Improving the impact resistance of recycled aggregate concretes with different types of fibers

Özet

In this study, the aim was to use different types of fibers to improve the impact re-sistance of recycled aggregate concrete (RAC) that normally shows poor perfor-mance against mechanical impacts compared to normal concrete (NC). For this pur-pose, 18 groups of concrete were cast using different parameters. The study exam-ined different types of concrete mixtures where the proportion of RCA (recycled coarse aggregate) used was 30% and 50% respectively, and where steel fiber-rein-forcement was used in proportions of 1% and 2%, and polypropylene fiber-rein-forcement was used in proportions of 0.1%. While the material performance of RAC compared to NC is analyzed in existing published literature, there is no evidence on whether the use of RCA and hybrid fibers affect the impact properties of concrete. Drop weight impact testing was conducted on test specimens and the impact re-sistance of these specimens was studied at 28 days. It was observed that the increas-ing use of RCA reduced the impact resistance. The use of 30% RCA does not signifi-cantly influence the strength of concrete. According to the results, the performance of both the NC and RAC was increased with an increase in the volume fractions of steel fiber used. In addition, hybrid fiber-reinforced concretes showed the best re-sults of all the concrete groups.