Autoclaved reactive powder concrete: the effects of steel micro-fibers and silica fume dosage on the mechanical properties

Abstract

Reactive Powder Concrete (RPC) is a type of ultra-high performance cement based composite with high strength and ductility. RPC was developed in the 1990s by Bouygues' laboratory in France. It is a special type of concrete which has properly optimized micro grain, binder phase and steel micro-fibers. RPC can achieve compressive strength values between 150–800 MPa, while traditional concrete which is used in current structures usually has 20–50 MPa compressive strength. In addition, its high performance under flexural loads is the most important advantage of RPC in the field of civil engineering. RPC has the potential to compete with steel from the point of aesthetics and structural capability. One of the curing methods to enhance the strength of this composite material is autoclaving. Autoclave curing needs additional SiO2 source to fill micro pores and strengthen hydration products. In the scope of this study, the effect of volume fraction of steel micro-fibers and silica fume dosage as SiO2 source on mechanical properties of RPC under autoclave curing was investigated. High performance cementitious composites were produced with 0%, 1%, and 2% volume fractions of steel micro-fibers. Nine mixtures with three different silica fume dosages were produced. Workability of fresh state and flexural-compressive strengths of hardened specimens were determined. In addition, fracture energies of the mixtures under bending loads were evaluated.