Effect of recycled agricultural and industrial by-products on mechanical and durability properties of ultra high-performance fiber reinforced concrete

The use of recycled agricultural and industrial by-products as partial cement replacements may reduce cement consumption and associated environmental impacts. This study investigates the effects of replacing cement with rice husk ash (RHA), fly ash (FA), glass powder (GP), and ground granulated blast furnace slag (GGBFS) at 10% and 20% replacement levels on the fresh and hardened properties of ultra-high-performance fiber-reinforced concrete (UHPFRC). Performance depended on both material type and replacement level. GGBFS20% achieved the highest 28-day compressive strength of 149.1 MPa, an increase of 8.5% compared with the control. It also achieved the highest splitting tensile strength of 10.9 MPa, representing an 18.5% increase, and the highest flexural strength of 29.4 MPa, corresponding to a 19.0% increase. RHA10% increased the 28-day compressive, splitting tensile and flexural strengths by 3.1%, 12.0%, and 11.7%, respectively. FA generally reduced mechanical strength, particularly at 20% replacement, whereas GP reduced compressive, splitting tensile and flexural strengths. FA20% exhibited the highest workability. GGBFS reduced water absorption by approximately 20% and 30% at 10% and 20% replacement, respectively, while RHA20% exhibited the highest water absorption. Overall, RHA10% and GGBFS showed favorable performance for selected properties.