SOME ASPECTS OF HOW TO ENSURE THAT ROAD ASPHALTS SATISFY CERTAIN QUALITY REQUIREMENTS --BITUMEN, FLEXIBLE AND DURABLE. 3RD EUROBITUME SYMPOSIUM 1985, THE HAGUE, NETHERLANDS, SEPTEMBER 11-13, 1985

Long-term research aiming at defining road asphalt properties is primarily concerned with the effects of these properties on the performance of asphalts. The research findings are expected to provide information about the behaviour of asphalt layers over the period of service life. Within the frame of these research activities, a larger number of control tests than before have been undertaken on b 80 and b 65 road asphalts from 1982 to 1985 to ensure that the requirements laid down in din 1995 are satisfied. Apart from these control tests, the standard testing methods themselves are tested as to their suitability for describing the hardening or ageing of bituminous materials, e.g., the loss on-heating test with the sample exposed to draught and a temperature of 165 deg c for a period of 150 minutes in a rotating flask (din 52 016). At first, samples of binders from mixing plants producing bituminous mixes for asphalt concrete surfacings were experimentally used within the frame of major construction projects. The specific locations of placement were registered and the performance characteristics of the surfacings observed, measured and recorded for subsequent evaluation. After about 1000 tests on binder samples and evaluation of the results between 1982 and 1983, the following can be said: (a) the limits derived with respect to the tests on penetration, softening point (ring and ball) and fraass breaking point largely coincide with the requirements laid down in din 1995. (b) the values remain clearly below the limits both for increased softening point values or decreased penetration under the effect of heating. (c) as for the ductility of b 80 at 10 deg c and B 65 at 13 deg c before and after heating, the relatively low number of results did not allow specific requirements to be derived. The results turned out to be highly sensitive to changes in the test temperatures specified. The factor analyses carried out thus far indicate that the test methods employed to describe ageing or hardening processes cannot be compared. The softening point of materials after heating and the resulting ageing process appears to be of relative significance. The results of the determination of ash content, weight loss and breaking point under thermal effects do not provide information on changes in the properties defining the quality of road asphalt. Due to the short service time of the experimental surface courses signs of damage have not yet been observed. For the covering abstract of the symposium see IRRD 815173.