Comportamento mecânico de misturas asfálticas com agregado sinterizado de argila modificadas por nanomaterial de multicamadas de grafeno

Abstract

The mechanical behavior of asphalt mixtures of the Asphalt Concrete (CA) type was studied with the use of Calcined Clay Sintered Aggregate (ASAC), as a coarse aggregate, modified by graphene multilayer nanomaterial, and the effect of the samples aging on the mechanical performance. The purpose of this study was to analyze the mechanical performance of this alternative aggregate, the impact of the addition of graphene multilayer nanomaterials in the asphalt mixtures to be used in asphalt paving works in the city of Manaus, and also to demonstrate the importance of the aging in this process. In the composition of the CA were used the 50/70 asphalt binder, commercialized in the Amazon Region, the Manaus, sand as a fine aggregate, and the Portland cement, as the filer. All of these materials were physically characterized according to SUPERPAVE. The following materials were analyzed: 1) the reference mixture (without use of graphene multilayers and aged); 2) mixture with graphene multilayers aged, and 3) mixture without the graphene multilayers and unaged. It was determined the mechanical performance of these composites according to the Diametral Compressive Tensile Strength (RT) and Resilience Modulus (MR) tests. In the RT tests, the specimens of the three types of mixtures were subjected to temperatures of 25 °C, 40 °C and 60 °C. For MR, in particular, the mechanical behavior was studied at temperatures of 25 °C and 40 °C. The results showed that in the tensile strength test, there was an increase in RT values with the addition of graphene at temperatures of 25 ° C and 40 ° C. As far as the reference mixture is concerned, the values obtained from RT exceed the minimum set by the standard, and the unaged mixture did not obtain that minimum. Thus, the aged composites (reference material and graphene) meet the technical requirements, with increasing the mechanical performance with the addition of graphene multilayers to the aged blends, about 9.8% at 25 ° C and 8.1% at 40 ° C. Aging gives mixtures a 63% increase in RT compared to the unripe at 25 ° C, 97% at 40 ° C and 50% at 60 ° C. Regarding the Resilience Modulus, the tests showed that there was an increase in MR values, in the mixture with the addition of graphene nanomaterial and, for the three mixtures, there is maintenance of values, with the variation of the percentage of RT, which means that all composites studied are not very susceptible to temperature variation, with satisfactory mechanical resistance. It is demonstrated, therefore, that the ASAC aggregate has technical feasibility to be used in asphalt paving, that the multilayer nanomaterial of graphene shows itself as promising modifying material in this field, and that the aging process is essential in the execution of the asphalt mixtures.