INVESTIGATION OF FRACTURE PARAMETERS OF CONCRETE INCORPORATING BASALT FIBERS

Concrete is a brittle material that should be enhanced with better tensile strength and toughness capacity. Concrete matrix is generally reinforced with fibers which are extremely helpful inhibiting the crack propagation and supplying the ability of strain accumulation into concrete matrix. In this study, an environment friendly type of fiber was introduced into concrete for the investigation of mechanical properties and fracture characteristics by size independent double-K fracture parameters asserted in the literature. Effect of basalt fibers with different lengths and contents were investigated under notched three-point bending tests and relevant parameters obtained and calculated, were compared for two distinct parameters: fiber length (6, 12, 24 mm) and content (0, 0.1%,0.3%, 0.5%, 1%). Shorter fibers confronted dispersion problems when used in higher content whereas 12 mm fiber specimens performed more stable results. Fracture energy dissipation was found to be linearly increasing with increasing fiber content and also longer fibers were found to be more efficient. Double-K fracture parameters were found to be resourceful when considering toughness and ductility of the material besides these parameters indicated useful information regarding the precracking and post-cracking behavior of concrete. SEM investigations were also conducted to monitor the bonding between basalt fibers and concrete matrix.