Flexible Pavement: Types, Distress, and Maintenance

Posted on May 7, 2024 in Other subjects

  1. What was the total cost in Ringgit Malaysia (RM) or USD of PLUS (Project Lebuhraya Utara Selatan Berhad) highway of length 772 km during its construction period.

North south interurban toll expressway: Johor Bahru to Bukit Kayu Hitam: 791.2 (772) km. cost: USD 2.6 billion —– or RM 6.6 billion (Straits times, world bank report on 30, 09, 1993)

  1. Why PMS is needed for existing pavements?

In the past, pavement was maintained but not managed. The pavement engineer’s experience tended to dictate the selection of maintenance and rehabilitation (M&R) techniques with little regard given to life-cycle costing or to priority as compared to other pavement requirements in the network. In today’s economic environment, as the pavement infrastructure has aged, a more systematic approach to determining M & R needs and priorities is necessary. Pavement networks must now be managed, not simply maintained.

  1. What are types of recycling and explain them in brief?
  2. cold in place recycling of pavements with cement or emulsion or foamed bitumen (CIPR) >50mm
  3. Hot in place recycling or hot plant mix recycling (HIPR) 50mm,>
  4. Hot mix asphalt recycling in plant, defined as the process in which all or some portion of the pavement structure is removed, reduced to desired size, mixed hot with additional asphalt cement at a central plant.
  5. What are the detrimental effects of cracks?
  6. Loss of water-proofing of the pavement layers.
  7. Loss of load spreading ability of the cracked material.
  8. Pumping and loss of fines from the base course.
  9. Loss of riding quality through loss of surfacing.
  10. Loss of appearance.
  11. What are the possible causes of cracks?
  12. Depression.
  13. Fatigue life of the surfacing being exceeded.
  14. Age embrittlement of the surfacing.
  15. Reflection of cracks in underlying layers.
  16. Shrinkage.
  17. Poor construction joints.
  18. Draw a typical pavement section and show the location of fatigue and rutting?

6.jpg

  1. Draw a tentative graph showing proctor values and explain MDD and OMC?

7.jpg

  1. What is the major difference between California Bearing Ratio (CBR) and Plate Load Test?

CBR test assesses the strength of soil, whereas, plate load test is used to evaluate the support capability.

  1. Draw a curve of pavement deterioration with age and show the trigger values in terms of pavement condition indices (PCI).

9.jpg

  1. What are the principal causes of asphalt hardening?

Oxidation

Loss of volatiles

Physical hardening

Exudative hardening

  1. What are the fields falls under restoration?
  2. Pothole patching
  3. Grooving/cold milling
  4. Crack sealing
  5. Application of pavement rejuvenating agent
  6. Slurry seal
  7. Thin hot mix overlay
  8. Surface dressing
  9. Resurfacing with gap graded mix
  10. Resurfacing with porous asphalt
  11. What are the criteria used to address the structural and functional failures of flexible pavement?

Pavement is considered fail if it exhibits a rut depth 20mm

Pavement is considered fail if 20% of the surface area has cracked

  1. What is the pavement preservation?

Pavement preservation is the sum of all activities undertaken to provide and maintain serviceable roadways, including preserving the investment, extending service life, enhancing performance, ensuring cost-effectiveness, and reducing user delays.

  1. Show a prediction model of flexible pavement with a simple graph?

14.jpg

  1. What are the elements in network level?
  • It deals with the pavement network as a whole
  • It’s related to high-level decisions, relating to network-wide planning, policy, and budget
  • Managers at this level might compare the benefits and costs for several alternatives
  • They will also identify the greatest network benefit-cost ratio over the analysis period.
  1. Write down the five most common types of flexible pavement distress.

Bleeding – Cracking – Rutting – Fatigue – Drainage Problem

  1. Draw a graph to show the projected condition of a roadway with a treatment and without treatment?

17.jpg

  1. What are the basic affecting factors for pavement, needed to address for all pavement design procedures?
  2. Classification of the road
  3. Traffic
  4. Available material
  5. Geometry
  6. Type of pavement
  7. Drainage
  8. Subgrade quality
  9. Climate
  10. What problems are needed to address during a project level evaluation, answer to the point?
  11. Distress
  12. Roughness
  13. Friction
  14. Rutting
  15. What is the rehabilitation process involved for pavements?
  16. Restoration
  17. Structural resurfacing
  18. Full-depth reconstruction
  19. Partial-depth reconstruction
  20. Recycling
  21. What are the major differences between California Bearing Ratio (CBR) and Resilient Modulus (Mr) of subgrade soil.

Whereas CBR test evaluates the potential strength of soil, resilient modulus is a stiffness property obtained under repeated/cyclic load test. The determination of resilient modulus requires sophisticated equipment and skilled personnel for laboratory and field testing. Therefore, some agencies continue to use CBR to estimate resilient modulus for flexible pavement design.

  1. What are the differences between maintenance works and rehabilitation works for flexible pavements?
  2. Maintenance: Pavement maintenance corrective (reactive) maintenance
  3. Rehabilitation: Major maintenance
  4. What is the difference between preventive maintenance and corrective maintenance?

Preventive maintenance is a planned strategy of cost-effective treatments to an existing roadway system, but corrective maintenance activities are performed in response to the development of deficiencies that negatively impact the safe, efficient operations of the facility and future integrity of the pavement section.

  1. What is the main objective function used in the optimization model?

The main objective function used in the optimization model is to find the best function among other alternatives.

  1. What is the main use of cold mixture asphalt?

For patching potholes for small projects or mainly pothole repairing.

  1. What are the main destructive factors for a flexible pavement?
  2. Penetration of water in pavement layers
  3. Aging
  4. Hardening
  5. Cracking
  6. What are the factors used to prioritize rank projects?

Pavement distress

Ride or pavement roughness

Traffic

Economic factors

Functional class

Accidents

Friction and skid resistance

Geometric deficiencies

Structural capacity

Engineering judgment

Age and location

What functional conditions are used for network level consideration?

Riding surface is smooth in the longitudinal and transverse direction

Surface distress is within tolerable limits (30%>)

Riding surface possesses adequate skid resistance properties

Rutting is not excessive (12 – 15 mm)

What are the factors needed to consider in selecting rehabilitation methodology?

Structural

Surface distresses

Drainage

Materials

Traffic

What are the structural responses for a flexible pavement, and depends on which layer of pavement?

  1. Stress

Strain

Deflection

Pavement structural response depends on the support of the subgrade layer. Surface deflection is highly dependent on subgrade support.

  1. What are the desirable properties of subgrade?

Adequate shear strength

Adequate permeability

Ease and permanency of compaction

Volume stability

  1. What is the strength tests needed for subgrade evaluation?

CBR – resilient modulus – Dcp – plate load test – haveem – resistance value – triaxial test

  1. Define structural number and how you determine the remaining life of flexible pavement?

SN=a1D1+a2D2+a3D3

Where: a1, a2, a3 are the layer thickness so structural number is a function of layer thickness layer coefficient and drainage coefficient.

  1. Define the following terms in brief?
  2. Permeability:

Is the degree to which these void spaces are interconnected

  1. Porosity:

Is the amount of void space between the particles that make up a soil or rock

  1. Emulsified asphalt and cutback asphalt:

Emulsified asphalt and cutback asphalt use emulsifying agent and water or petroleum solvents, respectively, to liquefy the asphalt for use in roads or other construction projects.

  1. What are the factors involved in drainability of subgrade?
  2. Grain size
  3. Depth of water table
  4. Soil plasticity
  5. Topography
  6. Define resilient modulus and why resilient modulus is important in pavement design?

Resilient modulus (Mr) is the elastic modulus based on the recoverable strain under repeated load, and is defined as Mr=MR=sd/εr

Mr is used to determine stress, strain and deflection in pavement design as input parameter.

  1. What are the different types of surface courses used in flexible pavement, in general?
  2. Hot Mix Asphalt (HMA)
  3. Highly Compacted Mixture (HMA)
  4. Cold asphalt (CMA)
  5. Porous asphalt
  6. Stone Mastic Asphalt (SMA)
  7. Fiber Mastic Asphalt (FMA)
  8. Novachip
  9. What is the demarcation line in consideration of thickness in cold and hot in-place recycling?

CIPR>50mm

HIPR

  1. What is the rut depth in consideration for selecting structural failure of flexible pavement?

20 mm

  1. What are the stabilizing agents used for asphalt pavement recycling?
  2. Lime
  3. Cement
  4. emulsions

Q1.  What do you mean by sustainable pavement, give two examples of   

        sustainable pavement? 

Sustainable pavement is environmentally friendly

Example: porous asphalt, warm mix asphalt (WMA)

Q2.  What do you mean by green pavement, give an example? 

        When rain collects on nonporous pavement, it runs off, carrying the oil from        

        vehicles with it

        Example:  porous asphalt

Q3.  Draw a graph to show projected condition of a roadway with a treatment

        and Without a treatment.

2Q==

Q4. What are the strength parameters required to carry out for the evaluation of

       asphalt pavement layers including sub-grade?

  • CBR

Resilient modulus

DCP

Plate load test

Hveen resistance value

Triaxial test

Q5.  What are the factors needed to address the pavement condition assessment?

  1. Service and user perception

Physical condition

Structural integrity / load-carrying capacity

Safety and sufficiency

  1.  Environmental

Q6.  From the visual data, how to calculate the deduct score for pavement

        condition index (PCI)? Explain to the point

  1. Functional distress(FU): porosity, ravelling, potholes, patching, and stripping
  2. Structural cracking (S): slippage cracking, reflection cracking, fatigue cracking, shrinkage cracking, and settlement cracking
  3. Structural distortion (S): shoving, rutting, and sub-grade shear failure
  4. Friction (Fr): no surface texture, polished aggregate, bleeding, oil spill
  5. Miscellaneous (M): poorly repaired trenches, open joints, high crown, low kerb, damaged gutter, edge scouring, damaged footpath, and damaged kerb

Q7.    Draw a flowchart showing tentatively network level data elements.

2Q==

Q9. Why PMS is needed for existing pavement?

        The reasons are:

      –   Shortage of budget for rehabilitation

      –   So, we need some sort of prioritization and ranking

      –  According to network situation and available budget, that can be

 achieved through the criteria of PMS

Q10.   What are the detrimental effects of cracks?

  1. Loss of water-proofing of the pavement layers.
  2. Loss of load spreading ability of the cracked material.
  3. Pumping and loss of fines from the base course.
  4. Loss of riding quality through loss of surfacing.
  5. Loss of appearance.

Q11.  What are the possible causes of cracks?

  1. Depression.
  2. Fatigue life of the surfacing being exceeded.
  3. Age embrittlement of the surfacing.
  4. Reflection of cracks in underlying layers.
  5. Shrinkage.
  6. Poor construction joints

Q12.  Draw a typical pavement section and show the location of fatigue and rutting.

9k=

Q13.  Draw a tensile graph showing protector tests, and what are the purposes to

          do the tests?

9k=

Q14.    In general, how many categories are in rehabilitation processes and what  

            are those?   

  1. Restoration
  2. Structural resurfacing
  3. Full depth reconstruction
  4. Partial depth  reconstruction
  5. Recycling

Q15.   Draw a tentative curve of pavement deterioration with time/ESAL and

           show the trigger value in terms of pavement condition indices (PCI).

9k=

Q16.  What are the principal causes of asphalt hardening?

  • Oxidation

Loss of volatiles

Physical hardening

Exudative  hardening

Q17. What are the fields falls under restoration?

  • Crack sealing

Chip sealing

Slurry sealing

Micro surfacing

 Ultrathin bonded overlay – Novachip

Smoothseal

Thin HMA overlays with  repairs

  • Thin HMA overlays without  repairs

Q18. What are the criteria used to address the structural and functional failures

         of a flexible pavement

Pavement is considered fail if it exhibit a rut depth 20mm

Crack surface area ˂20% functional , Crack surface area >20% structural

      Pavement is considered fail if 20% of surface area has cracked

Rutting depth ˂ 20mm functional ,  Rutting depth > 20mm structural

Q19. Show a prediction model of flexible pavement with a simple graph?

2Q==

Q20.  Write down the five most common types of flexible pavement distress.

  • Rutting
  • Cracks
  • Ravelling
  • Bleeding
  • Patching
  • Potholes

Q21. What are the basic affecting factors for pavement, needed to address for all

          pavement design procedure?  

  • Support provided by the in-place soil (sub-grade)
  • Expected traffic loads for the design period
  • Environment factors
  • Drainage
  • Available materials
  • Capabilities of construction forces
  • Cost

Q22. What problems are needed to address during a project level evaluation,    

          answer to the point?

  1. Classification of the road
  2. Traffic
  3. Available material
  4. Geometry
  5. Type of pavement
  6. Drainage
  7. Sub-grade quality
  8. climate

Q23.  Distinguish between thin overlay and structural overlay?

  • Thin overlay: 40 mm and below
  • Structural overlay: 40 – 200 mm

Q24.  What are the differences in between preventive maintenance and reactive maintenance?

preventive maintenance: It is used to arrest minor deterioration, retard progressive failure, and reduce the need for corrective maintenance. It is performed prior to significant distress.

Corrective (reactive) maintenance: It is performed after a deficiency occurs in the pavement; i.e., loss of friction, moderate to severe rutting, or extensive cracking.

 Q25.  What is the main use of cold mixture asphalt?

For patching pothole for small project or

           Mainly pothole repairing  (potholes patched)

Q26. What are the main destructive factors for a flexible pavement?

  • Traffic load (Heavy vehicles)

Action of water

Temperature fluctuations

Ultraviolet radiation

Aging

  • Cracking

Q27. What functional conditions are used for network level consideration?

1. Riding surface is smooth in the longitudinal and transverse direction (˂ IRI6)

2. Surface distress are within tolerable limits (˂30% area)

3. Skid resistance( friction)

4. Rutting is not excessive (12 – 15 mm)

Or ( distress, roughness, friction, Rutting)

Q28. What are the desirable properties of sub-grade?

  • Adequate shear strength

Adequate permeability

Ease and performance of compaction

Volume stability

  • Performance of strength?

Q29. What are the strength tests needed for  sub-grade evaluation?

  • CBR   

Resilient modulus

DCP

Plate load test

Hveen  resistance value

  • Triaxial test

Q30. Define emulsified asphalt and cutback asphalt.

  Cutback bitumen are constituted from the penetration grade (80/100) grade bitumen dissolved in a solvent to reduce viscosity for ease of handling and  operating bitumen emulsion is the globules of bitumen suspended in an aqueous medium by means of suitable emulsifying agents.

Q31.  What are the factors involved in drain ability of sub-grade

  • Grain size

Depth of water table

Soil plasticity

  • Topography

Q32.  In general, what are the types of surface courses used in flexible pavement?

  • Hot Mix Asphalt (HMA)

Stone Matrix Asphalt (SMA)

Porous asphalt

Novachip

Dense Graded Asphalt

Open Graded Asphalt

Gap Graded Asphalt

  • Warm-Mix Asphalt (WMA)

Q33.  What is the rut depth in consideration for selecting structural failure of flexible pavement

  1. 20 mm

Q34.  Why recycling is done on flexible pavement?

  • Less waste
  • Lower costs
  • Speed in work
  • Increase disposal cost
  • High quality aggregates unavailable
  • Environmental friendly
  • Construction materials

Q35.  What are the equipment used to measure road surface distress?

  • Road scanner

British skid resistance pendulum

DCP

  • Benkelman beam

Q36. Different between maintenance work and rehabilitation works.

  • Maintenance works: Pavement maintenance corrective (reactive) maintenance
  • Rehabilitation work: Major maintenance

Q37. What are the equipment used to determine structural assessment of flexible  

         pavement?

  • DCP

FWD, HWD   [FWD=falling weight Deflectometer]

RWD, RDD

  • Benkelman beam

Q38.  What are the structural responses for a flexible pavement, and depends on  

          which layer of pavement?

  • Stress
  • Strain
  • Deflection

        Pavement structural responses depends on the support of the sub-grade layer.

        Surface deflection is highly dependent on sub-grade support.

Q39.  Write down five main reasons for pavement deterioration?

  • Heavy traffic load

Water

Temperature

Poor construction joint

  • Ultraviolet radiation

Q40.  Define structural number with equation.

          SN = a1D1 +a2D2m2 + a3D3m3

          Where, a1, a2, and a3  are the layer coefficients of surface, base and sub-base

          D1, D2, and D3 are the layer thickness of  base and sub-base

          m2, m3  are the drainage coefficients of base and sub-base course  So, structural number is a function of  ƒ  layer thickness, layer coefficient and      drainage coefficient.

1. What are types of recycling and explain them in brief?

  1. cold in place recycling of pavements with cement or emulsion or foamed bitumen (CIPR) >50mm
  2. Hot in place recycling or hot plant mix recycling (HIPR) 50mm,>

Hot mix asphalt recycling in plant, defined as the process in which all or some portion of the pavement structure is removed, reduced to desired size, mixed hot with additional asphalt cement at a central plant.

2. What is the major difference between California Bearing Ratio (CBR) and Plate Load Test?

CBR test assesses the strength of soil, whereas, plate load test is used to evaluate the support capability.

3. What is the pavement preservation?

Pavement preservation is the sum of all activities under taken to provide and maintain serviceable road ways, including preservation the investment, extending service life, enhancing performance, ensuring cost effectiveness and reducing user delays.

4. What are the elements in network level?

  • It deals with the pavement network as a whole
  • It’s related with high level decision, relating to network wide planning, policy and budget
  • Mangers at this level might compare the benefits and cost for several alternatives
  • They will also identify on greatest network benefit-cost ratio over the analysis period.

5. What are the major difference between California bearing ratio (CBR) and Resilient Modulus (Mr) of sub-grade soil.

Whereas CBR test evaluates the potential strength of geometrical resilient modulus is a stiffness property obtained under repeated/cyclic load test. The determination of resilient modulus requires sophisticated equipment and skilled personnel for laboratory and field testing. Therefore, some agencies continue to use CBR to estimate resilient modulus for flexible pavement design. 

6. What is the main objective functions used in optimization model?

Optimization model is to find best function among other alternatives

7. What are the factors used to priority rank projects?

  • Pavement distress
  • Ride or pavement roughness
  • Traffic
  • Economic factors
  • Functional class
  • Accidents
  • Friction and skid resistance
  • Geometric deficiencies
  • Structural capacity
  • Engineering judgment

 Age and location

8. What are the factors needed to consider in selecting rehabilitation methodology?

  • Structural
  • Surface distresses
  • Drainage
  • Materials

Traffic

9. Define the following terms in brief?

  1. Permeability:

Is the degree to with these void spaces are interconnected

  1. Porosity:

Is the amount of void space between the particles that makeup a soil or rock

  1. Emulsified asphalt and cutback asphalt:

Emulsified asphalt and cutback asphalt use emulsifying agent and water or petroleum solvents, respectively, to liquefy the asphalt for use in roads or other construction projects.

10.  Define resilient modulus and why resilient modulus is important in pavement design?

Resilient modulus (Mr) is the elastic modulus based on the recoverable strain under repeated load, and is defined as Mr=MR=sd/εr

Mr is used to determine stress, strain and deflection in pavement design as input parameter

11. What is the demarcation line in consideration of thickness in cold and hot in-place recycling?

CIPR>50mm

HIPR

12. What are the stabilizing agents used for asphalt pavement recycling?

  • Lime
  • Cement

emulsions