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1 Design Consideration of Asphalt Mixtures Containing RAP and/or RAS: Impact of Recycling Agents Louay N. Mohammad Sam Cooper, Jr. Department of Civil and Environmental Engineering LA Transportation Research Center Louisiana State University 2014 SEAUPG Annual Meeting Nashville, Tennessee November 17 20, 2014 Presentation Outline Background Objective/Scope Methodology Mix experiment Binder Experiment Results Summary/Conclusions 1

2 Background Practice of utilizing RAP and/or RAS in new asphalt mixtures has increased in recent years economic and environmental benefits RAP has most widely used materials Wearing Course: 15% Binder Course: 20% Base Course: 30% RAS has emerged as a material of interest to the paving community RAP and/or RAS valuable components in asphalt mixtures With increased demand and limited supply of aggregate and binder Potential benefits are high on use high percentages of RAP state agencies have not proceeded to use high percentages of RAP on their roadways non-uniformity of RAP materials agency s lack of confidence in the long term performance data and specifications. problem is further augmented when RAS is used in conjunction with RAP Sustainability Development that meets the needs of the present without compromising the ability of future generations to meet their own needs Economical Sustainability Balanced cost-revenue relationship Environmental Sustainability Friendly to the ecosystems Minimize use of natural resources Reduce energy consumption Reduce greenhouse gas emissions Social Sustainability: Materials Performance Better or same performance Meet society s needs 2

3 Asphalt binder 18 to 30% Mineral matter Recycles Asphalt Shingles 40 to 60% granules and fillers Fibers 8 to 12% Recycles Asphalt Shingles Supply (US) 10M: Post Consumer 01M: Manufactures Waste Benefits Sustainability Partial aggregate and binder replacement Prevent landfilling of valuable resource Improved rut resistance* Concerns Consistency of asphalt content Availability of the asphalt binder Quality of the asphalt binder Performance Intermediate and low temperature Dale Rand, TXDOT CMRA Webinar 1/13/11 shingles/ off/shingle/ 3

4 Typical Asphalt Mixture Design Volumetrics Voids in the Total Mix, VTM Voids in the Mineral Aggregate, VMA Voids Filled with Asphalt, VFA Densification Stages during lab compaction process VOLUME air asphalt MASS Total Volume aggregate aggregate Total Mass Use of RAS in HMA/WMA? AASHTO MP AASHTO MP Use of RAS as an Additive in Hot Mix Asphalt (Asphalt) Provides Standard definitions for RAS Process RAS 100% passing 12.5 mm sieve Allows blending of RAS with fine aggregate Prevent agglomeration Addresses deleterious materials 4

5 How to incorporate RAS in HMA/WMA? AASHTO PP53 AASHTO PP Standard Practice for Design Considerations When Using RAS in Asphalt Mixtures Design Considerations When Using RAS in Asphalt Mixtures Determining the Shingle Aggregate Gradation and Specific Gravity Determining Adjustment to the New Asphalt Binder Grade RAS asphalt availability factor is Objective Evaluate the high, intermediate, and low temperature laboratory performance conventional asphalt mixtures mixtures containing RAP and/or RAS Effect of recycling agents (RAs) 5

6 Scope 12.5 mm Asphalt Mixture RAS: Post Consumer Binder: PG 70 22M Mix ID Mix Code RAP RAS Reccling Agent Mix 1 70CO 0 0 None Mix 2 70PG5P 0 5 None Mix 3 52PG5P RA PG Mix 4 70PG5P RA % V. D. O. Mix 5 70PG5P RA % N.O. Mix 6 70PG5P15RAP RA (0.75% + 5%) V. D. O. Scope 12.5 mm Asphalt Mixture RAS: Post Consumer Binder: PG 70 22M Mix ID Mix Code RAP RAS Reccling Agent Mix 1 70CO 0 0 None Mix 2 70PG5P 0 5 None Mix 3 52PG5P RA PG Mix 4 70PG5P RA % V. D. O. Mix 5 70PG5P RA % N.O. Mix 6 70PG5P15RAP RA (0.75% + 5%) V. D. O. 6

7 Scope 12.5 mm Asphalt Mixture RAS: Post Consumer Binder: PG 70 22M Mix ID Mix Code RAP RAS Recycling Agent Mix 1 70CO 0 0 None Mix 2 70PG5P 0 5 None Mix 3 52PG5P RA PG Mix 4 70PG5P RA % V. D. O. Mix 5 70PG5P RA % N.O. Mix 6 70PG5P15RAP RA (0.75% + 5%) V. D. O. The Experiment Design mixture with no RAS and/or RAS Calculate OAC VMA, VTM Add RAS (W/O and With Recycling Agents) Calculate OAC VMA and VTM similar to conventional mix Binder replacement Add RAP/RAS + Recycling Agents Calculate OAC VMA and VTM similar to conventional mix Binder replacement 7

8 Sample Preparation Design Consideration OAC=5.3% No Recycling Agent Asphalt Binder Content, % RAS Binder Virgin Binder 46% 100% 43% 100% 0.0 Mix 1 (No RAS) Mixture Type Available RAS Binder = 26 * 5% RAS = 1.3 Mix 1 = 70CO 8

9 Design Consideration OAC=5.3% No Recycling Agent (RAS) Virgin Binder ~ 90% Asphalt Binder Content, % RAS Binder Virgin Binder % % Mix 1 (No RAS) Mix 2 B Mix 2 A Available PCWS RAS Binder = 28% * 0.05 = 1.4% Available Binder Factor = (0.5/1.4)*100 36% Mixture Type Mix 1 = 70CO Mix 2 = 70PG5P Mixture Design Concerns Recycled binder Ratio (RBR) Recycled binder content / total binder content Design binder content Mix with No RAS 5.3% binder Scenario 1 (100% availability) RBR = 1.40 / 5.3 = 0.26 Scenario 2 ( < 100% availability ) RBR = 0.50 / 5.3 = 0.09 Increase the RBR Recycling Agents Softening Rejuvenators RBR = Ensuring structural performance + volumetrics high temperature intermediate temperature low temperature performance moisture damage resistance RAS Type %RAS Total AC Content %RAS in Mix Design %RAS AC Binder Available PCWS

10 Mixture Design Concerns Classes of Recycling Agents REJUVENATING AGENTS RAS Type %RAS Total AC Content %RAS in Mix Design %RAS AC Binder Available PCWS SOFTENING AGENTS Lube Extracts Extender Oils (aromatic oils) Anti-Stripping Agent Naphthenic Oil (RA-3) Vegetable Derived Oils (RA-2) Purpose of Recycling Agents Softening Agents lower the viscosity of the aged binder Rejuvenators Lube Stock Lubricating or Crankcase Oil Slurry Oil Asphalt Flux Oils Soft Asphalt Binders (RA-1) help restore physical and chemical properties of aged binder contain a high proportion of maltene constituents Mixture Design Concerns Classes of Recycling Agents REJUVENATING AGENTS Purpose of Recycling Agents Softening Agents lower the viscosity of the aged binder Rejuvenators RAS Type %RAS Total AC Content help restore physical and chemical properties of aged binder contain a high proportion of maltene constituents %RAS in Mix Design %RAS AC Binder Available PCWS SOFTENING AGENTS Lube Extracts Lube Stock Extender Oils (aromatic oils) Lubricating or Crankcase Oil Anti-Stripping Agent Slurry Oil Naphthenic Oil RA 3 Asphalt Flux Oils Vegetable Derived Oils RA 2 Soft Asphalt Binders -- RA 1 10

11 Design Consideration OAC=5.3% Recycling Agent (RAS, RA) Asphalt Binder Content, % Mix 1 (No RAS) Available PCWS RAS Binder = 28% * 0.05 = 1.4% Actual Recycle Binder Factor = (1.2/1.4)*100 86% Mixture Type Mix 1 = 70CO Design Consideration OAC=5.3% Recycling Agent (RAS, RA) 6.0 RA Asphalt Binder Content, % % 100% Mix 1 (No RAS) Mix 3 B Mix 3 A Mixture Type Available PCWS RAS Binder = 28% * 0.05 = 1.4% Actual Recycle Binder Factor = (1.2/1.4)*100 86% Mix 1 = 70CO Mix 3 = 52PG5P RA 1 11

12 Design Consideration OAC=5.3% Recycling Agent (RAS, RA) 6.0 RA 1 RA 2 Asphalt Binder Content, % % 100% 100% % Mix 1 (No RAS) Mix 3 B Mix 3 A Mix 4 B Mix 4 A Available PCWS RAS Binder = 28% * 0.05 = 1.4% Actual Recycle Binder Factor = (1.2/1.4)*100 86% Mixture Type Mix 1 = 70CO Mix 3 = 52PG5P RA 1 Mix 4 = 70PG5P RA 2 Design Consideration OAC=5.3% Recycling Agent (RAS, RA) 6.0 Virgin Binder: 87%, 74%, 77% RA 1 RA 2 RA 3 Asphalt Binder Content, % % 100% 100% 100% 86% 100% 0.0 Mix 1 (No RAS0 Mix 3 B Mix 3 A Mix 4 B Mix 4 A Mix 5 B Mix 5 A Available PCWS RAS Binder = 28% * 0.05 = 1.4% Actual Recycle Binder Factor = (1.2/1.4)*100 86% Mixture Type Mix 1 = 70CO Mix 3 = 52PG5P RA 1 Mix 4 = 70PG5P RA 2 Mix 5 = 70PG5P RA 3 12

13 Design Consideration OAC=5.3% Recycling Agent (RAP and RAS RA) RA 2 Virgin Binder: 58% Asphalt Binder Content, % % 100% 0.0 Mix 1 (No RAP/RAS) Mix 6 B Mix 6 A Available PCWS RAS Binder = 28% * 0.05 = 1.4% Mixture Type Available RAP Binder = 5.5% * 0.15 = 0.8% Total Recycle Binder Available = 1.4% (RAS) + 0.8% (RAP) = 2.2% Mix 6 Recycle Binder Ratio = 2.2/5.3 = 41.5% Mix 1 = 70CO (No RAP/RAS) Mix 6 = 70PG5P15RAP RA 2 air Effect of RAs on Recycled Binder Ratio asphalt 0.45 No Recycling Agents Recycling Agents aggregate aggregate Recycle Binder Ratio Mix 1 = 70CO Mix 2 = 70PG5P Mix 3 = 52PG5P RA 1 Mix 4 = 70PG5P RA 2 Mix 5 = 70PG5P RA 3 Mix 6 = 70PG5P15RAP RA Mix 1 No RAP/RAS Mix 2 B 5% RAS Mix 3 B 5% RAS Mix 4 B 5% RAS Mix 5 B 5% RAS Mix 6 B 5% RAS + 15%RAP RA 1 RA 2 RA 3 RA 2 Mixture type 13

14 Laboratory Performance Mixture Testing Increase Use of Reclaimed materials Mechanistic Tests Pavement Performance Intermediate Temperature Fracture/Fatigue High Temperature Permanent deformation Features Based on measuring fundamental properties Simple, repeatable, easily-calibrated, quick, not requiring highly-trained personnel, Can utilize low-cost equipment. Sensitive to subtle changes in mixture properties Laboratory Performance Tests High temperature Performance Loaded Wheel Tracking Test Intermediate temperature Performance Semi Circular Bending Test Low temperature performance Thermal Stress Restrained Specimen Test Triplicates VTM: 7 ±0.5% 14

15 SEAUPG Nashville, Tennessee 15

16 Thermal Stress Restrained Specimen Test AASHTO TP10 93 Apply thermal loading 10 ±1 C per hour until specimen fracture Continuously record Load, displacement, temperature Determine the low temperature cracking susceptibility of asphalt concrete Determine temperature and tensile strength at fracture Results 16

17 Loaded Wheel Tracking Test Results, 50 C RAP and/or RAS No Recycling Agents Recycling Agents Rut Depth, 20K Passes, mm Mix 1 = 70CO Mix 2 = 70PG5P Mix 3 = 52PG5P RA 1 Mix 4 = 70PG5P RA 2 Mix 5 = 70PG5P RA 3 Mix 6 = 70PG5P15RAP RA Mix 1 No RAP/RAS Mix 2 B 5RAS Mix 3 B 5RAS Mixture type Mix 4 B 5RAS Mix 5 B 5RAS Mix 6 B 15RAP+5RAS RA 1 RA 2 RA 3 RA 2 Semi Circular Bend Test Results, 25 C RAP and/or RAS 0.6 No Recycling Agents Recycling Agents Mix 1 = 70CO Mix 2 = 70PG5P Mix 3 = 52PG5P RA 1 Mix 4 = 70PG5P RA 2 Mix 5 = 70PG5P RA 3 Mix 6 = 70PG5P15RAP RA 2 J c, KJ/m RBR = 0 % Mix 1 No RAP/RAS RBR = 9.4 % Mix 2 B 5RAS RBR = 13.2 % Mix 3 B 5RAS Mixture type RBR = 26.4 % Mix 4 B 5RAS RBR = 22.6 % Mix 5 B 5RAS RBR = 41.5% Mix 6 B 15RAP+5RAS RA 1 RA 2 RA 3 RA 2 17

18 Thermal Stress Restrained Specimen Test RAP and/or RAS 50.0 No Recycling Agents Recycling Agents 45.0 Fracture Temperature, C Mix 1 = 70CO Mix 2 = 70PG5P Mix 3 = 52PG5P RA 1 Mix 4 = 70PG5P RA 2 Mix 5 = 70PG5P RA 3 Mix 6 = 70PG5P15RAP RA RBR = 0 % Mix 1 No RAP/RAS RBR = 9.4 % Mix 2 B 5RAS RBR = 13.2 % Mix 3 B Mix 4 B Mix 5 B Mix 6 B 5RAS 5RAS 5RAS 15RAP/5RAS RA 1 RA 2 RA 3 RA 2 Mixture type RBR = 26.4 % RBR = 22.6 % RBR = 41.5% Thermal Stress Restrained Specimen Test RAP and/or RAS Fracture Temperature, C Mix 1 = 70CO Mix 2 = 70PG5P Mix 3 = 52PG5P RA 1 Mix 4 = 70PG5P RA 2 Mix 5 = 70PG5P RA 3 Mix 6 = 70PG5P15RAP RA No Recycling Agents RBR = 0 % Mix 1 No RAP/RAS 16 RBR = 9.4 % Mix 2 B 5RAS RBR = 13.2 % Mixture type Recycling Agents RBR = 26.4 % RBR = 22.6 % RBR = 41.5% Mix 3 B Mix 4 B Mix 5 B Mix 6 B 5RAS 5RAS 5RAS 15RAP/5RAS RA 1 RA 2 RA 3 RA

19 Objective Binder experiment Correlate the molecular structure of asphalt binders of conventional asphalt mixtures through chemical analysis as well as of mixtures containing RAS with their cracking potential. Gel Permeation Chromatography (GPC) Fourier Transform Infrared Spectroscopy (FTIR) Investigation of the Impact Recycling Agent Concern with mixture performance NRA vs RA Chemical analysis Gel Permeation Chromatography 19

20 Summary / Conclusions Laboratory performance evaluation of asphalt mixtures containing RAS Design / Durability Design of Asphalt Mixtures Availability of binder from RAS AASHTO PP78 over-estimates the actual shingle asphalt binder availability factor 36% - 46% -- W/O RA 86% - 100% -- RAs Volumetric-based design Not sufficient Compliment with mechanistic tests Performance related Criteria Summary / Conclusions High Temperature (LWT) All mixtures performed well Addition of RAS/RAP increased mixtures resistance to rutting Mixture with RA-1 had highest rut depth (7mm,20K passes) Intermediate Temperature (SCB) No adverse effects Mixes 1 and 2 (NRAs) Design approach considered Lower Jc values Mixes 4 6 (RAs) RAS: Jc increased : RA-1 to RA-2 to RA-3 RAP/RAS: addition of RAP has a positive effect RAP contained SBS Low Temperature (TSRST) No adverse effects Mixes 1 and 2 (NRAs) Reduction in Fracture temperature mixes 4 6 (RAs) Fracture temperature did track the low temp PG grade pf extracted binder 20

21 Summary / Conclusions Effect of Recycling Agents Use of soft binder (RA 1) did not improve fracture properties. RA 3 performed better than RA 2 at intermediate temp. RA 2 enhanced extraction of asphaltenes from RAS. Molecular fractionation through GPC of RAS samples confirmed the presence of associated asphaltenes in great concentrations. High concentrations of HMW asphaltenes decrease the fracture resistance of the asphalt mixtures Presence of SBS additives enhances the compatibility with the HMW asphaltenes. Use of RAs evaluated did not reduce the concentration of the highly associated asphaltenes Did not improve the cracking resistance Thoughts! Is 100% blending of available RAS binder desired? Addition of additives that enhances the compatibility with the HMW asphaltenes Candidate SBS 21

22 T H A N K Y O U 22