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Abstract(s)
Quando os pavimentos rodoviários apresentam sinais de degradação que apontam para o início dum estado de ruína, é essencial intervir ao nível da reabilitação estrutural, nomeadamente através da aplicação de camadas de reforço.
Neste contexto, o objetivo do trabalho apresentado centra-se no estudo dos métodos e metodologias que permitem dimensionar, no âmbito de uma ação de reabilitação a nível estrutural, a espessura de camadas betuminosas de reforço para pavimentos flexíveis.
Para o efeito descrevem-se dois procedimentos expeditos de dimensionamento de reforço baseados na determinação da espessura efetiva do pavimento, um com recurso aos ábacos do Asphalt Institute e outro ao manual português MADIPAV; e duas abordagens empírico-mecanicistas baseadas nas deflexões reversíveis, uma com aplicação das formulações de dimensionamento da Shell e outra com a determinação dos fatores de carga.
A análise e a aplicação das abordagens a dois casos de estudo permitiu concluir que os métodos expeditos baseiam-se num processo de cálculo mais simples, em que não são explicitamente consideradas as características mecânicas das camadas do pavimento existente, fornecendo soluções sobredimensionadas. Por outro lado, os métodos empírico-mecanicistas são os que estruturalmente melhor avaliam os pavimentos, uma vez que são exigidos ensaios de carga para caracterizar o comportamento estrutural do pavimento, sendo assim possível determinar as características mecânicas para os materiais granulares e misturas betuminosas através de retro análise, dando origem a soluções mais sustentadas.
As espessuras de reforço obtidas para os casos de estudo diferem significativamente, verificando-se que a aplicação das abordagens empírico-mecanicistas deram origem a valores que correspondem aproximadamente a metade dos obtidos na aplicação dos métodos expeditos.
When road pavement shows signs of degradation which point to the beginning of a ruin state, it is fundamental to step in terms of structural rehabilitation, namely by applying overlay layers. Therefore, the purpose of the presented study focuses on studying the methods and methodologies of thickness design of bituminous concrete overlays for flexible pavements, as part of a rehabilitation action at a structural level. For this purpose, two expedite procedures for overlay thickness design based on the calculation of the effective thickness of the pavement are described. One of the procedures requires the use of abacuses from the Asphalt Institute and the other uses the Portuguese manual MADIPAV. Two mechanistic-empirical approaches based on the reversible deflections are also described, one of them with the application of Shell pavement design formulas and the other one through calculation of load factors. The analysis and the use of those two approaches (expedite and mechanistic-empirical) to two case studies led to the conclusion that the expedite methods are based on a simpler calculation process, in which the mechanical properties of the existing pavement layers are not explicitly taken into account, which lead to oversized solutions. On the other hand, the empirical-mechanistic methods are the ones that best evaluate the pavement in a structural point of view, since load tests are required to characterize its structural behavior. Thus, it’s possible to determine the mechanical properties for the granular materials and bituminous mixtures through backcalculation, which leads to more sustainable solutions. The overlay thicknesses obtained for the case studies differ significantly so that it appears that the application of mechanistic-empirical approaches led to values that are approximately half of those obtained by applying expedite methods.
When road pavement shows signs of degradation which point to the beginning of a ruin state, it is fundamental to step in terms of structural rehabilitation, namely by applying overlay layers. Therefore, the purpose of the presented study focuses on studying the methods and methodologies of thickness design of bituminous concrete overlays for flexible pavements, as part of a rehabilitation action at a structural level. For this purpose, two expedite procedures for overlay thickness design based on the calculation of the effective thickness of the pavement are described. One of the procedures requires the use of abacuses from the Asphalt Institute and the other uses the Portuguese manual MADIPAV. Two mechanistic-empirical approaches based on the reversible deflections are also described, one of them with the application of Shell pavement design formulas and the other one through calculation of load factors. The analysis and the use of those two approaches (expedite and mechanistic-empirical) to two case studies led to the conclusion that the expedite methods are based on a simpler calculation process, in which the mechanical properties of the existing pavement layers are not explicitly taken into account, which lead to oversized solutions. On the other hand, the empirical-mechanistic methods are the ones that best evaluate the pavement in a structural point of view, since load tests are required to characterize its structural behavior. Thus, it’s possible to determine the mechanical properties for the granular materials and bituminous mixtures through backcalculation, which leads to more sustainable solutions. The overlay thicknesses obtained for the case studies differ significantly so that it appears that the application of mechanistic-empirical approaches led to values that are approximately half of those obtained by applying expedite methods.
Description
Keywords
Pavimentos Rodoviários Flexíveis Métodos de Dimensionamento de Camadas de Reforço. Reabilitação Estrutural Reforço