USE OF REJUVENATORS (RECYCLING AGENTS) WITH RECYCLED MATERIALS. Transportation Short Course October 10, 2017

Transcription

1 USE OF REJUVENATORS (RECYCLING AGENTS) WITH RECYCLED MATERIALS Transportation Short Course October 10, 2017

2 MOTIVATION Reclaimed Asphalt Pavement (RAP) Workability Compaction Recycled Asphalt Shingles (RAS) Performance (cracking, raveling)

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6 HOW DO WE EXPRESS RAP AND RAS CONTENT? Traditionally, by % of total mix (10% RAP & 5% RAS) Recently, Recycled Binder Ratio or RBR (decimal) RBR = RAPBR + RASBR = Pb RAP P RAP Pb total + Pb RAS P RAS Pb total

7 TxDOT ITEMS 340, 341, 344

8 RECYCLED BINDER RATIO (RBR) Advantages: RAPB & RASBR Weighted average of multiple components Disadvantages: Assumes 100% blending Proposed shorthand notation A/B D/E A = RAP % of total mix B = RAS % of total mix C = RAPBR (decimal) D = RASBR (decimal)

9 HOW CAN MORE RAP AND RAS BE USED IN SURFACE MIXTURES? RAP Virgin Binder Recycling Agents Rejuvenated Mixture RAS Virgin Aggregates Rejuvenated Blend

10 WHAT ARE RECYCLING AGENTS? Chemical products added to recycled asphalt mixtures To reduce mixture stiffness (asphaltene to maltene ratio) To improve the low-temperature and high-temperature PG Other benefits: better workability, better compaction, etc.

11 WHAT TYPES OF RECYCLING AGENTS ARE AVAILABLE?

12 S DArea (a.u.) h* at 15ᵒC and 10 rad/s (Pa.s) HOW TO SELECT A RECYCLING AGENT? Chemistry (FT-IR) Rheology (DSR) 60 RTFO PAV 20 PAV 40 1.E+06 Original RTFO PAV 20 PAV E E+04 1.E+03 1.E+02 1.E+01 0 T1 T2 A1 V2 V1 B 1.E+00 T1 A1 V2 B RA with smallest D FT-IR registered minimal D in rheology T1 w/ greatest D in rheology & among highest D FT-IR

13 HOW TO SELECT A RECYCLING AGENT? RA with smallest D FT-IR registered minimal D in rheology T1 w/ greatest D in rheology & among highest D FT-IR

14 HOW MUCH RECYCLING AGENT SHOULD I ADD TO THE MIXTURE? High-Temp PG (DSR) Unaged RTFO aged Low-Temp PG (BBR) 20-hour PAV aged ΔT c = (T S T m )

15 High Temp. PG Grade ( ( C) Low Temp. PG PG Grade ( ( ( C) RECYCLING AGENT DOSAGE SELECTION DETAILED METHOD RECYCLED BLENDS: Virgin binder + Recycled binder (extracted & recovered) + a) No recycling agent b) Low dosage (2% or 5%) c) Higher dosage (~10%) Original G*/sin(d) Original RTFO G*/sin(d) G*/sin(d) PAV m-controlled RTFO G*/sin(d) PAV S-controlled 90 0 y = -1.7x y = -1.8x A (6.0,70) RBR (Tx (PG PG TxRAP TxMWAS T1) T) y = -1.3x B (6.0,-23) y = -0.7x DTc = -9.0 C Target Grade: Dosage (%) Blend Grade: Selected Dosage: 6.0%

16 Virgin Binder Continuous PG (⁰C) RAP Binder Continuous PG (⁰C) RECYCLING AGENT DOSAGE SELECTION QUICK METHOD RECYCLED MATERIALS: Virgin binder Recycled binder (extracted & recovered) No recycled blends High-Temp PG only Unaged only WI PG WI RAP and WI PG WI RAP RBR Measured Continuous PGH 0.31 RBR Measured Continuous PGH 0.5 RBR

17 RECYCLING AGENT DOSAGE SELECTION QUICK METHOD Estimate the High-Temp PG of the blend PGH Blend = RAP BR PGH RAP + (RAS BR PGH RAS ) + (B BR PGH Base ) Estimate the recycling agent dosage Recycling Agent (%) = PGH Blend PGH Target / slope rate Recycling Agent (%) = PGH Blend PGH Target / 1. 72

18 WHAT ABOUT BLENDING? Most DOTs assume 100% RAP/RAS binder blending In reality PARTIAL BLENDING 100% Blending Perfect Blending 0% Blending Black Rock

19 Binder Blending Binder Blending RAP binder content after mixing with virgin binder WHAT FACTORS AFFECT BLENDING? 8% 7% 6% 5% 4% 3% Artificial RAP 0% Blending 100% Blending 5.11% 4.27% 4.50% 6.01% 100% 80% RAP RAP+RA (added to the binder) RAP+RA (added to the RAP) Stiffer RAP yielded lower binder blending 73.4% 75.6% 86.9% 2% 100% 80% 60% RAP 1 RAP 2 RAP 3 RAP % 86.1% 67.5% 60% 40% 40.8% 43.7% 53.0% 40% 40.1% 20% 20% 0% 0% RAP 1 RAP 2 RAP 3 RAP 4 High Temp PG RAP aging TX RAP NH RAP

20 Binder Blending Binder Blending RAP binder content after mixing with virgin binder WHAT FACTORS AFFECT BLENDING? 8% 7% 6% 5% 4% 3% Artificial RAP 0% Blending 100% Blending 5.11% 4.27% 4.50% 6.01% 100% 80% RAP RAP+RA (added to the binder) RAP+RA (added to the RAP) Marginal increase when the recycling agent was added to the binder 73.4% 75.6% 86.9% 2% 100% 80% 60% RAP 1 RAP 2 RAP 3 RAP % 86.1% 67.5% 60% 40% 40.8% 43.7% 53.0% 40% 40.1% 20% 20% 0% 0% RAP 1 RAP 2 RAP 3 RAP 4 High Temp PG RAP aging TX RAP NH RAP

21 Binder Blending Binder Blending RAP binder content after mixing with virgin binder WHAT FACTORS AFFECT BLENDING? 8% 7% 6% 5% 4% 3% Artificial RAP 0% Blending 100% Blending 5.11% 4.27% 4.50% 6.01% 100% 80% RAP RAP+RA (added to the binder) RAP+RA (added to the RAP) Higher blending when recycling agent was added to the RAP 73.4% 75.6% 86.9% 2% 100% 80% 60% RAP 1 RAP 2 RAP 3 RAP % 86.1% 67.5% 60% 40% 40.8% 43.7% 53.0% 40% 40.1% 20% 20% 0% 0% RAP 1 RAP 2 RAP 3 RAP 4 High Temp PG RAP aging TX RAP NH RAP

22 RAP CHARACTERISTICS Source PG Continuous Continuous High-Temp PG ( C) Low-Temp PG ( C) ΔT c ( C) Texas Indiana Nevada New Hampshire Wisconsin Delaware

23 TAKEAWAYS There is a push to increase the amount of recycled materials in asphalt mixtures. But, construction and performance issues still exist. It is possible to increase the amount of recycled materials by incorporating recycling agents. There are many recycling agents currently available and not a standard way of selecting the right one.

24 TAKEAWAYS There are ways of estimating the recycling agent dosage with minimal testing. Partial blending occurs between the recycled materials binder and the virgin binder in the mixture. Degree of blending depends on the characteristics of the recycled materials (aging) and how the recycling agent is added to the mixture.

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26 THANK YOU! Amy Epps Martin (979) Edith Arámbula Mercado (979)