The performance of crack injection repair methods depends on bond and other material properties defined local to the repaired crack. Important properties include not only bond strength at the interface between the concrete and injection material, but also on the fracture properties of the adjacent bulk concrete and the injection material itself. This work first presents experimental results for several concrete beam specimens repaired by crack injection techniques. Using rigid-body-spring networks, a corresponding series of numerical specimens are fractured, repaired, and reanalyzed to clarify the mechanisms of fracture and strength gain in the repaired members. The numerical approach, which is based on an energetic fracture mechanics modeling of cracking, is used to interpret the failure modes observed during the experimental program. The analyses indicate that the crack injection material restricts natural crack movement, which leads to additional strength and energy consumption.