=
VOLUME: 09, Issue 06, Paper id-IJIERM-IX-VI, December 2022 174
A STUDY ON ROAD PAVEMENTS FAILURE AND THEIR MAINTENANCEPritam Kumar
Department of Civil Engineering, School of Engineering and Technology, K.K. University, Nalanda (Bihar), 803115
Deepak Kumar
Assistant Professor, Department of Civil Engineering, School of Engineering and Technology, K.K. University, Nalanda (Bihar), 803115
Abstract - Generally it is observed that after the opening of newly constructed road or well- maintained or newly widened road which is very good in the terms of level of service. But it is after some time with the use of traffic volume and constantly changing weathers, especially after monsoon or in monsoon the road quality is decorated at every use of traffic and after some time it gets completely decorated with uneven crack, pot holes, ruts, crack etc. This problem is very much common in every road. Hence the quality and level of service is dropped down drastically as the road user increases but maintenance is overlooked.
Pavements fail prematurely because of many factors. There are four primary reasons pavements fail prematurely, Like Failure in design, Failure in construction. Failure in materials, failure in maintenance.
The key to proper maintenance of asphalt pavements is to understand the causes of failures and the action needed for correction before any repair work is done. To make the most of maintenance budgets, proven methods must be used to correct failures and to prevent their recurrence.
According to the Foundation for Pavement Preservation, pavement maintenance involves doing the right treatment at the right place, at the right time. To achieve this, good management and an understanding of the choices are required. The type of traffic plays very important role for the life of pavement. The pavement design should be perfect, precise and with long future vision of expected traffic in coming years. If the pavement is done perfectly as per design than heavy maintenance is reduced & only periodical maintenance occurs.
1 INTRODUCTION
For the development of the economical of a country transportation system takes a special role. By means of good transportation system safe, rapid, comfortable, convenient, communication for people becomes possible and which is essential for distribution of various goods in the country that is the basic important for economical, industrial and environmental. For developing country good highway system is very important to gain the way of modern society. For good highway system various factors of deterioration of the road should be considered. Maintenance of the highway is very important for the whole traffic management. With weak maintenance system of the road various defects in the roads are main causes of accident. So, to be a successful engineer, a person should not only able to design the road, but also skill-ful to maintain the road.
Pavement deterioration process starts directly after opening the road to traffic. This process starts very slowly so that it may not be noticeable, and over
time it accelerates at faster rates. To ensure the risk of premature deterioration is minimized, it is necessary to use the best practice method in planning, design, construction and maintenance of the road. This can be achieved by examining pavements that have failed prematurely, with the focus being on determining the causes of failure so that it can be prevented in the future. The greater understanding of pavement failures that could be gained from detailed investigations could be valuable in reducing the costs associated with pavement failures in the future. In many cases the failure of pavement structure can be directly attributed to inadequate maintenance and ineffective evaluation programs. It is important to find out a method to minimize the maintenance cost under a limited budget. For that purpose it is quite important to consider a simplified method for inspection and evaluation of pavement failures.
Some of the important roles roads in India’s economy are:
=
VOLUME: 09, Issue 06, Paper id-IJIERM-IX-VI, December 2022 175
1. Connection to villages.2. Communication in hilly terrain.
3. Carriers of freight and passengers complementing the railways
4. Helps agricultural development 5. Administrative convenience, etc.
1.1 Types of Highway Construction
Earth road and gravel roads.
Soil stabilized roads.
Water bound macadam (WBM) road.
Bituminous or black-top roads.
Cement concrete roads.
1.2 Types of Pavements:-
From the point of view of structural performance, pavements can be classified as:
Flexible
Rigid
Semi-rigid
Composite
Fig. 1 Pavement Layers 1.3 Design of Flexible Pavements:- In the design of flexible pavements, it has yet not been possible to have a rational design method wherein design process and service behaviour of the pavement can be expressed or predicted theoretically by mathematical laws.
Flexible pavement design methods are accordingly either empirical or semi- empirical. In these methods, the knowledge and experience gained on the behaviour of the pavements in the past are usefully utilized.
There are some various methods used to design of flexible pavement:
Group Index Method
California Bearing Ratio Method
California R Value or Stability meter method
Tri axial test method
McLeod method
Burmister method
1.4 Traffic and Loading:-
There are three different approaches for considering vehicular and traffic characteristics, which affects pavement design.
Fixed traffic:- Thickness of pavement is governed by single load and number of load repetitions is not considered. The heaviest wheel load anticipated is used for design purpose. This is an old method and is rarely used today for pavement design.
Fixed vehicle:- In the fixed vehicle procedure, the thickness is governed by the number of repetitions of a Standard axle load. If the axle loads is not a standard one, then it must be converted to an equivalent axle load by number of repetitions of given axle load and its equivalent axle load factor.
Variable traffic and vehicle:- In this approach, both traffic and vehicle are considered individually, so there is no need to assign an equivalent factor for each axle load. The loads can be divided into a number of groups and the stresses, strains, and deflections under each load group can be determined separately; and used for design purposes. The traffic and loading factors to be considered include axle loads, load repetitions, and tyre contact area.
2 LITRATURE REVIEW
Many research and study has been carried out on highway design, highway failure, cause of failure and its maintenance. In this study Highway failure, its cause and maintenance observed.
Z B Rashid et. al. (2007) emphasized on the parameters influencing the performance of pavements and to identify them. For efficient maintenance of road pavements, the deficiencies in our existing highway system need to be clearly understood.
Proper design, regular inspection and maintenance of pavement is of utmost importance and in preserving the investment made on highway system and in providing comfort and safety to the road user.
Dr. Ndefo Okigbo et. al. (2007) studied the conditions of the roads in Nigeria and their effects to the citizen, government and the economy of the country. Some of the identified causes
=
VOLUME: 09, Issue 06, Paper id-IJIERM-IX-VI, December 2022 176
were; poor design and construction, poormaintenance of already built highways, use of low quality materials in construction, poor workmanship and poor supervision of construction work. Some of the recommendations to remedy the situation are; Use of the appropriate design of the roads, avoiding unnecessary congestion of the roads especially heavy traffics that were not meant for the roads in the first place, prompt maintenance of the roads, application of suitable construction material in the construction.
Mr. Devidas Chavade et. al.
(2008) worked on the on-going researches about the defects in Flexible and Rigid pavement and the maintenance in Flexible and Rigid pavements. The essential objective should be to keep the road surface and appurtenances in good condition and to extend the life of the road assets to its design life. Broadly, the activities include identification of defects and the possible cause there off, determination of appropriate remedial measures; implement these in the field and monitoring of the results.
S.K. Jain et. al. (2008) says from his study that cracking consists of visible discontinuities in surface and can be an indication of the pavement’s structural condition and serious. The main problem with cracks is that they allow moisture into pavement, giving accelerated deterioration of pavement. Cracks can occur in a wide variety of patterns .They may result from a large number of causes, but generally are the result of either ageing and embrittlement of surfacing, environmental conditions, structural or fatigue failure of the pavement, or any other causes.
According to Ahmed et. al.
[2008], potholes are an indication of structural surface failure and they result from growth of a break in the surfacing, often as a result of severe alligator cracking.. Once water enters pavement layers, the base and/or subgrade become wet and unstable, and the resultant degradation leads to rapid growth of pothole area and depth.
Aaron Steinfieldc et. al. (2010) emphasise on snow removal and how it is critical for winter highway maintenance operations. However, it is subject to significant risk due to adverse operating environmental conditions such as total
visual whiteout, low tire/road traction, difficulty for detecting roadway boundaries and obstacles buried in or obscured by snow.
S. A. Wada et. al. (2010) worked on road detoriation. Road deterioration is a critical situation for road sector because of the high cost for construction of new roads and maintenance of existing roads and routes. Therefore, better funding and management should be provided in order to keep the pavements in good condition and from getting damaged due to the aforementioned distresses.
P. Kumar et. al. (2010) reported that before going into the maintenance strategies, highway engineers must look into the causes of failures of bituminous pavements. They found that failures of bituminous pavements are caused due to many reasons or combination of reasons.
It has been seen that only three parameters i.e. unevenness index, pavement cracking and rutting are considered while other distresses have been omitted while going for maintenance operations.
Caltrans et. al. [2011] categorized the main types of pavement failures as either deformation failures or surface texture failures. Deformation failures include corrugations, depressions, potholes, rutting and shoving. These failures may be due to either traffic (load associated) or environmental (non load associated) influences. It may also reflect serious underlying structural or material problems that may lead to cracking.
Surface texture failures include bleeding, cracking, polishing, stripping and raveling. These failures indicate that while the road pavement may still be structurally sound, the surface no longer performs the function it is designed to do, which is normally to provide skid resistance, a smooth running surface and water tightness. Other miscellaneous types of pavement failures include edge defects, patching and roughness.
In many pavement failures, excess moisture is the main cause of failure or a contributing cause. Queensland Transport (2012) reported the effect of moisture content changes on the strength and stiffness of pavement materials. They found that excess moisture reduces the strength and stiffness of pavement materials, being worse for the subgrade
=
VOLUME: 09, Issue 06, Paper id-IJIERM-IX-VI, December 2022 177
material, than for the subbase or base.Excess moisture and particularly high degrees of saturation result in significant pore pressures within the material.
Depending on the degree of saturation, failure may occur as any of rapid shear or bearing failure, premature rutting, lifting of wearing course due to positive pore pressures, or embedment of cover aggregate due to weak base.
According to Woods and Adcox [2014], pavement failure may be considered as structural, functional, or materials failure, or a combination of these factors. Structural failure is the loss of load carrying capability, where the pavement is no longer able to absorb and transmit the wheel loading through the structure of the road without causing further deterioration. Functional failure is a broader term, which may indicate the loss of any function of the pavement such as skid resistance, structural capacity, and serviceability or passenger comfort.
Materials failure occurs due to the disintegration or loss of material characteristics of any of the component materials.
M. Zumrawi, (2018) says from his study that for nearly all types of pavement failure, moisture is often the primary or a contributing cause of failure. Moisture entry through the surface may be caused by inadequate pavement surface drainage during construction, exposure of surface to rain during construction, or porous or open graded asphalt. He found moisture entry from the side may be caused by pondage in pits or poorly constructed surface drainage, and lateral movement of water into pavement. Other factors affecting the moisture in a pavement include the general drainage condition, such as the effectiveness of drainage structures, shoulder cross-fall and condition, longitudinal grade, and whether the pavement is constructed on cut or fill.
3 METHODOLOGY AND MATERIAL USED
3.1 Materials Used in Pavement Cement:-
The natural cement is obtained by burning and crushing the stones containing clay, carbonate of lime and some amount of carbonate of magnesia.
The clay content in such stones is about
20 to 40 percent. The natural cement is brown in colour and its best variety is known as the Roman Cement. The natural cement resembles very closely eminent hydraulic lime. It sets very quickly after addition of water. It is not so strong as artificial cement and hence it has limited use in practice. The artificial cement is obtained by burning at a very high temperature a mixture of calcareous and argillaceous materials. The mixture of ingredients should be intimate and they should be in correct proportion. The calcined product is known as clinker. A small quantity of gypsum is added to the clinker and it is then pulverized into very fine powder which is known as the cement.
3.2 Properties of Cement:-
Following are the important properties of good cement which primarily depend upon its chemical composition, thoroughness of burning and fineness of grinding:
It gives strength to the masonry.
It is an excellent binding material.
It is easily workable.
It offers good resistance to the moisture.
It possesses a good plasticity.
It stiffens or hardness early.
3.3 Harmful Constituents of Cement:- The presence of the following two oxides adversely affects the quality of cement:
Alkali oxides K2O and Na2O
Magnesium oxide MgO
3.4 Aggregate:-
Construction aggregate, or simply
"aggregate", is a broad category of coarse particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geo synthetic aggregates. Aggregates are a component of composite materials such as concrete and asphalt concrete; the aggregate serves as reinforcement to add strength to the overall composite material. Due to the relatively high hydraulic conductivity value as compared to most soils, aggregates are widely used in drainage applications such as foundation and French drains, septic drain fields, retaining wall drains, and road side edge
=
VOLUME: 09, Issue 06, Paper id-IJIERM-IX-VI, December 2022 178
drains. To put it another way, aggregatesare used as a stable foundation or road/rail base with predictable, uniform properties (e.g. to help prevent differential settling under the road or building), or as a low-cost extender that binds with more expensive cement or asphalt to form concrete.
Fig. 2 Aggregates
The American Society for Testing and Materials publishes an exhaustive listing of specifications for various construction aggregate products, which, by their individual design, are suitable for specific construction purposes. These products include specific types of coarse and fine aggregate designed for such uses as additives to asphalt and concrete mixes, as well as other construction uses. State transportation departments further refine aggregate material specifications in order to tailor aggregate use to the needs and available supply in their particular locations.
3.5 Sand:-
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles. The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non- tropical coastal settings is silica(silicon dioxide, or SiO2), usually in the form of quartz.
As the term is used by geologists, sand particles range in diameter from 0.0625mm (or 1⁄16 mm, or 62.5 μm) to 2 mm. An individual particle in this range size is termed a sand grain. The next larger size class above sand is gravel, with particles ranging from 2 mm up to 64 mm (see particle size for standards in use).
The next smaller size class in geology is
silt: particles smaller than 0.0625 mm down to 0.004 mm in diameter. The size specification between sand and gravel has remained constant for more than a century, but particle diameters as small as 0.02 mm were considered sand under the Albert Atterberg standard in use during the early 20th century. A 1953 engineering standard published by the American Association of State Highway and Transportation Officials set the minimum sand size at 0.074 mm. A 1938 specification of the United States Department of Agriculture was 0.05 mm sand feels gritty when rubbed between the fingers (silt, by comparison, feels like flour).
3.6 Bitumen:-
Bitumen is a black, oily, viscous material that is a naturally-occurring organic by product of decomposed organic materials.
Also known as asphalt or tar, bitumen was mixed with other materials throughout prehistory and throughout the world for use as a sealant, adhesive, building mortar, incense, and decorative application on pots, buildings, or human skin. The material was also useful in waterproofing canoes and other water transport, and in the mummification process toward the end of the New Kingdom of ancient Egypt. It is also flammable. And, thanks to recent scholarship, this gooey stuff is also identifiable to source.
Fig. 3 Bitumen 3.7 Points to Consider:-
The producer of bituminous mixtures, in purchasing a specified bitumen binder will expect that binder to possess the properties he has specified.
The producer will expect the binder to be delivered at the time he has specified, not before, holding tanks may not be empty and cleaned, and not after, he may have run out of
=
VOLUME: 09, Issue 06, Paper id-IJIERM-IX-VI, December 2022 179
that particular binder and had tocease production causing "knock on"
problems.
The producer will expect binders to be delivered at agreed temperatures that do not cause handling or storage problems.
The producer should be able to store bitumen in the manner recommended by the supplier and in accordance with various appropriate British Standards specifications.
The producer should incorporate the purchased binder into bituminous mixtures, regarding amount, type and mixing temperature, as specified in a British Standard specification or Published Document, as set down in the design of a proprietary material, or as an agreed design/specification supplied by the Engineer.
The production plant will use a
"recipe" to manufacture any bituminous mixture whether a
"specified" mixture or a proprietary material, even if the material is to be assessed on a
3.8 Construction of Bituminous Roads:- Bituminous pavements are in common use in India and abroad. Flexible pavements could be strengthened in stages by constructing bituminous pavement layers one after another in a certain period of time unlike the cement concrete pavement construction. The problem associated with the construction of bituminous pavements is control of the proper viscosity of the bituminous- aggregate mixtures during mixing and compaction operations. Bituminous constructions are also adopted for base and binder courses of pavements on heavy-traffic roads.
3.9 Types of Bituminous Constructions:-
The followings construction techniques are in use:
Interface treatments like prime coat and tack coat
Surface dressing and seal coat
Ground or penetration type constructions.
Penetration Macadam
Built-up Spray Grout
Premix which may be any one of the following:
Bituminous bound macadam
Carpet
Bituminous Concrete
Sheet Asphalt or Rolled Asphalt
Mastic Asphalt
3.10 Methods of Construction:-
Premix types of Bituminous Constructions are generally carried out in the field using appropriate plants. There are two types of Mixing Plant and Travelling Plant. The canter mixing plant consists of units for batching different materials, separate heating units for mixed aggregates and bitumen and a mixing unit of large capacity. The aggregates, filler and bitumen are transported to the site of the mixing plant which is stationed at a suitable location and the bituminous mix is again transported from the plant to the construction site. Generally there is very good control on the quality of the mix obtained from the central mixing plant.
The travelling Plant is a smaller unit and can be shifted from time to time the road side as the bituminous construction progresses. In hot mix constructions the heated aggregates are mixed with heated bitumen in a central or travelling plant. In cold mix method, the aggregates at atmospheric temperature are mixed with bituminous material of low viscosity in cold or after slight heating.
Fig. 4 Asphalt Surfacing
3.11 Bituminous Construction Procedures:-
In this Article, the material requirements, plant and equipment and construction process Employed for the following types of bituminous constructions have been presented:
Surface Dressing
Grouted or Penetration Macadam
Built-up Spray Grout
Bitumen Bound Macadam
=
VOLUME: 09, Issue 06, Paper id-IJIERM-IX-VI, December 2022 180
Bitumen Carpet
4 RESULTS AND DISCUSSION
The objective of this study is to establish guidelines describing systematic method for inspection and evaluation of pavement failures and to find out the possible causes of these failures. The proposed method has some basic steps as follows:
i. Inspection and Evaluation plan ii. Pavement condition survey iii. Experimental work
iv. Determine probable cause(s) of failure
v. Select the best maintenance option vi. Report on outcomes
4.1 Inspection and Evaluation Plan Planning is important to ensure that inspection and evaluation of pavement failures were carried out their intended tasks within a reasonable time frame and at the lowest cost.
When planning the evaluation program, a general review of the problem should first be conducted, along with the possible scope of inspection and maintenance work that may need to be carried out.
This plan should be drafted, addressing goals, budgeting constraints, operations planning and the investigative synthesis.
The technical team should be decided upon.
4.2 Pavement Condition Survey
The pavement condition survey may include visual examination of pavement failures, the effectiveness of drainage structures and other details such as topography and alignment should be recorded, and the soil and geology of the surrounding areas may also be of importance in determining the causes of the pavement failure. An effective visual survey of pavement failures is essential, to ensure that the cause of the failure can be diagnosed efficiently and it is a guide to what testing should be carried out and where. In addition, it will provide valuable site information that may have an influence on the best maintenance operation. Distress surveying should be carried out on failed pavement sections to find out the amount, type, and condition or severity level of distress, as well as the condition or effectiveness of any previously applied distress treatments.
4.3 Experimental Work
The experimental work includes filed and laboratory testing. Field testing program can assess the strength of the pavement materials. The conventional field tests may be carried out include Benkelman Beams, Dynamic Cone Penetration (DCP) test, roughness and surface evenness measurement, skid resistance testing.
Coring on pavement structure may be used to provide material samples for laboratory testing, and also allows visual examination of pavement layers.
Laboratory testing should be conducted on representative samples taken from pavement layers to determine physical characteristics of the materials.
The tests on soils and aggregates may aim to measure the index properties by particle size and shape, the plasticity and specific gravity and to assess the strength by the compaction and California Bearing Ratio (CBR) tests. Geotechnical tests may include measurement of the shear strength, consolidation and determine the water table level during site investigation.
Asphalt tests may be used to measure the consistency by penetration, viscosity and ductility. Marshall Tests for stability and flow measurements of asphalt concrete sample and extraction test is also necessary to perform.
4.4 Selection of the Best Maintenance Option
To select the best maintenance option, it is necessary to list a variety of alternatives that may be feasible, from an initial examination of the conditions. These possible alternatives can then be subjected to much more detailed examination of economic, design and construction factors.
Table 1 Severity levels of the measured distresses
=
VOLUME: 09, Issue 06, Paper id-IJIERM-IX-VI, December 2022 181
Table 2 Classifications of distresses onbasis of covered area percentage
5 CONCLUSION
Engineers have been always with open mind to adopt any material available to them for its use for the construction purposes. It is logical to see that the purpose of highway construction is to provide a firm and even surface for the carriageway or the pavement which could stand the stress caused due to number of load applications.
The various materials used in the construction of highway are Cement, Soil, Aggregates,& Bitumen. Therefore, the materials should of good quality to ensure good quality of pavement construction.
There are various methods of construction of highway such as bituminous construction or concrete construction.
The major Flexible pavement failures are fatigue cracking, rutting, and thermal cracking. The fatigue cracking of flexible pavement is due to horizontal tensile strain at the bottom of the asphaltic concrete.
Preserving and keeping each type of roadway, roadside, structures as nearly as possible in its original condition as constructed or as subsequently improved and the operation of highway facilities and services to provide satisfactory and safe transportation, is called maintenance of Highways. Highway Maintenance must be planned for rapid performance and to cause least possible disruption or hazard to traffic.
REFERENCES
1. S. Madanat, M. Ben-Akiva, “Optimal inspection and repair policies for infrastructure facilities,” Transportation Science, Vol. 28, pp. 55-62, 1994.
2. P. Kumar, A. Gupta, “Cases studies of bituminous pavements,” Compendium of Papers from the First International
Conference on Pavement Preservation.
Chapter 7, paper 52, pp 505 – 518, 2010.
3. W. Woods, A. Adcox, “A General Characterization of Pavement System Failures, with Emphasis on a Method for Selecting a Repair Process,” Journal of Construction Education, Vol. 7, No. 1, pp. 58 – 62, 2004.
4. [4] Caltrans, Flexible Pavement Rehabilitation Manual, California Department of Transportation, Sacramento, CA, June, 2001.
5. S. Jain, P. Kumar, “Report on Causes of Cracks Occurrence in Ramghat - Aligarh Road in U.P.,” Report Submitted to PWD, Aligarh. 1998.
6. A. Ahmed, Pavement Distresses Study:
Identification and Maintenance (case study), M.Sc. thesis, University of Sudan, 2008.
7. P. Sikdar, S. Jain, S. Bose, P. Kumar, (1999).
“Premature Cracking of Flexible Pavements,”
Journal of Indian Roads Congress, Paper No.
461, Volume 60, Issue 3, pp. 355 – 398.
1999.
8. M. Zumrawi, “Pavement design for roads on expansive clay subgrades,” University of Khartoum Engineering Journal 3 (1), 51 – 57, 2013.
9. O. Omer, A. Elsharief, A. Mohamed, “Failure Investigation for Recently Constructed Road in Khartoum State,” Journal of Geological Resource and Engineering, pp 20 – 31, 2014.
10. Queensland Transport, Pavement Rehabilitation Manual, Pavement, Materials, Geotechnical Branch, State of Queensland, April 2012.
11. M. Zumrawi, “The impacts of poor drainage on road performance in Khartoum,” Research Article, International Journal of Multidisciplinary and Scientific Emerging Research (IJMSER), available online, Vol. 3, No. 1, pp. 901 – 907, Oct. 2014.
12. N. Mubarak, Effect of rising ground water on engineering structure at some areas in Omdurman town, M.Sc. Thesis, University of Khartoum, Sudan, 2011.
13. Hodges, J, “Overseas Road Note 31”. 4th ed., London: Overseas Center, 1993.
14. Anonymous: Flexible Pavement Distress, (2009).
http://www.training.ce.washington.edu/pave ment-elevation /flexible distress/09.
15. Mr. EtikalaNagaraju 2015. “Pavement Rehabilitation and Maintenance”, International Journal of Civil Engineering (SSRJ – IJCE), Volume 21, Issue 6, PP. 38 – 40. Magdi M.E. Zumravi 2015. “Survey and Evaluation of Flexible Pavement Failures”, International Journal of Science and Research (IJSR), Volume 4, Issue 1, PP. 1602 – 1607.
16. Study on Failures and Maintenance of Flexible Pavement”, International Journal of Scientific Engineering and Technology Research (IJSETR), Volume 3, Issue 4, PP.
2984 – 2990.
17. Dalia Said, Abd El Halim A.O and Jorge C.Pais (2008) 'Study of the Causes and Remedies Premature Surface Cracking of Asphalt Pavements'. EPAM3-3rd European Pavement and Asset Management Conference, Coimbra, Portugal. 7-9 July,2008.
=
VOLUME: 09, Issue 06, Paper id-IJIERM-IX-VI, December 2022 182
18. Abdulkareem Y.A and K.A Adeoti (2004) 'Road Maintenance and National Development'.
National Engineering
19. http://www.pavementinteractive.org/article/
Reflection-cracking/ Accessed on 7th November,2015
20. Dalia Said, Abd El Halim A.O and Jorge C.Pais (2008) 'Study of the Causes and Remedies Premature Surface Cracking of Asphalt Pavements'. EPAM3-3rd European Pavement and Asset Management Conference, Coimbra, Portugal. 7-9 July,2008.
21. Sultan Tarawneh and Mohmd Sarireh (2013) 'Causes of Cracks and Deterioration of Pavement on Highways in Jordan From
Contractors Perspective'. Journal of Civil and Environmental Research, Vol.3 November,2013.
22. Tom V. Mathew and K.V Krishna Rao (2007) 'Introduction to flexible pavement design'.
NPTEL Publications in Introduction to Transport Engineering.
23. Okikbo, K. (2012) 'Causes of Highway Failures in Nigeria'. International Journal of Engineering, Science and Technology (IJEST), Vol.4 November11,2012.
24. L.R Kadyali and N.B Lal (2012) 'Principles and Practice of Highway Engineering'.
Khanna Publishers, New Delhi 110002
