Development and FE Implementation of a Non-Linear Constitutive Model for Asphalt
Professor A.C. Collop (formerly NTEC) - Principal Investigator
Professor G.D. Airey (NTEC) - Co-Investigator
Dr J.R.A. Grenfell (NTEC) - Research Fellow
Sponsored by EPSRC.
In association with TU Delft, Shell, Aggregate Industries and TRL.
Background
Premature rutting of asphalt pavements still represents a serious practical problem for heavily trafficked roads, particularly under high temperature conditions. While the incidence of wheel track ruts in the highway does not usually imply structural failure, particularly in heavy-duty pavements, it does represent a serviceability failure, since ruts cause a hazard to traffic, particularly in wet weather. The purpose of this project is to produce a model which can be used to predict deformation in asphaltic materials. This would lead to a better understanding of road materials and could also be used as a predictive tool for determining the performance of different mixes under specific climatic and traffic loading conditions.
This project is a continuation of some collaborative work between the Nottingham Transportation Engineering Centre (NTEC) and Delft University of Technology. This research was focussed on the development and Finite Element (FE) implementation of a non-linear elasto-visco-plastic constitutive model for asphalt with visco-plastic damage to model quasi-static permanent deformation in asphalt (Collop et al., 2002). The work was extremely successful and forms the basis for this research.
Methods
Two asphaltic materials were chosen for the testing program. A 10 mm Dense Bitumen Macadam (DBM), which is a typical binder course and a 30/10 Hot Rolled Asphalt (HRA), which is a typical wearing course. There were two reasons why these particular materials were chosen as. Firstly, they are known to have very different failure mechanisms, DBM dominated by aggregate interlock and HRA dominated by the strength of the binder. Secondly, a vast database of mechanical testing data for these particular materials already exists within the NTEC.
The initial part of the project involves laboratory element testing in both tension and compression over a range of stress levels and temperatures to characterise fundamental mixture behaviour. Data from these element tests is then used to determine parameters for the model, which is being developed simultaneously in Delft. Small-scale wheel tracking tests will then be carried out in order to gain further parameters and then begin the validation process. Full-scale wheel tracking will be carried out to complete the validation process. The final objective of this project will be to produce guidelines that identify the testing needed to determine the parameters required by the constitutive model for any mixture.
Further Information
A web page has also been set-up associated with this project for the purpose of data transfer between project partners. This page is password protected and only project partners have access to these pages. If you are a project partner wishing to access these pages, please click on the following link.:
Constitutive Modeling Data Transfer Pages