CO2-reduced fiber sprayed concrete for permanent tunnel linings (Part 2): a rheological investigation

As part of an ongoing research project "SpOC" (sprayed optimized concrete), CO2-reduced fiber sprayed concrete (FSpC) is being developed as a permanent and thin inner tunnel lining. Concerning shotcrete mixtures to be used as such permanent lining, adding micro- and macrofiber and chemical admixtures to reduce crack risk and to improve the mechanical properties and durability seems to be a smart approach. However, adding such components will change the rheological behavior and can lead to pumping problems. Therefore, this paper presents the rheological investigation of different fiber-reinforced sprayed concrete mixes. We will demonstrate the fiber's influence on the fresh properties and how to optimize them.