pavement design session 09-12 matakuliah: s0753 – teknik jalan raya tahun: 2009

Pavement DesignSession 09-12

Matakuliah : S0753 – Teknik Jalan RayaTahun : 2009

Bina Nusantara University 3

Contents

• Pavement Classification• Load & Stress Distribution •Load Analysis•Pavement design for Rigid Pavement•Pavement Design for Flexible Pavement•Overlay•Pavement Construction


Pavement Classification

Classification :1.Flexible Pavement2.Rigid Pavement3.Composite


Flexible PavementThose which are surfaced with

bituminous / asphalt materials. These types of pavements are called "flexible" since the total pavement

structure bends or deflects due to traffic loads. A flexible pavement structure is generally composed of several layers of materials which can accommodate this "flexing".


Flexible Pavement


Types of Flexible Pavement

Dense-graded

Open-graded Gap-gradedCEE 320

Steve Muench


Rigid Pavement

Rigid pavements. Those which are surfaced with

portland cement concrete (PCC). These types of pavements are called

"rigid" because they are substantially stiffer than flexible pavements due to PCC's high stiffness.


Rigid Pavement


Types of Rigid Pavement• Jointed Plain Concrete Pavement (JPCP)

CEE 320Steve Muench


Types of Rigid Pavement• Continuously Reinforced Concrete Pavement

(CRCP)

Photo from the Concrete Reinforcing Steel Institute

CEE 320Steve Muench


Rigid Pavement

JOINT


Composite

• Composite. Those which are surfaced with portland cement concrete (PCC) and bituminous /

asphalt materials as overlay construction

Bina Nusantara University 14Flexible Pavement

Load & Stress Distribution



Surface

Base

Subbase

Subgrade

P ( Load )

Flexible Pavement

Bina Nusantara University 16Rigid Pavement



Surface

Subbase or base

Subgrade

P ( Load )

Rigid Pavement



Pavement Design• Several typical methods

– Design catalog– Empirical

• 1993 AASHTO method

– Mechanistic-empirical• New AASHTO method (as yet unreleased)


Design Catalog

Example design catalog from the Washington Asphalt Pavement Association (WAPA) for residential streets


Empirical• 1993 AASHTO Flexible Equation

• 1993 AASHTO Rigid Equation

07.8log32.2

1

109440.0

5.15.4log

20.01log36.9log 10

19.5

10

101810

RoR M

SN

PSI

SNSZW

25.075.0

75.0

10

46.8

7

10

101810

42.1863.215

132.1log32.022.4

1

10624.11

5.15.4log

06.01log35.7log

kE

DJ

DCSp

D

PSI

DSZW

c

dctoR


Terms – Flexible

• W18 (loading)– Predicted number of ESALs over the pavement’s life.

• SN (structural number)– Abstract number expressing structural strength– SN = a1D1 + a2D2m2 + a3D3m3 + …

• ΔPSI (change in present serviceability index)– Change in serviceability index over the useful pavement life– Typically from 1.5 to 3.0

• MR (subgrade resilient modulus)– Typically from 3,000 to 30,000 psi (10,000 psi is pretty good)


Terms – Rigid• D (slab depth)

– Abstract number expressing structural strength– SN = a1D1 + a2D2m2 + a3D3m3 + …

• S’c (PCC modulus of rupture)– A measure of PCC flexural strength– Usually between 600 and 850 psi

• Cd (drainage coefficient)– Relative loss of strength due to drainage characteristics and

the total time it is exposed to near-saturated conditions– Usually taken as 1.0


Terms – Rigid• J (load transfer coefficient)

– Accounts for load transfer efficiency– Lower J-factors = better load transfer– Between 3.8 (undoweled JPCP) and 2.3 (CRCP with tied

shoulders)

• Ec (PCC elastic modulus)– 4,000,000 psi is a good estimate

• k (modulus of subgrade reaction)– Estimates the support of the PCC slab by the underlying layers– Usually between 50 and 1000 psi/inch


Pavement design for Rigid Pavement

The following input variables are needed for the AASHTO rigid pavement design procedure:•¨ 28-day Concrete Modulus of Rupture, psi¨ 28-day •Concrete Elastic Modulus, psi¨ •Effective Modulus of Subbase/Subgrade Reaction, pci¨ •Serviceability Indices •¨ Load Transfer Coefficient •¨ Drainage Coefficient ¨ •Overall Standard Deviation •¨ Reliability, %¨ •Design Traffic, •18-kip Equivalanet Single Axle Load (SEAL).



28-day Concrete Modulus of Rupture, MrThe Mr of concrete is a measure of the flexural strength of the concrete as determined by breaking concrete beam test specimens. A Mr of 620 psi at 28 days should be used with the current statewide specification for concrete pavement design. If the Engineer selects an alternate value for Mr, then it must be documented with an explanation.



28-day Concrete Elastic ModulusElastic modulus of concrete is an indication of

concrete stiffness. It varies depending on the coarse aggregate type used in the concrete. Although the value selected for pavement design could be different from the actual values, the elastic modulus does not have a significant effect on the computed slab thickness. A modulus of 5,000,000 psi should be used for pavement design. The use of a different value must be documented with an explanation.



Effective Modulus of Subbase/Subgrade Reaction: k-valueThe AASHTO guide allows pavement designers to take into account the structural benefits of all layers under the concrete slab. It also allows designers to consider the effect of loss of support of the underlying material due to erosion or deterioration.The slab support is characterized by the

modulus of subgrade/ sub base reaction, otherwise known as the k-value. It can be measured in the field by applying a load equal to 10 psi on the subgrade/subbase combination using a 30-inch diameter steel plate. The k-value is then calculated by dividing 10 psi by the measured deflection (in inches) of the layers under the plate.



Serviceability IndicesFor concrete pavement design, the difference between the initial and terminal serviceability is an important factor. An initial serviceability value of 4.5 and a terminal serviceability value of 2.5 are to be used in the procedure, which results in a difference of 2.0. Different values, if used, must be documented and justified.



Load Transfer CoefficientThe load transfer coefficient is used to

incorporate the effect of dowels, reinforcing steel, tied shoulders, and tied curb and gutter on

reducing the stress in the concrete slab due to traffic loading. The coefficients recommended in the AASHTO Guide were based on findings from the AASHO Road Test.



Drainage CoefficientThe drainage coefficient characterizes the quality of drainage of the sub base layers under the concrete slab. Good draining pavement structures do not give water the chance to saturate the subbase and subgrade; thus, pumping is not as likely to occur.

http://manuals.dot.state.tx.us/dynaweb/colcomun/glo/@ebt-link;cs=default;ts=default;pt=1640?target=IDMATCH(id,sub0004);book=glo;collection=colcomun



Reliability, %The reliability value represents a

"safety factor," with higher reliabilities representing pavement structures with less chance of failure. The AASHTO Guide recommends values ranging from 50% to 99.9%, depending on the functional classification and the location (urban vs. rural) of the roadway. If the Engineer decides to use a different value, then it must be documented and justified


Pavement design for Flexible Pavement

•Determine the desired terminal

serviceability, pt•Convert traffic volumes to number of equivalent 18-kip single axle loads (ESAL)

•Determine the structural number, SN

•Determine the layer coefficients, ai•Solve layer thickness equations for individual layer thickness



Variables included in Nomographs

•Reliability, R•Incorporates a degree of certainty into design process•Ensures various design alternatives will last the analysis period

•Resilient Modulus for Roadbed Soil, MR•Generally obtained from laboratory testing



Variables included in Nomographs

Effective Modulus of Sub-Grade Reaction, kSub-base typeSub-base thicknessLoss of supportDepth to rigid foundation

Drainage Coefficient, mi•Use in layer thickness determination•Applies only to base and sub-base


Flexible Pavement – Construction

CEE 320Steve Muench


Rigid Pavement – Construction

Fixed form

CEE 320Steve Muench


Rigid Pavement – ConstructionSlipform

CEE 320Steve Muench

pavement design session 09-12 matakuliah: s0753 – teknik jalan raya tahun: 2009

Documents

rigid pavement slide

bina nusantara university

rigid pavement pavement

rigid pavement joint

rigid pavement rigid

flexible pavement structure

composite slide

pavement design session