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Evaluation of properties of recycled asphalt concrete hot mix
This study was undertaken to evaluate the laboratory performance of recycled asphalt concrete mixtures and to compare these results to those measured for conventional asphalt concrete mixtures. To make these comparisons, samples of aged asphalt concrete were obtained from three locations where recycling was planned. These samples were blended with new aggregate and new asphalt materials to produce six different recycled mixtures. Two aggregate types, a crushed gravel and a crushed limestone, were used to produce two conventional mixtures and to blend with the reclaimed asphalt pavement to produce the six recycled mixtures. Three asphalt materials which were obtained to produce the various mixtures being evaluated consisted of AC-20 for preparing the conventional mixtures and AC-5 and a recycling agent for preparing the recycled mixtures. This study evaluates the relative durability, low temperature, water susceptibility, and fatigue properties for the eight mixtures. Tests were conducted on the asphalt binder (combined binder for recycled mixtures) prior to mixing with aggregate and after being recovered from the mixtures used to evaluate fatigue properties. The Shell BISAR computer program was used to predict the stresses and strains for two typical pavement sections under a given loading condition. The computed stresses and strains were then analyzed along with the laboratory fatigue tests to predict the fatigue performance of the various mixtures. The results of this study indicated a satisfactory comparison between laboratory performance of recycled mixtures and conventional mixtures. Fatigue analysis indicated that the conventional mixtures would provide the greatest fatigue resistance in thick asphalt concrete layers at lower temperatures while the recycled mixtures would provide the greatest fatigue resistance in thin asphalt layers at higher temperatures. Water susceptibility was shown to be related more to aggregate type than to mixture type. The data show that recycled mixtures prepared with the recycling agent produced mixtures with the lowest durability and poorest low temperature performance when compared to the recycled mixtures prepared with AC-5 or when compared to the conventional mixtures.
Ph. D. in Philosophy Texas A & M University 1983
Includes bibliographical references (leaves 144-149).