Gravity induced flow to characterize rheological properties of printable cement‐based materials

Abstract

This paper presents testing methods based on the deformation and fracture of fresh cementitious materials subjected only to their own weight. These new methods are dedicated to the study of cementitious materials designed for 3D concrete printing in order to verify rheological requirements related to the process. The first testing method consists of measuring the tip deflection of fresh cementitious materials, horizontally extruded, enabling the determination of the apparent elastic modulus of the material. The second test consists of measuring the tensile strength of material filament leaving the nozzle of a vertical downward extruder. The results of both methods are based on the video capture of the deformation of the materials loaded by gravity, and provide results that are in agreement with tests performed with conventional testing machines (tensile and unconfined compression tests). This work demonstrates the potential of video capture of the gravity induced deformation of cementitious materials to describe the behavior of cementitious materials in the fresh state or for the in‐line control of the 3D concrete printing process.