Characterization of thermal insulating micro-surfacing modified by inorganic insulating material

In order to improve the thermal field of asphalt pavement, novel micro-surfacing modified by two types of inorganic insulating materials was prepared in this paper to achieve thermal insulating effect on asphalt road pavement. The thermal conductivity and micro structures of sepiolite and sericite were tested and characterized by thermal conductivity test and scanning electron microscope analysis (SEM), respectively. Based on laboratory and field experiments, the thermal insulating effects of micro surfacing with sepiolite and sericite on the asphalt road pavement were evaluated in the heating or cooling process, respectively. Specifically, the field test was performed during specific experimental periods selected from summer and winter, which included the extreme high and low temperatures during the whole year. The British pendulum slip test, wet-track abrasion loss test, rutting test and permeability test were conducted to assess the pavement performances of thermal insulating micro surfacing (TI micro surfacing). Finally, the mechanism of thermal insulating effect was explained based on the Knudsen Effect and SEM photo. The results showed that: (i) sepiolite and sericite had great potentials to achieve good thermal insulating effects on pavement originated from low thermal conductivity and special micro-structure; (ii) micro-surfacing sample with sepiolite and sericite increased the thermal resistance of pavement and slowed down the process of thermal conductivity between pavement and environment; (iii) In some situations, micro-surfacing with thermal insulating material could be a barrier for heat absorbing or releasing; (iv) the adding of sepiolite and sericite had no obviously negative impacts on pavement performances of micro-surfacing.