This paper describes a project that is part of NL-LAB, a larger, long-term program at Delft University of Technology, Netherlands, which aims to establish the predictive capacity of the current European functional tests for Dutch asphalt concrete (AC) mixtures. In this NL-LAB program, the functional characteristics of resistance to rutting (EN 12697-25), fatigue (EN 12679-24), stiffness (EN 12697-26), and moisture sensitivity (EN 12697-12 and EN 12697-23) are determined for specimens that are (a) mixed and compacted in the lab, (b) mixed in the plant and compacted in the lab, and (c) mixed in the plant and compacted in the road. Eventually, these tests will provide insight into the effect of mixing and compaction on the functional characteristics. The project described in this paper focused on the indirect tensile strength (ITS) and the triaxial cyclic compression test for two AC mixes. The properties found for all three stages of preparation were analyzed with the use of formalistic expressions from the NCHRP Design Guide 1-37A, Level 2, for the estimation of performance indicators. This project aimed to see if these relations remained valid for the Comité Européen de Normalisation tests, especially for mixes with high recycled asphalt pavement content. In the Netherlands, 50% reclaimed asphalt pavement is standard. It was found that the NCHRP Design Guide 1-37A expressions fit the Comité Européen de Normalisation test data quite well for the reclaimed asphalt pavement that contained mixes, especially for the ITS. Currently, another two construction projects are being sampled, and the results will be used to validate and improve the relations.@en

Sinds 2008 werken we in Nederland met functionele eigenschappen voor asfalt beton. Hierbij wordt niet zo zeer op het “recept” van het asfalt gestuurd, als wel op de eigenschappen ervan die van belang zijn voor het gedrag in de weg. Binnen het NL-LAB programma wordt de relatie tussen deze functionele eigenschappen en het gedrag in de weg gevalideerd. Hierbij wordt ook gekeken naar de invloed van mengen en verdichten op de functionele eigenschappen. Binnen dit programma is er voor de eerste twee projecten gekeken naar de relatie tussen de mengselsamenstelling en de indirecte treksterkte en weerstand tegen permanente vervorming. Dergelijke relaties zijn in de historie van de wegenbouw vaker met succes gebruikt. Veranderingen in proeven, materialen, mengselsamenstelling en gebruikscondities vragen echter om validatie en calibratie. Het meest recente stelsel van relaties tussen samenstelling en functionele eigenschappen is dat van de Mechanistic Empirical Design Guide. In deze bijdrage wordt beschreven hoe deze relatie worden gebruikt als uitgangspunt voor het koppelen van mengselsamenstelling van twee AC mengsels aan de indirecte treksterkte (ongeconditioneerd) en de weerstand tegen permanente vervorming. Hierbij wordt ook gekeken of het effect van mengen en verdichten zichtbaar is in de data.@en

In the Netherlands, the functional approach described in the 2008 European Asphalt Concrete standards was selected, specifying mixtures by their stiffness, fatigue resistance, permanent deformation, moisture sensitivity and limited composition data. The requirements for the functional specifications were based on the existing experience with a large number of mixes. Since the introduction of the standards, unexpected developments like improved performance in all functional tests with increasing RAP content, led to questions about the predictive quality of the laboratory determined functional characteristics for field performance and the potential causes of a mis-match between lab and practice. These questions led to a large, long term project in the Netherlands (NL-LAB) in which the functional characteristics are determined in the process of construction projects. They are determined on (I) material mixed and compacted in the lab, (II) mixed in the plant and compacted in the lab and (III) mixed in the plant and compacted in the road. These tests will eventually provide insight in the effect of mixing and compaction. The pavement sections are monitored in time, to allow the link with pavement performance. The sections will be sampled during their service life to see changes occur in their functional properties. For the road industry, that tries to guarantee pavement performance by accurate selection of materials, the possibility of design information based on both laboratory and in situ results would be beneficial. Two mixes for base layers with different mix compositions and amounts of RAP are analysed using formalistic expressions originating from Design Guide Level II for estimation of various performance indicators. This project uses expressions to analyse the differences between the mixes in the three cases described above. It addresses the possibility of utilizing these expressions during preliminary mix design to guide the selection of mix composition parameters towards a desired optimum.@en