1. THE EFFECT OF TEMPERATURE AND COMPOSITION TO THE RHEOLOGICAL PROPERTIES OF ASPHALT PAVEMENTS A. László GÖMZE Dr., Róbert GÉBER, Judit CSÁNYI Tamásné University of Miskolc, Faculty of Material Science and Engineering, Department of Ceramics and Silicate Engineering e-mail: femgomze@uni-miskolc.hu, femgeber@uni-miskolc.hu INTRODUCTION As the result of the highway construction program in Hungary, the interest for the rheological properties of asphalt pavements, in favour of the optimization of asphalt mixtures – compositions, that are not tracked in summer was grown. Well known, that the viscosity of viscous materials, viscoelastic materials, and viscoplastic materials is dinamically decreases, if the temperature increases. The decrease of viscosity by leaps and bounds could be extremely dangerous in case of asphalt pavements in the range of 55 – 75 °C, due to the crossing cars on the low viscosity pavements are suffer inelastic deformation. On the basis of Rheo-tribometre instrument developed by A. L. Gömze and others, the authors have investigated and tested asphalt mixtures with different composition of mineral raw materials, and would like to reveal and review the dependence of the rheological properties of these pavements against the temperature, and the intensity of the dependence. SUMMARY According to the shear tests it is verifiable that the necessary shearing stress for shearing, and viscosity of the specimens decrease by the increase of temperature. If the applied bitumen content is 3,4 %, than there are local maximum and local minimum points on the diagrams in all cases. These differences are influenced by the grain size of the filler. The decrease of grain size is causes the increase of specifical surface of the filler, but there is no linear contact between the grain size and the rheological parameters. Former laboratory tests acknowledged that viscosity reduce by the increase of temperature According to the shear tests it is verifiable that the necessary shearing stress for shearing, and viscosity of the specimens decrease by the increase of temperature. If the applied bitumen content is 3,4 %, than there are local maximum and local minimum points on the diagrams in all cases. These differences are influenced by the grain size of the filler. The decrease of grain size is causes the increase of specifical surface of the filler, but there is no linear contact between the grain size and the rheological parameters. Former laboratory tests acknowledged that viscosity reduce by the increase of temperature. Fig. 2. Design of Rheo-tribometre instrument Content of the specimens: - Quartz sand (Fehérvárcsurgó), - Limestone-powder (Tatabánya) – as filler – in 3 different grainsize (0,09 mm - 0,063 mm - 0,032 mm), - Bitumen (Százhalombatta, type B50/70; bitumen content:2,9%, 3,4% and 3,9%) ) Fig. 3. Effective viscosity of asphalt mixtures at different bitumen content THE BASIS OF ASPHALT-RHEOLOGY Asphalt is an artificial material, which is manufactured by rolling and based on a combination of bitumen, stone-powder and ballast stone. Asphalt is an artificial material, which is manufactured by rolling and based on a combination of bitumen, stone-powder and ballast stone. The basis of rheological properties, testing methods and rheological modelling of asphalt mixtures was bought from Gezencvej [1.] in the middle of 1960 years. According to Gezencvej, asphalt – as structural building material – was known as viscous material, and was used the Burgers rheological model. In 2005 a new rheological model for asphalt was created by the associates of the department [2.], which is describes effectively and real the physical and mechanical processes in asphalt concretes and in asphalt mixtures made with bitumen. These models are shown on Fig. 1. Fig. 1. The (old) Burgers rheological model and the new rheological model of asphalts and asphalt mixtures made with bitumen THE RHEOLOGICAL EQUATIONS The rheological equation of asphalt mixtures and asphalt concretes with different composition, which are contains also the destructive and non-destructive material structures, was described with the following equation: where: : first derivative by time of the deformation of the material system : second derivative by time of the deformation of the material system : static liquid limit of the material system; [MPa] : first derivative by time of the shear stress t r : delay time of elastic deformation; [s] t fr : tension-relaxation time of the material system; [s] Effective viscosity can be defined by the previous equation as follow: SHEAR TESTS OF ASPHALT MIXTURES During the shear tests standard Marshall-specimens were tested with the Rheo-tribometre instrument [3.] (Fig. 2.). REFERENCES [1.]L.B. Gezencvej : Aszfaltbeton útburkolatok; Közdok, 1964. [2.]Gömze A. L. – Kovács Á.: Aszfaltkeverékek reológiai tulajdonságainak vizsgálata; Építőanyag 57. évf. 2. szám. (2005) [3.]Gömze A. L. - Czél Gy. –– Kocserha I.: U0200079 számú mintaoltalmú találmány; Magyar Szabadalmi Hivatal, Budapest. (2002)