Rheology of Semi-Solid Fresh Cement Pastes and Mortars in Orifice Extrusion

Xiangming Zhou, Zongjin Li, Mizi Fan, and Huapeng Chen 1 School of Engineering and Design, Brunel University, Uxbridge, Middlesex, United Kingdom UB8 3PH Tel: +44 1895 266 670, Fax: +44 1895 269 782, Email: [email protected]. 2 Department of Civil and Environmental Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, Tel: +852 2358 8751, Fax: +852 2358 1534, Email: [email protected]. 3 School of Engineering and Design, Brunel University, Uxbridge, Middlesex, United Kingdom UB8 3PH Tel: +44 1895 266 466, Fax: +44 1895 269 782, Email: [email protected]. 4 School of Engineering, University of Greenwich at Medway, Chatham Maritime, Kent, United Kingdom ME4 4TB Tel: +44 1634 883 031, Fax: +44 1634 883 153, Email: [email protected]. Abstract: Short fiber-reinforced semi-solid fresh cement pastes and mortars, tailored for extrusion, have much lower water-to-binder ratio and higher viscosity than normal cement pastes or mortars. The rheology of these pastes or mortars cannot be characterised by traditional rheology test methods suitable for normal fresh cement pastes or mortars with much greater water-to-binder ratio and lower viscosity. In this paper, orifice extrusion is employed to calibrate rheology of the semi-solid fresh cement mortar. An analytical model is developed for orifice extrusion of semi-solid pastes and mortars obeying a rigid-viscoplastic constitutive relationship, von-Mises yield criterion and the associated flow rule. Orifice extrusion results are interpreted using the analytical model and the established experiment data interpretation method and the associated rheological parameters are derived for the semisolid fresh cement mortar. This study provides a simple analytical model, together with experiment and data interpretation methods, for characterizing the complex intrinsic rheological behaviour of semi-solid fresh cement pastes or mortars.