engleski

Influence of aging on the rheological properties of ethylene vinyl acetate polymer modified bitumens

Polymer modified bitumens, PMBs, are increasingly used for pavement construction due to their excellent road performance. The physical and chemical characteristics of PMBs are easily changeable during production, storage, transportation, mixing with aggregates, laying and compaction, where PMBs are exposed to the influence of temperature and oxygen [1]. During PMBs in-service life, because of the inevitable contact with the natural environment it is also exposed to influence of temperature and oxygen. As a consequence, during these processes, lead to bitumen oxidation, polymer degradation, dehydrogenation, loss of volatiles and physical hardening, which may cause PMBs to become stiff, brittle and easily damaged [2]. To prevent deterioration pavements it is significance to comprehend the aging of PMBs correctly, seek new insight so to enhance the durability of PMBs and prolong the service life of pavements. This paper describes the polymer modification of road bitumen with different contents of thermoplastic copolymer ethylene- vinyl acetate, EVA, after termooxidative aging. The primary and secundary rheological characteristics, storage modulus, loss modulus and creep -recovery of the EVA PMBs were analysed by dynamic shear rheometer. The primary viscoelastic functions were determined in dependence as a function of frequency at temperatures in BIT use. The master curves were designed at reference temperature of 30°C. The results indicated that thermoplastic copolymer, EVA, improve the viscoelastic properties of PMBs at high temperatures. PMBs modified with EVA have less sensitivity to the changes of shear stress, respecitvely significantly reduce the permanent deformation under repeated loads compared to the unmodified bitumen. Acknowledgements. This work has been financially supported by the Ministry of Science, Education and Sport of the Republic of Croatia (Project no. 125-1252971-2578). [1] S. Haddadi, E. Ghorbel, N. Laradi, Const Build Mater 2008, 22, 1212. [2] X. Lu, U. Isacsson, J Appl Polym Sci 2000, 76, 1811.

polymer modified bitumen; termooxidative aging; rheological properties

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