Rheological and mechanical properties of admixtures modified 3D printing sulphoaluminate cementitious materials

3D printing for cement-based material is recently supposed to be the rapidly and innovative forming technology in the building industry. This paper is concentrated on the rheological and mechanical properties of hydroxypropyl methyl cellulose (HPMC), water-reducing agent (WRA) and lithium carbonate (Li2CO3) modified 3D printing sulphoaluminate cementitious materials based on the extrusion system of 3D printing. Experimental results show that HPMC notably increases the stress and viscosity of cement paste and the plastic viscosity need to reach 1.650 ∼ 2.538 Pa·s for the build-up of 3D structures. While the cement paste with WRA and Li2CO3 present low shear stress and apparent viscosity. Furthermore, the setting time and rheological properties of 3D printing cement paste with hybrid admixtures are investigated using response surface methodology (RSM). The optimal hybrid additions of admixtures enable the 3D printing paste to achieve a favorable deformation rate and higher compressive strength. In conclusion, utilization of admixtures has a great potential to develop 3D printing sulphoaluminate cementitious materials used in buildings, which can effectively control the printable properties and rheological behaviors.