QUALITY ASSURANCE AND TRACEABILITY OF RECYCLED MATERIALS PROCESSED CONTINUOUSLY ON SITE

摘要

On-the-road recycling processes are more and more complex and the engineers are willing to use the conventional functions typical of stationary plants even when self-propelled machines are to be employed on the job site. Today, the recycling of recycling asphalt product (RAP) is becoming a primary concern in order to ensure long lasting treatments and good adhesion of the recycled material to the remaining layers. As far as the first point is concerned, the manufacturers have not succeeded in integrating the following functions with the new recycling processes: 1. Particle size control of RAP and aggregates (if required), 2. Particle size correction by using an on-board crusher, 3. Continuous weighing of wet recycled material, 4. Continuous measuring of moisture contents in the recycled material, 5. Continuous addition of mixed binders, such as cement or modified bitumen emulsions, according to the actual through-flow, 6. Change to the moisture contents in order to better control emulsion breaking for optimum compaction. Forced mixing of the elements by using a pugmill similar to those employed in stationary plants. The whole process is monitored through the use of an advanced controller so that the data can be regularly transmitted via telephone modem to a service centre where the problems can be diagnosed and instructions are given to change the operating procedures. As far as the second point is concerned, a special machine has been developed. It comes with cleaning brushes and an automatic collector for all the material to be recycled. The re-handled material is stored on a thoroughly clean surface. An emulsion tack coat layer is pulverized throughout the entire section by using a specific piece of equipment on board the machine. This arrangement is essential to guarantee long service life and to ensure the layers are firmly joined together.