Investigations of electrical conductivity and damage healing of graphite nano-platelet (GNP)-taconite modified asphalt materials

This proof of concept study investigates the electrical conductivity and damage healing capability of graphite nano-platelet (GNP)-taconite modified asphalt materials. Different combinations of GNP and taconite concentrate are added to an asphalt binder, and the electrical conductivity is measured by a four-probe conductivity test. Similar combinations of GNP and taconite concentrate are used to prepare asphalt mixture specimens to investigate the healing capability. Semi-circular bend (SCB) tests are performed at low temperature in two stages. First, specimens are damaged by loading them into the post peak region using crack mouth opening displacement (CMOD) control. The specimens are then subjected to microwave heating, after which they reloaded to measure the strength capacity. It is shown that the addition of GNP and taconite concentrate could effectively enhance the electrical conductivity of asphalt binders. The results also demonstrate the influence of humidity on the measured conductivity. The SCB fracture tests show that the application of microwave energy to the pre-damaged specimens restores their original load capacity, a clear indication of damage healing.