Comparison of the lifetime predicted by elastic analyses between two pavement structure candidates considering truck overloading

In Thailand, crushed rock, which is a common material for the base layer of a flexible pavement structure, is becoming insufficient or has to be transported from distance. Lateritic soil is largely available, but its bearing capacity is not sufficient, unless improved with cement. For rural roads, thin-asphalt surface pavement structure with the crushed rock base is common. With increasing traffic volume and truck overloading, the pavement structure must be strengthened. In this study, the lifetime of this pavement structure type strengthened by increasing asphalt’s thickness (Structure I) was compared with the one by replacing the crushed rock with the cemented lateritic soil for the base layer (Structure II). Both linear elastic analysis (LEA) and non-linear elastic analysis (NLEA) were performed for prediction of the lifetime, and then comparison was made. Stress state-independent elastic Young’s moduli (E) of pavement structure materials were estimated from CBR test results and used in LEA, while stress state-dependent E were determined by triaxial compression tests and used in NLEA. It was found that LEA gives a shorter lifetime for Structure I, while NLEA for Structure II. Adding more cement to the base layer of Structure II results in a comparable lifetime to that of Structure I and the construction cost is significantly cheaper. However, with increasing of truckload, the lifetime of Structure II is shortened more rapidly than that of Structure I, and therefore more cement should be added to maintain a comparable lifetime.