In this project the deformation behaviour of a rolled asphalt mixture is investigated, and the influence of temperature on the deformation mechanism of the mixture is assessed, based on a series of uniaxial creep and creep recovery experiments conducted under compressive stress and controlled temperature. Firstly, the experiments were conducted for various temperature levels, loading time, and number of load applications. It is found that the total strain consists of the elastic, plastic, viscoelastic and viscoplastic strain components. The temperature and number of load cycles hardly affects the elastic strain, but the plastic increases with temperature and decreases with number of load applications at constant stress levels. The timedependent (viscoelastic and viscoplastic) and the instant (elastic and plastic) deformation reduced respectively to viscoelastic and elastic deformation components at low temperature. Secondly the relationship between the total strain and the variables, time, temperature, stress and number of cycles are successfully modelled mathematically. After this, the model is introduced into the finite element method. Also an approximate approach for permanent deformation in a flexible pavement is presented and a non-linear finite element program "CEPVP" with consideration of the pavement temperature profile was devised. The calculation was conducted using program `CVEVP". It was found that there was a great agreement between the computation and the test. Finally, a general comparison of program 'CVEVP' and package ANSYS was conducted. Considering the effects of mechanical parameters of bituminous materials, time of loading, thickness of asphalt and granular layers and environmental temperature, calculation of permanent deformation of bituminous pavement was carried out using program `CVEVP'. Some findings were concluded. For example, it was found that the plastic properties of asphalt mixture are the important factor in calculating the permanent deformation of flexible pavements, particularly at the upper end of the temperature spectrum.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:259911 |
| Date | January 1994 |
| Creators | Zheng, Li |
| Publisher | London South Bank University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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