Browsing by Author "Van Zyl, Stiaan"
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- ItemRelationship between the age related performance of a typical bituminous binder in South Africa and the fatigue performance of the asphalt mixture(Stellenbosch : Stellenbosch University, 2018-03) Van Zyl, Stiaan; Jenkins, Kim Jonathan; Gerber, Johan Andries Kritzinger; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: The primary factor affecting the durability of bituminous binders is ageing. Ageing causes an increase in stiffness which leads to non-load associated cracking in asphalt mixtures. Laboratory ageing has been used to determine the change in a binder’s rheology to predict how a binder would age in the field. Age-related parameters are calculated from a binder’s properties to determine a binder’s behaviour when exposed to ageing. These parameters give an indication of the rate of ageing. An asphalt mixture in a pavement structure is subjected to repeated loading rendering the asphalt mixture to deteriorate. This phenomenon is called fatigue. Fatigue, in asphalt, has become one of the major distress modes in a flexible pavement structure. The fatigue life of a pavement is predominantly influenced by the stiffness of the asphalt mixture, which in turn is influenced by the stiffness of the binder. Binders were subjected to different levels of ageing to determine the age-related parameters that indicate the degree of ageing of a binder. The binders were subjected to 4 different levels of ageing resulting in five different ages, namely Unaged, RTFO, PAV1, PAV2 and PAV4. The Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR) were used to determine the rheological properties of the binders. Models were used to predict the behaviour of the binders and to calculate the age-related parameters. Asphalt beams were produced to simulate repeated loading on an asphalt mixture. The stiffness of the asphalt mixture was determined by performing tests at different temperatures. Thereafter, the fatigue life of the asphalt mixture was determined at two different temperatures. The age-related performance of the binder was analysed with the fatigue performance of the asphalt mixture to determine a relationship between the age-related performance of a binder and the fatigue performance of the asphalt mixture. The Glover-Rowe (G-R) parameter gives an indication to the ductility of a material at intermediate temperatures and is used to assess the ageing of a binder. The DTc parameter, on the other hand, indicates the thermal cracking at lower temperatures and is used to assess the thermal cracking susceptibility after ageing. The G-R parameter gave a good correlation with the DTc parameter. Both described the ageing of the binder due to laboratory ageing very well. The G-R parameter was used as the age-related parameter of the binder to obtained a relationship. The fatigue results performed on the asphalt mixture at two temperatures showed a good correlation with each other regarding the slope of the fatigue-strain relationship. A relationship between the age-related parameter of the binder and the fatigue of the asphalt mixture was obtained.