CHARACTERIZATION OF COLD RECYCLED ASPHALT MIXTURES
Abstract
Increased interest in improving the quality of the cold-recycled paving mixtures has made it necessary to better understand the behavior of these mixes and to develop a suitable mix design method. In this study, the long-term behavior of the cold-recycled asphalt mixtures was investigated through nine experimental designs. The scope of the study covered two types of pavement material, three levels of oxydized condition of the old binder and one type of virgin aggregate. The added softening agents included a high-float asphalt emulsion AE-150, a foamed asphalt, and the rejuvenating agents, Reclamite, Mobilsol and DUTREX 739. Specimens of the recycled mixes were compacted with the gyratory machine, and gyratory indices were obtained during the compaction process. The resilient modulus, Hveem Stabilometer R-Value and Marshall parameters were obtained on the compacted recycled mixes. The Water Sensitivity Test was used to evaluate the resistance of the recycled mixes to water. The results of the study indicated that most of the rejuvenating action of the added binder on the old binder took place during the compaction process. The binders of the recycled mixes which underwent the initial softening during the compaction process generally increased in stiffness with increasing curing time. The results indicated that the gyratory stability index and the gyratory elasto-plastic index could be used to determine the optimum binder content of a recycled mix. However, they could not be used to estimate the resilient modulus or the Marshall stability of the mix. A higher compactive effort generally produced a higher resilient modulus and Marshall stability of the recycled mix. When the binder content is too high, a higher compactive effort generally produces a lower Hveem R-value. The structural performance of these recycled mixes was compared to that of an asphalt concrete using a linear elastic multilayer analysis. A mix design procedure for cold recycled asphalt mixtures was recommended from the results of this study.
Degree
Ph.D.
Subject Area
Civil engineering
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