Sudden winter disorders on pavements and behaviour of bituminous materials under frost/thaw conditions

摘要

Some recent winters as in 2009/2010 have given rise in France, but also in otherrnEuropean countries, to important disorders in the upper part of pavements. Those arernmostly characterized by the onset of series of pot-holes, which have the particularity tornappear suddenly and quasi simultaneously on long road distances. Thus several road andrnmotorway sections, several tens of kilometres long, have been concerned during the samernday, with the need sometimes for immediate closure to traffic. Beside, such significantrndisagreement to road users are accompanied by important costs of repair, not integratedrninto the scheduled program of maintenance.rnThen such events have led the French Road administration to launch several studies inrnorder to understand the phenomenon, to remedy to it and prevent future disorders of thernsame kind. On the one hand, these studies include detailed site analyses of the observedrnpathology and of the circumstances of disorders onset (pavement structures, traffic,rnclimatic conditions, pavement sampling...).rnOn the other hand and on the basis of the site analyses, the RST and IFSTTAR havernlaunched a laboratory testing program to study the behaviour under frost and thaw actionrnof bituminous materials, which have preliminary been partially saturated with water. Somernof these tests are closed in their principle to those performed to evaluate the frost/thawrnbehaviour of pavement unbound granular materials layers. The measurements showrnobvious parasite strain effects, due to the liquid/solid phase changes of the waterrncontained into the porous space of the tested materials, which are believed to be at thernorigin of the disorders observed at the pavement surface. The article deals with the resultsrnobtained in lab and with the doors now opened to explain the phenomenon.