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Bay area tech_committee_mtg_2014_02_04-haiping_zhou

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Presentation b Haiping Zhau of Caltrans at the CalAPA Bay Area Technical Committee meeting Feb. 4, 2014

Presentation b Haiping Zhau of Caltrans at the CalAPA Bay Area Technical Committee meeting Feb. 4, 2014

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  • 1. Report of Optimum Binder Content and RAP Binder Replacement Dry Weight of Aggregate (DWA) versus Total Weight of Mix (TWM) RAP Binder Replacement Calculation For Bay Area Tech Committee Meeting - Feb. 4, 2014
  • 2. DWA vs. TWM - Quick Answer From DWA From DWA 3.00 3.50 4.00 4.50 5.00 5.50 6.00 6.50 6 50 7.00 7.50 8.00 8.50 9.00 To TWM To TWM 2.91 3.38 3.85 4.31 4.76 5.21 5.66 6.10 6 10 6.54 6.98 7.41 7.83 8.26 e.g., 5.75% DWA => 5.44% TWM
  • 3. Footnote • • • • • • • • • • Va = Volume of air voids, percent Vb = Total volume of asphalt binder, percent Vba = Volume of absorbed asphalt binder, percent Vbe = Volume of effective asphalt binder, percent V l f ff ti h lt bi d t VFA = Volume of voids filled with asphalt binder, percent VMA = Volume of voids in mineral aggregate, percent VMA = Volume of voids in mineral aggregate percent Vmb = Bulk volume of compacted mix Vmm = Voidless volume of paving mix p g Vsb = Bulk volume of mineral aggregate (for bulk specific gravity) Vse = Effective volume of mineral aggregate
  • 4. Example E ample
  • 5. Example Using the Matrix Total W i ht f By Dry Weight f By Total W i ht T t l Weight of B D W i ht of B T t l Weight Mix, g Aggregate of Mix 9 Weight f W i ht of Aggregate, g C E D=E/(1+E) A=C*D B=C-A 1200.0 0.0600 0.0566 67.9 1132.1 Weight of Asphalt, g Weight of Aggregate, g Total Weight of By Total Weight By Dry Weight of Mix, g of Mix Aggregate 8 Weight f W i ht of Asphalt, g C D E=D/(1-D) A=C*D B=C*(1-D) 1200.0 0.0600 0.0638 72.0 1128.0 1200.0 0.0566 0.0600 67.9 1132.1
  • 6. More Examples Total Weight of By Dry Weight of By Total Weight Mix, g Aggregate of Mix Weight of Asphalt, g Weight of Aggregate, g C E D=E/(1+E) D E/(1 E) A=C*D A C*D B=C-A B CA 1200.0 4.50% 4.31% 51.7 1148.3 1200.0 5.00% 4.76% 57.1 1142.9 1200.0 5.50% 5.21% 62.6 1137.4 1200.0 6.00% 5.66% 67.9 1132.1 1200.0 6.50% 6.10% 73.2 1126.8
  • 7. RAP Use: % RAP vs. BR • Use RAP in HMA based on RAP percentage by  p g y weight of aggregate or by weight of the total  mix.  • The use of RAP can reduce the need for virgin The use of RAP can reduce the need for virgin  binder and impact the binder properties, thus  RAP may also be specified according to  percentage binder replacement (BR).  • The percentage of RAP used in the mix can be  selected by determining the contribution of the  selected by determining the contribution of the RAP binder toward the total binder in the mix by  weight. 
  • 8. Section 39 “For HMA mixtures using RAP the For HMA mixtures using RAP, the  maximum binder replacement is 25.0  percent for surface course and 40.0  f f d p percent for lower courses.”
  • 9. Binder Replacement (BR)
  • 10. CT - Binder Replacement (BR) CT: The amount of total binder replaced by  CT: The amount of total binder replaced by binder in RAP is computed as follows: A  (1  C ) BR  1  A B C Where: A = binder content from RAP, in decimal B = total RAP in total mix, in decimal C = total binder content in total mix, in decimal
  • 11. CT - Example 1
  • 12. CT - Example 2 50% 45% 40% 35% 30% 25% 20% 15% 10% 5% 0% Binder in RAP Binder in RAP 7.0% 6.5% BR, % = BR % = 25.0 6.0% 5.5% 5.0% 4.5% 4.0% 4% 5% 6% 7% Total Binder in Mix, % % RAP Bind der Replacem ment, % % RAP = 25.0 50% 45% 40% 35% 30% 25% 20% 15% 10% 5% 0% Binder in RAP 4.0% 4.5% 5.0% 5.5% 6.0% 6.5% 7.0% 4% 5% 6% 7% Total Binder in Mix, %
  • 13. References • Caltrans Construction Practice Directive (CPD) 13‐4 Caltrans Construction Practice Directive (CPD) 13 4 • California Test 367 ‐ Method of Test for Determining  Optimum Bitumen Content (OBC), Nov. 2010 Optimum Bitumen Content (OBC) Nov 2010 • Caltrans, Section 39, Proposed 2015 SS • FHWA R l i d A h lt P FHWA, Reclaimed Asphalt Pavement in Asphalt  t i A h lt Mixtures: State of The Practice.  http://www.fhwa.dot.gov/publications/research/in http://www fhwa dot gov/publications/research/in frastructure/pavements/11021/003.cfm