In the foam asphalt method, which is generally used in the cold on-site recycling of highway flexible pavements and in the full depth recycling method, air and some (about 2%) water are added to the bitumen, increasing the volume of the bitumen, so that more material is covered with a small amount of bitumen. When cold water and air are injected into the hot bitumen, the water evaporates quickly so that the bitumen particles become bubbles.

In this method, the volume of bitumen can be increased 15-20 times. The advantages of the foam asphalt method are given below ;

• Foam asphalt increases the shear strength of granular materials and reduces moisture sensitivity. In addition, the foam asphalt method provides a more elastic behavior of the mixture, thus increasing the fatigue life.
• It is more economical than other recycling and stabilization methods as it reduces transportation and binder expenses.
• It saves time as the foam asphalt is compacted immediately and thus the prepared road is opened to traffic in a short time.
• It saves energy as the aggregate and recycling material do not need to be heated.
• It is an environmentally friendly method as it causes less evaporative material to be released into the nature.
• It offers storage facility since bitumen is not filtered.
• The foam asphalt method offers a wider working season. Even in cold weather or light rain, work can be done, and under these conditions, the production does not adversely affect the quality.