Mechanical properties of 3D bio-printing cement-based materials

Abstract

The aim of this paper is to investigate the effect of different mix composition on mechanical properties of a printable mortar. For the mix design, two binders such as fly ash (FA), and silica fume (SF) were used with Portland cement II and sand for a water/binder ratio of 0.50.  Sisal fibres (SFR), superplasticiser (SP), and viscosity modifying agents VMA composed of diutan gum and nano-clay (NC) were used in the investigation.  New method was proposed to take cubes from fresh layers’ mortar. The tensile strength was obtained by using dumb bell test.  All results of the compressive strengths of layers were lower than the standard cast cubes of all mixes by up to 30%, this can be attributed to the fact that the layered cubes are not homogeneous and were not compacted (entrapped air).

The addition of silica fume didn’t not affect too much the compressive strength.  The addition of more fibres led to a slightly reduction of compressive and flexural strengths due to the air entrapped, but it improved the direct tensile strength.  SP didn’t affect significantly the compressive strength.