THE NAMUR TEST ROAD : BEHAVIOUR OF VARIOUS TYPES OF CONTRACTION JOINTS AFTER FIVE YEARS OF TRAFFIC

Abstract

This report deals with the observations andmea­ surements made in order to study the behaviour of various types of contraction joints in the Namur test road, which was constructed in Belgium, in 1979, within the framework of the activities of P.I.A.R.C. 's Technical Commit­tee on Concrete Roads. The concrete overlay, with a thickness of 20 to 23 cm, was intended to strengthen an asphaltic pavement, carrying about 17000 vehicles/ day. Six types of joints were constructed, namely undowelled 'joints, joints with evenly spaced dowels and joints with variably spaced joints, each sealed and unsealed. Observation shows that on an average only one joint in three is active. Slab rocking movements, during the passage of a 13 ton axle, were until the end of 1981 only detectable in 40 cases out of 140 joints with an amplitude of the order of one hundredth of a millimeter. At the end of 1984, those measurements point out a different behaviour between dowelled and undowelled joints, yet without practical consequences, seeing the very low level of those movements in comparison to standard concrete roads. No apparent defects resulted from unsealed joints. The high quality asphaltic underlayers and the efficient drainage system for infiltrated water are surely important factors of the excellent behaviour of all the joint variants.