#Sunshine2015 Impact of Vechile Load on Asphaltic Pavement thickness by Kolo s.s. #Akure #NSE

1. IMPACT OF VEHICLE LOAD ON ASPHALTIC PAVEMENT
THICKNESS
by
*Kolo, S. S., **Jimoh Y. A., **Adeleke O. O. and
***Adama A. Y.
*Department of Civil Engineering, Federal University of Technology Minna,
**Department of Civil Engineering, University of Ilorin and
***Civil Engineering Section, Niger State Ministry of Works.
E-Mail: bukysayo123@yahoo.com
GSM No. +2348036879855,
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2. Outline of Presentation
Introduction
Materials and methods
 Results and discussion
 Conclusion.
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3. Introduction:
 Road networking is one of the strategic priorities for
economic, social and political development of every country.
 In Nigeria, roads are constructed without much regard to
standards and design/construction techniques.
 Asphalt is a mixture of mineral aggregates (crushed stones
and gravel) and binder (usually bitumen).
 Asphalt which is a firm and tough substance, is used for
roads, streets, and airport run-ways construction (Roberts et
al., 1996).
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4. Introduction con’t
 The roads are constructed to carry traffic load that is not
beyond the capacity of the road.
 Unfortunately most of these designed roads still failed with
time.
 Some of the failure are tag to increasing axle loads, high tire
pressures and high temperature, among others.
 Many researchers like Huang (1993) & Kennedy et al.,
(1996) have discovered that asphalt settles when it is
trafficked .
 The settlement was also classified into primary, secondary
and tertiary stages (Carpenter, 1993).
 It is also stated by these researchers that, a general 10mm
settlement on asphalt pavement is acceptable.
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5. Why is the Issue on the Paper Important ?
 Despite the efforts of the Federal Ministry of Works (FMW)
and recently Federal Roads Maintenance Agency, (FERMA) to
ensure good performance of the roads in Nigeria , the roads are
still in poor state.
 If this is not looked into, the usual problems of delays, damage
to vehicles, accidents, stress etc resulting from poor roads will
continue.
 It is aimed that the life span of a newly constructed road
pavement can be determined when volume of traffic are
determined and the usage of road can be controlled.
 It is believed that if the roads are in good condition, movement
of goods and services will be easy, cheap, faster and save a lot
of foreign currency
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6. Materials and Methods:
 Selection of materials and equipment used
 Site selection of failed pavement
spots/locations
 Placement of hot mix asphalts on the
selected failed spots of pavement
 Traffic count for estimation of traffic
induced loads
 Weekly monitoring of settlements
 Result and data presentation and analysis.
Engr. S.O. Moses FNSE 6

7. Materials and Methods cont’d:
Materials
 The HMA material used was produced in a laboratory
after observing all necessary standards and procedures.
 This was then placed at the selected road spots of
Minna-Suleja Road, Minna-Kontagora Road and
Minna- Bida Road.
 The equipment used include Survey Instrument,
Levelling Staff (4 metre) (1mm division), Scale Rule,
Brush, Diggers, Shovels and a Pattern Compactor.
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8. Materials and Methods cont’d:
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Plate I: Pothole Patching
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9. 9
Vehicle
Type
Weight
Per Axle
(Ton)
Equivalent
Factor
(E.F) per
Axle
MINNA
-
SULEJA
ROAD
ADT
(No.)
Esa
(millions
Repetition
per day)
Total esa
Per day
(millions
Repetition
per day)
MINNA
- BIDA
ROAD
ADT
(No.)
Esa
(millions
Repetition
per day)
Total esa
Per day
(millions
Repetition
per day)
MINNA -
KOTANGOR
A ROAD ADT
(No.)
Esa
(millions
Repetition
per day)
Total esa
Per day
(millions
Repetition
per day)
Car
0.250,
0.60
0.000033 5346 0.176
12,323
4581 0.151173
20,955
2657 0.0877
7,607
(2axle)
Mini Bus
(2axle) 1.290,
2.390
0.00864 318 2.75 247 2.13408 65 0.5616
Medium
Bus (3axle)
15.350,
14.260,
17.260
45.32 34 1,541 64 2,900 42 1,898.92
Heavy Bus
(4axle)
9.300,
16.170,
14.920,
14.640
66.06 33 2,180 160 10,570 34 2,246.04
Truck
(5axle)
4.730,
17.710,
17.910,
19.430,
18.340
111.68 77 8,599 67 7,483 31 3462.08
Traffic and Axle Load Survey Result
Table 1 is the result of the traffic count conducted on the selected roads.
Table 1: Average daily traffic count and Axle load for all vehicles in one direction
Results and Discussions:
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10. 10
Week
Minna-Suleja Road Minna-Bida Road Minna-Kontagora Road
Settlement
Loading
esa/week Settlement
Loading
esa/week Settlement
Loading
esa/week
1 100.46 86,261 100.46 146,678 100.46 53,249
2 100.44 172,522 100.41 293,356 100.43 106,498
3 100.41 258,783 100.39 440,034 100.41 159,747
4 100.40 345,044 100.38 586,712 100.4 212,996
5 100.39 431,305 100.37 733,390 100.37 266,245
6 100.38 517,566 100.35 880,068 100.37 319,494
7 100.38 603,827 100.35 1,026,746 100.35 372,743
8 100.37 690,088 100.33 1,173,424 100.35 425,992
9 100.36 776,349 100.32 1,320,102 100.34 479,241
10 100.34 862,610 100.32 1,466,780 100.34 532,490
11 100.33 948,871 100.28 1,613,458 100.34 585,739
12 100.32 1,035,132 100.27 1,760,136 100.34 638,988
13 100.30 1,121,393 100.27 1,906,814 100.33 692,237
14 100.30 1,207,654 100.26 2,053,492 100.33 745,486
Settlement Result
Table 2 Shows the results of the settlement pattern obtained in the field. The average
readings of the marked points are presented in Table 2. Also shown in the table is the
axle load per week as calculated in Table 1.
Table 2: Settlement of asphalt on the studied roads

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100.25
100.3
100.35
100.4
100.45
100.5
0 500,000 1,000,000 1,500,000 2,000,000 2,500,000
Thickness(mm)
Loading ESA (kN)
Minna-Kotangora
Road
Minna-Suleja Road
Minna-Bida Road
Figure 1: Road Settlement
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Field Settlement Evaluation
 The road settlement curves in figure 1, show settlement with
increase in traffic loads which is in accordance with the relevant
researches.
 The observed Minna – Suleja Road, Minna – Kontagora Road and
Minna – Bida Road were discovered to have settlement of 16mm,
20mm and 13mm respectively,
 The model equation for pavement settlement was obtained as:
 Y=
where
 Y= Settlement
 x = Axle load
 R2 = 0.967

13. Conclusion/ Recommendation
 It can be concluded that vehicular load on
pavement results to gradual decrease in
pavement thickness either in whole or partial
 With the use of the above equation the lifespan
of a road can be predicted
 It was observed that the more a pavement is
loaded the earlier its fails.
 It is therefore recommended that when a road
is newly constructed it should be monitored to
the failure point and the thickness determined
before and after failure.
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15. 15
Questions??
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