Compounding Features of Special Molding Mixes for 3D Printing Technology

World experience shows that to ensure the speed of building construction and minimize labor costs, the technology of layer-by-layer synthesis (3D printing or three-dimensional extrusion) will develop rapidly in the next decade. In modern Russian conditions, 3D printing is ideal for mass and individual construction of low-rise houses and cottages. The main idea of construction printing is to create a finished product or structure with a single device. For a stable technological process of construction of low-rise buildings by layer-by-layer synthesis, special fast-hardening molding mixes are offered, including clinker minerals, gypsum binders, mineral and organic additives, as well as fine aggregate. The joint insertion of gypsum binders of α - and β - modification (G-5BII and GVVS-16) into the composition of CGB contributes to the early structure formation of stone on CGB. The insertion of modifying additives into its composition - the hyperplasticizer MARP SU 84, the thickener MARF (Forbocrete 9010) and the hydrophobic rheological additive MAPF №T 10 can significantly reduce the water demand of the binder by 28…56%) and improve plasticity, while the compressive strength increases by 2 times in 2 h, by 1.7 times in 1 day, and by 1.5 times in 7 days. Developed for 3D additive technologies, molding mixtures based on CGB and quartz sand quickly harden and gain strength, providing concrete compressive strength class B3.5 in the early stages of hardening (1 day), and at the age of 7 days – B7.5.