Fracture Behavior of Functionally Graded Concrete Materials for Rigid Pavements
Currently, in concrete pavements, a single concrete mixture design and structural surface layer are selected to resist mechanical loading without an attempt to affect concrete pavement shrinkage, ride quality, or noise attenuation adversely. An alternative approach is to design sublayers within the concrete pavement surface that have specific functions and thus to achieve higher performance at a lower cost. The objective of this research was to address the structural benefits of functionally graded concrete materials (FGCMs) for rigid pavements by testing and modeling the fracture behavior of different combinations of layered plain concrete materials and concrete materials reinforced with synthetic fibers. The three-point bending-beam test was used to obtain the softening behavior and fracture parameters of each FGCM. The peak loads and initial fracture energy between the plain, fiber-reinforced, and FGCMs were similar; this signified similar crack initiation. The total fracture energy clearly indicated the improvements in fracture behavior of FGCM relative to full-depth plain concrete. The fracture behavior of FGCM depended on the position of the fiber-reinforced layer relative to the starter notch. The fracture parameters of both the fiber-reinforced and plain concrete were embedded into a finite element-based cohesive zone model. The model successfully captured the experimental behavior of the FGCMs and now can be implemented to predict the fracture behavior of proposed FGCM configurations and structures such as rigid pavements. This integrated approach (testing and modeling) is promising and demonstrates the viability of FGCM for designing layered concrete pavement systems.