Evaluation of moisture sensitivity of asphalt mixtures by investigating dynamic creep test and permanent deformation behavior

Articles in Press

Document Type : Original Article

Authors

1 Assistant Professor, University of Qom

2 Tafresh University

10.22034/tri.2021.280811.2890

Abstract

According to previous studies and investigations, different parameters are involved in the moisture sensitivity and stripping of asphalt mixtures, which are associated with the aggregate, asphalt, mixture design and construction, environment, and traffic. The main goal of the present research is to evaluate the stripping under various environmental and traffic conditions and to assess its counter effect on the permanent deformation of asphalt mixtures. For this purpose, the dynamic creep test has been performed on the conditioned and unconditioned mixtures with dense graded to compare their behaviors in the presence and absence of moisture. In this method, by applying an axial dynamic load, to the samples that are saturated, the dynamic entry and exit of water into their pores were modeled. Then the theory was used that water penetrates to the surface between the aggregate and bitumen and causes poor adhesion between bitumen and aggregate and poor cohesion in the structure of bitumen. In other words, the phenomenon of stripping is revealed. Stripping accelerates the failure rate of the asphalt mixture, resulting in permanent deformation of the specimen exposed to moisture. Through the examination of different temperature and loading combinations, it was concluded that, at high temperature, with the increase of frequency, the stripping potential decreases; and at low temperature, with the increase of frequency, the stripping potential increases. By analyzing the mechanical characteristics of the samples it was observed that the ratio of creep modulus to resilient modulus is an appropriate criterion for the evaluation of permanent deformation in samples and that by using this ratio, the stripping potential and moisture effect can be investigated at high temperatures. Also, it was found that at high temperatures, the asphalt mixtures are more sensitive to temperature than to moisture.

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Main Subjects

Journal of Transportation Research

Articles in Press, Accepted Manuscript
Available Online from 16 November 2021

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