Effect of Taconite on Healing and Thermal Characteristics of Asphalt Binder

Based on the positive effect of metal material on the healing property of asphalt binder, this study evaluated the merits of using taconite (an iron-containing filler from iron-mine tailings) to promote the healing performance of asphalt binder. Samples of asphalt binder modified with three different dosages of taconite were tested by a thermal conductivity (TC) device. The presence of taconite can provide TC values in asphalt mastic and thereby allow inductive heating to improve healing in asphalt pavement. Laboratory experiments were used to evaluate the healing property of asphalt mastic containing 10%, 20%, or 30% by weight taconite. The healing property was measured using a healing index based on the complex modulus. The TC values were tested using a new testing method, and then the relationship between TC values and healing performance was analyzed. In the range of content of taconite used in this study, TC gradually increased with increased taconite. The results of the study showed that the presence of taconite improved the healing property of asphalt mastic. For a healing time of 900 s, a loading strain of 5%, and degree of damage of 50%, an increased dosage of taconite led to an increased healing property of modified asphalt binder, although the increase in the promoting effect on healing performance was not significant. This study also evaluated the effect of several factors that influence the healing property of asphalt mastics. The content of taconite, the healing time, the loading strain level, and the degree of damage affected the healing performance of asphalt mastics modified by taconite. Since taconite is a byproduct of mining iron-bearing sedimentary rock in which the iron minerals are interlayered with quartz, chert, or carbonate, our use of this so-called waste from mining and its application in construction is expected to promote resource conservation and recycling while enhancing sustainability in pavements.