1. Portorož, Slovenia SURFACE CHARACTERISTICS OF ASPHALT PAVEMENTS WITH SYNTHETIC LIGHTWEIGHT AGGREGATE Massimo LosaMassimo Losa University of Pisa – Department of Civil EngineeringUniversity of Pisa – Department of Civil Engineering Associate ProfessorAssociate Professor losa@ing.unipi.itlosa@ing.unipi.itlosa@ing.unipi.it Co-authors: R. Bacci, P. Leandri, L. Alfinito, M. CerchiaiCo-authors: R. Bacci, P. Leandri, L. Alfinito, M. Cerchiai

2. Portorož, Slovenia Outline oAims of this work oMix design oLaboratory tests oField performance oConclusions

3. Portorož, Slovenia 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. Portorož, Slovenia Characteristics of the expanded clay Bulk Specific Gravity [kg/m 3 ]1130 Water Absorption [%]17 Crushing Resistance [N/mm 2 ]> 45 Polishing Stone Value [%]> 65 Use of Expanded Clay in Asphalt Mix Rounded granules Rough and porous surface Porous closed cell internal structure Mechanical Resistance

5. Portorož, Slovenia BasaltGravelSand Expanded Clay Mineral Filler Proportions by Volume [%]13.2 37.329.66.7 Proportions by Weight [%]15.616.644.815.08.0 Aggregate Blending

6. Portorož, Slovenia PSV=+20% Accelerated Polishing Test

7. Portorož, Slovenia Laboratory Mix Design

8. Portorož, Slovenia Indirect Tensile Strength ITSR Specifications ITS dry Specifications

9. Portorož, Slovenia Optimum Asphalt Content

10. Portorož, Slovenia M R =+67% Resilient Modulus

11. Portorož, Slovenia Experimental Surface

12. Portorož, Slovenia Macrotexture measurement Device Sampling Rate Sampling Interval Vertical Resolution Measuring Speed Profile Length Stationary Profilometer 16 kHz0.1 mm0.05 mmManual750 mm Mobile Profilometer 16 kHz1 mm0.05 mm20 km/h-

13. Portorož, Slovenia Mean Profile Depth

14. Portorož, Slovenia Texture spectrum

15. Portorož, Slovenia Friction

16. Portorož, Slovenia Acoustic performance oCPX (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. Portorož, Slovenia 7 dB(A) V=50 km/h Sound pressure level at 50 km/h

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

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

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

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

22. Portorož, Slovenia Sound Absorption Coefficient

23. Portorož, Slovenia 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. Portorož, Slovenia Conclusions 2/2 The texture spectrum has fairly low amplitudes for > 8 mm high amplitudes for < 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. Portorož, Slovenia Thank you for the attention www.ing.unipi.it/leopoldo