Structural design for sustainable pavements

Abstract

Pavement construction is a very energy intensive process, and it results in a significant usage of water, and emission of chemicals in the environment. Maintenance and rehabilitation of pavements also utilize a significant amount of energy, time and natural resources such as aggregate. Therefore, ensuring the durability and good performance of a pavement through proper structural design is a step towards making sustainable pavements. Structural design of pavements has evolved significantly over the years, from purely empirical to mechanistic-empirical, although, in most countries around the world, the empirical design process is followed for the design of asphalt pavements, which constitute the majority of roads in most countries. This is because of the inherent complexities, uncertainties and lack of single unified theories in the case of pavements. Furthermore, because of the variations in climate and types of aggregate and asphalt binder, and possibly type of traffic, across the globe and across large countries, and the dependence of pavement behavior on the climatic conditions, it is not possible to use any specific model for all countries or an entire country. But there is no doubt that a rational structural design procedure is needed in every country to ensure that the design with the optimum combination of performance and impact on the environment is selected. This paper presents the cost and environmental implications of different structural designs, and explores the concept of structural design for sustainable pavements with an example. It is shown that similar design life could be achieved by utilizing different combinations of base/binder and surface courses of a pavement, and the use of composite pavement, with Portland cement concrete and asphalt pavement layers could very well be the most optimum solution in reducing the impact of pavement construction and maintenance on the environment.