Performance of Paving Interlayer-Reinforced Asphalt Pavement Jenny - PowerPoint PPT Presentation

Performance of Paving Interlayer-Reinforced Asphalt Pavement Jenny Liu, Ph.D., P.E. University of Alaska Fairbanks September 7, 2016 CESTiCC September Webinar

Acknowledgments  Tencate Geosynthetics North America  AKDOT&PF Northern Region  Emulsion Products  CESTiCC  Jenny Liu’s Materials and Pavement group 2

Outline  Introduction  Materials and laboratory tests  Pavement structural analysis  FEM simulation analysis  Field test sections  Conclusions 3

Introduction  AC overlay is one of the most effective methods used in pavement maintenance and rehabilitation  Paving interlayers have been used in AC overlays for a number of benefits:  waterproofing control against infiltration of free surface water into base and subgrade  retarding of reflection of existing cracks and distresses  Bi-axial interlayer (traditional) reinforces pavement in two directions only 4

Introduction  Multi-axial interlayer may provide potentially more efficient reinforcement in multi-directions  In cold regions such as Alaska and other northern states, pavement and paving interlayers are more prone to distresses due to severe climatic conditions.  Identify/validate expected performance of multi-axial interlayer and added value over the conventional biaxial interlayers  Explore how paving interlayers function in AC pavements in cold regions 5

Material  HMA  Job mix formula from Rich Hwy North Pole Interchange paving project, Surface mix, Marshall mix design  NMAS 12.5 mm (1/2”), PG 64-34 binder, 5.4%  VTM 4%, VMA 16% and VFA 75%  Paving interlayers PGM-G50/50 PGM-G 4 PGM-G100/100 Bi-axial, two-yarn Multi-axial Bi-axial, three-yarn 6

Laboratory Testing  Property tests of interlayers  Asphalt retention  Grab strength  Performance tests for interlayer-reinforced HMA  Shear strength  Permeability  Indirect tension test (IDT) 7

Asphalt Retention ASTM D6140 (135 o C) PG 64-34: 145 o C PGM-G 4 PGM-G50/50 PGM-G100/100 liter/m 2 Asphalt 0.828 1.236 1.281 Retention gal/yard 2 0.183 0.273 0.283 8

Grab Strength Breaking Tensile load (N), ASTM D4632 PGM-G 4 PGM-G50/50 PGM-G100/100 Saturated 2290 2023 4071 Unsaturated 1941 1926 3783 % Difference 18% 5% 8% 9

Specimen Fabrication Spray binder Place the fabric 10

Specimen Fabrication 11

Shear Test 12

Shear Test 13

Shear Test 14

Permeability ASTM PS 129-01 15

Permeability Maximum acceptable permeability, 125×10 -5 cm/s 16

IDT Creep 17

IDT Creep Summary of Creep Compliance (1/MPa) Temperature Time (s) Material ( o C) 10 20 50 100 200 500 1000 Control 4.90 18.39 46.22 68.08 90.64 121.33 145.55 G 4 5.23 12.31 25.03 35.19 46.20 63.59 78.94 20 G50 7.96 19.87 34.17 44.58 55.30 70.97 83.98 G100 5.09 14.54 30.74 44.70 60.00 82.36 100.45 Control 0.27 0.34 0.60 1.04 1.31 1.71 1.84 G 4 0.19 0.26 0.52 0.81 1.00 1.16 1.23 -10 G50 0.19 0.26 0.45 0.70 0.90 1.11 1.24 G100 0.14 0.19 0.40 0.63 0.82 0.97 1.06 Control 0.09 0.09 0.11 0.14 0.17 0.20 0.20 G 4 0.06 0.07 0.08 0.11 0.15 0.17 0.16 -30 G50 0.05 0.05 0.07 0.10 0.14 0.16 0.17 G100 0.05 0.05 0.06 0.09 0.13 0.15 0.15 18

IDT Creep b) a) a) 20 o C, 0.15kN vertical load b) -10 o C, 1.5kN vertical load c) -30 o C, 12kN vertical load c) 19

Laboratory Tests Summary  G 4 (multi-axial) had lowest asphalt retention, 2 nd highest grab tensile strength.  The fabrics need to be placed glass side facing down to achieve the maximum interface bonding strength in the field application.  Permeability of reinforced was 1/10 of control.  G 4 reinforced had highest creep stiffness at 20°C, twice higher than control.  Paving interlayer would provide extra resistance to thermal contraction in cracked pavement. 20

Pavement Structural Analysis Dynamic Modulus (|E*|) Master Curve 21

Pavement Structural Analysis  Bitumen Stress Analysis in Roads (BISAR) - |E*|, 21°C, 10 Hz, Surface layer 22

Pavement Structural Analysis  AKFPD - Alaska Flexible Pavement Design 23

FEM Simulation Model configuration 24

FEM Simulation G50/50 (bi-axial) G 4 (multi-axial) Meshed model 25

FEM Simulation Final meshed FEM model 26

FEM Simulation G50/50 (bi-axial) G 4 (multi-axial) Distribution of tensile stress 27

FEM Simulation Results 28

FEM Simulation Results 29

Field Test Sections  Test sections – Richardson Highway, Alaska  2 in HMA, 4 in ATB, 4 in D-1 granular base, 300 ft paving interlayer  Pre-construction field evaluation in May 2013  Four 300-ft sections established in July, 2013  G 4 , G50/50, G100/100 and control section  Regular field evaluations since 2013 30

Field Construction 31

Field Evaluation Results 266 ft of longitudinal cracks (May 2014) No visible cracks (October 2013) New minor transverse and moderate New minor transverse crack (June 2015) longitudinal cracks (June 2016) Control section 32

Field Evaluation Results Both longitudinal and transverse No visible cracks (October 2013) cracks present (May 2014) New minor transverse and New minor transverse crack (June 2015) longitudinal cracks (June 2016) G 4 interlayer test section 33

Field Evaluation Results Both longitudinal and transverse No visible cracks (October 2013) cracks present (May 2014) New minor longitudinal crack on the New minor longitudinal crack (June 2015) shoulder (June 2016) 34 G50/50 interlayer test section

Field Evaluation Results No visible cracks (October 2013) New major transverse cracks (May 2014) No new transverse or longitudinal crack, No new crack (June 2015) but polishing is very obvious (June 2016) G100/100 interlayer test section 35

Field Evaluation Results Transverse Longitudinal Longitudinal Section crack (#) crack, NB (ft) crack, SB (ft) Previous 1 300 medium-major 7 minor 0 13 minor New 2 4 minor 4 medium-major 0 Control (area 4) Total 304 medium-major 11 minor 0 13 minor Previous 8 minor 63 minor 14 minor G 4 (areas 2 & 3) New 2 minor 14 minor 0 Total 10 minor 77 minor 14 minor Previous 1 major 78 minor 60 minor New G50/50 (area 9) 0 0 20 minor Total 1 major 78 minor 80 minor Previous 1 major 0 0 G100/100 (area 10) New 0 0 0 Total 1 major 0 0 1 Previous−Data collected by June 2015; 2 New−Data collected in June 2016. 36

Conclusions  Laboratory investigation confirmed the benefits of adding a paving interlayer  Pavement structural analysis showed fatigue resistance of reinforced was higher than control  G100/100 reinforced showed the highest fatigue resistance, G 4 ranked 2 nd  FEM analysis revealed G 4 reinforced had more effective stress distribution and less maximum tensile strain than G50/50 reinforced  All interlayer-reinforced test sections showed better pavement performance than the control 37

Thank you! CESTiCC September Webinar