Rubberized Warm Mix Asphalt Mixtures Using Foaming Technology
Rubberized Warm Mix Asphalt Mixtures Using Foaming Technology Workshop on Recycled Materials in Infrastructure Applications
Punith V. Shivaprasad, Ph. D. Research Assistant Professor in the Glenn Department of Civil Engineering at Clemson University
Introduction on WMA Warm-mix asphalt allows the producers of asphalt material to lower the production temperatures at which the material is mixed and placed on the road
History on WMA • 1995-96 - First European experiments • 1997-99 – First pavements constructed in Europe • 2002 - NAPA Study Tour to Europe • 2003 - Featured at NAPA’s Annual Convention • 2004 – Demonstration at World of Asphalt – First U.S. field trials (Aspha-min) in FL and NC • 2005-06 – Numerous field trial, some “production” paving in MO – NCAT publishes research on Aspha-min, Sasobit, and Evotherm • 2007 – till date – FHWA Scan – AASHTO/NCHRP research projects underway
Major Research Projects from FHWA • NCHRP 9‐43 “Mix Design Practices for Warm Mix Asphalt” $500,000 • NCHRP 9‐47A “Engineering Properties, Emissions, and Field Performance” $900,000 • NCHRP 9‐49 “Performance of WMA Technologies: Stage I ‐ Moisture Susceptibility” $450,000 • NCHRP 9‐49A “Performance of WMA Technologies: Stage II ‐ Long‐Term Field Performance” $900,000 • NCHRP 9‐52 “Short‐Term Laboratory Conditioning of Asphalt Mixtures” $800,000 – includes short‐term laboratory conditioning of WMA mixtures for mix design and performance testing • NCHRP 9‐53 “Asphalt Foaming Characteristics for Warm Mix Asphalt Applications” $700,000 • Total – $4.25 Millions
Goals for Warm Mix Asphalt (WMA) • Use existing Hot Mix Asphalt plants • To meet existing standards for Hot Mix Asphalt specifications • Focus on dense graded mixes for wearing courses • WMA quality = Hot Mix Asphalt quality
Use of Recycled Materials in Asphalt Industry • Recycled materials can be a source of: - good-quality and cost-effective - benefit the environment by extending the life of limited natural resources - extending landfill life - using recycled materials can frequently improve materials performance - increased utilization of recycled materials would substantially increase the overall usage in asphalt pavements.
Major Byproducts and Recycled Materials Used in Asphalt Pavements • Crumb rubber • Roofing shingles • Reclaimed asphalt pavement
• Others: - Coal Fly Ash, Blast Furnace Slag, Sewage Sludge Ash; Steel Slag ;Sulfate Wastes; Waste Glass; Bag House Fines; Foundry Sand ; Kiln Dusts; Mineral Processing Wastes; MSW Combustor Ash; Nonferrous Slags; Quarry Byproducts
WMA Technologies
– Attractive technology
• • • • •
Mixing and compaction temperature Popularity longer paving seasons, longer hauling distances Ability to open the site to traffic sooner Reduced aging of the binder in mixtures and thus reduced cracking • Energy consumption & emissions • Save Money
– Technical issues
• Moisture Susceptibility • Rutting Susceptibility
Key Issues Needs to Addressed • Lowering temperatures (212-285°F) may not allow for proper drying of aggregates in asphalt mixtures • Presence of moisture could prevent binder and aggregate from adequately bonding and leading to moisture damage of the mixtures
• Reduced oxidative aging of the binder during production may increase the asphalt’s susceptibility to rutting • A lower high-temperature PG, in combination with increased, effective asphalt contents from lower asphalt absorption, would create asphalt mixtures that might be more prone to rutting
Rubber Modified Asphalt Using Foaming Technology • Objective – Determine applicability of crumb rubber addition to WMA and HWMA using foaming technology – Compare with conventional control mixtures
• Parameters – Crumb Rubber Size (~40 Mesh, Ambient Type) – Crumb Rubber Addition Rate (~10%) – Binder Type (PG 64-22) – Compaction Temperatures (4 Different Temp’s) – Aggregate Type (3 Types) – Recycled Asphalt Pavement (3 Types) – Moist aggregates
Mixing Process Using Foaming Technology for Rubber Modified Asphalt
Compaction Effort for Rubberized WMA Mixes 275F
80
245F
215F
185F
60 40 20
Aggregate A
Aggregate B
25% RAP
15% RAP
0% RAP
25% RAP
15% RAP
0% RAP
25% RAP
15% RAP
0 0% RAP
Gyrations for ITS Pills
100
(a) ITS Test Results
Aggregate C
ITS Mixture Type 275F
245F
215F
185F
80
60 40 20
Aggregate A
Aggregate B
APA Mixture Type
Aggregate C
25% RAP
15% RAP
0% RAP
25% RAP
15% RAP
0% RAP
25% RAP
15% RAP
0 0% RAP
(b) APA Test Results
Gyrations for APA Pills
100
Dry ITS (kPa)
ITS Test Results For Rubberized WMA 1000 900 800 700 600 500 400 300 200 100 0
275F
245F
215F
185F
(a) Dry Test Results
0% RAP 15% RAP 25% RAP 0% RAP 15% RAP 25% RAP 0% RAP 15% RAP 25% RAP Aggregate A
Aggregate B
Aggregate C
(b) Wet Test Results
Wet ITS (kPa)
Mixture Type 1000 900 800 700 600 500 400 300 200 100 0
275F
0% RAP
15% RAP 25% RAP Aggregate A
0% RAP
245F
15% RAP 25% RAP Aggregate B
Mixture Type
215F
0% RAP
185F
15% RAP 25% RAP Aggregate C
Tensile Strength Ratio (%)
Tensile Strength Test Results 140
275F
245F
215F
185F
120 100 80 60 40 20 0 0% RAP
15% RAP
25% RAP
0% RAP
Aggregate A
15% RAP
25% RAP
Aggregate B
0% RAP
15% RAP
25% RAP
Aggregate C
Mixture Type
TSR Test Results Aggregate A 0% 15% 25% CT (0F) RAP RAP RAP 275F 83 112 245F 89 105 215F 102 116 185F 98 129
Aggregate B 0% 15% 25% RAP RAP RAP 86 101 75 82 107 73 77 89 94 88 94 98
Aggregate C 0% 15% 25% RAP RAP RAP 75 83 89 82 82 91 88 67 76 90 67 81
Note: 0% RAP Tests are underway for Aggregate A
Preliminary Results for Rutting of Rubberized WMA for Different Compaction Temperatures Aggregate B CT (oF) Control 15% RAP 25% RAP
Dry Rut Depth (mm) 275F 5.3 4.0
Aggregate C CT (oF) Control 15% RAP 25% RAP
245F 5.4 5.5 4.0
215F 6.9 4.8
185F 6.1 4.6
Dry Rut Depth (mm) 275F 5.5 5.8 3.6
245F 5.2 6.4 4.7
215F 5.5 4.7 4.7
185F 5.6 5.4 5.1
Conclusions • With increasing compaction temperatures, the number of gyrations required to achieve target air voids (7%) decreases significantly for the selected aggregates • Based on the wet ITS results, with the addition of RAP, the resistance to moisture susceptibility of the rubberized WMA mixes is improved • For the selected aggregates based on the TSR results, mixes using aggregate C are more prone for moisture induced damage containing moist aggregates • With the increase in RAP content, improvement in resistance to rutting susceptibility of the rubberized WMA is observed for mixtures containing moist aggregates using foaming based technology
Acknowledgements South Carolina Department of Health and Environment Control (DHEC) and Asphalt Rubber Technology Service (ARTS) of Clemson University.
Thank You
Punith V. Shivaprasad, Ph. D. Research Assistant Professor in the Glenn Department of Civil Engineering at Clemson University
Introduction on WMA Warm-mix asphalt allows the producers of asphalt material to lower the production temperatures at which the material is mixed and placed on the road
History on WMA • 1995-96 - First European experiments • 1997-99 – First pavements constructed in Europe • 2002 - NAPA Study Tour to Europe • 2003 - Featured at NAPA’s Annual Convention • 2004 – Demonstration at World of Asphalt – First U.S. field trials (Aspha-min) in FL and NC • 2005-06 – Numerous field trial, some “production” paving in MO – NCAT publishes research on Aspha-min, Sasobit, and Evotherm • 2007 – till date – FHWA Scan – AASHTO/NCHRP research projects underway
Major Research Projects from FHWA • NCHRP 9‐43 “Mix Design Practices for Warm Mix Asphalt” $500,000 • NCHRP 9‐47A “Engineering Properties, Emissions, and Field Performance” $900,000 • NCHRP 9‐49 “Performance of WMA Technologies: Stage I ‐ Moisture Susceptibility” $450,000 • NCHRP 9‐49A “Performance of WMA Technologies: Stage II ‐ Long‐Term Field Performance” $900,000 • NCHRP 9‐52 “Short‐Term Laboratory Conditioning of Asphalt Mixtures” $800,000 – includes short‐term laboratory conditioning of WMA mixtures for mix design and performance testing • NCHRP 9‐53 “Asphalt Foaming Characteristics for Warm Mix Asphalt Applications” $700,000 • Total – $4.25 Millions
Goals for Warm Mix Asphalt (WMA) • Use existing Hot Mix Asphalt plants • To meet existing standards for Hot Mix Asphalt specifications • Focus on dense graded mixes for wearing courses • WMA quality = Hot Mix Asphalt quality
Use of Recycled Materials in Asphalt Industry • Recycled materials can be a source of: - good-quality and cost-effective - benefit the environment by extending the life of limited natural resources - extending landfill life - using recycled materials can frequently improve materials performance - increased utilization of recycled materials would substantially increase the overall usage in asphalt pavements.
Major Byproducts and Recycled Materials Used in Asphalt Pavements • Crumb rubber • Roofing shingles • Reclaimed asphalt pavement
• Others: - Coal Fly Ash, Blast Furnace Slag, Sewage Sludge Ash; Steel Slag ;Sulfate Wastes; Waste Glass; Bag House Fines; Foundry Sand ; Kiln Dusts; Mineral Processing Wastes; MSW Combustor Ash; Nonferrous Slags; Quarry Byproducts
WMA Technologies
– Attractive technology
• • • • •
Mixing and compaction temperature Popularity longer paving seasons, longer hauling distances Ability to open the site to traffic sooner Reduced aging of the binder in mixtures and thus reduced cracking • Energy consumption & emissions • Save Money
– Technical issues
• Moisture Susceptibility • Rutting Susceptibility
Key Issues Needs to Addressed • Lowering temperatures (212-285°F) may not allow for proper drying of aggregates in asphalt mixtures • Presence of moisture could prevent binder and aggregate from adequately bonding and leading to moisture damage of the mixtures
• Reduced oxidative aging of the binder during production may increase the asphalt’s susceptibility to rutting • A lower high-temperature PG, in combination with increased, effective asphalt contents from lower asphalt absorption, would create asphalt mixtures that might be more prone to rutting
Rubber Modified Asphalt Using Foaming Technology • Objective – Determine applicability of crumb rubber addition to WMA and HWMA using foaming technology – Compare with conventional control mixtures
• Parameters – Crumb Rubber Size (~40 Mesh, Ambient Type) – Crumb Rubber Addition Rate (~10%) – Binder Type (PG 64-22) – Compaction Temperatures (4 Different Temp’s) – Aggregate Type (3 Types) – Recycled Asphalt Pavement (3 Types) – Moist aggregates
Mixing Process Using Foaming Technology for Rubber Modified Asphalt
Compaction Effort for Rubberized WMA Mixes 275F
80
245F
215F
185F
60 40 20
Aggregate A
Aggregate B
25% RAP
15% RAP
0% RAP
25% RAP
15% RAP
0% RAP
25% RAP
15% RAP
0 0% RAP
Gyrations for ITS Pills
100
(a) ITS Test Results
Aggregate C
ITS Mixture Type 275F
245F
215F
185F
80
60 40 20
Aggregate A
Aggregate B
APA Mixture Type
Aggregate C
25% RAP
15% RAP
0% RAP
25% RAP
15% RAP
0% RAP
25% RAP
15% RAP
0 0% RAP
(b) APA Test Results
Gyrations for APA Pills
100
Dry ITS (kPa)
ITS Test Results For Rubberized WMA 1000 900 800 700 600 500 400 300 200 100 0
275F
245F
215F
185F
(a) Dry Test Results
0% RAP 15% RAP 25% RAP 0% RAP 15% RAP 25% RAP 0% RAP 15% RAP 25% RAP Aggregate A
Aggregate B
Aggregate C
(b) Wet Test Results
Wet ITS (kPa)
Mixture Type 1000 900 800 700 600 500 400 300 200 100 0
275F
0% RAP
15% RAP 25% RAP Aggregate A
0% RAP
245F
15% RAP 25% RAP Aggregate B
Mixture Type
215F
0% RAP
185F
15% RAP 25% RAP Aggregate C
Tensile Strength Ratio (%)
Tensile Strength Test Results 140
275F
245F
215F
185F
120 100 80 60 40 20 0 0% RAP
15% RAP
25% RAP
0% RAP
Aggregate A
15% RAP
25% RAP
Aggregate B
0% RAP
15% RAP
25% RAP
Aggregate C
Mixture Type
TSR Test Results Aggregate A 0% 15% 25% CT (0F) RAP RAP RAP 275F 83 112 245F 89 105 215F 102 116 185F 98 129
Aggregate B 0% 15% 25% RAP RAP RAP 86 101 75 82 107 73 77 89 94 88 94 98
Aggregate C 0% 15% 25% RAP RAP RAP 75 83 89 82 82 91 88 67 76 90 67 81
Note: 0% RAP Tests are underway for Aggregate A
Preliminary Results for Rutting of Rubberized WMA for Different Compaction Temperatures Aggregate B CT (oF) Control 15% RAP 25% RAP
Dry Rut Depth (mm) 275F 5.3 4.0
Aggregate C CT (oF) Control 15% RAP 25% RAP
245F 5.4 5.5 4.0
215F 6.9 4.8
185F 6.1 4.6
Dry Rut Depth (mm) 275F 5.5 5.8 3.6
245F 5.2 6.4 4.7
215F 5.5 4.7 4.7
185F 5.6 5.4 5.1
Conclusions • With increasing compaction temperatures, the number of gyrations required to achieve target air voids (7%) decreases significantly for the selected aggregates • Based on the wet ITS results, with the addition of RAP, the resistance to moisture susceptibility of the rubberized WMA mixes is improved • For the selected aggregates based on the TSR results, mixes using aggregate C are more prone for moisture induced damage containing moist aggregates • With the increase in RAP content, improvement in resistance to rutting susceptibility of the rubberized WMA is observed for mixtures containing moist aggregates using foaming based technology
Acknowledgements South Carolina Department of Health and Environment Control (DHEC) and Asphalt Rubber Technology Service (ARTS) of Clemson University.
Thank You
