Rheological Characterisation of the Strain-Hardening Limestone Calcined Clay Cement (SHLC3) Composites for Shot-Creting

Strain-hardening cement-based composites (SHCC) are attractive candidates to strengthen concrete elements under exceptional loadings, owing to their elevated dissipation capability. For advanced application technologies, like, e.g. shotcrete, the deterministic control of the rheological parameters is necessary for successfully handling the material in the fresh state, especially when highly reactive binder systems such as limestone calcined clay (LC3) are adopted. In this article, an advanced rheological technique, namely large-amplitude oscillation shear (LAOS), is adopted to characterise the intrinsic rheological properties of strain-hardening limestone calcined clay-based (SHLC3) composite, including ultra-high molecular weight polyethylene (UHMWPE) fibres. To evaluate the efficiency of the LAOS technique, the fibre-reinforced composite and the corresponding mortar (i.e. without fibres) are investigated in terms of shear stress, shear strain, storage and loss moduli, complex viscosity at the critical and the cross-over strain, as these parameters effectively govern the technological processes at the fresh state of shotcrete, like pumping and spraying and the quality of adhesion with the substrate.