Papers by Author: Ning Li

Abstract: The conductive behavior of asphalt concrete can be improved with the addition of conductive materials, thus a multifunctional asphalt-based composite can be obtained. The conductive asphalt-based composite modified by graphite was studied extensively. Conductive materials percentages may have influences on performance of asphalt mixture. The performance of an asphalt pavement is significantly affected by its resistance to permanent deformation and its fatigue performance. The paper presents the results of a project aimed at investigating static and dynamic response as cracking and fatigue behaviors of conductive asphalt-based composite using the ITT. In particular ITT were performed in which the graphite percentages, loading mode was varied. As test results indicate that the addition of graphite shows positive influence on the indirect tensile strength, failure stiffness modulus in static loading test, especially in high loading speed. The number of load cycles to fatigue failure presents a bit decrease with graphite percentages in dynamic loading test. After adding discontinuous carbon fibers, conductive asphalt-based composite shows good fatigue property, which can prevent crack propagation. It can be concluded that the combined modification brings reinforcement effect to asphalt concrete and improves its mechanical and fatigue properties.

Abstract: It is currently interesting to use thermal or electrical conductive asphalt concrete for snow-melting and maintenance of asphalt pavements in winter. The addition of conductive fillers may have negative effects on the mechanical properties of asphalt concrete. The performance of conductive asphalt concrete is greatly affected by the initial crack and its propagation. Laboratory tests for neat and conductive asphalt concrete include Dynamic Modulus Test (DMT) and Indirect Tensile Fatigue Test (ITFT). DMT tests indicates that the value of dynamic modulus of asphalt concrete decreases with the increasing graphite content. It means that the conductive asphalt concrete achieves lower stiffness. It can be concluded from ITFT tests that the fatigue life (load cycle times) of conductive asphalt concrete is more than neat ones when stress level is under 1.0 MPa. Meanwhile higher fatigue resistance of conductive asphalt concrete is observed when carbon fibers (2 weight % of total aggregate) were added together with 22% graphite, especially at low stress levels.