A Simple DTT Sample Preparation Method for Repeatable Testing Results

摘要

The Direct Tension Test (DTT) of asphalt binders is designed to determine their failure strain and the stress at failure at the tested temperatures. With the second generation of Direct Tension Testers, the repeatability of the testing results is greatly improved. Nevertheless, the variation of the testing results is still too large, especially for harder materials. Dr. Ho, Dr. Dongre, and the North East Asphalt User Producer Group (NEAUPG) have proposed to use additional heat sources like heated ceramic tiles or metal plates beneath the moulds. This paper presents a very simple method to improve the repeatability of DTT results. During the preparation process of DTT specimens, the samples were poured in the oven and kept there for an additional three minutes. By comparing the results between those obtained when following exactly the preparation procedure described in American Association of State Highway and Transportation Officials (AASHTO) T314-02 and those with a slight modification in the sample preparation, it can demonstrate that the modification improves the repeatability greatly. This will simplify the task of the laboratory technicians and increase the productivity of the testing results.