Permanent strain development dynamics for asphalt pavement materials

This article gives the summary of the author’s PhD thesis supervised by Prof Dr Sc Ing Juris Rihards Naudžuns and defended on 10 November 2010 at the Riga Technical University. Introduction provides characteristics of the object of the research – asphalt concrete – from chemical, physical and mechanical aspects. The current situation on the roads and in Latvian transport industry has been described, and urgency of the problem, the necessity to eliminate deficiencies and the economic effect has been substantiated. The aim and tasks of the thesis have been formulated. Chapter 1 is devoted to survey of the literature which provides new and the already known (classical) modelling methods of stress and strain of road pavement layers, as well as description of advantages and deficiencies of these methods. Chapter 2 contains description of test methods used in the Promotion thesis. Properties of experimental specimens and their raw materials have been compared. Methods of designing asphalt mixtures are described. Chapter 3 provides analysis of external factors causing asphalt concrete permanent strain – temperature and transport load. In Chapter 4, test specimens have been experimentally tested with the help of the performance testing methods (wheel tracking test, uniaxial cyclic compression test and triaxial cyclic compression test). Plastic deformations have been determined and deformation rates have been calculated. In Chapter 5, the asphalt pavement quality provision system has been developed on the basis of the analysis of the obtained results and recommendations have been provided for minimising rutting. This thesis is written in Latvian and is available on http://ortus.rtu.lv/ web page and from the author upon request