LAUSR

Abstract In this paper, systematic supercritical carbonation tests of steel-polypropylene hybrid fiber reinforced concrete (SPFRC) were carried out to evaluate the performance of SPFRC under supercritical condition. The effects of the long-diameter ratio of steel fiber, volume fraction of steel fiber, and polypropylene fiber on the carbonation depth and compressive strength of concrete under supercritical condition were studied. A one-dimensional mathematical model for the physical-chemical coupling process of supercritical carbonation of cement-based materials was established. The relational model between the equivalent porosity and the compressive strength of fully carbonated SPFRC was also proposed. Results indicate that the carbonation process can be accelerated by either the addition of steel fibers or polypropylene fibers. The carbonation depths of SPFRC increase with the increase of the addition of steel fibers and polypropylene fibers. The compressive strength after carbonation is significantly increased. The maximum relative compressive strength was obtained when the volume fraction of steel fiber and polypropylene fiber were 1.5% and 0.0% and the long-diameter ratio of steel fiber was 60, respectively. This paper provides a model to evaluate the equivalent initial porosity of SPFRC and a basis for the future efficient treatment of SPFRC by supercritical carbonation.