Fracture Behavior of Fiber Reinforced Concrete Using the Double Cantilever Beam Technique

摘要

The fracture behaviors of concrete and fiber reinforced concrete is studied using contoured double cantilever beam specimens accommodating cracks up to 24 inches in length. Several reinforcing parameters are explored and include fiber length, aspect ratio, volume fraction of fibers, initial notch depth and matrix composition. Experimental results are used to evaluate the fracture properties of fiber reinforced concrete by linear-elastic or elastic-plastic fracture analysis techniques. They include the stress intensity factor K, the crack opening displacement COD, the fracture energy (equivalent strain energy or J-integral) and R-curve analysis. It is observed that different fracture energies can be derived for the same specimen depending on the technique used. Some of the more significant findings are (1) the stress intensity factor of plain mortar increases with crack extension and seems to stabilize at a crack extension of about 8 inches, no crack stabilization is observed for fiber reinforced mortar; (2) an initial crack opening angle (COA) is identified for plain mortar, it defines an angle at which the crack starts propagating regardless of its length; (3) large pseudo-plastic zones develop at the crack front of fiber reinforced specimens and depend on the reinforcing parameters.