Edge-Oxidized Graphene Oxide as Additive in Fiber-Reinforced Concrete: Effects on Fresh and Hardened Properties

This study experimentally investigates the effects of edge-oxidized graphene oxide (EOGO), which is a low-cost carbon-based nanomaterial, on fresh and hardened properties of normal portland cement concrete (PCC) and fiber-reinforced concrete (FRC). Interestingly, adding EOGO to normal concrete mixtures improves the workability of concrete. In this regard, EOGOs as an additive were applied to FRCs in order to improve FRCs' low workability without losing mechanical enhancement due to EOGOs. Two fiber types of basalt fiber (BF) and steel fiber (SF) were used in this study. First, 0.05% of EOGO by the cement weight was mixed in basalt FRC (BFRC) mixture, which is 0.1% of the BF by the concrete volume. Second, considering the results of BFRC, 0.1% of EOGO was employed in steel FRC (SFRC) mixture with 1.0% of SF by the concrete volume. Testing was aimed at investigating the effects of EOGO on the workability and mechanical strengths of the FRC mixtures. The test results illustrate that the EOGO improves workability more than 100% in the SFRC mixture but about 20% in the BFRC mixture. The EOGO provides a slight increase of both compressive and flexural strengths for normal concrete and SFRC mixtures. In contrast, it was observed that the EOGO increases the flexural strength of SFRC in terms of initial crack generation and range of elastic behavior. The EOGO-SFRC required more than 30% of energy to reach the initial crack point than the SFRC mixture.