Effect Of Coated Chlorine-Based Deicing Additive On Ice-Melting And Pavement Properties Of Asphalt Concrete

Asphalt pavement covered ice causes traffic inconvenience and even leads to accidents, so it is of great significance to decrease the freezing point of ice on asphalt road. Asphalt mixture filled with coated chlorine-based deicing additive has the function of melting ice. Its advantages include little Chloride ion releasing quantity, high efficiency of melting ice and excellent long-term efficacy, which attracts more and more attention. The addition of deicing agent to asphalt concrete affects its pavement performance and the structure of deicing additive impacts the melting ice performance. Thus, it is of great importance to improve long-term deicing properties of asphalt mixture including salt and reduce the impact of deicing additive to asphalt concrete.The coated chlorine-based deicing additive was prepared via the method of organic coating, and the structure of prepared additive was characterized. Then the effect of different types of organic coated chloride salt ice melting agent on performance of asphalt concrete, melting properties and its long-term performance has been researched. Main conclusions are as follows:(1)The coated chlorine-based deicing additive was prepared with different types of coating agent. Scanning electron microscopy(SEM) images showed that coated agent could be well coated on the surface of chloride salt particles. As the coating agent ratio increased, the coating level turned better. The melting point of coating agent C1 and C2 was higher, so they had a thicker coating layer. The melting point of C3 was relatively lower, thus the sodium chloride particle surface was covered with thinner layer. Results of freezing point test showed that using sodium chloride as ice melting salt released more slowly. By using coating agent C1, the freezing point was higher and the releasing turned slower. With the increase of dosage of coating agent, the freezing point became higher, which showed that the coating performance enhanced gradually.(2) The coated chlorine-based deicing additive had little influence on high temperature and low temperature performance of asphalt concrete, while low temperature and high temperature performance of asphalt concrete was poor when mixed with pure chlorine salt. It showed that the influence of chlorine salt to high temperature and low temperature performance of asphalt concrete could be improved by coating. The mix of coated chloride salt could significantly reduce the soaking remnants stability and intensity ratio of frozen and melted of asphalt concrete. Select C1 with high melting point as coated agent and appropriately increase coating agent dosage, which could make a better water stability of asphalt concrete. Melting agent coated with 5% of the sodium chloride also improved the water stability of asphalt concrete.(3)The short-term performance of deicing can be affected by the composition and structure of coated chlorine-based deicing additive. C3 coated additive with low melting point remained excellent short-term deicing property, and with the augment of coating agent, the short-term deicing performance gradually reduced. Along with the amount of deicing additive increases, the short-term deicing performance of asphalt concrete improved, while set the sodium chloride as melting salt performed better.(4)The composition and structure of coated deicing additive has effect on long-term performance of asphalt concrete. The chloride precipitation increased while freezing adhesive strength and freezing point on asphalt concrete surface decreased after immersion 12 h when coated with agent C1. As a result, long-term deicing performance turned well. The sustaining activity ameliorated with the ratio of coating agent augments. But when the ratio increased greater than A3, the augmenter of sustaining activity turned little. It could remain better long-term performance when using sodium chloride as melting salt and the ratio of deicing additive became 5%.(5)The experiments of outdoor snow-melting showed that the coated chlorine-based deicing asphalt concrete still had a certain degree of snowmelt performance when soaking 12 h, while the asphalt concrete mixed with pure chlorine salt had almost no effect on melting snow. Thus the sustaining performance of coated chlorine asphalt concrete had been proved by coating.