Cold recycling is a method of reconstructing any flexible pavement where the need arises from structural failures. These failures include: transverse cracking, wheel rutting, potholes, surface irregularities, or a combination of the above. Equipment and methods have evolved from mule-drawn disc-harrows and tractor grouser bars to 1000 hp units with special equipment capable of pulverizing bituminous concrete in place to a precise depth, mixing that material with a liquid binder and repaving to an accurate grade and profile. Flexible pavements up to 6" in thickness can be pulverized and blended with a liquid stabilizing agent thereby greatly increasing their load carrying capacity. Cold recycled bituminous material is placed and compacted by the same methods as used for hot bituminous material. Laydown may be by laydown machine or, in some instances, the material can be laid with a motor grader. Compaction to obtain the required density can be achieved by either a heavy pneumatic, vibratory, or static steel roller, or any combination of rollers.
Testing of the material to be cold recycled is very important. Today there are a number of cold recycling agents along with the various types of emulsions that restore the old asphalt cement to very near its original characteristics. When the pulverized material has been properly sized, mixed with the additive in the amount determined by testing, laid and compacted to the required density, surfaced with a chip seal coat, thin hot mix overlay or other light surfacing, a long lasting, low cost pavement can be constructed with a minimum of new material.
Another successful approach is the in-place full depth reclamation method where all of the pavement structure and a portion of the sub-grade are blended and pulverized to form a homogenous mass utilizing the existing asphalt cement as a binding agent, thus producing new construction standards without depleting aggregate resources.
Asphalt Recycling & Reclaiming Association