Abstract
For asphalt pavement structures, semi-rigid road base course has to sustain repeated high-axle load during its service life and the performance of semi-rigid road base materials directly influences the durability of pavement structures. The dynamic compressive resilience modulus of two commonly used semi-rigid road base materials, cement stabilized aggregates (CSG) and lime-fly ash stabilized aggregates (LFSG) were evaluated at different frequencies using a Universal Testing Machine (UTM). The results showed that LFSG had higher dynamic modulus than that of CSG and the load frequency had less influence on the dynamic modulus of these two semi-rigid road base materials. The four-point bending test was applied to measure the flexural-bending strength and the fatigue life of these two semi-rigid materials. A higher flexural-bending strength of LFSG indicated its better bearing capacity than that of CSG. The fatigue life of LFSG and CSG decreased with the increase of stress–strength ratio and the LFSG performed better in terms of fatigue resistance. The fatigue damage models of CSG and LFSG based on Stress-Life (S-N) curve are established. As per incremental-recursive mechanics, a general modulus degradation model was established and verified by the results of full-scale accelerate loading test. This model cannot only be used to predict the fatigue deterioration of semi-rigid road base materials under different stress levels, but is also able to calculate the current bending elastic modulus based on its initial modulus value.
Highlights
An asphalt pavement can be recognized as a multiple-layer structure, which is typically composed of asphalt surface layers, road base layers and road sub-base layers
As a non-linear fatigue damage curve in Figure 14, the Ei is the initial modulus of the material, Np is the accumulated loading cycles, dE is the decrement of modulus
This research assessed the mechanical performance of semi-rigid road base materials (LFSG and cement stabilized aggregate (CSG)) under the dynamic load
Summary
An asphalt pavement can be recognized as a multiple-layer structure, which is typically composed of asphalt surface layers, road base layers and road sub-base layers. The two commonly used semi-rigid road base materials are lime-fly ash stabilized aggregate (LFSG) and cement stabilized aggregate (CSG). Incremental-recursive mechanics of continuous damage was applied in this research to establish a modulus degradation model related to the stress ratio. Mechanical-empirical Pavement Design Guide (MEPDG) used the incrementalrecursive to analyze the fatigue and permanent deformation of asphalt pavement [29]. The characteristic of this method is to separate the whole process into several stages. The incremental-recursive model is establishing the relationship between the modulus degradation rate (dE/Ei) and loading cycles (N) (Equation (11)): dE Ei
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