The effect of temperature changes on mechanistic performance of hotmix asphalt as wearing course with different gradation types

The performance of hot mix asphalt serves as wearing course with different aggregate gradation types, namely dense graded and gap graded, is empirically determined using Marshall test. Based on data bitumen penetration, bitumen softening point, volume of bitumen, volume of aggregate and volume of voids, the mechanistic performance of bitumen (for example : bitumen stiffness) and hot mix asphalt (such as asphalt mix stiffness and fatigue life asphalt mix) in relation with temperature changes can be predicted. This mechanistic performance of hot mix asphalt are solved by Shell nomograph that can be simulated by software BANDS 2.0. The mixture consists of Asphalt Concrete-Wearing Course (AC-WC) and Hot Rolled Sheet-Wearing Course (HRS-WC) by considering their different gradations, in addition to its widely using as wearing course in Indonesia. The study was initiated by testing bitumen and asphalt mixture materials, including asphalt penetration 60/70 according to Bina Marga (2010) specification of coarse aggregate and fine aggregate. Subsequently, preparation of gradation mixture for AC-WC and HRS-WC based on Bina Marga (2010) was carried out, followed by Marshall Test with five variations of bitumen content on each asphalt mixture to determine optimum bitumen content. Based on the result of optimum bitumen content, specimens were made to determine the Marshall properties of the two diverse gradation asphalt mixtures using Marshall Test. Furthermore, by using data bitumen penetration, bitumen softening point and Marshall test, i.e. volume of bitumen, volume of aggregate and volume of voids, the mechanistic performance of hot mix asphalt was measured. It indicated the difference of Marshall properties between the dense graded and gap graded mixture. The first asphalt mixture has greater stability, VFWA (Void Filled With Asphalt) and MQ (Marshall Quotient) in compared with the second mixture. On the contrary, the second mixture has higher values of flow, VIM (Void In the Mix) and VMA (Void in Mineral Aggregate). The results of BANDS 2.0 simulation, mechanistic performance of hot mix asphalt shows that temperature changes influence bitumen stiffness, asphalt mix stiffness and fatigue life asphalt mix. The higher the temperature, the lower the bitumen stiffness and asphalt mix stiffness and the higher the fatigue life asphalt mix. At the same temperature, asphalt mix stiffness of dense graded mixture is higher than gap graded mixture. The other way for fatigue life asphalt mix.