Misturas asfálticas recicladas a quente contendo aditivos: avaliação do desempenho mecânico, econômico e ambiental.

Abstract

The paving industry has been increasingly encouraged to act more circularly, associating economic development with a better use of natural resources, due to the significant impacts that its activities impose mainly on the environment and financial resources. One of the practices consistent with the circular economy trend is the use of Reclaimed Asphalt Pavement (RAP) in hot mix asphalt. Some methods have been adopted in order to increase the amount of RAP, without compromising the mechanical performance of recycled hot­mix asphalt, with emphasis on warm mix asphalt additives and oils of animal and vegetable origin. In this work, it was decided to evaluate the incorporation of zeolite and cottonseed oil in these mixtures, at different levels. In the first phase, the degree of relative activation of the RAP binder(DoA') was determined using mechanical and volumetric parameters. In the second phase, the interference of the additives in the mechanical characteristics of the RAP was verified through the evaluation of the properties of indirect tensile test, resilient modulus and volumetry of samples made with 100% RAP with the direct addition of the additives, in different temperature conditions and conditioning times. In the third phase, by means of blending charts, the maximum recycling rates were established as a function of the critical temperatures of bioligands formulated with cotton oil. For this study, two sets of recycled hot mixes asphalt were analyzed: with 15%, 25% and 33% of RAP, containing, respectively, 4%, 6% and 10% of cottonseed oil; and with 15%, 25% and 33% RAP, containing 0.3% zeolite. In the fourth phase, the recycled hot­mixes asphalt were evaluated both for mechanical performance aspects, as well as for environmental and economic aspects, through an integrated analysis of mechanical properties (tensile strength, resilient modulus, Lottman, Cantabro, Flow Number, resistance to fatigue), circularity index, life cycle assessment and life cycle cost assessment. According to the DoA'v values, the temperature of 140°C promoted greater activation of the aged binder. Both additives brought benefits in the interaction with RAP, confirmed by the results of Vv, RT and MR. All recycled hot­mixes asphalt, regardless of the type of additive, showed satisfactory mechanical performance in all tests carried out. The integrated analysis of the mechanical, environmental and economic dimensions identified that the recycled hot­mixes asphalt alternative containing 0.3% zeolite and 25% RAP is the most advantageous, as it met the mechanical criteria, presented good environmental performance and is the second alternative among those studied with less financial investment. In the set of recycled hot­mixes asphalt with cotton oil, the alternative with 10% cotton oil and 33% RAP is the most advantageous, even though it is the alternative that presented the greatest environmental damage. The integrated analysis pointed out the need to balance the environmental and economic gains and losses when the project for recycled hot­mixes asphalt involves a residual additive or not.