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open graded friction course (OGFC)


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pavement design and rehabilitation

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open graded friction course (OGFC)

  1. 1. PD&R
  2. 2. open gradation of aggregate lacks the mid-sized aggregates Dense graded. Gap graded Open graded
  3. 3. • Open-graded and gap-graded aggregate skeleton, nominal aggregate sizes of 12.5 mm or less, and higher than normal asphalt binder contents and are placed in thicknesses of less than 1 in. OGFC consists of an aggregate with relatively uniform grading and little or no fine aggregate and mineral filler
  4. 4. OGFC is composed of open porous gradation an internal structure of interconnected voids Minimum 18% air voids
  5. 5. Where to use? – High traffic to aid in cleaning mixture and justify added cost. – Areas with high frequency of wet weather accidents. – Balance against possible increase winter accidents. – Should not be used on short segments or bridge decks.
  6. 6. To provide high skid resistance and superior surface drainage OGFC is used. So the ride quality and safety is the main concern to use OGFC.
  7. 7. Their macro texture facilitates drainage of water from the tire/pavement interface, Reduce the potential for hydroplaning: by providing drainage channels for water to flow beneath the pavement surface
  8. 8. The sheet of surface water that causes hydroplaning is drained through the mix to the edge of the pavement. Graded Aggregate Base Subgrade Dense Graded Asphalt OGFC Surface Water
  9. 9. OGFC reduces the amount of splash and spray.
  10. 10. SKID RESISTANCE - Which pavement would you rather drive on in a storm?
  11. 11. Quiet, it's smooth, silent it feels like you're driving on sponge rubber
  12. 12. • Experiencing glare while driving is irritating and dangerous for all drivers. • visual acuity and peripheral vision are reduced as people get older. • Rain and night-time driving are the biggest contributors to accidents.
  13. 13. "Low textured" surfaces reflect more light and act like mirrors.
  14. 14. The color of the road surface affects daytime visibility. The lighter the surface color, the greater the potential for glare.
  15. 15. •Mitigation of Flushing and Bleeding: Its open void structure increases the pavement friction and allows absorption of free surface asphalt to overcome bleeding pavements.
  16. 16. Provide and maintain good high speed, frictional qualities
  17. 17. • durability and flexibility. • increases resistance to moisture damage. • increases resistance to bleeding. • reduces aging of the mix. • increased resistance to rutting. • noise level decreases. • the tolerance to higher stress and strains. • maintain viscoelastic properties for a much longer period Asphalt rubber OGFC
  18. 18. Winter Maintenance • Freeze early and last to thaw • Difficult to remove snow and ice • icy areas where tire chains, or snowplows are commonly used, OGFC has exhibited raveling distress. • May need special deicing chemicals • Require more treatments. • Possible issue on bridge decks • Problems with transitions to normal surface
  19. 19. The fines from mud and sand can fill the voids and reduce the drainage capacity of the OGFC. The OGFC must be kept clean to prevent clogging.
  20. 20. Measurements to improve its properties: • Production temperatures are increased to dry aggregate components and thus improve AC adhesion. • Coarser gradations and thicker layers are used to improve permeability. • Setting minimum percentages for air voids at 18%.
  21. 21. How to improve the performance of OGFC mixes • Polymer additives: – reduces premature oxidation. • Hydrated lime: – stripping agent • Rubberized asphalt: – improving durability • Mineral fibers: – increase the ability of asphalt to coat the aggregate
  22. 22. • Raveling due to softened binder from oil and fuel drippings. • Raveling due to oxidation and hardening of the binder. • Raveling due to lack of compaction or low asphalt content. • Delamination due to improper tack coat application OGFC overlays may exhibit the following distress modes:
  23. 23. • Shear failures in high stress areas. • Cracking due to fatigue. • Cracking due to reflection from below