SURFACE CHARACTERISTICS OF ASPHALT PAVEMENTS WITH SYNTHETIC LIGHTWEIGHT AGGREGATE

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SURFACE CHARACTERISTICS OF ASPHALT PAVEMENTS
WITH SYNTHETIC LIGHTWEIGHT AGGREGATE

• Massimo Losa
• University of Pisa Department of Civil
  Engineering
• Associate Professor
• losa_at_ing.unipi.it
• Co-authors R. Bacci, P. Leandri, L. Alfinito, M.
  Cerchiai

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Outline

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

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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

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Use of Expanded Clay in Asphalt Mix

• Rounded granules
• Rough and porous surface
• Porous closed cell internal structure
• Mechanical Resistance

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Aggregate Blending
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Accelerated Polishing Test
DPSV20
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Laboratory Mix Design
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Indirect Tensile Strength
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Optimum Asphalt Content
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Resilient Modulus
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Experimental Surface
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Macrotexture measurement
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Mean Profile Depth
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Texture spectrum
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Friction
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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)

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Sound pressure level at 50 km/h
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Sound pressure level at 80 km/h
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CPXL at 50 km/h
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CPXL at 80 km/h
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Sound absorption

• Adrienne Method (ISO 13473-1)

• Kundt Impedance Tube (ISO 10534-2)

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Sound Absorption Coefficient
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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

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Conclusions 2/2

• The texture spectrum has
• fairly low amplitudes for l gt 8 mm
• high amplitudes for l lt 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

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Thank you for the attention

• www.ing.unipi.it/leopoldo