DO MODIFIED BINDERS PAY? --BITUMEN, FLEXIBLE AND DURABLE. 3RD EUROBITUME SYMPOSIUM 1985, THE HAGUE, NETHERLANDS, SEPTEMBER 11-13, 1985

Do modified binders pay? -so far it has not been possible to give a clear and definite answer to this question. It requires a period of approximately 5 years to obtain a reliable reading of test results. The aim of this report is to present a summary of the results registered in Denmark until now. From 1975 till 1980 we have experienced a decrease in the life span of asphalt concrete wearing courses and -at the same time -a tremendous cut in the funds for maintenance, and these two factors have resulted in a general interest in modified binders which -at least theoretically -should be able to improve the traditional materials, so that an increased life span of the pavements would be realistic. According to our knowledge, various modified binders have been in use in Denmark for about five years -in the hot-mix production and in surface dressings as well as in different kinds of sealing of old asphalt surfaces. In this paper the possible advantages of these modifiers are discussed, but since a long test period is required in order to obtain any reliable results, the experience reported in this paper should be looked upon as preliminary. Modification of bitumen in Denmark has been studied primarily by suppliers of bitumen, and the original research results have been more or less unknown to the asphalt industry, thus being forced to accept the prophecies of extended life span or other positive properties. This paper gives a description of the various types of modification of bitumen, such as special treatments at the oil refinery without using any modifying agents -as well as the addition of a number of different modifiers, i.e. Highly complicated combinations of long molecule chains, and more simple combinations of metal salts, natural rubber or latex. A number of specimens has been taken from wearing courses with and without modified bitumen, and these specimens have been cut into bars and exposed to fatigue testing in a three-point bending machine. The results of these tests and the performance of the bitumen are now being discussed.(a) for the covering abstract of the symposium see IRRD 815173.