1. Sub-Grade Preparation-Equipment Caterpillar Paving Products
Asphalt 105: Equipment
Sub-Grade Preparation-Equipment
Compaction & Grading
Speaker: Steve McCown
Market Professional
Caterpillar Paving Products
Peoria, IL

2. Growth Happens! The Real World
Todays Reality for most contracting agencies is…..
Growth Happens!
The majority of our budget dollars are spent on maintenance and rehabilitation of existing roads.
WHY?

3. The Real World
Our challenge is not the proper construction of new roads but how to better manage the dollars we have to improve & maintain our existing streets and highways.
Public Pressure/Perception
Loss of Revenues
Ability to draw new business and development
Media attention

4. Evolution of a Road

5. Evolution of a Road Dirt road light traffic light loads.
Improved Dirt road with layer of gravel
Widened Dirt road for 2-way traffic
Improved with asphalt for increased traffic/loads
Entered maintenance mode….

6. Typical Fix - Overlay
Re-paving on top of a weak base is a short term fix

7. Typical Fix - Mill & Fill
Alternative for mildly distressed roads where re-profiling is needed.

8. Cold Planing Process
Cold planing removes a portion of the asphalt layer (profiling)
Process suitable when base is in good condition and will support axle loads
Process suitable when cracks do not extend full depth of asphalt layer
Asphalt Layer
Aggregate Base

9. Cold Planing Process Cold planing does not remedy base problems
Process does not remove cracks that penetrate to base
New asphalt layer will show reflective crack quickly
Poor economics (future maintenance)
Asphalt Layer
crack
Aggregate Base
void

10. Typical Fix - Reconstruction Process
Scarification of existing pavement

11. Typical Reconstruction Process
Removal of the scarified material

12. Typical Reconstruction Process
Material hauled to dump site for later processing as RAP.

13. The Full Depth Reclamation alternative
It is a Process, Performed in Cold, which pulverizes and mixes Existing pavement structure In Place with a certain amount of Underlying Base Material to form an Improved and Upgraded Road Base

14. Full Depth Reclamation
Proven process that provides quality results economically
Fast-growing maintenance alternative
Easily adapts to current highway maintenance design criteria

15. Full Depth Reclamation
Process is different from cold planing or cold-in-place recycling
Rotor always penetrates through the asphalt into the base
Rotor depth can be set to blend desired portion of the existing base/sub-base with the asphalt layer
Asphalt
Aggregate Base
Reclaimed Material

16. Full Depth Reclamation Process
Eliminates full depth cracking
Opens base for stabilization
Provides better support for new asphalt layer
Cost savings by re-using existing pavement material and done in-place
Asphalt Layer
Aggregate Base

17. Major Indicators for Full Depth Reclamation
Deep cracking
Reflective cracking
Pothole patching
Rutting/shoving
Frost heaves
Parabolic shape
Insufficient base strength

18. Reclaimed Material
Material leaving mixing chamber well-graded & homogenous
Pulverized material will not be smaller than the original aggregates
Normal max. particle size of 50 mm (2")
Eliminates cracks, ruts, bumps & potholes in asphalt layer

19. Common Stabilizing Agents
Asphalt emulsion
Foamed asphalt
Portland cement
Fly ash
Dry lime
Lime slurry
Calcium chloride

20. Benefits of Full Depth Reclamation
Aggregate can be added to base
Perfect use for RAP!
Work is done in-place, saving expensive removal & replacement of deteriorated layers
Versatility in the process as well as the types of structures

21. Secondary Road Reclamation
Roads not designed to support today’s higher traffic volume & loads
High opportunity for reclamation on secondary roads
Ideal candidates for both strengthening & widening

22. City Street Reclamation
Where frequent cracking & patching are present
Can be substituted for overlay or cold planing
With adequate traffic control, street can remain open
Businesses and home owners benefit from open road

23. State Road Reclamation
Higher quality structures rehabilitated with corresponding gains in base strength
0,8 to 1,6 km (1/2 to 1 mile) of two-lane road processed per day

24. Interstate Highway Reclamation
Portion of asphalt layer milled & remaining asphalt is pulverized & blended with the base
Full asphalt layer is recycled or reclaimed
Thinner wear course maybe possible

25. Airport Reclamation
Reclamation rather than overlay eliminates reflective cracking
New surface on top of upgraded, uniformly compacted base
Life of the new asphalt structure is increased

26. Pre-Project Evaluation
Core Sampling – asphalt layer
– base/sub-base
– sub-grade
Pavement Condition Survey
– buried obstacles
– cracking
– rutting/shoving
– settlement
– heaving
– potholes

27. Granular Materials & Soils – Lab Tests
Attenberg Limits – ASTM D 4318
Sand Equivalent Value – ASTM D 2419
Sieve Analysis – ASTM C 136
Materials finer than No. 200 sieve – ASTM C 177

28. 75 mm (3") Asphalt or Less – Lab Tests
Extraction of Bitumen – ASTM D 2172
Sieve Analysis – ASTM C 136
Materials finer than No. 200 sieve – ASTM C 177

29. 75 mm (3") Asphalt or More – Lab Tests
Recovery of Asphalt – ASTM D 1856
Penetration of Bituminous Materials – ASTM D 5
Viscosity of Asphalt – ASTM D 2171

30. Equipment Requirements
Full Depth Reclamation Process
– reclaiming machine (with additive system)
– motor grader(s)
– compactor(s)
Auxiliary Equipment (all may not be required)
– tanker truck (water, emulsion)
– end or bottom dump trucks
– water distributor truck
– wheel loader
– oil distributor truck (fog/curing seal)

31. Full Depth Reclamation Process
First step is to pulverize existing asphalt layer with portion of the base
Sizing is controlled by operator who balances machine speed & rear door opening
Typical sizing specs – 100% 50 mm (2") – 95% 38 mm (1.5") – 25% max. fines

32. Additive Application
Additives applied after pulverization or after rough grading
Sprayed through on- board emulsion spray system or tanker truck
Pulverization & mixing passes are usually separate for better consistency

33. Additive Application
Additives are often applied directly to the pulverized material
Amounts are specified in liters sq/m gal (sq/yd)
Additional aggregate can also be added after pulverization if required. Perfect use for RAP!

34. Mixing Passes
Multiple passes may be needed to achieve adequate homogeneity
Sequence of mixing passes depends on the additive characteristics
Mixing depth needs to match the pulverization depth to ensure consistent material

35. Compaction of Reclaimed Material
Normally after the mixing pass if additives are used
Delayed if asphalt emulsion is used
Typical compaction sequence – initial or breakdown – intermediate – finish

36. Shaping Reclaimed Material
Performed after breakdown compaction
Final shaping occurs after crown & grade are established & all compaction is complete
Loose material should be removed for proper bonding of the asphalt prime coat or curing seal

37. Curing of Stabilized Base
Required for development of strength & minimization of shrinkage cracks in portland cement or fly ash
In asphalt emulsion – water loss is required for base to set & harden
Heavy traffic not allowed during curing – may cause base failure

38. Quality Control Gradation Additive content Moisture content
Mix uniformity
Compaction
Layer thickness
Finished surface

39. Placing the Pavement Layer
May follow pulverization, shaping & compaction, if no stabilizing agents were utilized
May be possible to apply a thinner asphalt layer or economical chip seal
Purpose of reclamation – creation of a higher value, stronger base

40. Typical Asphalt Pavement Structure
Hot Mix Asphalt
Crushed Stone Base
Sand & Gravel Sub-base
Sub-grade

41. Construction Materials Coefficients
HMA a1 = 0.42 D1 = 125 mm (5")
CSB a2 = 0.14 D2 = 150 mm (6")
Sand a3 = 0.11 D3 = 200 mm (8")
& Gravel

42. Structural Number (SN) Formula
SN = a1D1 + a2D2 + a3D3
Example:
SN = (0.42)(5) + (0.14)(6) + (0.11)(8)
SN =
SN = 3.82

43. Determining the Structural Number
Class of road – (terminal serviceability typical )
Climatic conditions
Sub-grade soil support value
Equivalent wheel load repetitions
Expected life before major maintenance

44. New Pavement Structure
HMA a1 = 0.42 D1 = 125 mm (5")
CSB a2 = 0.14 D2 = 150 mm (6")
Sand a3 = 0.11 D3 = 200 mm (8")
& Gravel
SN = Life Expectancy = 15 Years Terminal Serviceability = 2.00

45. Pavement Structure after 15 Years
Deteriorated HMA a1 = 0.42 D1 = 125 mm (5")
Decompacted CSB a2 = 0.14 D2 = 150 mm (6")
Decompacted Sand a3 = 0.11 D3 = 200 mm (8")
& Gravel
Present Serviceability = Terminal Serviceability = 2.00

46. Rehabilitation Techniques
75 mm (3") HMA overlay
Reconstruction – mill full depth asphalt removal – re-shape and compact existing crushed stone base – 125 mm (5") HMA overlay
Full depth reclamation – 200 mm (8") asphalt and base pulverization – stabilize with 7,57 L (2 gal/sq yd) asphalt emulsion – 75 mm (3") HMA overlay

47. Overlay Alternative HMA Overlay a1 = 0.42 D1 = 75 mm (3")
Deteriorated HMA a2 = 0.15 D2 = 125 mm (5")
Decompacted CSB a3 = 0.06 D3 = 150 mm (6")
Decompacted Sand a4 = 0.06 D4 = 200 mm (8")
& Gravel
SN = 2.85

48. Mill & Fill Alternative
HMA Overlay a1 = 0.42 D1 = 75 mm (3")
Deteriorated HMA a2 = 0.06 D2 = 125 mm (2")
Decompacted CSB a3 = 0.06 D3 = 150 mm (6")
Decompacted Sand a4 = 0.06 D4 = 200 mm (8")
& Gravel
SN = 2.22

49. Reconstruction Alternative
HMA Overlay a1 = 0.42 D1 = 125 mm (5")
Reconstructed CSB a2 = 0.14 D2 = 150 mm (6")
Decompacted Sand a3 = 0.07 D3 = 200 mm (8")
& Gravel
SN = 3.50

50. Reclamation Alternative
HMA overlay a1 = 0.42 D1 = 75 mm (3")
Reclaimed ATB a2 = 0.25 D2 = 200 mm (8")
Decompacted CSB a3 = 0.09 D3 = 75 mm (3")
Decompacted Sand a4 = 0.06 D4 = 200 mm (8")
Gravel
SN = 4.01

51. Structural Number Comparison
Technique SN
Overlay 2.85
3” Mill & Fill 2.22
Reconstruction 3.50
Full Depth Reclamation 4.01

52. Estimated Service Life
Technique SN Life
Reclamation years
Reconstruction years
Overlay years

53. Typical Overlay Project
Overlay. The process: Place and compact leveling course with average 1 inch (25 mm) hot mix asphalt concrete. Place and compact 3 inch (76 mm) wearing course of hot mix asphalt concrete.
Example Only: Cost per Square Yard Cost per Mile
Leveling Course, 1" (25 mm) avg. hot mix $4.40* $77,440.00
Wearing Course, 3" (76 mm) (hot mix) $13.20* $232,320.00
Total estimated cost for one mile $17.60* $309,760.00
* Based on asphalt price of $80/ton

54. Typical Overlay Project
Overlay. The process: Place and compact leveling course with average 1 inch (25 mm) hot mix asphalt. Place and compact 2 inch (50 mm) wearing course of hot mix asphalt concrete.
Example Only: Cost per Square Yard Cost per Mile
Leveling Course, 1" (25 mm) avg. hot mix $4.40* $77,440.00
Wearing Course, 2" (50 mm) (hot mix) $8.80* $154,880.00
Total estimated cost for one mile $13.20* $232,320.00
* Based on asphalt price of $80/ton

55. Typical Reclamation Project
Full Depth Reclamation. The process: Pulverize the existing roadway structure and shoulder material to a width of 30 feet (9.1 m) and a depth of 6 inches (152 mm), reshape and mix asphalt emulsion at a rate of 2.0 gallons (7.6 liters) per square yard (square meter) to a depth of 6 inches (152 mm). Shape and compact the emulsion treated base, apply fog seal and allow to cure. Finish with a hot mix asphalt wearing course after proper curing period.

56. Typical Reclamation Project
Example Only: Cost per Square Yard Cost per Mile
Pulverizing $ $13,904.00
Grade Preparation $ $ 4,576.00
Water $ $ 1,936.00
Mixing $ $ 9,328.00
Emulsion $ $47,168.00
Grading and Compaction $ $ 7,392.00
Fog Seal $ $ 2,992.00
3-inch Hot Mix $ $232,320.00
Total Estimated Cost for One Mile $ $331,584.00

57. Expected Service Life/Cost Comparison
Expected Service Life/Cost Comparison. While many factors influence the useful life of any road or street, there has been sufficient experience with full-depth reclamation to predict service life (assuming minimal maintenance). In the above example, using asphalt emulsion for added binder in the new base and a 3“ (76 mm) wearing course, an 18-year life for the reclaimed structure is expected.
The same street or road corrected with leveling course and a 3“ (76 mm) wearing course, has a projected life of 12 years. The potential for reflective cracking and accelerated deterioration is much greater on overlaid surface than on reclaimed and paved structures. Therefore, the reclaimed road will last longer and provide better long-term value.

58. Expected Service Life/Cost Comparison
Initial Cost per Mile
Service Life Before Major Maintenance
Cost/Year Per Mile
Reclaimed Road $331, years $18,421.00
Overlaid Road 3” $309, years? $25,813.00
Overlaid Road 2” $232, years? $29,040.00
Even though the initial cost to reclaim and pave with hot mix asphalt is usually about 15-30% higher than the overlay method, in the long term, full depth reclamation is about 20-40% more economical because reclaimed roads last longer!

59. Structural Layer Coefficients (AASHTO)
Sandy Gravel 0.07
Crushed Stone 0.14
Cement Treated (not soil cement) compressive strength at 7 days
– 650 psi or more 0.23
– 400 psi to 650 psi 0.20
– 400 psi or less 0.15
Bituminous Treated (ATB) – course-graded 0.20 – 0.30
– sand asphalt 0.30
Lime Treated 0.15 – 0.30

60. Other Benefits Less Fuel Consumed Fewer Emissions
Less Traffic Disruption
Less Business Interruption
Preserve Natural Resources

61. Thank You!
QUESTIONS?

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