irc flexible pavement design notes

7/25/2019 Irc Flexible Pavement Design Notes

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IRC Design Method for Flexible Pavements

Atul Narayan, S. P.

IIT Madras

September 6, 2015


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Outline

Introduction

Scope

Pavement Analysis

Pavement distress models

Subgrade Properties

Material Properties of Pavement Materials

Traffic

Design Catalogue


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Subordinate learning objectives

To analyze the stress-strain distribution in pavements for given

loading conditions.

To estimate pavement distresses based on stresses and

strains in pavement structure.

To explain the effect of mechanical properties on pavement

behavior and performance.

To analyze the stresses and distresses caused by vehicle

loading.

To estimate the expected volume of traffic in design life.


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Outline

Introduction

Scope

Pavement Analysis


Subgrade Properties


Traffic

Design Catalogue


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Scope

Source: IRC 37


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Scope (cont.)

Source: IRC 37


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Outline

Introduction

Scope

Pavement Analysis


Subgrade Properties


Traffic

Design Catalogue


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Pavement Analysis

Pavements are analyzed through layered elastic analysis.

All assumptions made in Burmisters layer theory are also

used here.

Pavement analysis was conducted using IITPAVE.


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Outline

Introduction

Scope

Pavement Analysis


Subgrade Properties


Traffic

Design Catalogue


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Distress ModelsFatigue:

Nf =2.21 104

3.89t M

0.854R

(for 80% reliability

) (1)

Nf =0.711 104

3.89t M

0.854R (for 90% reliability) (2)

Fatigue life considering effect of binder content and air void content

Nf =

0.5161C

10

4

3.89

t M

0.854

R (3)C =10M (4)

M =4.84 VbVb+Va

0.69 (5)

Rutting:

Nr =4.1656 108

4.5337v (for 80% reliability) (6)

Nf =1.41 108


There are fatigue life equations for cementitious layers as well


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Outline

Introduction

Scope

Pavement Analysis


Subgrade Properties


Traffic

Design Catalogue


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California Bearing Ratio

It is the pressure required to penetrate a standard cylindrical

sample of soil at 1.25 mm/min, expressed as a percentage of

the pressure required for a standard material (usually crushed

rock).

It can be determined in-situ using a Dynamic Cone

Penetrometer (600 cone) test (ASTM D6951-09)

log10 CBR =2.465 1.12 log10 N (8)

whereNis penetration in mm per blow.


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Resilient Modulus from CBR

MR =10CBR, CBR =5 (9)

MR =17.6(CBR)0.64, CBR >5 (10)whereMRis the resilient modulus in MPa.


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Distress ModelsFatigue:

Nf =2.21 104

3.89t M

0.854R

(for 80% reliability

) (11)

Nf =0.711 104

3

.89

t M0

.854

R (for 90% reliability) (12)Fatigue life considering effect of binder content and air void content

Nf =0.5161C 1043.89

t M0.854

R (13)

C =10M (14)

M =4.84 VbVb+Va

0.69 (15)

Rutting:

Nr =4.1656 108


Nf =1.41 108


There are fatigue life equations for cementitious layers as well


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Outline

Introduction

Scope

Pavement Analysis


Subgrade Properties


Traffic

Design Catalogue

S


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Subbase and Base

Granular Bases and Subbases:

MRgsb =0.2h0.45MRsubgrade (18)

Cementitious Granular Subbase:

Ecgsb =1000UCS (19)

whereUCS is the 28-day unconfined compressive strength

Unbound base:

MRgb

=0.2h0.45MRsubgrade

(20)

Poissons ratio of all base and subbase materials can be taken as

0.35

Bi i l


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Bituminous layers

Bituminous layers are classified into bituminous concrete (BC)

and dense bituminous macadam (DBM)

Resilient modulus can be determined by laboratory

experiments

Otherwise, typical values may be taken from the table below


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O tli


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Outline

Introduction

Scope

Pavement Analysis


Subgrade Properties


Traffic

Design Catalogue

Load Eq i alenc Factors


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Load Equivalency Factors

Single axle Singlewheel axle load in kN65

4

(21)

Single axle Dualwheel axle load in kN

80 4

(22)

Tandem axle Dualwheel axle load in kN148

4

(23)

Tridem axle Dualwheel

axle load in kN

224

4

(24)

Vehicle Damage Factors


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Vehicle Damage Factors

It is the same as truck factors used in AASHTO and Asphalt

Institute Design Method

VDF is the equivalent number of standard axles per

commercial vehicle (depends on commercial vehicle)

Sometimes, the average VDF of all commercial vehicles

(considering the volume of each) is also called VDF

VDF must be arrived by conducting axle load surveys

Axle Load Survey


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Axle Load Survey

Indicative VDF Values


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Indicative VDF Values

Design Traffic


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Design Traffic

N =365 (1 + r)n 1r

A D F (25)

where

Nis the cumulative number of standard axles in msa

ris the yearly growth rate of traffic

nis the design life of the pavement

Ais the initial number of Commercial Vehicles Per

Day (CVPD)

D is the Lane distribution factor

F is the average VDF

Lane Distribution Factor


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Lane Distribution Factor

Recomended Values:

Single-lane roads: 100%

Two-lane single carriageway roads: 50% Four-lane single carriageway roads: 40%

Dual carriageway roads: 75% of CVPD in each direction

Outline


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Outline

Introduction

Scope

Pavement Analysis


Subgrade Properties


Traffic

Design Catalogue

Design Charts


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Design ChartsChoice 1: Granular Base and Granular Subbase

Design Charts (cont )


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Design Charts (cont.)Choice 1: Granular Base and Granular Subbase

Design Charts


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Design ChartsChoice 2: Bituminous Pavements with Cemented Base and Cemented Subbase with Crack

Relief Interlayer of Aggregate


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Design Charts


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Design ChartsChoice 3: Cemented Base and Cemented Subbase with SAMI at the Interface of Cemented

Base and the Bituminous Layer

SAMI - Stress Absorbing Membrane Interlayer

Design Charts (cont.)


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g ( )Choice 3: Cemented Base and Cemented Subbase with SAMI at the Interface of Cemented

Base and the Bituminous Layer

Design Charts


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gChoice 4: Foamed Bitumen/Bitumen Emulsion Treated Rap/Aggregates Over Cemented

Subbase



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g ( )Choice 4: Foamed Bitumen/Bitumen Emulsion Treated Rap/Aggregates Over Cemented

Subbase

Design Charts


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gChoice 5: Cemented Base and Granular Subbase with Crack Relief Layer of Aggregate

Interlayer Above the Cemented Base



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Choice 5: Cemented Base and Granular Subbase with Crack Relief Layer of Aggregate

Interlayer Above the Cemented Base

Sample Calculations


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IRC Recommendations


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irc flexible pavement design notes

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