DBPapers
DOI: 10.5593/SGEM2014/B62/S26.036

RHEOLOGICAL PARAMETERS OF 100% RECYCLED HALF-WARM ASPHALT MIXTURES

P. Kucera, J. Zak
Wednesday 1 October 2014 by Libadmin2014

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-21-6 / ISSN 1314-2704, June 19-25, 2014, Book 6, Vol. 2, 275-282 pp

ABSTRACT
Since 1960s several railway administrations have utilized asphalt mixtures instead of conventional granular subballast in selected tracks or track sections. Gained experiences have shown that asphalt layers provide a good support for ballast bed, distribute load equally to subgrade and due to their impermeability protect subgrade from rain water penetration. However, production of conventional asphalt mixtures demands high amounts of energy and natural materials, particularly bitumen and aggregates. Production of asphalt mixtures at lower temperatures can significantly decrease energy consumption of the process. A possible way to preserve resources of natural materials is utilization of high percentages of recycled asphalt pavement material in production of asphalt mixtures. This study is focused on investigation of 100% recycled half-warm asphalt mixtures development of a new approach to design subballast layers made of these mixtures is proposed. The design approach employs deformation modulus as the main criterion for assessment of bearing capacity of subballast layers. To evaluate the effect of subballast, made of recycled asphalt mixtures, on the bearing capacity of railway track bed it is necessary to gather enough data including deformation modulus on formation surface, subballast thickness and resulting deformation modulus on subballast surface. The data can be gathered by measurements on real structures, measurements on physical models or by numerical modeling. For the purpose of this study, the latter approach was chosen. First steps to establish a corresponding material model were carried out. The creep compliances were calculated from direct compression test as the dimensionless physical parameter of recycled asphalt mixtures. The effect of several stress levels is presented and the linear-viscoelastic boundaries are assessed. The measured creep compliances were fitted with the Kelvin-Voight model.

Keywords: recycled, asphalt mixture, subballast, creep, linear viscoelasticity