مروري بر روشهاي طرح اختلاط آسفالت بازيافت سرد با امولسيون هاي قيري

A Review on Emulsified Cold in Place Recycling Mix Design Methods

The main objective of bituminous mix recycling is to reuse the existing surfacing materials for pavement rehabilitation purposes. Cold-mix recycling is one of the commonly used methods that require less energy than the other recycling or rehabilitation techniques. However, there is not universally accepted method for cold recycling mix design. In general, using laboratory tests, empirical formulas or past experiences on different projects can help in determining a preliminary bituminous content for the mix. Adjustments are then applied during construction phases. The most comprehensive design processes are those including AASHTO (modified Marshall mix design method), Asphalt Recycling and Reclaiming Association (ARRA), Asphalt Institute and a few others. The optimum recycling additive content (ORAC) can be selected to optimize one or more of the strength properties. Strength testing has consisted of Marshall stability and flow, unconfined compression, Indirect Tensile Strength (ITS) or Resilient Modulus. The second approach to selecting the ORAC is to evaluate the compacted voids in total mix (VTM). The ORAC is selected to give a VTM between 9 and 14 percent at the peak density. Regardless of the recycling mix design method used, it is recommended that a coating test be performed to determine pre-mix moisture content for coating. Recent work has known that 75 blow Marshall compaction at field mix ambient temperatures of approximately 400C resulted in densities comparable with field densities.