Abstract: Through three-point bending fracture tests of the concrete beams repaired with epoxy resin, fracture properties of the unrepaired and repaired concrete are compared, and the influence of coarse aggregate content on double-K fracture toughness and fracture energy is analyzed. The results show that the maximum bearing capacity of concrete can be greatly improved after being repaired with epoxy resin, while the critical crack opening displacement is almost unaffected. And the fracture behavior of repaired concrete can be restored and improved effectively. When the coarse aggregate content is 0 (mortar), 18%, 36% and 54%, initial toughness increases by 56.5%, 28.2%, 21.5% and 21.1% respectively; unstable fracture toughness increases by 13.1%, 6.0%, 5.5% and 8.2%, and fracture energy increases by 41.3%, 39.1%, 38.1% and 23.2% respectively. Meanwhile, the fracture parameters of unrepaired and repaired concrete show an ascending tendency with the coarse aggregate content, and their increasing rates gradually slow down.

Key words: concrete, fracture, epoxy resin, epoxy-injection repair, coarse aggregate content