and Pavement Performance: Field Observations
Robert Charlier[20], Pierre Hornych, Mate Srsen, Ake Hermansson, Gunnar Bjarnason, SigurSur Erlingsson and Primoz Pavsic
Abstract This chapter presents a mechanical behaviour study, i. e. the bearing capacity as a function of the moisture degree. The field point of view is expressed and the chapter summarises a number of observations on road behaviour, in relation to variations of moisture. First, the road structure is recalled with respect to the mechanical analysis point of view. Then some observations onfield under temperate climate, humid, are given. In a second step, the specific case of frost and thawing are discussed.
Keywords Bearing capacity ■ moisture level ■ field measurement ■ stiffness ■ rutting ■ thawing
This chapter introduces the study of mechanical behaviour, i. e. it seeks to describe bearing capacity as a function of the moisture degree. This description is based on a summary of road behaviour with respect to variations of water content as observed in-situ.
Initially, the road structure is presented from the point of view of a mechanical analysis. The mechanical and hydraulic specific behaviour of each subgrade layer is discussed. Next, the chapter briefly analyses water penetration and the water effect on the road structure layers before illustrating the water-induced mechanical effects. The change of water content over time is shown for specific locations that are subjected to a humid, temperate, climate. Then a consideration of the development of ruts, i. e. the strains and deformation, with time is given. A discussion of the stiffness of a road structure is also given as it relates to the moisture level. A clear decrease of the stiffness and an increase of the strain accumulation are observed when the moisture increases.
In the second part of the chapter, specific cases of frost and thawing action are discussed. In particular, the stiffness decrease during and after thawing is described. Field measurements of temperature, of layer moisture and of deflectometer stiffness are presented.
