Session 40 Prabir Kumar Das

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  • 1. KTH – Väg- och Banteknik Oct 26, 2011 Page
  • 2. Oct 26, 2011 The objective of this work was to investigate the influence of commercial wax additives for lowering energy consumption during asphalt production and paving with a focus on: 1. Cracking performance 2. Moisture Damage 3. Low Temperature-Cracking Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking
  • 3. Oct 26, 2011 The effects of wax additives for lowering energy consumption during production and construction is known, but no study has focused explicitly on the cracking and durability properties of the resulting asphalt pavement. Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking
  • 4. Commercial Wax Oct 26, 2011
    • Commercial wax (Sasobit, Montan wax) is used as energy reducing agent and flow improver
    • Lower the mixing temperature of the asphalt, thus reducing energy consumption and emissions
    • Wax may increase the asphalt pavement resistance to plastic deformation
    Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking
  • 5. Introduction To Test Materials Oct 26, 2011 Aggregate: Two different types of dense graded aggregate (crushed granite and feldspar, Skärlunda)with maximum size of 11mm used according to Swedish road standards (ATB VÄG, 2004) Binder: Original (70/100) - as a base binder Original + 4% Sasobit Wax (FT-paraffin) Original + 4% Montan Wax (asphalten B) Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking
  • 6. Binder Test Results shows the improvement in Rutting Resistance Oct 26, 2011 Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking           Characteristics Units Original 70/100 Original + 4%Sasobit Original + 4% MW Softening Point o C 46 89 85 Penetration dmm 81 45 52 Brookfield visc. At 135 0 C mPas 345 270 263 Brookfield visc. At 165 0 C mPas 101 80 82 Force Ductility Nm 1.38 4.03 3.54 Bending Beam Rheometer S / m-value -12 0 C Mpa 150 / 0.395 208 / 0.311 182 / 0.323 S / m-value -18 0 C Mpa 414 / 0.3 462 / 0.252 421/ 0.271 S / m-value -24 0 C Mpa 832 / 0.205 881 / .195 796 / .214 LST 0 C -16 -15 -16 LmT 0 C -18 -13 -15
  • 7. Complex Modulus Increase for Improved Rutting Resistance Oct 26, 2011 Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking
  • 8. CRACKING PERFORMANCE USING SUPERPAVE IDT Oct 26, 2011
    • Three specimens from each mixture were tested at 0 0 C:
      • Resilient modulus test
      • Static creep test
      • Indirect tensile strength test
    Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking
  • 9. ENERGY RATIO CONCEPT Oct 26, 2011 Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking Ref: Florida Cracking Model
  • 10. HMA FRACTURE MECHANICS PERFORMANCE PREEDICTION Oct 26, 2011 Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking For example, AG1-O = Aggregate type 1 mixed with Base binder….etc
  • 11. CONCLUSIONS FROM MIXTURE PERFORMANCE Oct 26, 2011 Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking
    • Addition of wax makes the binder stiffer
    • Complex modulus results on binder showed improve stiffness at higher temperatures (i.e. improved rutting resistance!)
    • Adding wax to the binder increases the cracking resistance measured by the Superpave IDT
  • 12. APPROACH Oct 26, 2011 Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking
    • Moisture damage in asphalt mixtures is typically evaluated by the tensile strength ratio of moisture conditioned and dry samples
    • However a single parameter such as tensile strength is not enough to conclude moisture damage performance (Birgisson et al. 2003, 2004)
    • In this study the HMA fracture mechanics framework was used to evaluate moisture damage
  • 13. Creep rate at 1000 sec of the mixtures Oct 26, 2011 Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking For example, AG1-O = Before Conditioned and AG1-O-C = After Conditioned
  • 14. Moisture Damage Ratio of ER Oct 26, 2011 Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking For example, AG1-O = Aggregate type 1 mixed with Base binder….etc
  • 15. Conclusions from Mixture Performance tests Oct 26, 2011 Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking Compared to unmodified mixtures, wax modified mixtures gives : - Lower Creep rate. - Higher Energy Ratio So, addition of wax shows better moisture damage performance.
  • 16. Low Temperature Cracking Oct 26, 2011 Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking
    • Laboratory Experiments:
    • Binder Test:
    • DMA (Dynamic Mechanical Analysis)
    • BBR (Bending Beam Rheometer)
    • Mixture Test:
    • TSRST (Thermal Stress Restrained Test)
    • Superpave IDT (Indirect Tensile Strength Test)
  • 17. SUMMARY OF MIXTURES FRACTURE PROPERTIES Oct 26, 2011 Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking
  • 18. TSRST TEST RESULTS Oct 26, 2011 Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking
  • 19. Conclusions For Low Temperature Performance Oct 26, 2011 Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking So, Using 4% commercial wax as an additive has a minor or may be no negative effect in Low Temperature Cracking performance.           Test Result Binder DMA and BBR Minor Negative Effect Mixture TSRST Minor Negative Effect Superpave IDT Small Positive Effect
  • 20. Thank You Oct 26, 2011 Page Motivation Materials Cracking Performance Moisture Damage Low Temperature Cracking