RESUMO GIGANTE, A.C. Avaliação da susceptibilidade térmica e do efeito das condições ambientais no enrijecimento de misturas asfálticas densas à luz de seus comportamentos resiliente. 2007. 169 f. Dissertação
Abstract:The objectives of this paper are the following: (a) to compare rotational viscosities of unaged and modified asphalt binders with the same performance grade, (b) to compare mixing and compaction temperatures obtained by different methods and (c) to evaluate the effect of these temperatures on the optimum binder contents of mixes designed according to the Superpave criterion. AC+EVA, AC+rubber and AC+rubber+PPA have the greatest viscosities among the binders studied here, whereas the neat one and AC+PPA have the lowest viscosities. Mixing and compaction temperatures were found to be very high for AC+rubber, AC+rubber+PPA and AC+EVA in the conventional method, whereas temperatures from 20 to 45 °C lower were found for the majority of the binders in the simple method. Mixing and compaction temperatures were reduced for the majority of the binders with the exception of the neat binder, AC+PPA, AC+SBS+PPA and AC+EVA+PPA. In spite of these reductions, the Superpave mixture design projects were well succeeded.
Resumo: A seleção de proporções adequadas dos modificadores a serem adicionados ao ligante asfáltico de base é uma questão fundamental na produção de ligantes asfálticos modificados. O objetivo deste trabalho é apresentar um procedimento para a definição das concentrações de borracha moída e de óleo extensor na produção de ligantes asfalto-borracha. O procedimento em questão é de natureza empírica e tem fundamentação na teoria estatística de experimentos com misturas. Compõe-se, basicamente, do delineamento de um experimento com misturas, o qual orienta a seleção de amostras cujas propriedades são monitoradas e, posteriormente, modeladas visando a confecção de gráficos de efeitos de componentes e de superfícies de resposta. Um estudo de caso é empregado para aplicar este procedimento, no qual os parâmetros da dosagem Marshall servem de referência para a seleção de concentrações de borracha moída e de óleo extensor para a composição de ligantes asfalto-borracha cujas propriedades atendam requisitos de especificação.Abstract: Selecting the appropriate proportions of modifiers to add to the base asphalt binder is a key-factor to produce modified asphalt binders. This research aims at presenting a procedure to define the concentrations of crumb rubber and extender oil to produce asphalt-rubber binders. The procedure is empiric and is based on the statistical theory of experiments with mixtures. It consists of two parts: (a) designing of an experiment with mixtures, that drives the selection of mixtures whose properties will be monitored and (b) fitting of mixture models, based on which response trace plots and contour plots will be generated. A case study is used to apply the procedure. Marshall parameters are used as a reference to select the concentrations of crumb rubber and extender oil to produce asphalt-rubber binders whose properties meet specification limits.
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