Characteristics of undamaged asphalt mixtures in tension and compression

Abstract

Cracking in asphalt pavements is the net result of fracture and healing. The ability to accurately measure and predict the appearance of cracking depends on being able to determine the material properties that govern the rate of development of these two contrary aspects of cracking. This study is devoted to identifying the datum material properties in undamaged samples. It will make use of viscoelastic formulations and of well-known mechanics concepts the way in which these properties are altered by the composition of the mixture. Also introduced in this study is a process that makes extensive use of the pseudo-strain concept in decomposing the strain components. One of the many benefits of this approach is the ability to measure the fatigue endurance limit of an asphalt mixture with a simple test that requires only half an hour. The study begins with a detailed discussion of these concepts and properties and the test methods that simply and accurately measure them. One of the great advantages of using mechanics is that it provides a rapid and efficient way to predict the rate of appearance of the two aspects of pavement cracking, fracture and healing. Mechanics requires the use of material properties. An accurate and efficient determination of undamaged material properties is fundamental and important to the prediction of the performance of asphalt mixtures. It is found that the undamaged properties of an asphalt mixture are different when they are loaded in tension or in compression and this distinction is important. This study addresses the efficiency of the laboratory testing methods, and the effects of the volumetric material components and environmental factors such as temperature and ageing on the undamaged material properties. It also introduces the non-destructive tests that must be made in order, subsequently, to measure the damaged properties of the same materials.