Matric suction and its effect on the shape stability of 3D printed concrete

Abstract

The mix design of 3D printed concrete has adopted various types of binders and additives to enhance its casting performance and shape stability. Matric suction, as an attractive force among partially unsaturated particles of the binders and additives, influences the shape stability of firm cement paste composing 3D printed concrete. Higher matric suction induces higher compressive strength (or green strength) and higher elastic modulus. The extended Mohr-Coulomb failure envelope describes the stress state of the 3D printed concrete considering its matric suction. Variation of the matric suction takes parallel shifting and rotation of the shape failure envelope. The test results on the matric suction finally confirm the effect of binders and additives. Change in the water-to binder ratio contributes to higher matric suction related to the paralel shift of the Mohr-Coulomb failure envelope, while incorporating nanoclay or polycarboxylate ether affects the internal friction angle of the binder.