A method for making a reinforced concrete structure and reinforcement agents are provided. In some embodiments, the method includes obtaining a mold for the reinforced concrete structure. A lattice is formed within the mold, where the lattice includes inter-locking ringed fibers and where each inter-locking ringed fiber is a fiber formed into a ringed structure that is inter-locked with at least one neighboring inter-locking ringed fiber in the lattice. The lattice is then encased by filling the mold with concrete. In some embodiments, the reinforcement agents are a plurality of ringed fiber-structures, each of which is coiled into a ringed structure that may or may not inter-lock with at least one neighboring ringed fiber(s)-structure.