On the utilization of rice husk ash in high-performance fiber reinforced concrete (HPFRC) to reduce silica fume content

The HPFRC refers to a category of fiber-reinforced cement-based materials that have the remarkable capability to flex and strengthen prior to shattering. At present, research is being conducted with the intention of producing a worldwide guideline for the development of structures using HPFRC. However, due to its high initial price and constrained availability, its implementation is challenging, particularly in developing countries. In this study, the effects of fly ash (FA) and rice husk ash (RHA) were examined, with 10%, 20%, and 30% of the cement replaced with FA. Furthermore, the mix providing maximum compressive strength was then taken to replace the silica fume content at 10, 20, 30, and 40% by RHA, steel fiber was also added to optimize the compressive and flexural ductility performance of the specimens. An extensive evaluation of fresh, mechanical, microstructural, and durability of HPFRCs were carried out. In addition, the eco-mechanical properties of fiber-reinforced concrete are studied by taking into account the post-peak behavior of the manufactured specimens and associated CO2 emissions. Test results show that the maximum improvement in compressive, tensile, and flexural strengths was 6.49%, 12.85%, and 5.27%, respectively, at 10% RHA replacement. In addition, as the concentration of RHA increased, the flexural bending toughness increased between 7.4% and 9.2%, with good agreement between the analytical models and the experimental results of the uniaxial compressive stress–strain. Moreover, the gradual increase in RHA concentration improved the durability of the HPFRCs, as evidenced by a maximum reduction in sorptivity coefficient of up to 48 percent for 30% RHA replacement. Finally, the investigation shows how the eco-mechanical index (EMI) can be used to evaluate material design options for HPFRCs.