A laboratory-scale pavement testing facility with a movingvehicle load can be used to simulate reliably the stresses causedby traffic in the road structure and is therefore well suitedto the testing of materials and structures. The measuring systemdeveloped here can be used to determine reliably both elasticand permanent deformations within the structure, which, in turn,can be used to determine relative strains.

The mechanical properties of the unbound base course and theirsignificance for the performance of the whole road structure dependon the thickness of the bound layer and the quality of the material.When the asphalt concrete (AC) layer is thin, it would be goodto have grading with Fuller's "n" value equal to 0.4or 0.5 in the unbound base course. When the bound layer consistsof very soft asphalt, in turn, it would be good to aim at a gradingcurve with "n" = 0.5. A large maximum grain size inthe base course minimizes both permanent and elastic strains.

Compaction of the unbound layers also has a distinct effecton the mechanical properties of the layer. A high degree of compactionminimizes permanent strains. Effective compaction, however, resultsin grinding of the materials. The compaction of unbound roughmaterials and their grinding during compaction can be evaluatedwith the Intensive Compaction Tester gyratory compactor both quicklyand inexpensively.