ,esilient modulus Poisson ratio

1%eel load causes stress distribution :'ig 2?2; )ori@ontal> tensile or compressive Aertical> ma(imum are compressive9 decrease #it%

dept% *emperature distribution> a''ects magnitude o'

stresses



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Components

Sub-grade (roadbed) course: natural material thatserves as the foundation of the pavement structure

Sub-base course: above the sub-grade, superior tosub-grade course

Base course: above the sub base, granular materialssuch as crushed stone, crushed or uncrushed slag,gravel, and sand

Surface course: upper course of the road pavement,should withstand tire pressures, resistant to abrasive

forces of traic, provide skid-resistant driving



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Economic !nal-sis

< Di''erent treatments results indi''erent designs

< Evaluate cost o' di''erentalternatives



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ensitivit- !nal-sis

< =nput di''erent values o' tra''icvolume

< Compare resulting di''erences inpavement

< /airl- signi'icant di''erences in !D*

do not -ield e$uall- signi'icantdi''erences in pavement t%ic&ness



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O*)E, =UE

Drainage Boints 0rooving :noise vs? %-droplaning; ,umble strips

Climate Level and t-pe o' usage



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/!=LU,E E!+PLE

Primaril- related to design or li'e.c-cle9 not construction

!ll images 'rom Distress=denti'ication +anual 'or t%e Long. *erm Pavement Per'ormance

Program 9 Publication o? /)1!.,D.3.379 Bune 23



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/!*=0UE C,!C"=0



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,U**=0



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)OA=0



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PU+P=0

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28 Pavement Design (1).ppt