A prototype simple shear and compaction apparatus with application to asphaltic concrete.

摘要

The focus of this research is on simple shear deformation of asphaltic concrete and its connection to the problem of permanent deformation (rutting) in asphaltic concrete pavements caused by heavy traffic conditions and high temperature. Emphasis is placed on the mechanics of damage (rutting) to the upper asphaltic concrete layers. Rutting is a major problem in countries with a hot climate, heavy traffic, and unregulated axle weight. This research summarizes some information gathered from the literature on the importance given to the general problem of permanent deformation of asphalt mixtures and the procedures and constitutive models used to design asphaltic concrete mixture, pavement structures, and to evaluate asphaltic concrete stability. Results from this effort showed contact stresses are under-estimated in pavement structure, surface shear stress due wheel contact are not considered in asphalt concrete design, and equipment used in asphalt concrete laboratories are not suitable to simulate the state of stress at which an element under a wheel is subjected to. In this research, the behavior of an asphaltic concrete mixture, used on a project in Arizona, is evaluated through fundamental mechanics and appropriate laboratory experimental verification. Much of the research effort is devoted to the design and development of a new compaction and simple shear apparatus. The general behavior of aslphalt concrete material under a complete cyclic loading and under one-half cyclic loading is presented. The general trend of the vertical deformation indicated that asphalt concrete tends to shakedown after a sufficient number of cyclic loadings.