Mix design methodology for self-compacting flexible-fiber reinforced concrete based on rheological and mechanical concepts

A new design methodology for self-compacting flexible fiber-reinforced concrete (SCFFRC) based on rheological criteria, specifically the plastic viscosity of the suspension, is developed. Firstly, the effect that the flexible fiber produces on the plastic viscosity in Newtonian suspensions is studied. Next, an equation for the calculation of the plastic viscosity in cementitious suspensions reinforced with flexible fibers is presented. Starting from the basis that the rheological behavior of the suspension differs between rigid and flexible fibers, a micromechanical model is developed. This model allows determining the dosage of self-compacting flexible fiber-reinforced concrete, which is adapted from the one proposed for self-compacting steel fiber-reinforced concrete (De La Rosa et al., 2018). The model predicts the behavior of the material based on the geometric and mechanical characteristics of the fiber (aspect ratio and modulus of elasticity), the rheological properties of the cementitious matrix in which they are suspended, and the shear rate of the process. Finally, the results of the characterization of several reinforced concrete with different types of flexible fibers are shown according to the design methodology developed.