Analysis of Stress and Strain in Flexible Pavement Structures Comprised of Conventional and High Modulus Asphalt Using Viscoelastic Theory

Abstract

Permanent deformation of pavements has become a persistent issue to be solved in Vietnam because of hot climatic conditions and high traffic volume. In order to deal with the problem, many attempts have been made by local authorities, researchers and practitioners, e.g. modification of the mixture gradation, improving bitumen rheology and high-quality control of manufacturing and construction of asphalt concrete (AC). SBS-modified bitumen or polymer modified bitumen (PMB) has been applied in Vietnam for many years and very good results in preventing rutting distress have been gained. However, in very high trafficked road and slow-speed area like intersection, PMB did not perform very well. Recently, high modulus asphalt concrete (HMAC) has been considered in the country as an alternative for PMB asphalt concrete. Since the thickness of flexible pavement structures in Vietnam is normally very small, ranging from 12 to 15 cm for asphalt layers while HMAC is stiffer than conventional AC, there are still concerns about the fatigue life of pavement structures comprised of HMAC. The aim of this study is to characterize the linear viscoelastic (LVE) behavior of HMAC and conventional AC and to analyze the LVE behavior of pavement composed of HMAC or (and) AC to evaluate its possible use in Vietnam. The results show that the use of HMAC will decrease the values of stress and strain at the bottom of the second asphalt layer, which increases the resistance to bottom-up fatigue cracking of the pavement.