Laboratory evaluation of a sustainable additive for anti-icing asphalt

Abstract

This laboratory study developed a novel type of sustainable additives for anti-icing asphalt pavement, featuring an excellent anti-icing capacity, low-temperature anti-icing effectiveness, superior anti-icing longevity, and enhanced mechanical properties. The additives were fabricated through a surface treatment approach, in which the functional aggregate, zeolite containing calcium chloride (CaCl2), was coated by a microporous epoxy layer. The desired anti-icing performance and mechanical properties of asphalt mixture were achieved, using this type of additives. The results of fog-freezing friction tests are very promising. Specifically, the anti-icing capability of asphalt mixture was significantly improved by the addition of the additives at both −3.9 °C and − 9.4 °C, and the friction coefficient of the pavement at 60 min after moisture spray reached up to 0.75 at −3.9 °C and 0.56 at −9.4 °C in the first test and arrived 0.56 at −3.9 °C and 0.41 at −9.4 °C in the second test. Both tests were conducted after seven days of rest subsequent to a ten-day soaking test, which was used to evaluate the effective anti-icing period. The effective anti-icing periods of asphalt pavement containing the prepared additives are theoretically calculated, with the minimum “anti-icing service life” at least 3.4 years. Scanning electron microscopy images illustrated that a slower salt-releasing rate was achieved via a smaller size and lower quantity of the pores in the epoxy layer and its uncompromised integrity. Incorporation of the additives exhibited limited effect on the moisture susceptibility of the asphalt mixture. The rutting resistance, fatigue cracking resistance, and thermal cracking resistance of the asphalt mixture were improved to various extents, as a result of incorporating these anti-icing additives. The improvements in these durability properties of asphalt mixture were interpreted by the asphalt-epoxy chemical reactions, as revealed by Fourier transform infrared spectrometry and differential scanning calorimetry.