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Abstract(s)
As administraçÔes de estradas em todo o mundo tĂȘm tomado consciĂȘncia, ao longo das Ășltimas dĂ©cadas, da importĂąncia de alargar o ciclo de vida dos materiais constituintes das diferentes camadas dos pavimentos rodoviĂĄrios. Um dos principais problemas verificados nos pavimentos rodoviĂĄrios Ă© a formação de cavados de rodeira, que surgem devido ao acentuado crescimento do volume de trĂĄfego rodoviĂĄrio e da sucessiva passagem de rodados de veĂculos pesados, em especial, em zonas com velocidades baixas. A existĂȘncia de cavados de rodeira, agravam as condiçÔes de conforto e segurança dos utentes na circulação rodoviĂĄria, uma vez que favorecem a acumulação de ĂĄgua sobre a superfĂcie do pavimento, reduzindo a aderĂȘncia pneu/pavimento, podendo originar fenĂłmenos de hidroplanagem.
Esta dissertação tem como principal objetivo, o estudo de formulação de misturas betuminosas a aplicar em camadas de desgaste, com vista a melhorar a adesividade entre o agregado e o betume e, consequentemente, aumentar a resistĂȘncia Ă deformação permanente.
Estudaram-se quatro misturas diferentes, trĂȘs delas misturas tradicionais que diferem no tipo de fĂler e na curva granulomĂ©trica, e a quarta, uma mistura descontĂnua, com a adição de um promotor de adesividade, na forma de fibras celulĂłsicas impregnadas com uma amina.
No estudo de formulação de cada mistura, analisaram-se algumas propriedades, tais como baridade e porosidade. O ensaio Marshall realizou-se com o intuito de determinar o teor Ăłtimo de betume para cada tipo de mistura. Posteriormente, realizou-se o ensaio de afinidade entre agregado e ligante, o ensaio de sensibilidade Ă ĂĄgua e, por Ășltimo, o ensaio wheel tracking, para a avaliação da resistĂȘncia Ă deformação permanente.
Dos resultados obtidos, verificou-se no ensaio de afinidade entre agregado e ligante, que a adição do promotor de adesividade, sob a forma de fibras celulĂłsicas impregnadas com uma amina, contribuiu para um aumento de 10 % da superfĂcie de agregado coberta com betume, relativamente aos agregados sem a utilização deste promotor. No ensaio de sensibilidade Ă ĂĄgua, as misturas com fĂler granĂtico apresentam o valor mais baixo de ITSR (70 %), sendo as misturas com fĂler calcĂĄrio as que apresentam o maior valor de ITSR (93 %). Quanto aos resultados do ensaio wheel tracking, verificou-se que a utilização do fĂler calcĂĄrio traduz uma melhoria no comportamento face Ă deformação permanente das misturas betuminosas. A mistura com promotor de adesividade revelou o melhor resultado mĂ©dio na anĂĄlise deste parĂąmetro.
Over the past few decades, road administrations around the world have become aware of the importance of extending the life cycle of materials that make up the different layers of road pavements. One of the main problems encountered in road pavements is the formation of rut depth due to increase in the volume of road traffic and the successive passage of heavy vehicle, especially in areas with low speeds. The existence of rut depth makes the conditions of comfort and safety of road users decrease, favoring the water accumulation on the pavement surface, reducing tire / pavement friction, which can lead to hydroplaning phenomena. The main objective of this dissertation is to study bituminous mixtures design to be applied in surface layers to improve the affinity between aggregate and bitumen and, consequently, to increase resistance to permanent deformation. Four different mixtures were studied, three of them traditional mixtures, differing in the type of fĂler and in aggregates grading curve, and the fourth, a discontinuous mixture, with the addition of an affinity promoter in the form of cellulosic fibers impregnated with an amine. In the bituminous mixtures design, some properties, such as bulk density and porosity, were analyzed. The Marshall test was carried out with the purpose of determining the optimum bitumen content for each type of mixture. Subsequently, was performed the affinity between aggregate and bitumen test, the water sensitivity test and, finally, the wheel tracking test, for the evaluation of resistance to permanent deformation. From the results obtained, it was found that in affinity between aggregate and bitumen test, the addition of the affinity promoter, in the form of cellulosic fibers impregnated with an amine, contributed to a 10% increase in the aggregate surface covered with bitumen, relative to the aggregates without the use of this promoter. In the water sensitivity test, the mixtures with granitic fĂler present the lowest ITSR value (70%), and the mixtures with limestone fĂler are the ones with the highest ITSR value (93%). Regarding the results of the wheel tracking test, it was verified that the use of the limestone fĂler translates an improvement in the behavior against the permanent deformation of the bituminous mixtures. The mixture with affinity promoter showed the best average result in the analysis of this parameter.
Over the past few decades, road administrations around the world have become aware of the importance of extending the life cycle of materials that make up the different layers of road pavements. One of the main problems encountered in road pavements is the formation of rut depth due to increase in the volume of road traffic and the successive passage of heavy vehicle, especially in areas with low speeds. The existence of rut depth makes the conditions of comfort and safety of road users decrease, favoring the water accumulation on the pavement surface, reducing tire / pavement friction, which can lead to hydroplaning phenomena. The main objective of this dissertation is to study bituminous mixtures design to be applied in surface layers to improve the affinity between aggregate and bitumen and, consequently, to increase resistance to permanent deformation. Four different mixtures were studied, three of them traditional mixtures, differing in the type of fĂler and in aggregates grading curve, and the fourth, a discontinuous mixture, with the addition of an affinity promoter in the form of cellulosic fibers impregnated with an amine. In the bituminous mixtures design, some properties, such as bulk density and porosity, were analyzed. The Marshall test was carried out with the purpose of determining the optimum bitumen content for each type of mixture. Subsequently, was performed the affinity between aggregate and bitumen test, the water sensitivity test and, finally, the wheel tracking test, for the evaluation of resistance to permanent deformation. From the results obtained, it was found that in affinity between aggregate and bitumen test, the addition of the affinity promoter, in the form of cellulosic fibers impregnated with an amine, contributed to a 10% increase in the aggregate surface covered with bitumen, relative to the aggregates without the use of this promoter. In the water sensitivity test, the mixtures with granitic fĂler present the lowest ITSR value (70%), and the mixtures with limestone fĂler are the ones with the highest ITSR value (93%). Regarding the results of the wheel tracking test, it was verified that the use of the limestone fĂler translates an improvement in the behavior against the permanent deformation of the bituminous mixtures. The mixture with affinity promoter showed the best average result in the analysis of this parameter.
Description
Keywords
Adesividade Deformação Permanente Fibras CelulĂłsicas FĂler Misturas Betuminosas