Geopolymers are high-performance, cost-effective materials made from industrial waste that ideally fit the needs of 3D printing technology used in construction. The novelty of the present work lies in the investigation of methods to mix geopolymer concrete from fly ash (FA) class F, ground granulated blast furnace slag (GGBS), and raw calcined kaolin clay (RCKC) to determine the mixing procedure which provides the best mechanical strength and structural integrity. The experimental results show that aluminosilicates with different reaction parameters when mixed one after another provide the optimal results while the geopolymer concrete possesses the highest compressive strength and the denser structure. The results demonstrated that the reactivity of GGBS, FA, and RCKC increased for different depolymerization speeds of the selected aluminosilicates. This research will provide results on how to improve the mixing order for geopolymer synthesis for 3D printing demands. The highest compressive strength and denser structure of geopolymer concrete is achieved when each type of aluminosilicate is mixed with an alkaline medium separately.

The paper summarizes the research results of sintering and durability of wall ceramic materi-als modified by diopside-containing raw products and based on low-melting-point clays and loams, and kaolinand high-melting-point clay faience. Mechanical-and-physical properties of ceramic materials are identified and studied after annealing, depending on the diopside content. It is shown that depending on the content and introduction of clay minerals in the ceramic mixture, both coarse (0.5–1 mm) and fine (0.06 mm, dominating particle size of 0.01–0.015 mm) dis-persed diopside particles can be used. It is found that for loams with the clay mineral content of less than 10 wt.%, the addition of finely-dispersed diopside particles is more efficient. The latter provides ceramic sintering at 1000–1100 °С and increases its strength by 1.5–2 times. The intro-duction of dispersion diopside particles in the faience mixture lowers the annealing temperature from 1250 to 1150 °С with a simultaneous increase in its strength.

In this paper a composite material consisting of silicon nitride, zirconium nitride and aluminum nitride is obtained from a complex ferro-aluminum-silicon-zirconium (FASZ) alloy by self-propagating high-temperature synthesis. The effect of the sample diameter, nitrogen pressure, the dispersity and density of the initial ferro-aluminum-silicon-zirconium powder on the amount of absorbed nitrogen, rate and temperature characteristics of combustion under the nitrogen atmosphere is investigated. It is shown that with increasing pressure the amount of absorbed nitrogen and the rate and temperature of combustion increase. Increasing the density of the initial powder leads to decreasing the amount of absorbed nitrogen and the rate and temperature of combustion. Increasing the diameter of the initial samples, consisting of ferroalloy powder, does not lead to a significant change in the amount of absorbed nitrogen, but decreases the rate of combustion and increases the temperature of synthesis. Changes in the dispersity of the initial ferro-aluminumsilicon-zirconium do not significantly affect the amount of absorbed nitrogen and the rate and temperature of combustion. It has been revealed that the combustion wave front propagates along the sample under the nitrogen atmosphere in a nonstationary mode, and the obtained composites have a macro-heterogeneous structure. The optimal conditions of nitriding ferro-aluminum-silicon-zirconium are found: nitrogen pressure, diameter of the initial sample, dispersity and density of the initial powder. The critical parameters of nitriding ferro-aluminum-silicon-zirconium by self-propagating high-temperature synthesis, at which the combustion wave front forms and propagates in the initial ferroalloy, are revealed. The probable reactions of nitriding the initial material in the combustion wave are given. The phase composition of the products obtained by nitriding ferro-aluminum-silicon-zirconium is determined by X-ray diffraction analysis. A composite material containing silicon nitride, aluminum nitride and zirconium nitride is obtained.