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 Co-authors: R. Bacci, P. Leandri, L. Alfinito, M. CerchiaiCo-authors: R. Bacci, P. Leandri, L. Alfinito, M. Cerchiai

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

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

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

Portorož, Slovenia BasaltGravelSand Expanded Clay Mineral Filler Proportions by Volume [%] Proportions by Weight [%] Aggregate Blending

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

Portorož, Slovenia Laboratory Mix Design

Portorož, Slovenia Indirect Tensile Strength ITSR Specifications ITS dry Specifications

Portorož, Slovenia Optimum Asphalt Content

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

Portorož, Slovenia Experimental Surface

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-

Portorož, Slovenia Mean Profile Depth

Portorož, Slovenia Texture spectrum

Portorož, Slovenia Friction

Portorož, Slovenia Acoustic performance oCPX (ISO CD ): Reference speed: 50 – 80 km/h Measurements at different times Close Proximity Index (CPXL) every 5 wheel rounds (9.6 m)

Portorož, Slovenia 7 dB(A) V=50 km/h Sound pressure level at 50 km/h

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

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

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

Portorož, Slovenia Sound absorption “Adrienne” Method (ISO ) “Kundt” Impedance Tube (ISO )

Portorož, Slovenia Sound Absorption Coefficient

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

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

Portorož, Slovenia Thank you for the attention