Low-Temperature-Tar Content of Bituminous Materials. Part 2. Dense Tarmacadam Basecourse with Crushed-Rock Aggregate

摘要

The purpose is to compare the tar-content requirements for low-temperature and coke-oven tars when used in a dense tarmacadam basecourse with crushed-rock aggregate. The Marshall Test procedure was used to obtain the optimum binder contents, using a constant aggregate grading and the two types of tar. This limited study, of the binder requirement for dense tarmacadam basecourse confirms that the content (by mass) of the low-density, low-temperature tar should be less than that of high-density C.O. tar. The average low-temperature-tar content by volume for the two different aggregates corresponds closely to the volume of C.O. tar recommended in BS 4987. Hence, to evaluate the low-temperature-tar requirement by mass, it is necessary only to correct the value recommended in BS 4987 by the ratio of the densities of the two types of tar, i.e., to divide the BS 4987 value by 1.11. The use of low-temperature tar at this reduced level based on the Marshall optimum binder content therefore corresponds to a saving of about 11% in binder. (ERA citation 08:017081)