Abstract: For the structure of asphalt overlays on rubblized portland cement concrete (PCC) slab, properties of materials in each layer vary greatly. It is therefore not proper to be simulated by one mechanical model. For this reason, a numerical method which combines the finite difference and discrete element method (DEM) is proposed; in which the rubblized PCC slab is described using DEM while the asphalt overlays is simulated by the finite difference method. For purpose of smooth transition between continuous and discontinuous domains, conditions of compatibility and equilibrium along the corresponding boundaries need to be satisfied in the computation process. To illustrate the effects of rubblization more clearly, the rubblized PCC slab is further divided into three sublayers as the small particles layer, the surface layer and bottom layer. The mechanical response of the interaction between the rubblized PCC slab and overlays is discussed through varied the particles sizes. The results have shown that the tensile stress and strain at the bottom of the asphalt overlays are proportional to the particle size of the small particles layer. It is also found that the smaller the particles size of the surface layer is, the larger the tensile stress, strain are. In other words, strength loss of the old PCC is proportional to degree rubblization of the slab. This shows that the degree of rubblization should be properly controlled.

Key words: road engineering, asphalt overlays on rubblized portland cement concrete slab, finite difference, discrete element method, coupling