SIRIN, Investigation of, 1/8 Fax: +1-352-392-3394 E-Mail: tia@ce.ufl.edu INVESTIGATION OF PROBLEMS IN BINDER EXTRACTION FROM CONVENTIONAL AND RUBBER MODIFIED ASPHALT MIXTURES Okan Sirin University of Gaziantep, Turkey Mang Tia University of Florida, USA Abstract Reflux extraction tests were performed on both conventional and rubber-modified asphalt mixtures to investigate the problems in the discrepancies between the actual and the measured binder contents, their causes and possible solutions to these problems. During the preliminary evaluation, it was found that most of the rubber remains on the filter paper and a small amount of asphalt binder also remains in the aggregate and can not be completely extracted. Further investigation has shown that the amounts of rubber and asphalt which remain on the filter paper vary from one test to another and therefore, the amount of extracted binder and rubber can not be determined with high level of certainty. The results also indicated that the extracted aggregate absorbs some moisture from the air after it was dried and left in air to cool to room temperature. This increase in weight causes an error in computing the asphalt content. This problem can be solved by leaving the extracted aggregate to cool in a desiccator for a minimum of three hours before weighing. 1. Introduction In quality control and assurance of production of asphalt mixtures, it is necessary to extract the binder from the asphalt mixtures to determine their binder content accurately. However, discrepancies between the actual binder contents and the measured binder contents often arise. This problem is especially severe when a binder extraction test is performed on a crumb-rubber-modified asphalt mixture. It has been found that most of the rubber could not be extracted from the rubber asphalt mixture by the conventional Reflux extraction process [1,2]. In a proposed extraction method for rubber asphalt mixtures by Ista and Choquet [3], the rubber particles had to be separated from the mixture by a very involved process of suspension, centrifugation and filtration. This paper presents the results of an investigation on the causes of the problems in binder extraction of conventional and rubber asphalt mixtures, and possible solutions to these problems.