Tanya Nash State Materials Office 1 Asphalt Overview Asphalt CQC (Specs 334 and 337) Miscellaneous Information, Specification Changes, and Research 2 3 1” Friction Course 4” Structural Course 8” Base (Limerock or Asphalt) 12” Stabilized Subgrade 4 Blend of: Asphalt binder (6%) Aggregate (94%) Method of Design Hubbard Field (…1960’s) Marshall (1960’s – 1998) Superpave (1998 ….) Produced through an asphalt plant 5 “Binds” the aggregate together. Provides….. the “glue.” lubrication for compaction. durability (resistance to cracking). The most expensive part of an asphalt mix. 7 Where does asphalt come from? Crude Oil 9 How does crude get here? Pipeline Ship 10 Oil Refinery 11 12 CRUDE OIL DISTILLATION (TYPICAL) 1000 ASPHALT TEMPERATURE oF 800 GAS OIL 600 DIESEL KEROSINE 400 GASOLINE 200 GAS 0 0 20 40 60 PERCENT DISTILLED 80 100 13 Grading system based on climate PG 67-22 Performance Grade Average 7-day max pavement design temp Min pavement design temp 14 Florida: PG 67-22 (153°F to -8°F) Old AC-30 / 60 pen Actually PG 67-10 Minnesota: Arizona: PG 58-34 (136°F to -29°F) PG 70-10 (158°F to 14°F) 15 PG 67-22 – Standard Grade <20% Reclaimed Asphalt Pavement (RAP) PG 64-22 20 – 29% RAP Recycling Agent (RA) ≥ 30% RAP PG 76-22 PG 67-22 base asphalt + SB or SBS Polymer ≤ 20% RAP 16 Asphalt Rubber Binders ARB-5 - Dense graded friction course (≤ 20% RAP). ARB-12 - Open graded friction course (no RAP). ARB-20 - Asphalt Rubber Membrane Interlayer (ARMI). No Rap allowed. 17 Structural Courses (334) Superpave SP-9.5, SP-12.5, SP-19.0 Friction Courses (337) FC-9.5, FC-12.5, FC-5 (OGFC) Base Courses (234) B-12.5 Other Asphalt Treated Permeable Base (ATPB) ▪ Used under PCC pavements 18 Purpose: Load carrying portion of pavement Superpave Mix Design Three mixes based on max aggregate sizes 9.5 mm (SP-9.5) 12.5 mm (SP-12.5) 19.0 mm (SP-19.0) Five Traffic Levels (A-E) Based on 18,000 lb. Equivalent Single Axle Loads (ESAL’s) Low traffic = A, High traffic = E Concept: Put the right mix on the right road Higher traffic level is not necessarily better 19 15,000 lb 6,000 lb 0.48 ESAL + 0.01 ESAL 34,000 lb 1.10 + = 34,000 lb 12,000lb 1.10 + 0.20 0.49 ESALs = 2.40 ESALs 20 ESALS come from planning Traffic Levels are found in the Contract Traffic Level ESAL’s A < 300,000 ESAL’s B 300,000 < 3 million ESAL’s C 3 million < 10 million ESAL’s D 10 million < 30 million ESAL’s E ≥ 30 million ESAL’s 21 3% 1% 19% D B C 40% TL-A TL-B TL-C TL-D TL-E 37% 22 Coarse mixes – More coarse aggregate than fine Higher density requirement Greater likelihood of being permeable Placed thicker Tough workability Fine mixes – More fine aggregate than coarse Similar to old FDOT Type S mixes Shown on the mix design 25 Fine graded SP-12.5 mix 27 Coarse graded SP-19.0 mix 28 Purpose: Provide a pavement surface with good tire/pavement friction. Required on all jobs with: Design Speed ≥35 mph, except rural 2-lane roads with 5-yr projected AADT of ≤3,000. Use polish resistant aggregate Oolitic limestone (Dade & Broward Counties) Granite (Georgia & Canada) Siliceous Wackestone (Canada) Shell rock (Palm Beach Co.) Use asphalt rubber binder (ARB) or PG76-22. 29 Good microtexture ▪ Function of the aggregate Superpave mixes: ▪ FC-9.5 (1” thick) ▪ FC-12.5 (1 ½” thick) ▪ Formerly called FC-6 100% oolite or 60% granite ▪ If granite, then can contain 20% RAP, otherwise no RAP. ARB-5 or PG 76-22 depending on traffic level. 30 Required on high speed multi-lane facilities. ▪ Design Speed ≥ 50 mph Good macrotexture. ▪ Minimize hydroplaning. FC-5 (3/4” to 7/8” thick) 100% friction approved aggregate (No RAP). ARB-12 or PG76-22. Stabilizing fibers (more asphalt, less draindown). Granite aggregate requires hydrated lime. 31 FC-5 Nassau County 32 Close-up FC-5 Macrotexture 33 B-12.5 Superpave Mix Traffic Level B May substitute an SP-12.5 It’s basically the same mix! 34 Questions/ Comments? 35