Preparation and 3D printing building application of sulfoaluminate cementitious material using industrial solid waste

The iron and steel industry, the power industry, and the mining industry each produce large volumes of industrial solid waste. These industrial solid waste are dumped in huge volumes over a wide geographical distribution, causing far-reaching environmental harm in China. To date, the preparation of eco-friendly construction materials from industrial solid waste is one of the feasible large-scale utilization methods. This paper studied the preparation of different types of environmentally benign novel green sulfoaluminate cementitious materials with different contents of Ca4Al6SO16 and Ca2SiO4 by using stone tailing, coal gangue, secondary aluminum slag, and desulfurization gypsum. Moreover, the prepared solid-waste-based sulfoaluminate cementitious material (SCM) was used to further prepare 3D printing material. The results show that the optimal calcination conditions are 1260-1290 degrees C for about 1 h, and the main mineral phases in the clinker system are Ca4Al6SO16, Ca2SiO4, and Ca4Al2Fe2O10. The compressive strengths of hydrated specimens reached 40, 61, and 86 MPa after curing for 1d, 3d, 28 d, respectively, and the main mineral phases of the hydration product were ettringite, alumina gel, and silica gel. After improving its properties by using a suitable accelerant and retardant, the SCM showed advantages of a controlled setting time in the range of 15-80 min, rapid hardening, and rapid attainment of mechanical strength. The compressive strength of hydrated specimens reached 15-20 MPa after curing for 2 h, and the modified SCM proved to be eminently suitable for 3D printing applications. These results provided not only a sustainable mode for 3D printing construction materials and development, but also an innovative strategy for full utilization of industrial solid waste.