Using the Multiple-Stress Creep-Recovery (MSCR) Test p y ( ) Mike Anderson, Asphalt Institute John Bukowski, FHWA North Central Asphalt User Producer Group Meeting North Central Asphalt User Producer Group Meeting 15 February 2012 Indianapolis, IN p
Acknow ledgments • DTFH61-08-H-00030 DTFH61 08 H 00030 – Cooperative Agreement between the FHWA and the Asphalt Institute and the Asphalt Institute • John A. D’Angelo • Asphalt Binder ETG A h lt Bi d ETG • Member Companies of the Asphalt Institute – Technical Advisory Committee
Discussion • Background Background • Basics of the MSCR test • How do MSCR results (J nr ) relate to H d MSCR lt (J ) l t t rutting? • How can MSCR Recovery be used and what does it indicate? • How does the specification work? • Educational and implementation activities Educational and implementation activities
DSR Operation: AASHTO T315 Spindle Position Position One cycle B is complete... A A Time A C B C A
Shortcomings of G* /sin δ • G*/sin δ as a High Temperature Parameter G /sin δ as a High Temperature Parameter – Properties determined in Linear Viscoelastic (LVE) region (LVE) region • No damage behavior – Rutting is a non-linear failure – Polymer-modified systems engaged in non-linear region • Characterizes stiffness – Related to rutting Related to rutting
Effect of Phase Angle 1.00 0.98 0.96 δ Sin δ 0.94 0.92 0.90 60 65 70 75 80 85 90 Phase Angle, degrees
High Temperature Testing • Repeated Shear Creep Repeated Shear Creep – Analogous to mixture test (RSCH) – Performed in DSR Performed in DSR • Controlled shear stress (i.e., 25 Pa or 300 Pa) • 100 cycles 100 cycles • 1-second load, 9-second rest per cycle • High test temperature (HT-?) g p ( ) – Response: permanent shear strain ( γ p ) or strain slope
Repeated Shear Creep 14 14 rain, % 12 10 10 Recoverable shear strain Recoverable shear strain ear Str 8 Instantaneous 6 erm. Sh shear strain Permanent 4 shear strain 2 Pe 0 0 2 4 6 8 10 Time, seconds
Repeated Shear Creep NCHRP 9-10: PG 82 Binders Repeated Shear Creep (70C 300Pa) Repeated Shear Creep (70C, 300Pa) n, % 14 12 12 ar Strai 10 8 m. Shea 6 4 2 Perm 0 0 2 4 6 8 10 Time seconds Time, seconds
Repeated Shear Creep NCHRP 9-10: PG 82 Binders R Repeated Shear Creep (70C, 300Pa) t d Sh C (70C 300P ) ain, % 14 Ox 12 ear Stra 10 8 PE-s 6 6 erm. Sh 4 SBS-r 2 Pe 0 0 200 400 600 800 1000 Time seconds Time, seconds
Multiple-Stress Creep-Recovery (MSCR) Test: AASHTO TP70 ( ) • Performed on RTFO-aged Binder Performed on RTFO aged Binder • Test Temperature – Environmental Temperature Environmental Temperature – Not Grade-Bumped • 10 cycles per stress level 10 cycles per stress level – 1-second loading at specified shear stress • 0.1 kPa 0.1 kPa • 3.2 kPa – 9-second rest period
MSCR Test • Calculate Non-recoverable Creep Calculate Non recoverable Creep Compliance (J nr ) – Non-recoverable shear strain divided by y applied shear stress • “J” = “compliance” • “nr” = “non-recoverable” “ ” “ bl ” • Calculate Recovery for each Cycle, Stress – Difference between strain at end of recovery Diff b t t i t d f period and peak strain after creep loading
MSCR 14 14 rain, % 12 10 10 Recoverable shear strain Recoverable shear strain ear Str 8 Instantaneous 6 erm. Sh shear strain Non-recoverable (permanent) 4 shear strain 2 Pe 0 0 2 4 6 8 10 Time, seconds
MSCR – Non-Recoverable Compliance (J nr ) Compliance (J nr ) Unrecovered Shear Strain 80 80 J J nr = Applied Shear Stress 70 60 60 ain, % 50 Cycle 3 Unrecovered (permanent) strain 40 40 Stra Cycle 2 Unrecovered 30 (permanent) strain 20 20 Cycle 1 Unrecovered 10 (permanent) strain 0 0 0 5 10 15 20 25 30 35 40 Time, seconds
MSCR – Non-Recoverable Compliance (J nr ) Compliance (J nr ) 0.1 kPa Shear Stress 0 80 0.80 Unrecovered Shear Strain 0.70 J nr = Applied Shear Stress 0 60 0.60 0.50 0.197 rain 0.1 kPa = 1.97 kPa -1 J nr = 0.40 0 40 Str 0.30 0 20 0.20 0 197 0.197 Cycle 1 Unrecovered 0.10 (permanent) strain 0 0 0 5 10 15 20 25 30 35 40 Time, seconds
Relationship betw een Jnr and ALF Rutting 25 6kPa ALF Rutting 25.6kPa 2.5 Jnr = (4.74*Rut Depth) - 1.17 R 2 = 0.82 2 1.5 Jnr MSCR can adjust for field conditions and has excellent relations to performance relations to performance. 1 0 5 0.5 0 0 0 0.1 0 1 0 2 0.2 0 3 0.3 0 4 0.4 0 5 0.5 0 6 0.6 0 7 0.7 0 8 0.8 ALF Rutting, in
Mississippi I55: 6yr rutting J J nr 3.2 kPa 3.2 kPa 4 4 6 yr Jnr 3.2 kPa y = 0.2907x + 0.1297 binder mod true grade rut mm 70C 3.5 Ultrapave SBR 70-27 4.5 1.7 R 2 = 0 7499 Styrelf SB 77-29 2 0.44 R = 0.7499 GTR 80 75-29 1.5 1.21 3 3 Sealoflex SBS 82-27 3 0.19 Multigrade 72-24 5 2.13 2.5 Cryo Rubber 75-28 7 1.62 Control 70-24 11 3.5 2 2 1.5 1 1 0.5 0 0 0 2 4 6 8 10 12 17
MSCR: What is % Recovery? • MSCR J MSCR J nr addresses the high temperature addresses the high temperature rutting for both neat and modified binders – but many highway agencies require polymers but many highway agencies require polymers for cracking and durability. • The MSCR % Recovery measurement can • The MSCR % Recovery measurement can identify and quantify how the polymer is working in the binder working in the binder.
MSCR Recovery 3.2 kPa Shear Stress 0.80 Peak Strain – Unrecovered Strain Recovery = 100% * Peak Strain 0.70 0.60 0.300 – 0.197 Strain Recovery = 100% * = 34.3% 0.50 0.300 0 40 0.40 S 0.30 0.300 0.20 0.197 Cycle 1 Unrecovered 0.10 (permanent) strain 0 0 0 5 5 10 10 15 15 20 20 25 25 30 30 35 35 40 40 Time, seconds
MSCR Recovery: Validate Polymer Modification Polymer Modification 100 The curve stopsat J =2 kPa -1 J values greater than 2 kPa -1 The curve stops at J nr = 2 kPa . J nr values greater than 2 kPa 90 are not required to have any minimum value of %Recovery. 80 70 70 Significant Delayed Significant Delayed Hi h Hi h High elasticity High elasticity l l ti it ti it overy, % 60 Elastic Response 50 Reco 40 30 20 20 10 0 Poor elasticity Poor elasticity 0 00 0.00 0 50 0.50 1 00 1.00 1 50 1.50 2 00 2.00 J nr , kPa -1
Table for MSCR % Recovery: Minimum Values Minimum Values Minimum % Recovery for Measured J Minimum % Recovery for Measured J nr values values J nr @ 3.2 kPa Minimum % Recovery 2.0 - 1.01 2 0 1 01 30% 30% 1.0 - 0.51 35% 0.50 - 0.251 45% 0.25 - 0.125 50%
Validate Polymer Modification PG 76-22 Binders: MSCR3200 110 100 90 @ 64C, % y = 29.82x -0.39 80 R² = 0.54 70 Rec3200 @ 60 50 -0.26 Recovery = 29.37*J nr y 40 40 nr R 30 20 0 00 0.00 0 10 0.10 0 20 0.20 0 30 0.30 0 40 0.40 0 50 0.50 0 60 0.60 Jnr @ 64C, kPa -1
Evaluation of the MSCR Test for Canadian Asphalt Binders p 90 80 80 @ 58°C, % UTI=86 70 UTI=92 60 88% y-3.2kPa @ UTI 98 UTI=98 50 71% 84% 40 UTI=104 30 50% Recovery 20 59% 10 50% 10% 0 0% 0% 0%0% 0%0% -10 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 Jnr-3 2kPa @ 58°C kPa -1 Jnr-3.2kPa @ 58 C, kPa
AASHTO MP19 PG 64 -10 -16 -22 -28 -34 -40 Original Binder DSR (T315) – temp @ 10 rad/s 64 G*/sin δ ≥ 1.00 kPa RTFO-Aged Binder RTFO Aged Binder MSCR (TP70) – temp 64 All Grades: Jnr,Diff ≤ 75% “S” Grade: Jnr 3 2 ≤ 4 0 kPa -1 S Grade: Jnr-3.2 ≤ 4.0 kPa 1 “H” Grade: Jnr-3.2 ≤ 2.0 kPa -1 “V” Grade: Jnr-3.2 ≤ 1.0 kPa -1 “E” Grade: Jnr-3.2 ≤ 0.5 kPa -1
AASHTO MP19 PG 64 -10 -16 -22 -28 -34 -40 PAV-Aged Binder @100 ° C DSR (T315) – temp @ 10 rad/s 31 28 25 22 19 16 “S” Grade”: G*sin δ ≥ 5000 kPa “H” Grade”: G*sin δ ≥ 6000 kPa “V” Grade” G*sin δ ≥ 6000 kPa “V” Grade”: G*sin δ ≥ 6000 kPa “E” Grade”: G*sin δ ≥ 6000 kPa BBR (T313) – temp @ 60 s 0 -6 -12 -18 -24 -30 All Grades: All Grades: Stiffness ≤ 300 MPa m-value ≥ 0.300
AASHTO MP19 • Grades Grades – Based on Climatic Temperature • High and Low Pavement Temperature • High and Low Pavement Temperature – Traffic Designation • “S” – Standard S Standard • “H” – Heavy • “V” – Very Heavy y y • “E” – Extreme
AASHTO MP19 • Grades Grades – Based on Climatic Temperature • High and Low Pavement Temperature • High and Low Pavement Temperature – Traffic Designation • “S” – Standard S Standard < 10 Million ESAL < 10 Million ESAL • “H” – Heavy 10-30 Million ESAL • “V” – Very Heavy y y > 30 Million ESAL • “E” – Extreme > 30 Million ESAL and standing traffic
AASHTO MP19 • PG 64-22V asphalt binder PG 64 22V asphalt binder – What do I need to test? – What are the temperatures and criteria? What are the temperatures and criteria?
PG 64-22V Asphalt Binder • Original (Unaged) Binder Original (Unaged) Binder – COC Flash Point • Must be ≥ 230°C • Must be ≥ 230 C – Rotational Viscosity @ 135°C • Must be ≤ 3 Pa-s Must be ≤ 3 Pa s – DSR (AASHTO T315) • G*/sin δ must be ≥ 1.00 kPa @ 64°C G /sin δ must be ≥ 1.00 kPa @ 64 C
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