In Europe, quality and enhancements are highly emphasised at the contractor level. European asphalt contractors have developed a high level of intercompany quality assurance and long-time experience with field performance of bituminous paving mixtures.
Given this background, a trend toward functional mixture requirements appears the logical path of the future. Designing the asphalt mixture and the performance of the final pavement is the contractor’s responsibility. To do this, the contractor needs reliable accelerated test methods and performance models on which he can rely his warranty.
The Superpave system, as it is today, does not provide the necessary information for proper evaluation of mixture performance. SHRP indeed did develop a full set of such tests. However, at this moment the practical suitability of the proposed Superpave tests for bituminous mixtures are questioned.
Superpave’s innovative performance- based binder specification presents a very interesting approach, especially when dealing with modified binders. It is the impression of the European asphalt industry that the validation and correlation to field performance, however, is not sufficiently documented in the work done by SHRP.
Numerous questions arise on how the specific tests and the specification limits will interact with the modified binders typically used in Europe as mentioned previously by the oil industry. These questions must, therefore, be answered before using the new tests.
The European asphalt industry believes that the role of the contractor must be stimulated. Developing innovative products and concepts is the task for the industry. To be able to do so, adequate and reliable test methods and principles of mix design and type testing must be available and sufficiently correlated to field experience.
Test methods must be suitable for use in the specific contractual relations used, including warranty projects. Consequently, for the European situation, test methods must be practical, implementable in daily operations, and suitable for the goal. Methods that are too complex, too expensive, and too slow, are not usable and efficient when managing product quality on a daily basis.
For quality control, tests and instruments are required that can be used within the regular production and construction of asphalt pavements. The structure in the European asphalt industry requires reliable and secure specifications in regard to mix design, type testing, and quality control.