Matteo Pettinari

Low rolling resistance pavements in Denmark

Low rolling resistance pavements can reduce fuel consumption by 4%.In Denmark the CO2 emission from the road transport alone is estimated to 4,6 mill ton pr. year. Implementing low rolling resistance pavement on the entire 4000 km of state roads in Denmark will provide a reduction in CO2 emission by 160.000 tons pr. year and saving the road users by 64 million litre of fuel. Approximately one fourth of the total energy consumption in Denmark is consumed by the road transport, a consumption that is continuously growing. About one third of the energy consumption from the road transport comes from overcoming rolling resistance between the tire and road. In 2011 Danish national funding gave the possibility to initiate the COOEE project, CO2 emission reduction by exploitation of rolling resistance modelling of pavements. The project involved two universities, Roskilde University and the Technical University of Denmark, the Scandinavian contractor NCC roads and the Danish Road Directorate. The challenge was to develop a road pavements with low rolling resistance that still provide other functionalities as friction to support traffic safety and low noise emissions. In Denmark three tests sections has been constructed between 2012 and 2014 – the paper presents the experience from construction these pavements as well as the obtained functionalities such as rolling resistance, skid resistance and evenness.

Three Different Ways of Calibrating Burger’s Contact Model for Viscoelastic Model of Asphalt Mixtures by Discrete Element Method

In this paper the viscoelastic behavior of asphalt mixture was investigated by employing a three-dimensional discrete element method. Combined with Burger’s model, three contact models were used for the construction of constitutive asphalt mixture model with viscoelastic properties in the commercial software PFC 3D , including the slip model, linear stiffness-contact model, and contact bond model. A macro-scale Burger’s model was first established and the input parameters of Burger’s contact model were calibrated by adjusting them so that the model fitted the experimental data for the complex modulus. Three different approaches have been used and compared for calibrating the Burger’s contact model. Values of the dynamic modulus and phase angle of asphalt mixtures were predicted by conducting DE simulation under dynamic strain control loading. The excellent agreement between the predicted and the laboratory test values for the complex modulus shows that DEM can be used to reliably predict the viscoelastic properties of asphalt mixtures.