Renato Bacci

Empirical Rolling Noise Prediction Models Based on Pavement Surface Characteristics

ABSTRACT Tyre/road noise is a complex phenomenon which is function of tyre, surface properties and speed. This study aims to define a rolling noise prediction model for a reference tyre, as a function of speed, on dense asphalt surfaces with medium-low macrotexture levels. The model was defined by relating texture levels of pavement profiles and rolling noise levels recorded at different speeds. The study also defines an extension of the model valuable for semi-porous surfaces, as a function of only surface characteristics. Both of the models serve as a support tool for mix design of low noise asphalt pavement surfaces.

Mechanical and Performance-Related Properties of Asphalt Mixes Containing Expanded Clay Aggregate

The use of artificial aggregates such as expanded clay in the production of asphalt concrete makes it possible to reduce both natural aggregate extraction and the use of nonrenewable raw resources, greatly benefiting the environment. Moreover, the expanded clay production process allows nondangerous waste materials to be reclaimed and thereby avoids the necessity to dispose of them in a landfill or dump–this benefits the environment and also offers economic advantages. This paper reports on the results of laboratory and in situ tests to evaluate the feasibility and advantages of using expanded clay in producing asphalt mixes for use in urban areas to reduce traffic noise. Some experimental low-noise asphalt surfaces were laid, with 15% of expanded clay by weight, and mechanical as well as performance properties were then evaluated. The mechanical characteristics, friction, and acoustic performance, in contrast to results with traditional asphalt surfaces, demonstrated the considerable benefits of using expanded clay in asphalt mixes for surface layers. In particular, the results of friction increase and noise-spectrum reduction are of interest.

A Statistical Model for Prediction of Critical Strains in Pavements from Deflection Measurements

ABSTRACT Existing pavements of collector rural roads are often characterized by a strong dishomogeneity in pavement layer thicknesses and mechanical properties of materials. In order to evaluate structural conditions of these pavements, they must be delineated in homogeneous sub-sections with regard to variations both in the thickness and the mechanical properties of pavement layers, but this task is often very difficult. For this purpose, this paper proposes a statistical model for the straight evaluation of critical strains in pavements by using the deflections measured by the Falling Weight Deflectometer and the layer thicknesses without backcalculating layer moduli. The model is calibrated on the basis of experimental data and it is useful to evaluate statistical parameters of the homogeneous sub-sections with the aim to evaluate the residual pavement life taking into account the reliability concepts.

Monitoring and Evaluating Performance Requirements of Flexible Road Pavements

This paper presents key findings of a research project which is entrusted with setting up guidelines for monitoring and evaluation of pavement performance requirements with the aim of improving durability and both road safety and environmental sustainability. The study has investigated some techniques for monitoring structural and surface characteristics of asphalt pavements, such as Ground Penetrating Radar, Falling Weight Deflectometer, Laser Profilometer, Skiddometer, and has addressed problems arising from the use of these techniques; the paper describes some measures needed to overwhelm them and for optimizing data collection procedures. In order to enhance the evaluation of asphalt pavements, the study has focused on data analysis and interpretation methodologies; it proposes refinements to the existing procedures for both data processing and interpretation.