Study on the improved recycled asphalt mixtures by microbubble-foamed asphalt

In Japan, recycled asphalt mixtures have accounted for around 75% of the total asphalt production volume in recent years, and the percentage is expected to remain at the same rate. Thus efforts must be made to secure good working environments through measures to reduce asphalt fumes produced during the manufacture of asphalt mixtures and construction, and improve the workability. In reviewing such measures, we focused on a mechanical warm-mix technique (foamed asphalt) carried out in the U.S. and Europe, and introduced it to Japan. When applying foamed asphalt to the recycled asphalt mixtures used in Japan, as the recycled asphalt aggregate content of the mixtures is too high compared to the U.S. and Europe. (50-70%), high effectiveness cannot be obtained if the foamed asphalt is used as it is.