Verification of the new viscoelastic method of thermal stress calculation in asphalt layers of pavements

Abstract

The new viscoelastic method of thermal stress calculations in asphalt layers has been developed and published recently by the author. This paper presents verification of this method. The verification is based on the comparison of the results of calculations with results of testing of thermal stresses in Thermal Stress Restrained Specimen Test. The calculations of thermal stresses according to the new method were based on rheological parameters of the Burgers model. The parameters were measured in laboratory at different low temperatures, at long time creep under constant loading. Five asphalt mixes were tested. Three of them were high modulus asphalt concretes and two conventional asphalt concretes. Specimens were prepared in exactly the same way both for rheological creep tests and for the Thermal Stress Restrained Specimen Test. The results of measured thermal stresses were compared with thermal stresses calculated from the new viscoelastic method developed by the author and in most cases a good agreement was found. For comparison, the measured stresses were compared with results of calculations according to the existing methods. The viscoelastic Monismith method failed in prediction of thermal stresses. The prediction from the quasi-elastic Hills and Brien method was underestimated, but better than from the Monismith method and worse than from the new viscoelastic method. The reasons of discrepancies were discussed.

Keywords:

• Low-temperature asphalt cracking
• calculation of thermal stresses in asphalt
• testing of thermal stresses in asphalt
• rheological properties of asphalt
• thermo-rheological simplicity of asphalt

Funding

It is to gratefully acknowledge that the part of the data presented in this article concerning rheological and TSRST tests and stress calculations according to the existing methods were obtained in a research project directed by the author and sponsored by the Polish General Directorate of National Roads and Motorways. Within this project, the rheological tests and the calculations according to the Monismith method were performed with the significant participation of Mr. Mariusz Jaczewski, and by the Hills and Brien method by Dr Marek Pszczola.