Comparison of Surface Modification Methods for Improving the Compatibility of Recycled Plastic Film-Based Aggregates

The surface modification of recycled plastic film-based aggregates was investigated to improve the compatibility between the aggregates and a cement paste. Surface modification was performed using ultraviolet-ozone treatment (UV-O₃), a silane coupling agent, O₂ atmospheric pressure plasma, and acrylic binder coating methods. The surface properties of the modified aggregates were analyzed using a contact angle measuring instrument. The results revealed that for all surface modification methods, the contact angle decreased with an increase in the treatment time. According to the comparative evaluation results of the changes in the surface characteristics of the aggregates through various surface modification methods, the contact angle reduction rates were 58.9%, 51.4%, 25.5%, and 24.5% for the O₂ atmospheric pressure plasma, the acrylic binder coating, the silane coupling agent, and the UV-O₃ method, respectively. After 48 h, the contact angle had increased by 110.9%, 29.9%, 16.4%, and 5.9% for the O₂ atmospheric pressure plasma, UV-O₃, the silane coupling agent, and the acrylic binder coating, respectively. Namely, the surface modification using the acrylic binder coating method was found to be the most effective method in terms of the wettability increase effect and the long-term storage stability.