Rheological Optimization of Steel Fiber-reinforced Self-compacting Concrete (SFSCC) Incorporating Calcareous Tuff Powder (CTP)

The purpose of this study is to formulate a steel fiber-reinforced self-compacting concrete (SFSCC) with optimal rheological properties, using calcareous tuff powder (CTP) as an addition and partial substitution for cement. The design of experiments (DOE) method was used to analyze the effect of fiber dosage, paste volume, and gravel-to-sand ratio on the SFSCC. A concrete rheometer was used to quantify the intrinsic rheological parameters. The rheological results of the SFSCC containing calcareous tuff powder indicate that both paste volume and fiber dosage significantly affect flow capacity, while plastic viscosity is exclusively governed by paste volume. The measured rheological parameters indicated that the steel fiber-reinforced selfcompacting concrete incorporating calcareous tuff powder is a high yield stress selfcompacting concrete (HYSCC), with yield stress values ranging from 62 Pa to 335 Pa and plastic viscosity values between 12 and 31 Pa.s. Rheological optimization through the DOE method allowed the identification of optimal composition factors, ensuring a targeted self-compacting behavior. The self-compacting behavior of the SFSCC observed in the rheometer was confirmed and validated at full scale, with slump flow values up to 72 cm and flow time (T500) between 3.0 seconds and 4.3 seconds. Keywords: Rheology, self-compacting concrete, Design of experiments method, Calcareous tuff powder, Steel fibers