ABSTRACT
The climate conditions in the Federal Republic of Germany make it necessary to ensure the frost-resistance of pavements. The aim is to prevent pavement damage by frost impact in the defined service life. The main pavement damage potential by frost penetration results from the thawing process (loss of load-bearing capacity due to insufficient drainage) as well as the freezing process (volume expansion of included water). The thickness of the construction is the main factor to guarantee the frost-resistance of pavements. The Chair of Pavement Engineering at the Technical University of Dresden performed a numerical simulation of the temperatures in pavements based on a climate database. This thermal simulation shows the possible depth and frequency of frost penetration. Due to extreme climatic conditions these freeze and thaw cycles are very common in most of the granular base layers of flexible pavements in central European countries. The deformation behaviour of the Unbound Granular Materials (UGM) used in structural pavement layers is very complex due to their inherit nonlinear stress dependency and the effect of bulk material factors, such as water content, density, grain size distribution, etc. Furthermore, thermal effects play an important role in the mechanical deformation of UGM if the following two conditions are met: (1) water is present and (2) the temperature fluctuates in the saturation range (i.e. changes from positive to negative °C, or vice versa). In this context, this paper presents selected results in addition of an investigation about the effect of the temperature on the mechanical deformation of UGM under cyclic triaxial conditions using the results of Repeated Load Triaxial (RLT) tests with Variable Confining Pressure (VCP).
