This thesis assessed the impacts of environmental factors (temperature and moisture) on the performance of flexible pavement along the Tarcha-Omo River highway in Ethiopia. Laboratory and field tests were conducted to analyze the effects of temperature and moisture on pavement materials. Temperature was found to decrease the elastic modulus of asphalt concrete. Moisture content above the optimum level reduced the California Bearing Ratio and resilient modulus of base, sub-base and subgrade materials. Poor drainage was also observed, which could lead to excessive moisture in the pavement structure and cause distresses over time. Recommendations included increasing pavement thickness in high rainfall areas and improving drainage facilities.

1. JIMMA UNIVERSITY
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2. JIMMA UNIVERSITY
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JIMMA INSTITUTE OF TECHNOLOGY
Faculty of Civil and Environmental Engineering
Highway Engineering Chair
MSc Thesis Final presentation
by:
Kebede Haile Folla
Advisors: Dr.Eng. Fikadu Fufa
Engr. Gutema Wakjira

3. 3
TITILE:
ASSESS THE IMPACTS OF ENVIRONMENTAL
FACTORS (TEMPERATURE AND MOISTURE) ON
THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
BY: Kebede Haile Folla
Advisors: Dr.Eng. Fikadu Fufa
Engr. Gutema Wakjira
Highway Engineering Chair

4. Outline of presentation
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1. INTRODUCTION
 Background
 Statement of problem
 Research questions
 Objectives of the study
 Scope and limitation of the study
 Significance of the study
2. METHODOLOGIES OF THE STUDY
3. RESULTS AND DISCUSSION
4. CONCLUSION AND RECOMMENDATION

5. ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND
MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
5
INTRODUCTION
1.1 Research Background
 Environmental factors are known to highly affect the concepts of design, actual
construction and ultimate performance of pavement structures.
 Pavement design depends on the boundary conditions, mainly temperature and
moisture, in addition to heavy loads from vehicles.
 Temperature of AC & water content in the base/sub base and subgrade are the
most critical factors that influence flexible pavement performance (Zuo.Gang,
2003)

6. ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND
MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
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INTRODUCTION
1.2 Statement of the Problem
 For existing pavement rehabilitation design and construction, it is
important to take into account the in-situ material and composite pavement
response relative to environment(Mukabi et al., 2003).
 In Ethiopia the design, construction and maintenance process of roads
mostly give attention to structural thickness of pavement, hence mostly the
concerning bodies focus on future traffic.
 Hence it is important to admit in practical the variation of pavement
material properties due to seasonal environmental changes ( Temperature
and moisture), at post construction time.

7. ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND
MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
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1.3 Research Questions
 What is the impact of temperature on the performance of selected highway
segment?
 What is the impact of moisture on the performance of pavement structure?
 How the drainage system is effective in removing excess water from the
pavement structure in selected highway segment?
`

8. ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND
MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
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1.4 Objectives
1.4.1 General Objective
To Assess the impact of environmental factors
(Temperature and moisture) on performance of
pavement structures

9. ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND
MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
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1.4.2 Specific Objectives
 to investigate the impact of Temperature on the performance of
selected highway pavement structure
 to analyze the impact of moisture on performance of pavement
through laboratory based investigation
 to examine the efficiency of the drainage system in removing the
excess water from the pavement structure for possible mitigation
`

10. ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND
MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
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1.5 Significance of the Study
It addresses the possible measurements to be taken in order
to assure the serviceability of the road and safety for traffic.
It fulfill knowledge gaps ( design &construction) in
Ethiopia.
It helps decision makers and especially the authoring
(ERA), road sector contractors and the design, supervision
firms of the sector.
It gives clue for further researchers.

11. ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND
MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
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1.6 Scope of the Study
This study is geographically limited to Tarcha Town - Omo
River Highway segment which section of B52 in Ethio Road
map
The study was limited on the environmental factors
(Temperature and Moisture) that can affect the performance of
flexible pavement structure.
Effects of heavy vehicles, maintenance practice and frequency
depending on the AADT and material quality are not included
and recommended for further researchers.

12. ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND
MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
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2.METHODOLOGIES OF THE STUDY
2.1 Study Area
 The selected highway segment Tarcha– Omo River is section of
link road described in Ethio road map as B52 that connects
Dawuro zone with its neighboring zones and regions. It links
SNNPR with OROMIA Region.
 Annual rainfall range from 1355.40 to 2565.50 mm and mean
monthly temperature varying from 11.7 to 23.5ºC for the first
study section and 21.56 to 33.12ºC for the second.

13. First section • Second section
ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND
MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
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14. ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE
AND MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
2.2 Study Design
The chart shows the
Overall framework of
methods used for
the study
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15. 15
2.4 Sampling and Testing Procedure
2.4.1. Field observation
ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND
MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY

16. 16
2.4.2. SAMPLE EXTRACTION AND COLLECTION
.
Nine samples were collected from three stations
These are
Base course, sub base and sub grade
ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND
MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY

17. ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND
MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
17
2.4.4. Laboratory tests Conducted
 Particle size distribution
 Modified proctor
 CBR
 Atterberg’s limit
 NMC

18. ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS
(TEMPERATURE AND MOISTURE) ON THE PERFORMANCE OF FLEXIBLE
PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
2.4.5 Study Variables
Independent
Variables
Temperature
Moisture
Side drainage
condition
Dependent Variable
 Performance of
pavement
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19. ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND
MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
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2.4.6. Test methods and Formula used
Test Method
Particle size
distribution
AASHTO T-27
NMC AASHTO T-256
Atterberg’s limit AASHTO T-89
Proctor AASHTO T-180
CBR AASHTO T-193
George,
K.P
&Husai
n 1986

20. ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND
MOISTURE) ON THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
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3.RESULTS AND DISCUSSION
3.1. Temperature impacts on pavement layers
 The impact of temperature variation on flexible
pavement abundantly occurs on the asphalt layer i.e
stiffness of AC and its impact is indirect to the rest of
pavement structures (Ksaibati, 2011 , Taha et al.,
2013, AASHO, 1993)
 The modulus of elasticity (E) determined for section
one was greater than section two whose ambient
temperature is high.

21. RESULTS AND DISCUSSION CONTINUE….
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 For first section
0
5
10
15
20
25
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
Temperature vs Elastic Modulus of asphalt
1st section
E(Mpa) Tasp max.T

22. RESULTS AND DISCUSSION CONTINUE….
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For second section
0
5
10
15
20
25
30
35
40
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Temperature vs Elastic Modulus of asphalt
2nd section
E(Mpa) Tasp max.T

23. RESULTS AND DISCUSSION CONTINUE….
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3.2. Impact of moisture on the performance of
selected highway segment
3.2.1. NMC ( Moisture content)

24. RESULTS AND DISCUSSION CONTINUE….
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Samples with highest NMC above the OMC level showed a
dramatic decline of CBR value and resulted with decreased Mr.
CBR & Mr
The values of Mr determined from CBR is dramatically decreased
for each sample of material in comparison with the existing value.

25. RESULTS AND DISCUSSION CONTINUE….
Existing and predicted CBR vs Mr
Existing Predicted by study
Station Material CBR(%) Mr (Mpa) CBR(%) Mr (Mpa)
89+320
BC 357.41 234.6
SB 128.61 30.29
SG 225.63 97.54
104+540
BC 358.44 316.12
SB 115.17 67.8
SG 189.2 59.4
124+000
BC 302.45 261.47
SB 130.56 128.5
SG 147.98 116.02
25

26. RESULTS AND DISCUSSION CONTINUE….
3.3.Efficiency of the drainage system in removing
the excess water from the pavement structure
Drainage quality is an important parameter which affects the
highway pavement performance
The excessive water content in the pavement base, sub-base, and sub-
grade soils can cause early distress and lead to a structural or
functional failure of pavement.
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27. RESULTS AND DISCUSSION CONTINUE….
27

28. RESULTS AND DISCUSSION CONTINUE….
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Hence, due to environmental factors ( moisture and
Temperature) the distress could be occurred are
Rutting
32%
potholes
12%
Reveling
6%
Edge
cracking
41%
Pumping
6%
Block
cracking
3%
Distresses observed

29. 4 .CONCLUSION AND RECOMMENDATIONS
4.1. Conclusion
 The elastic modulus of AC at section 2 showed decrease
in comparison with section 1 where temperature is less.
Hence, Revelling and Block cracking were observed
distresses. This implies that the temperature has impact
on AC layer.
 OMC<NMC, this implies the moisture content within
pavement materials varies after construction due to
fluctuation in moisture in the area, this could be due to
high rainfall, level of sub surface water below pav’t
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30. Conclusion Continued
 The Mr value dramatically decreased. This could be due
to the increased moisture content cause lubricating effect
causing lower inter-particle forces (BC&SB). Hence, the
decreased Mr value could caused distresses on pavement,
which results shortening of the service life of pav’t
 It has observed that shear strength, measured in CBR is
sensitive to moisture, this in turn resulted decrease in Mr
values of sub grade soil.
 The quality of drainage observed was poor. This could
caused excessive moisture in pavement structure and as
result the pav’t could distressed.
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31. RECOMMENDATIONS
 The pavement layer thickness should be considerably
increased or boulder base and sub base with less fine
materials should be used in cases of highways in areas where
the yearly rain fall >2000 mm and surrounded by agricultural
lands(ERA)
 The thickness of AC layer shall be increased in area where
temperature is high(ERA)
 Excess moisture should be eliminated, and the shoulders
rebuilt with good materials
 Attention should be given to construction of side and cross
drainage structures after preparation of sub grade layer prior
to starting the overlaying pavement layers.
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32. RECOMMENDATIONS…
For Further researchers
 Should be carried out on other factors that cause
variation of moisture or saturation in sub grades soil.
 Ground water and its fluctuation at d/t season
 The Mr value of current study was predicted from CBR
test results of materials. The Mr test alone shall conduct.
Additional test parameters like unconfined compressive
strength; PH value test, volumetric shrinkage, and
mineralogical tests should also be performed to have
more accurate test results
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33. ASSESSMENT OF IMPACTS OF ENVIRONMENTAL FACTORS (TEMPERATURE AND MOISTURE) ON
THE PERFORMANCE OF FLEXIBLE PAVEMENT:
THE CASE OF TARCHA- OMO RIVER HIGHWAY
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