Study of the mechanical properties, durability, and microstructure of an ultra-high-performance fiber-reinforced concrete containing recycled fillers

Abstract In this article, a specific mix design of the ultrahigh-performance fiber-reinforced concrete (UHPFRC) was proposed and applied for Algerian materials that are currently in use. In the absence of a general mix design that limits their use and reuses waste materials, the present mix design can help reduce the high manufacturing cost of this type of concrete and make it more environmentally friendly. Here, we have looked for a reference mix design based on local ordinary aggregates, and then, we introduced the recycled fillers from ceramic waste and granulated blast furnace slag into our mix design, and we studied their effects on the properties of the fresh state (density, workability, and air content) and in the hardened state, namely compressive and flexural tensile strength, modulus of elasticity, ultrasonic and sclerometer resistance, as well as durability tests (capillary and immersion absorption, porosity, and chemical resistance). The microstructure analysis was carried out using scanning electron microscopy, complemented by energy-dispersive X-ray spectroscopy. Comparison of the results of UHPFRC using ceramic waste and slag fillers with the control UHPFRC after 28 days shows an increase in compressive strengths of approximately 8 and 7%, respectively, as well as an increase in flexural tensile strengths of 17 and 2%, respectively. In addition, there was a decrease in porosity of 17 and 42%, respectively. The results reveal that it is possible to produce UHPFRC based on local materials and improve its performance, durability, and microstructure with recycled fillers.