Avaliação da resistência ao trincamento de misturas asfálticas finas com diferentes tamanhos máximos nominais

Abstract

Fatigue cracking is one of the most common problems in asphalt pavements. This distress is related to a small-scale phenomena. The literature attributes to the aggregate properties approximately 80% of the mixture resistance to rutting, and the other 20% to the asphalt binder properties. Regarding to the fatigue cracking, 60% of this responsability is attributed to the binder characteristics and the other 40% to the aggregates properties. Recently, authors have used the fine portion of the hot mix asphalt (HMA), known as Fine Aggregates Matrix (FAM), as an intermediate step to estimate the HMA fatigue resistance. By definition, the FAM portion is composed by fine aggregates, asphalt binder and filler. This study aims to understand the influence of the coarse aggregate properties in the HMA fatigue cracking process using the correspondent FAM portion. The HMA, with 12.5mm Maximum Nominal Size (MNS), was designed using the Superpave mix design protocol. Following the original HMA design, the FAM design was evaluated using three different aggregate MNS, 1.18 mm, 2.00 mm, and 4.00 mm. The FAM samples were subjected to controlled strain fatigue damage characterization using the Dynamic Shear Rheometer (DSR). The HMA and the corresponding FAM mixtures were also subjected to the semicircular bending (SCB) fracture test in order to measure the dissipated energy during the crack propagation. For the DSR results, master curves of dynamic modulus were different, indicating different stiffnesses between mixtures. The fracture test results obtained at 15°C were different for the FAM mixtures with different MNS. However, at 25°C, there were no considerable differences between the mixtures with different MNS.