| Abstrakt: |
Asphalt mixtures are the most widely used material in road construction. Therefore, it is necessary to know the properties of mixtures and their components, as well as changes in the properties occurring during the service life. The requirements for road durability are constantly increasing. Due to the effects during asphalt pavement production and service, there is a gradual degradation of properties. The article is therefore aimed at researching the relationship between the aging of the asphalt mixture and the aging of the bitumen binder, which is closely linked to the service life and roads durability. Selected asphalt mixtures (AC11 50/70 and AC11 PMB 45/80-75 used in most European countries) and binders were subjected to short-term (production and laying of the mixture) and long-term (service time, approx. 10-15 years) laboratory aging. For the results in the tested asphalt mixtures to be relevant, the same bitumen binders were used as in the binder research. The asphalts stiffness modulus (IT-CY method) was measured in the performed laboratory measurements, which reflects the elasticity and hardness of the asphalts. Laboratory tests of bitumen binders were performed, such as penetration, softening point, and weight loss. Because the penetration measurement test is performed at 25 °C, the stiffness modulus measurement tests were also performed at the same temperature. In general, a higher stiffness modulus was measured in AC11 50/70 mixtures. Lower stiffness was measured with the modified AC11 PMB 45/80-75 mixture; the variance in stiffness values caused by measurements at other test temperatures (10, 20, and 30 °C) was lower in this mixture. In both cases of measured asphalts and bituminous binders, the stiffness after short-term (STOA) and long-term (LTOA) laboratory aging of the samples increased. Due to short-term aging, the stiffness modulus values increased by 7.2 % (AC11 50/70) and 25 % (AC11 PMB), while the binder stiffness increased by 28.6 % (50/70) resp. 18.3 % (PMB 45/80-75) after RTFOT. For samples exposed to long-term aging, the increase in stiffness was higher compared to short-term aging by 10.3% (AC11 50/70) resp. 40 % (AC11 PMB) and the penetration decreased by 25.5 % resp. 28.3 %. Regarding the high-temperature properties of bitumen, a change of 50/70 binder was recorded, an increase in the softening point by 6.2 °C and 8 °C. When comparing the change in the stiffness of the bitumen binder and the change in the stiffness of the asphalt mixture at 25 °C, we can state that the stiffness of the binder changes by one unit, the stiffness modulus of the mixture changes by 381.6 MPa (50/70) and 702.2 MPa (PMB) due to short-term aging and by 587.4 MPa (50/70) and 1402.4 MPa (PMB) due to the effects of long-term aging. The change in stiffness modulus due to aging at 25 °C was smaller with AC11 50/70, but the measured values are significantly higher in comparison to AC11 PMB 45/80-75. [ABSTRACT FROM AUTHOR] |
