Characterization of rheology of fresh fiber reinforced cementitious composites through ram extrusion

Rheology behavior of fresh short fiber reinforced cementitious composites was investigated through ram extrusion. The experimental results were interpreted by a six-parameter Benbow-Bridgwater model. The effects of water contents, matrix composition, fiber volume and fiber types on the die entry and die land pressure were investigated and related to the compositions of the fresh short fiber reinforced cementitious composites. The six rheological parameters, together with the dynamic bulk stress and dynamic surface shear stress, were derived and compared for various composites. It was found that fresh short fiber reinforced cementitious composites had an obvious pseudo-plasticity and shear-thinning behavior. The water content, fiber concentration, fiber type and cement matrix influenced the rheology of the fresh composites in different mechanisms. The quantitative rheology parameters, such as bulk yield stress, dynamic bulk stress, wall shear yield stress and dynamic surface shear stress, provided promising interpretations for experimental results.