Superpave Asphalt Binder Specification

Transcription

1 Presented by Prof. Hamad I. Al-Abdul Wahhab Civil Engineering Department King Fahd University of Petroleum & Minerals Dhahran, Saudi Arabia Superpave Asphalt Binder Specification The grading system is based on Climate PG Performance Grade Min pavement temperature Average 7-day max pavement temperature

2 PG Specifications Based on rheological testing (study of flow and deformation) Asphalt cement is a viscoelastic material Behavior depends on: Temperature Time of loading Aging (properties change with time) SHRP Asphalt Binder Spec Performance Based -- permanent deformation -- fatigue cracking -- low temperature cracking Physical Properties -- criteria remain the same -- temperature at which criteria achieved varies -- measured on aged binder

3 ASPHALT GRADING SUMMARY SHEET - SHRP BINDER PERFORMANCE SPECIFICATION Asphalt ID: Original RTFOT RTFOT + PAV residue Flash Pt: C (Min: 230 C) Loss: % Time/Temp after PAV: C Grade Vis@135: cp (Max: 1.0%) (Max: 3000 cp) Dynamic Shear 10 rad/s (1.6Hz) Dynamic Shear 10 rad/s (1.6Hz) Flexural Creep (at 60 sec) G*/sinδ (kpa) > 1 kpa Dynamic Shear 10 rad/s (1.6Hz) G*/sinδ (kpa) > 2.2 kpa Temp C G*sinδ (MPa) < 5 MPa Temp C PG PG x PG x PG 76 x x PG Stiffness, S < 300 MPa * Required only * if Creep Stiffness (S) is between 300 and 600 Mpa, and m > Asphalt Grade : PG x Slope, m > 0.30 DT * (1mm/min) F. Strain > 1.0% Miscellaneous Spec Requirements CEC Avg 7-day Max, o C PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82 1-day Min, o C > 230 o C Flash Point < 3Pa. 135 o C > 1.00 kpa > 2.20 kpa (Flash Point) FP RV (Rotational Viscosity) DSR G*/sin δ (ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 % (PRESSURE AGING VESSEL) ORIGINAL PAV 20 Hours, 2.07 MPa (110) 100 (110) 110 (110) < 5000 kpa DSR G*/sin δ Mass Loss DSR G* sin δ S < 300 MPa m > Report Value > 1.00 % ( Bending Beam Rheometer) BBR S Stiffness & m - value (Bending Beam Rheometer) BBR Physical Hardening (Direct Tension) DT

4 Miscellaneous Spec Requirements Pumping and Handling -- rotational viscometer -- controlled by unaged binder 135 C 3 Pa-s Safety -- flash point COC -- controlled by flash point 230 C Aging During Hot Mixing/Construction -- RTFO -- controlled by mass loss 1.00 % CEC Avg 7-day Max, o C 1-day Min, o C > 230 o C < 3Pa. 135 o C Performance Grades PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG (Flash Point) FP (Rotational Viscosity) ORIGINAL RV > 1.00 kpa > 2.20 kpa 20 Hours, 2.07 MPa (ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 % (PRESSURE AGING VESSEL) DSR G*/sin δ DSR G*/sin δ PAV (110) 100 (110) 110 (110) < 5000 kpa DSR G* sin δ S < 300 MPa m > Report Value > 1.00 % ( Bending Beam Rheometer) BBR S Stiffness & m - value (Bending Beam Rheometer) BBR Physical Hardening (Direct Tension) DT

5 CEC How the PG Spec Works Spec Requirement Remains Constant Avg 7-day Max, o C 1-day Min, o C > 230 o C < 3Pa. 135 o C PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG (Flash Point) FP (Rotational Viscosity) ORIGINAL RV > 1.00 kpa DSR G*/sin δ (ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 % > 2.20 kpa 20 Hours, 2.07 MPa < 5000 kpa S < 300 MPa m > (PRESSURE AGING VESSEL) PAV (110) 100 (110) 110 (110) Test Temperature Changes DSR G*/sin δ DSR G* sin δ ( Bending Beam Rheometer) BBR S Stiffness & m - value Report Value > 1.00 % (Bending Beam Rheometer) BBR Physical Hardening (Direct Tension) DT How the Spec Works Spec. Requirement Remains Constant Dynamic Shear, AASHTO TP5-93 G*/sin δ, Min 1.00 kpa Test 10 rad/sec Test Temperature Changes

6 Permanent Deformation Courtesy of FHWA Function of warm weather and traffic High Temperature Behavior High in-service temperature Desert climates Summer temperatures Sustained loads Slow moving trucks Intersections Viscous Liquid

7 Pavement Behavior (Warm Temperatures) Permanent deformation (rutting) Mixture is plastic Depends on asphalt source, additives, and aggregate properties Rutting RV BBR DSR

8 CEC Avg 7-day Max, o C 1-day Min, o C > 230 o C < 3Pa. 135 o C Permanent Deformation PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG (Flash Point) FP (Rotational Viscosity) ORIGINAL RV > 1.00 kpa Unaged RTFO Aged > 2.20 kpa 20 Hours, 2.07 MPa (ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 % (PRESSURE AGING VESSEL) DSR G*/sin δ DSR G*/sin δ PAV (110) 100 (110) 110 (110) < 5000 kpa DSR G* sin δ S < 300 MPa m > Report Value > 1.00 % ( Bending Beam Rheometer) BBR S Stiffness & m - value (Bending Beam Rheometer) BBR Physical Hardening (Direct Tension) DT Spec Requirements To Control Rutting Dynamic Shear, TP5: G*/sin δ, Min 1.00 kpa Test 10 rad/sec Dynamic Shear, TP5: G*/sin δ, Min 2.20 kpa Test 10 rad/sec

9 Permanent Deformation Addressed by high temp stiffness G*/sin δ on unaged binder > 1.00 kpa G*/sin δ on RTFO aged binder > 2.20 kpa For the early part of the service life Permanent Deformation Question: : Why a minimum G*/sin δ to address rutting Answer: We want a stiff, elastic binder to contribute to mix rutting resistance How: : By increasing G* or decreasing δ

10 Material A Viscous Part = 4 δ Elastic Part = 3 G* = 5 Viscous Part 4 Sin δ = = G* 5 G* 5 = = 6.25 Sin δ 4/5 Material B Viscous Part = 3 δ Elastic Part = 4 G* = 5 Viscous Part 3 Sin δ = = G* 5 G* 5 = = 8.33 Sin δ 3/5 Large value means behaves more like elastic solid Fatigue Cracking Function of repeated traffic loads over time (in wheel paths)

11 Fatigue Cracking Addressed by intermediate temperature stiffness G*sin δ on RTFO + PAV aged binder < 5000 kpa > Later part of pavement service life Fatigue RV BBR DSR

12 CEC Avg 7-day Max, o C 1-day Min, o C > 230 o C < 3Pa. 135 o C Fatigue Cracking PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG (Flash Point) FP (Rotational Viscosity) ORIGINAL RV > 1.00 kpa > 2.20 kpa 20 Hours, 2.07 MPa (ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 % (PRESSURE AGING VESSEL) DSR G*/sin δ DSR G*/sin δ PAV (110) 100 (110) 110 (110) < 5000 kpa S < 300 MPa m > ( Bending Beam Rheometer) BBR S Stiffness & m - value PAV Aged (Bending Beam Rheometer) BBR Physical Hardening Report Value > 1.00 % DSR G* sin δ (Direct Tension) DT Specification requirement To control fatigue cracking Dynamic Shear, TP5: G*sin δ, Max 5000 kpa Test 10 rad/sec, C

13 Fatigue Cracking Question: : Why a maximum G* sin δ to address fatigue? Answer: We want a soft elastic binder (to sustain many loads without cracking) How: By decreasing G* or decreasing δ Material A Viscous Part = 3 δ Elastic Part = 4 G* = 5 Viscous Part 3 Sin δ = = G* 5 G* sin δ = 5 3/5 = 3 Smaller value means Better at dissipating stress Material B G* = 5 Viscous Part = 3.5 δ Elastic Part = 3.5 Viscous Part 3.5 Sin δ = = G* 5 G* sin δ = 5 3.5/5 =

14 Low Temperature Behavior Low Temperature Cold climates Winter Elastic Solid Pavement Behavior (Low Temperatures) Thermal cracks Stress generated by contraction due to drop in temperature Crack forms when thermal stresses exceed ability of material to relieve stress through deformation Material is brittle Depends on source of asphalt and aggregate properties

15 Thermal Cracking Low Temperature Cracking CEC Avg 7-day Max, o C PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82 1-day Min, o C > 230 o C (Flash Point) FP < 3Pa. 135 o C (Rotational Viscosity) ORIGINAL RV > 1.00 kpa DSR G*/sin δ (ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 % > 2.20 kpa 20 Hours, 2.07 MPa DSR G*/sin δ (PRESSURE AGING VESSEL) PAV (110) 100 (110) 110 (110) < 5000 kpa DSR G* sin δ S < 300 MPa m > PAV Aged Report Value > 1.00 % ( Bending Beam Rheometer) BBR S Stiffness & m - value (Bending Beam Rheometer) BBR Physical Hardening (Direct Tension) DT

16 Low Temperature Cracking CEC Avg 7-day Max, o C PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82 1-day Min, o C > 230 o C (Flash Point) FP < 3Pa. 135 o C (Rotational Viscosity) ORIGINAL RV > 1.00 kpa DSR G*/sin δ (ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 % > 2.20 kpa 20 Hours, 2.07 MPa DSR G*/sin δ (PRESSURE AGING VESSEL) PAV (110) 100 (110) 110 (110) < 5000 kpa DSR G* sin δ S < 300 MPa m > PAV Aged Report Value > 1.00 % ( Bending Beam Rheometer) BBR S Stiffness & m - value (Bending Beam Rheometer) BBR Physical Hardening (Direct Tension) DT Creep Stiffness, TP1: S, Max, 300 MPa m-value, Min, Test 60 sec, C Specification requirement To control Low temperature cracking Direct Tension, TP3: Failure Strain, Min 1.0 % Test 1.0 mm/min, C

17 Low Temperature Cracking Controlled by -- S on RTFO/PAV aged materials 300 kpa -- m-value on RTFO/PAV aged materials Alternate Control -- S on RTFO/PAV aged materials MPa -- m-value on RTFO/PAV aged materials tensile failure strain on RTFO/PAV aged materials 1.0% Effect of Loading Rate on Binder Selection Dilemma 90 kph specified DSR loading rate is 10 rad/sec (90kph) what about longer loading times? Use binder with more stiffness at higher temps slow - - increase one high temp grade stationary - - increase two high temp grades no effect on low temp grade

18 Effect of Loading Rate on Binder Selection Example for toll road PG for toll booth PG for weigh stations PG kph Slow Stopping Effect of Traffic Amount on Binder Selection 80 kn ESALs x 10 6 ESAL Consider increasing - - one high temp grade 30 x ESAL Recommend increasing - - one high temp grade Equivalent Single Axle Loads

19 New Binder Selection Adjustments for Traffic Level and Speed MP2 Adjustment to Binder PG Grade (2) Design ESAL s (1) Traffic Load Rate (Millions) Standing Slow Avg. Speed > 70 km/hr (Avg. Speed < 20 km/hr (Avg. Speed 20 to 70 km/hr < (3) to < to < to < (3) > (1) Design ESAL s are anticipated project traffic level expected on the design lane over a 20 years period. Regardless of the actual design life of the roadway, determine the design ESAL s for 20 years and choose appropriate N design level. (2) Increases the high temperature grade by the number of grade equivalents indicate (1 grade equivalent to 6 o C. (3) Consideration should be given to increasing the high temperature grade by 1 grade equivalent Summary of How to Use PG Specification Determine 7-day max pavement temperatures 1-day minimum pavement temperature Use specification tables to select test temperatures Determine asphalt cement properties and compare to specification limits

20 TURAIF AL-QURAYYAT ARAR AL-JAWF R. AL-QURAYYAT R. AL-JAWF RAFHA NORTH BORDER R. TABOUK KUWAIT TABOUK R. AL-QAISUMAH HAIL R E D S E A AL-WAJH MADINAH R. YANBU MADINAH PG MAKKAH R. JEDDAH MAKKAH TAIF HAIL R. AL-BAHA R. BAHA BURAYDAH AL-QASSIM R. AL-DAWADMI BISHA ASIR R. RIYADH RIYADH REGION PG PG SULAYYIL KHAMIS MUSHAYT NAJRAN R. ABHA NAJRAN SHARURAH JIZAN R. JIZAN DHAHRAN HAFUF ARABIAN GULF QATAR PG EASTERN PROVINCE U A E O M A N GULF OF OMAN Tentative Temperature Zoning for Asphalt Binder Specifications for the Gulf Countries ASPHALT GRADING SUMMARY SHEET - SHRP BINDER PERFORMANCE SPECIFICATION Asphalt ID: Original RTFOT RTFOT + PAV residue Flash Pt: C (Min: 230 C) Loss: % Time/Temp after PAV: C Grade Vis@135: cp (Max: 1.0%) (Max: 3000 cp) Dynamic Shear 10 rad/s (1.6Hz) Dynamic Shear 10 rad/s (1.6Hz) Flexural Creep (at 60 sec) G*/sinδ (kpa) > 1 kpa Dynamic Shear 10 rad/s (1.6Hz) G*/sinδ (kpa) > 2.2 kpa Temp C G*sinδ (MPa) < 5 MPa Temp C PG PG PG PG PG Stiffness, S < 300 MPa Required only * if Creep Stiffness (S) is between 300 and 600 Mpa, and m>0.30. Asphalt Grade : PG Slope, m > Failed Failed DT * (1mm/min) F. Strain > 1.0%

21 ASPHALT GRADING SUMMARY SHEET - SHRP BINDER PERFORMANCE SPECIFICATION Asphalt ID: Original RTFOT RTFOT + PAV residue Flash Pt: C (Min: 230 C) Loss: % Time/Temp after PAV: C Grade Vis@135: cp (Max: 1.0%) (Max: 3000 cp) Dynamic Shear 10 rad/s (1.6Hz) Dynamic Shear 10 rad/s (1.6Hz) Flexural Creep (at 60 sec) G*/sinδ (kpa) > 1 kpa Dynamic Shear 10 rad/s (1.6Hz) G*/sinδ (kpa) > 2.2 kpa Temp C G*sinδ (MPa) < 5 MPa Temp C PG PG PG PG PG Stiffness, S < 300 MPa Failed Required only * if Creep Stiffness (S) is between 300 and 600 Mpa, and m>0.30. Asphalt Grade : PG Slope, m > Failed DT * (1mm/min) F. Strain > 1.0% THANK YOU