Fatigue and fracture characterization of fiberglass grid-reinforced beam specimens using four-point bending notched beam fatigue test and digital image correlation technique

The purpose of this research is to develop an experimental and analytical framework for describing, modeling, and predicting the reflective cracking patterns and crack growth rates in GlasGrid (R)-reinforced asphalt pavements. In order to fulfill this objective, the effects of different interfacial conditions (mixture type, tack coat type, and grid opening size) on reflective cracking-related failure mechanisms and the fatigue and fracture characteristics of fiberglass grid-reinforced asphalt concrete beams were studied by means of four-point bending notched beam fatigue tests (NBFTs). Also, the digital image correlation technique was utilized to determine the lengths of the interfacial and vertical cracks during each test. The stress intensity factors (SIFs) at the crack tips were backcalculated using a finite element model and applying linear elastic fracture mechanic principles to the crack lengths. The local effect of the reinforcement on the stiffness of the system at a vertical crack-interface intersection or the resistance of the grid system to the deflection differential at the joint/crack (joint stiffness) for GlasGrid (R)-reinforced asphalt concrete beams was determined by implementing a joint stiffness parameter into the finite element code. The crack length and SIF test results were used to find the Paris' law parameters for each interlayer condition. According to the NBFT results, GlasGrid (R) reinforcement retards reflective crack growth by stiffening the composite system and introducing joint stiffness. The results also show that the higher the bond strength and interlayer stiffness values, the greater the joint stiffness and retardation effects.