UNIVERSITY OF GUYANAFaculty of Technology

Department of Civil Engineering

NAME: RIAZ ZALILREG.NO: 10/0933/0102

INTERNAL SUPERVISOR: DR. CHARLES GARRETT

TITLE

Pilot Study into the Use of Mechanistic-Empirical Design Technology for the Design of a Roadway Pavement in Vergenoegen

PRESENTATION OUTLINE Introduction Background Problem Statement Objectives Scope of project Methodology Pavement Design Approach Pavement Response Modeling Pavement Alternatives AASHTO 1993 Design AASHTO 2002 Evaluation Economic Evaluation Pavement Type Selection Pavement Structure Conclusion Recommendations

INTRODUCTION

Purpose of Access Road:1. Facilitate the movement of farmers to and from

the backlands2. Access route to arable farm lands for cultivation 3. Low volume roadwayGeometric Configuration:Length = 3 miles ( km)Width = 22 ft ( m)

BACKGROUND

The Access Road in VergenoegenLook at this road…I ain’t going deh!

BACKGROUNDLocation (6052’24.9’’N and 58021’51.30’’W)

Main Road

Access Road

Access Road

BACKGROUND

Condition (Wet Seasons)

BACKGROUND

Condition (Dry Seasons)

PROBLEM STATEMENT

The statement of problem is to design a new pavement structure for the access road in Vergenoegen that could fulfill all the traffic and environmental conditions while at the same time being an economically viable structure.

OBJECTIVES Quantify and characterize the loadings of the various

vehicles that uses the current facility Investigate and evaluate the potential of suitable pavement

alternatives for a cost effective alternative to accommodate the present and future traffic loads on the road

Evaluate the potential advantages and disadvantages of pavement alternatives

Carry out life cycle cost analysis on the various pavement alternatives to determine the most promising alternative

Design proposal of a suitable access road based on the most promising pavement alternative

LIMITATIONS

Selection is limited to the most feasible alternatives considered

Use of the AASHTO 1993 & AASHTO 2002 Guides for the Design of Pavement structures

Pavement distress is based on cracking and rutting predictions as computed from the pavement responses using the WinJULEA software

METHODOLOGY

1 Inputs

Materials

Traffic loadings

Environmental data

2 Design Alternati

ves

Layer thickness

design

3 Evaluati

on

Technical

Economical

4 Pavemen

t selection

Most feasible

alternative

5 Design Proposal

Site specific

conditions

PAVEMENT DESIGN APPROACHAASHTO 1993 Guide for the Design of Pavement Structures

AASHTO 2002 Guide for the Mechanistic-Empirical Design of Pavement Structures

PAVEMENT RESPONSE MODELING

PAVEMENT ALTERNATIVES

Alternative 1 Flexible PavementAlternative 2 Semi Rigid PavementAlternative 3 Cement Treated Pavement

AASHTO 1993 DESIGN

Design Traffic (Overall 18kips ESALs)

Graph Showing the Cumulative 18kips ESALs Over the 20 year Design Life

0 5 10 15 200

20000

40000

60000

80000

100000

120000

140000

160000

Cumulative 18kips ESAL

Time(years)

18kips ESAL

136, 584

AASHTO 1993 DESIGN

Design Traffic for 20 YearsW18 = DDxDLxW18

DD = 50% (0.5) DL = 100% (1)W18 = 136,584.6342 [18kips ESALs]

Therefore,W18 = 0.5 x 1 x 136, 584.6342 18kips ESALsW18 = 68, 293 [18kips ESAL]

AASHTO 1993 Design

Pavement Material PropertiesMaterial Function CBR (%) Modulus (psi) Structural Layer

Coefficient (Correlated from AASHTO 93 )

Hot Mix Asphalt Surface Course 400,000 @ 68F 0.43

Crusher Run Base Course 60 0.12

Cement Stabilized Material

Base Course 830,000 @ 7days 0.22

White Sand Subbase Course 6 0.06

In-Situ Soil Subgrade 2 3000

OTHER FACTORS

Design ParametersReliability, R = 75%Standard Deviation, So = 0.45Initial Serviceability, pi = 4.5Terminal Serviceability, pt = 2

DESIGN NOMOGRAPH

Required Structural Number

Design Chart for Flexible Pavements used for Estimating the Structural Number Required

LAYER THICKNESS COMPUTATION

Alternative 1 (Flexible Pavement)

Initial Structural Number 2.3

Layer Thickness Determination

Layer 1 Thickness, D1 (inch) 2

Layer 2 Thickness, D2 (inch) 6

Layer 3 Thickness, D3 (inch) 12

Final Structural Number 2.3

Asphalt Concrete

Crusher Run

Ordinary White Sand

2in

6in

12in

LAYER THICKNESS COMPUTATION

Alternative 2 (Semi Rigid Pavement)

Initial Structural Number 2.3

Layer Thickness Determination

Layer 1 Thickness, D1 (inch) 2

Layer 2 Thickness, D2 (inch) 4

Layer 3 Thickness, D3 (inch) 12

Final Structural Number 2.5

Asphalt ConcreteCement Treated

Base

Ordinary White Sand

2in

4in

12in

LAYER THICKNESS COMPUTATION

Alternative 3 (Cement Treated Pavement)

Initial Structural Number 2.3

Layer Thickness Determination

Layer 1 Thickness, D1 (inch) 1

Layer 2 Thickness, D2 (inch) 7

Layer 3 Thickness, D3 (inch) 13

Final Structural Number 2.3

Chip SealCement Treated

Base

Ordinary White Sand

1in

7in

13in

AASHTO 2002 EVALUATIONMaterial Function Resilient Modulus

(psi)Poisson’s Ratio

Hot Mix Asphalt Surface Course 400,000 0.25

Crusher Run Base Course 25,715 0.15

Cement Stabilized Material

Base Course 830,000 0.35

White Sand Subbase Course 8,182 0.3

In-Situ Soil Subgrade 3000 0.2

Note:All pavement layers were assumed to be fully bonded together at the

interfaces.

EVALUATION CRITERIATraffic Loadings

9000 lbs9,000 lbs18,000 lbs

Tire Radius = 6inches

Tire Pressure = 75psi

Fully Bonded Conditions

FLEXIBLE PAVEMENT

Bottom Up Cracking (HMA)

0 5 10 15 200

1

2

3

4

5

6

7

8

9

Bottom Up Cracking Prediction vs Time

Time (years)

% of lane area cracked

Chart Showing the % of Lane Area Cracked Over the Design Life for the Flexible Pavement as a Result of Bottom Up Cracking

FLEXIBLE PAVEMENT

Top Down (Longitudinal) Cracking (HMA)

0 5 10 15 200

1000

2000

3000

4000

5000

6000

7000

8000

Longitudional Cracking Prediction vs Time

Time (Years)

Feet/mile

Chart Showing the Length of Longitudinal Cracking of the Flexible Pavement Over the Design Life as a Result of Top Down Cracking

FLEXIBLE PAVEMENT

Rutting (Entire Pavement)

0 5 10 15 200.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

Rutting vs Time

Time(years)

Rutting (in)

Chart Indicating Total Rutting of the Flexible Pavement Over the Design Life

SEMI RIGID PAVEMENT

Bottom Up Cracking (HMA)

0 5 10 15 200

0.00005

0.0001

0.00015

0.0002

0.00025

Bottom Up Cracking vs Time

Time (years)

% of lane cracked

Chart Indicating Predicated % of Lane Area Cracked for the HMA Layer of the Semi Rigid Pavement Over the Design Life as a Result of Bottom Up

Cracking

SEMI RIGID PAVEMENT

Top Down (Longitudinal) Cracking (HMA)

0 5 10 15 200

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

Longitudinal Cracking Vs Time

Time (Years)

Feet/mile

Chart Indicating Predicted Longitudinal Cracking of the HMA Layer for the Semi Rigid Pavement over the Design Life as a Result of Top Down

Cracking

SEMI RIGID PAVEMENT

Rutting (HMA)

0 5 10 15 20

-0.005

2.60208521396521E-18

0.005

0.01

0.015

0.02

Rutting Vs Time

Time (years)

Rutting (in)

Chart Indicating Total Rutting in HMA Layer of the Semi Rigid Pavement Over the Design Life

SEMI RIGID PAVEMENT

Flexural Cracking (CTB)

0 5 10 15 200

200

400

600

800

1000

1200

Fatigue Cracking vs Time

Time(Years)

feet/500ft

Chart Indicating Length of Cracking at the Bottom of the Cement Treated Layer for the Semi Rigid Pavement Over the Design Life as a

Result of Fatigue Cracking

CEMENT TREATED PAVEMENT

Flexural Cracking (CTB)

0 5 10 15 20250

300

350

400

450

500

Fatigue Cracking vs Time

Time(years)

feet/500ft

Chart Indicating Length of cracks at the Bottom of the Cement Treated Layer for the Cement Treated Pavement over the Design Life as a Result

of Fatigue Cracking

ECONOMIC EVALUATIONPavement Alternatives Construction Cost/100m (G$)

Flexible Pavement 4, 601, 600

Semi Rigid Pavement 3, 153, 600

Cement Treated Pavement

1, 661, 400

Cost of Construction for Pavement Alternatives

PAVEMENT TYPE SELECTIONEvaluation

CriteriaConstruction

CostEase of

MaintenanceLife Cycle

CostFailure

potentialLoad

DistributionMoisture

SensitivityTotal

Weight 25 5 30 10 20 10 100Flexible Pavement

10 2 16 2 8 4 42

Semi Rigid Pavement

16 3 20 4 12 5 60

CTB Pavement

22 3.5 28 5 15 8 81.5

Decision Matrix for the Selection of the Most Suitable Pavement Alternative

PAVEMENT STRUCTURE

ROADWAY DESIGN

Subgrade

Shoulder

Chip Seal (1in) Cement

Treated Layer (7in)

White Sand (13in)

CONCLUSION

The pavement alternatives evaluated ranged from flexible, semi rigid to cement treated pavements

Utilization of the AASHTO 2002 Guide for the Design & Evaluation of Pavement Structures

The most viable pavement alternative is the cement treated pavement since it is the most cost effective pavement structure while optimizing the level of service to the road users

RECOMMENDATIONS

Calibration of the empirical models to local conditions to relate predicted distress to actual distress occurrence

The use of the axle load spectra concept instead of the 18kips ESAL concept

Modeling of the environmental conditions on the performance of the pavement structures (temperature & moisture)

Modeling of other distress modes such as reflective cracking

THE ENDTHANK YOU FOR LISTENING!

ANY QUESTIONS?