Effect of raw materials on the performance of 3D printing geopolymer: A review

Traditional building materials such as cement products release a large amount of carbon dioxide during their preparation and usage, which has a negative impact on the environment. On the other hand, 3D printing with geopolymer materials adopts renewable and low-carbon emission raw materials. It also possesses characteristics such as energy efficiency and resource-efficient utilization, which help to reduce carbon emissions and improve sustainability. Therefore, the development of them is of great significance. This paper comprehensively reviews the 3D printing of geopolymer systems, the impact of raw materials on processability, including flowability and thixotropy, and microstructure. The paper also conducts in-depth research on sustainability and environmental impact. The evaluation shows that the initial content of silicon, aluminium, and calcium in the silicate raw material plays an important role in the gel structure and microstructural development of the geopolymer. Aluminium can promote reaction rate, increase reaction degree, and product formation. Silicon helps improve the strength of the geopolymer and enhance its mechanical properties. Calcium facilitates the formation and stability of the three-dimensional network structure, further improving material strength and stability. Furthermore, the reactivity of raw materials is also a key factor affecting interlayer bonding and interface mechanical properties. Finally, considering sustainability, the selection of raw materials is crucial in reducing carbon emissions, energy consumption, and costs. Compared to cement, 3D printing with geopolymer materials has lower carbon emissions, energy consumption, and costs, thus which is considered as a sustainable material.