Experimental investigation on the flexural behavior of hybrid steel-PVA fiber reinforced concrete containing fly ash and slag powder

A series of four-point bending tests has been performed to investigate the flexural behavior of hybrid steel-PVA fiber reinforced concrete containing slag powder and fly ash. Three hybrid ratios (1:3, 1:1, 3:1) and five total fiber volume contents (1.0%, 1.5%, 2.0%, 2.5%, 3.0%) are highlighted in this work. In addition, Digital Image Correlation (DIC) measurement is used to capture the detailed formation and propagation of cracks during the loading process. The results indicate that Hybrid Fiber Reinforced Concrete (HFRC) has a higher bending strength than the plain concrete. Increasing the steel fiber volume content can improve the bending strength whereas adding more PVA fiber has a bad impact on the bending strength. However, during the post-peak stage, both the steel fiber and PVA fiber could enhance the flexural behavior (e.g., the bending stress and toughness) of HFRC. Furthermore, the toughness corresponding to L/100 is more suitable to evaluate the contribution of PVA fiber. Combining DIC results and images taken during the whole loading process, it is found that the introduce of PVA fiber would cause multiple small cracks, which leads to a higher crack resistance and a better load carrying capacity during the post-peak stage. The steel fibers work as bridges among macrocracks, resulting in the improvement of the bending strength and the toughness of HFRC. (C) 2019 Elsevier Ltd. All rights reserved.