Avaliação da textura de misturas asfálticas para uso em revestimentos aeroportuários a partir do uso do processamento digital de imagens

Abstract

Asphalt mixture design for application as surface layer in airport runways has to consider not only structural parameters, but must also consider texture and friction properties of the asphalt coating. Turbojet aircraft operation in commercial air transport increases the weight and the landing speed that airport pavements are subjected to. With that, the braking performance has become critical to the operation of airports. Depending on the pavement conditions, it is possible to occur hydroplaning or loss of traction and it can lead to take the pilot to lose airplane control. The adherence in the tire-pavement system is important to minimize the occurrence of such problem. However, there are not available methodology to predict texture properties and surface friction during the design of asphalt mixture. It happens even knowing that it is essential to select the mixture materials based on the adherence performance of the tire-pavement system. Texture and surface friction of a pavement is dictated by some parameters, such as: particle size distribution, aggregates shape properties, mixture compaction level and compaction method. Due the plurality of these properties, it is a hard to correlate them with texture and friction characteristics the asphalt mixtures that are used as surface layer of pavements. Based on that, the main objective of this work is to present a new methodology to evaluate surface texture of asphalt mixture applied in airports runways. The proposed technology verifies how aggregates shape properties, compaction, and inner structure of asphalt mixture correlate with the macro-texture and micro-texture of those material. Results showed that the aggregate gradation has influence in the results of macro-texture, being preponderant regarding the angularity of the aggregates. In addition, the compaction methodology used in the field and laboratory interferes in the surface texture of the asphalt coating. The macro-texture tends to increase as compaction level decreases. The macro-texture results obtained using digital image processing has a good relationship (R² = 0.71) with the sand patch results when the reading distance of the equipment was 0.30mm. When compared to the inner structure the correlation (R² = 0.43) between the orientation of the contacts of the aggregates and macro-texture was not satisfactory.