Experimental investigation of reinforcement strategies for concrete extrusion 3D printed beams

Abstract

This study investigates the structural behaviour of different reinforcement concepts for extrusion-based 3D concrete printed beams. As longitudinal reinforcement, unbonded post-tensioning and passive bonded reinforcement are explored. As shear reinforcement, fibres and cables placed between the layers of concrete are analysed. The results of four-point bending tests show that unbonded reinforcement leads to highly brittle failure without a proper activation of the shear reinforcement. The beams with conventional bonded reinforcement behave monolithically, with little influence of the concrete layering. Cables, as well as fibres, increase the shear resistance significantly. While cables have higher efficiency, fibres lead to finer and more closely spaced cracks.