There are no standards for testing the properties of 3D-printed materials; hence, the need to develop guidelines for implementing this type of experiment is necessary. The work concerns the development of a research methodology for interlayer bond strength evaluation in 3D-printed mineral materials. In additive manufactured construction elements, the bond strength is a significant factor as it determines the load-bearing capacity of the entire structural element. After we completed a literature review, the following three test methods were selected for consideration: direct tensile, splitting, and shear tests. The paper compares the testing procedure, results, and sample failure modes. The splitting test was found to be the most effective for assessing layer adhesion, by giving the lowest scatter of results while being an easy test to carry out.

The article presents a set of experimental-static models of the properties of fine-grained concretes on a cement–slag binder and quartz sand with the addition of a hardening accelerator made on a 3D printer. The influence of the factors of the composition of the mixture and the effects of their interaction on the studied properties of concrete was established. By analyzing the models, the influence of the factors of mixture composition on the studied properties was ranked. The nature and degree of interrelation of individual properties of concrete are shown. A method for calculating the optimal compositions of concrete for a 3D printer, providing the specified properties at a minimum cost, is proposed.

The article shows the effectiveness of the use of polymer additives for the production of fine-grained concrete mixtures and concretes based on using coal fly ash, which can be used as working mixtures for a 3D printer. Using mathematical planning of experiments, a set of experimental–statistical models was obtained that describes the influence of mixture composition factors including copolymer additive on the most important properties of ash-containing concrete mixtures and concretes for 3D concrete printing in the presence of a hardening accelerator additive. It is shown that when the dry mixture is mixed in water, the redispersed polymer powders are converted into an adhesive polymer dispersion, which, when the solution cures, creates “rubber bridges” in its pores and at the border with the base. They have high tensile strength and elastically reinforce the cement stone; in addition, they are also capable of not only significantly increasing the adhesion between the layers of the extruded mixture, but also significantly smoothing out such shortcomings of the cement stone as increased brittleness, low ultimate elongation, and a tendency to cracking.

This article presents the results of a study of the physical and mechanical properties of fine-grained fly ash concrete based on a combined reinforcement with steel and basalt fibers. The main studies were conducted using mathematical planning of experiments, which allowed the experiments to be algorithmized in terms of both the amount of experimental work and statistical requirements. Quantitative dependences characterizing the effect of the content of cement, fly ash binder, steel, and basalt fiber on the compressive strength and tensile splitting strength of fiber-reinforced concrete were obtained. It has been shown that the use of fiber can increase the efficiency factor of dispersed reinforcement (the tensile splitting strength to compressive strength ratio). To increase the resistance of basalt fiber, it is proposed to use fly ash in cement systems, which reduces the amount of free lime in the hydrating cement environment.

Compositions of fine-grained concrete mixtures that provide the minimum required strength values in 1 day (7.5 MPa) have been developed. A comparison was made of the test results of the properties of samples printed on a 3D printer with samples made according to the same recipes on a vibrating platform. A laboratory printer was designed and constructed to study the properties of extruded mixtures. The method was also proposed for measuring concrete mixes’ structural strength. Analysis of experimental data allowed the establishment of the features of the influence of the mineral additives and slag–alkaline binders for a comparison of basic physical and mechanical properties of concretes for 3D printing. It has been experimentally shown that possible undercompaction of the fine-grained mixtures formed on a 3D printer and decrease of properties are compensated by the introduction of hardening activator and superplasticizer additives. The novelty of this work lies in determining the comparative effect of various products of technogenic origin on the properties of mixtures for 3D printing.

By volume, cement concrete is one of the most widely used construction materials in the world. This requires a significant amount of Portland cement, and the cement industry, in turn, causes a significant amount of CO₂ emissions. Therefore, the development of concrete with a reduced cement content is becoming an urgent problem for countries with a significant level of production and consumption of concrete. Therefore, the purpose of this article is to critically investigate the possibility of using inert granite dust in combination with highly active silica fume in reactive powder concrete. The main physical and mechanical properties, such as the compressive strength at different curing ages and the water absorption, were studied using mathematical planning of experiments. The consistency and microstructure of the reactive powder concrete modified with granite dust in combination with silica fume were also analyzed. Mathematical models of the main properties of this concrete are presented and analyzed, and the graphical dependencies of the influence of composition factors are constructed. A more significant factor that affects the compressive strength at all curing ages is the silica fume content, increases in which to 50 kg/m³ lead to a 25–40% increase in strength at 1 day of age, depending on the granite dust content. In turn, an increase in the amount of granite dust from 0 kg/m³ to 100 kg/m³ in the absence of silica is followed by an increase in strength of 8–10%. After 3 days of curing, the effect of granite dust becomes more significant. Increases in the 28-day strength of 25%, 46% and 56% were obtained at a content of 50 kg/m³ of silica fume and 0 kg/m³, 100 kg/m³ and 200 kg/m³ of granite dust in concrete, respectively. It is shown that the effect of inert granite dust is more significant in combination with silica fume at its maximum content in the range of variation. The pozzolanic reaction between highly active silica and Ca(OH)₂ stimulates the formation of hydrate phases in the space between the grains and causes the microstructure of the cement matrix to compact. In this case, the granite dust particles act as crystallization centers.