Freeze and thaw field investigation of foamed asphalt cold recycling mixture in cold region

Cold recycling mixtures with foamed asphalt is one of the green and environmental-friendly construction technology in pavement rehabilitation. Most of the pavement recycling materials could be utilized with this kind of technology. Water, cement, aggregate and foamed asphalt will be added into the recycling asphalt pavement materials at the room temperature during the production of cold recycling mixtures. However, adding water into the mixtures may have a negative effect on the adhesion among foamed asphalt, new aggregate and recycling asphalt pavement materials. Especially in cold regions, the existence of excessive water in the mixtures may introduce the freeze-thaw durability issues during the winter-spring cycle. Therefore, it is important to clarify this durability issue of the foamed asphalt cold recycling mixtures in cold regions. In this study, an expressway pavement rehabilitation project with foamed asphalt cold recycling mixtures in the north of China had been selected to be test road. After initial material design in lab, the foamed asphalt cold recycling mixtures had been paved as the base layer. Then the field coring had been conducted, at the end of curing time and also after a freeze-thaw cycle. The performance tests on these coring samples indicate that the effect of freeze-thaw on the durability of the foamed asphalt cold recycling mixtures can not be neglected. The indirect tensile strength at dry and wet conditions, the modulus, and the fracture properties of the foamed asphalt cold recycling mixtures all had an obvious deterioration after undergoing the winter-spring cycle. Therefore, more structural frozen-resistant protection behaviors and advanced material design should be researched in the future.