ALF Crumb Rubber Modified Asphalt Louisiana s Experience Louisiana Transportation Conference Baton Rouge Louisiana February 9 th, 2009 Chris Abadie
Summary of Louisiana ss Experience Eight CRM asphalt pavement sections using eight different CRM processes Conventional sections constructed as controls Laboratory and field performance testing and observations to evaluate performance ALF test sections 2008 Interstate Projects
Locations
CRM Descriptions Location Project No. Description 1 OGFC (17.5% Arizona Wet) w/ AR Modified SAMI US 61 019 05 0024 CRM (17.5% Arizona Wet) Gap Graded Polymer Modified Gap Graded Wearing Conventional Dense Graded 832 23 0009 CRM (3% PlusRide Dry) Gap Graded LA 1040 CRM (3% PlusRide Dry) Gap Graded 853 10 0012 Conventional Dense Graded US 84 022 06 0041 CRM (5% Neste Wright, Wet) Dense Graded Conventional Dense Graded LA 15 026 10 0018 0018 CRM (10% Rouse, Wet) Dense Graded CRM (17.5% Arizona Ai Wet) )Gap GradedG d Conventional Dense Graded US 167 023 11 0028 CRM (1% Rouse, Dry) Dense Graded CRM (2% Generic, Dry) Gap Graded Conventional Dense Graded
Roadway Core Air Voids (5 7 years of service)
Comparisons of Field Performance Roadway core air void analysis Rut depth measurement International Roughness Index (IRI) DYNAFLECT system structural numbers Quality Control/Quality Acceptance data LA Pavement Management Section visual data
Lab vs. Field Performance Indirect Tensile Strength (ITS) and Resilient Modulus (M R ) measurements were compared against field performance Only a few showed good correlations and are noted throughout the presentation
US 61 Traffic and Mix Design Year/ADT % Truck Structural Number (SN) 1992/4000 20 29 2.9 Polymer Gap Graded CRM Gap Graded CRM OGFC Gradation (% Pass) Polymer Gap Graded CRM Gap Graded CRM OGFC Spec. Gravity 2.298 2.231 2.089 ¾ 100 100 100 Theo. Gravity 2.368 2.312 2.302 ½ 93 93 91 % Theo. Gravity 97.0 96.3 90.7 3/8 71 71 65 % VMA 17.1 18.1 27.6 No. 4 35 35 23 % VFA 82 81 66 No. 10 21 19 9 % Air Voids 3.0 3.5 9.3 No. 40 14 10 5 Stability (Lbs) 2115 2050 1010 No. 80 12 7 4 Flow (1/100) 11 24 32 No. 200 11.0 5.3 3.3 % AC 6.3 8.4 9.0
US 61 IRI
US 61 Random Cracking (0.50) (0.76) (0.83) (1.61) (ITS Strain)
US 61 Rut Depth
LA 1040 Traffic and Mix Design Year/ADT % Truck Structural Number (SN) 1993/7500 9 41 4.1 PlusRide Gap Graded Conventional Gradation (% Pass) PlusRide Gap Graded Conventional Spec. Gravity 2.176 2.316 ¾ 100 100 Theo. Gravity 2.246 2.415 ½ 98 97 % Theo. Gravity 97.0 95.9 3/8 72 91 % VMA 19.1 15.6 No. 4 32 57 % VFA 84 73 No. 10 22 37 % Air Voids 3.0 4.1 No. 40 14 21 Stability (Lbs) 1600 2030 No. 80 12 9 Flow (1/100) 26 11 No. 200 10.2 5.7 % AC 82 8.2 55 5.5
LA 1040 IRI
LA 1040 Random Cracking
LA 1040 Rut Depth
US 84 Traffic and Mix Design Year/ADT % Truck Structural Number (SN) 1994/8800 21 45 4.5 Neste Wright CRM Conventional Gradation (% Pass) Neste Wright CRM Conventional Spec. Gravity 2.394 2.401 ¾ 100 100 Theo. Gravity 2.477 2.480 ½ 94 94 % Theo. Gravity 96.6 96.8 3/8 90 90 % VMA 12.4 12.1 No. 4 64 64 % VFA 73 74 No. 10 39 39 % Air Voids 3.4 3.2 No. 40 21 21 Stability (Lbs) 2400 2300 No. 80 12 12 Flow (1/100) 10 8 No. 200 6.0 6.0 % AC 42 4.2 41 4.1
US 84 IRI
US 84 Random Cracking
US 84 Rut Depth
US 167 Traffic and Mix Design Year/ADT % Truck Structural Number (SN) 1994/6200 15 61 6.1 1% Rouse CRM 2% Generic CRM Conven. Gradation (% Pass) 1% Rouse CRM 2% Generic CRM Conven. Spec. Gravity 2.380 2.283 2.420 ¾ 100 100 100 Theo. Gravity 2.474 2.353 2.512 ½ 98 97 100 % Theo. Gravity 96.2 97.0 96.3 3/8 91 74 95 % VMA 14.0 16.3 13.8 No. 4 66 31 58 % VFA 73 82 73 No. 10 42 21 35 % Air Voids 3.8 3.0 3.7 No. 40 22 11 22 Stability (Lbs) 2000 2000 2000 No. 80 12 8 12 Flow (1/100) 10 16 11 No. 200 6.5 5.0 6.0 % AC 4.4 6.0 4.3
US 167 IRI
US 167 Random Cracking
US 167 Rut Depth
LA 15 Traffic and Mix Design Year/ADT % Truck Structural Number (SN) 1994/6250 10 55 5.5 Rouse Dense Graded CRM Gap Graded Conven. Gradation (% Pass) Rouse Dense Graded CRM Gap Graded Conven. Spec. Gravity 2.390 2.278 2.394 ¾ 100 100 100 Theo. Gravity 2.480 2.356 2.481 ½ 100 99 98 % Theo. Gravity 96.4 96.7 96.5 3/8 91 75 90 % VMA 13.3 19.6 13.0 No. 4 64 31 64 % VFA 73 83 73 No. 10 40 20 39 % Air Voids 3.6 3.3 3.5 No. 40 21 10 21 Stability (Lbs) 2000 1140 2400 No. 80 12 7 12 Flow (1/100) 9 17 11 No. 200 6.0 4.9 6.5 % AC 4.5 7.8 4.4
LA 15 IRI
LA 15 Random Cracking (0.68) (0.67) (1.92) (ITS Strain)
LA 15 Rut Depth
Pavement Condition Index
ITS Strength
ITS Strain
Summary of Results Conventional mixes showed higher laboratory performance CRM mixtures show better field performance (rut depth, random cracks, and IRI) than corresponding control section Both CRM wet and dry performed equally well or better than conventional mix types Including CRM significantly increases costs
Summary of Results After 7 to 10 years of service: CRM sections exhibited similar or lower IRI than control section CRM sections generally exhibited similar or lower rut depth than control section CRM sections generally exhibited similar or less distress cracking than control section
Recommendations CRM wet process to be implemented Shown to be excellent method for reducing traverse crack propagation in composite pavements Improves actual pavement performance Should increase life cycle of HMA pavements Increased use of this process will significantly decrease based on increased usage of process
DOTD Pavement Research Facility
Experiment 2: Comparative Performance of Conventional and Rubberized Hot Mix Asphalt Lane 1 Lane 2 Lane 3 (control) 1.5 2.0 3.5 8.5 10 PRM Wearing Course PAC 40 Binder Course PAC 40 Wearing Course AC30 Base PRM Base AC 30 Base Stone Base Soil Cement Working Table PRM: Powdered Rubber Modified
Experiment 2: Comparative Performance of Conventional and Rubberized Hot Mix Asphalt Rut Depth (in.) 0.6 0.5 0.4 0.3 0.2 Rubberized wearing course Conventional asphalt mix Rubberized base course 0.1 0 0 1 2 3 4 5 Cumulated 18-kip ESALs (million)
Experiment 2: Comparative Performance of Conventional and Rubberized Hot Mix Asphalt Implementation Recommendation: Modify Asphalt base course specifications to require rubberized asphalt or polymer modified asphalt. 0.04 0.03 T8 WC-PRM T8 WC Base PRM Base in permanent strai 0.02 0.01 0 0 1000 2000 3000 4000 5000 cycles
Life Cycle Cost Analysis Low Volume Road 2:1 EASL advantage Initial Construction $236,401/ln mi Mill 2 & Overlay 3.5 $66,965 $66,965 Modified Asphalt Base (40 yr design life) 0 15 30 40 Annualized cost = $18,702 / ln mi / yr AC 30 Asphalt Base (30 yr design life) Initial Construction Mill & Overlay Mill 2 w/ Structural Overlay 7 $230,936/ln mi $66,965 13 % $126,046 savings 0 15 30 Annualized cost = $21,409 / ln mi / yr 40
Implementation I 12 Millerville and I 10 Sorrento
Implementation Dry Process Dry Process I 12 Baton Rouge
I 12 SMA Hamburg (LWT) 15%CRM Dry Process w/ Vestenimer Average e Rut (mm) 12 10 8 6 4 2 0 PG 64 22 w/ 15% CRM PG 70 22m w/ 15% CRM 0 5000 10000 15000 20000 25000 Number of Passes
Implementation Wet Process PG 82-22rn Blended at Contractors Tank I-10 Gramercy to Sorrento
I 10 SMA Hamburg (LWT) 12 ut (mm) Average R 10 8 6 4 2 0 PG82 22RM PG76 22m (conv.) 0 5000 10000 15000 20000 25000 Number of Passes
I 10 and I 12 Mix Design I 10 I 12 Gradation (% Pass) I 10 I 12 Spec. Gravity 2.340 2.320 ¾ 100 100 Theo. Gravity 2.429 2.396 ½ 94 94 % Theo. Gravity 96.4 96.8 3/8 68 69 % VMA 17.7 16.9 No. 4 29 29 % VFA 80 81 No. 8 21 20 % Air Voids Vid 36 3.6 39 3.9 No. 16 18 17 % AC 6.2 6.1 No. 30 17 15 Density (lb/ft 3 ) 146.1 144.7 No. 50 14 13 No. 100 11 10 No. 200 8.4 8.0
LOUISIANA SUPERPAVE BINDER SPECS PG 82-22RM PG 76-22M PG 70-22M PG 64-22* High Volumn High Volumn Low Volumn Base mix ORIGNIAL BINDER FLASH POINT, 230 C Max., ROTATIONAL VISCOSITY, 135 C, 3 Pa * S, Max., DSR, G*/Sin Delta @ Specified High Temp., 1KPa, Min. (1.3 K Pa for PG64-22) RTFO aged; (1% Max. Loss in RTFO) DSR, G*/Sin Delta @ Specified High Temp., 2.2 KPa, Min. PAV aged, (uniform specs for all - 22 grades) DSR @ 25 C, G* x Sin Delta, = 5000 KPa Max.; (4000 max for 64-22) BBR, @-12 C, 300 MPa max stiffness and minimum slope of 0.300. *Note: PG 58-28 required when 21-30% RAP is used in base course mixes.
LOUISIANA SUPERPAVE BINDER SPECS, Modified Requirements Original Binder: Separation Test, 2 C max. difference on ring and ball PG76 22m; Force Ratio @ 4 C, 30 cm: F 2 / F 1 = 0.3 Min. PG 70 22m; Force Ductility @ 4 C, 30 cm. = 0.5 Lb. Min RTFO material: Elastic Recovery, Min. Recovery at 25 C, PG 82RM and PG76m 60% Min PG70m 40% Min
I 10 Binder Test Results sampled from contractors blend tank Original Binder 82C G*/Sin delta = 1.13 RTFO G*/Sin Delta = 2.34 65% Elastic Recovery
Observations PG76 22m (SBSmodified) mixturesset set laboratory performance standard. Dry Process and Wet Process Rubber Modified Asphalt have recently performed well in SMA. And should also be allowed in dense graded mixtures PG 82 22rm 22 is equal to PG 76 22m.
Thank You!