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SURFACE CHARACTERISTICS OF ASPHALT PAVEMENTS WITH SYNTHETIC LIGHTWEIGHT AGGREGATE

SURFACE CHARACTERISTICS OF ASPHALT PAVEMENTS WITH SYNTHETIC LIGHTWEIGHT AGGREGATE. Massimo Losa University of Pisa – Department of Civil Engineering Associate Professor losa@ing.unipi.it Co- authors : R. Bacci , P. Leandri, L. Alfinito , M. Cerchiai. Outline. Aims of this work

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SURFACE CHARACTERISTICS OF ASPHALT PAVEMENTS WITH SYNTHETIC LIGHTWEIGHT AGGREGATE

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  1. SURFACE CHARACTERISTICS OF ASPHALT PAVEMENTS WITH SYNTHETIC LIGHTWEIGHT AGGREGATE • Massimo Losa • Universityof Pisa – DepartmentofCivilEngineering • AssociateProfessor • losa@ing.unipi.it • Co-authors: R. Bacci, P. Leandri, L. Alfinito, M. Cerchiai

  2. Outline • Aims of this work • Mix design • Laboratory tests • Field performance • Conclusions

  3. Aims of this work • to evaluate the potentials of using expanded clay in high performance wearing layers • to evaluate the performance of such surfaces in order to assess their potential as a viable alternative to low noise open-graded asphalt surfaces in urban context

  4. Use of Expanded Clay in Asphalt Mix • Rounded granules • Rough and porous surface • Porous closed cell internal structure • Mechanical Resistance

  5. Aggregate Blending

  6. Accelerated Polishing Test DPSV=+20%

  7. Laboratory Mix Design

  8. Indirect Tensile Strength ITSR Specifications ITSdry Specifications

  9. Optimum Asphalt Content

  10. Resilient Modulus DMR=+67%

  11. Experimental Surface

  12. Macrotexture measurement

  13. Mean Profile Depth

  14. Texture spectrum

  15. Friction

  16. Acoustic performance • CPX (ISO CD 11819-2): • Reference speed: 50 – 80 km/h • Measurements at different times • Close Proximity Index (CPXL) every 5 wheel rounds (9.6 m)

  17. Sound pressure level at 50 km/h V=50 km/h 7 dB(A)

  18. Sound pressure level at 80 km/h V=80 km/h 7 dB(A)

  19. CPXL at 50 km/h V=50 km/h 5 dB(A)

  20. CPXL at 80 km/h V=80 km/h 5 dB(A)

  21. Sound absorption • “Kundt” Impedance Tube (ISO 10534-2) “Adrienne” Method (ISO 13473-1)

  22. Sound Absorption Coefficient

  23. Conclusions 1/2 • 30% by volume of expanded clay • 20% increase in polishing resistance with regard to basalt • No problems of moisture susceptibility arise • 70% increase in Resilient Modulus compared to a traditonal asphalt mix

  24. Conclusions 2/2 • The texture spectrum has • fairly low amplitudes for l > 8 mm • high amplitudes for l < 8 mm • The friction levels are twice the values recommended for newly constructed traditional asphalt surfaces; • The Mean CPXL has been reduced of roughly 5 dB(A) at about 6 months after laying; • The Acoustic absorption coefficient peak is very low and close to 0.4

  25. Thank you for the attention www.ing.unipi.it/leopoldo

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