Adsorption Characteristics of Chloride Ions by Calcined Hydrotalcite and Its Influence on the Salt Corrosion Resistance of Asphalt Binder

This study aims to address the issue of asphalt pavement performance deterioration caused by chloride salt erosion. Layered double hydroxides (CLDHs) calcined at different temperatures, including 400 °C, 500 °C, and 600 °C, were used for the modification of asphalt binder. The structural evolution and chloride ion adsorption characteristics of CLDHs were analyzed. The adsorption kinetic behavior of CLDHs for chloride ions was investigated by combining adsorption kinetic experiments and electrochemical titration experiments. Through characterizing the interfacial adhesion performance between CLDH-modified asphalt binder and aggregates, the chemical composition of asphalt-ash binder before and after salt corrosion, and the leaching stability of organic substances in an environment with abundant chloride ions, the influence of CLDHs on the salt corrosion resistance of asphalt-ash binder was quantified. The results indicate that chloride adsorption by CLDHs is predominantly chemisorption-driven. With increasing calcination temperature, the chloride adsorption capacity of CLDHs gradually improved. In chloride-rich environments, CLDHs significantly enhanced the interfacial adhesion between asphalt binder and aggregates, particularly for coarse aggregates with a particle size of 9.5-13.2 mm. Furthermore, CLDHs effectively suppressed the formation of carbonyl and sulfoxide groups during salt corrosion and substantially decreased the leaching of organic components from asphalt binder. In summary, CLDHs can specifically enhance the salt corrosion resistance of asphalt binder, with the 600 °C-CLDHs demonstrating the most significant improvement, followed by the 400 °C-CLDHs, while the 500 °C-CLDHs performed the least effectively.