The results of experimental studies aimed at improving the strength characteristics of cement stone and fine-grained self-compacting concrete through the use of polyfunctional modifying additives based on nano-silicon dioxide (nano-SiO2) and micro-dispersed mineral components are presented. It was established that the introduction of 0.03% nano-SiO2 by weight of cement increases the compressive strength of cement stone by up to 32%, which is associated with the intensification of clinker mineral hydration processes, the formation of an additional amount of low-base calcium hydrosilicates, and an increase in the number of crystallization centers in the early stages of hardening. The effectiveness of the combined use of nano-SiO2 with microsilica and micro-calcite, which are similar in composition to cement but differ in structure and functional activity, has been experimentally confirmed. The use of two-component systems made it possible to increase the flexural strength of cement stone by up to 29% compared to the reference samples. The greatest effect was achieved by adding a polyfunctional three-component additive, including nano-SiO2, microsilica, and micro-calcite, to the composition of fine-grained self-compacting concrete. The use of this system increased the compressive strength of concrete by 44% (to class B60) and the flexural strength by up to 12.5 MPa (an increase of 53.7% relative to the reference composition). It was additionally established that the complex of additives contributes to the acceleration of self-organization processes in the early stages of hardening by increasing the density of crystallization centers and a more uniform distribution of hydration products in the cement matrix volume.

This study presents a multiscale investigation of cement-based systems modified with silica fume (SF) and fly ash (FA) for self-compacting concrete (SCC). Cement pastes and mortars with replacement levels of 0%, 5%, 10%, and 15% were evaluated for rheological behavior, hydration kinetics, and microstructural evolution using rotational rheometry, semi-adiabatic calorimetry, scanning electron microscopy, and X-ray diffraction. The results show that SF increases plastic viscosity and promotes structural build-up due to its high specific surface area and pozzolanic reactivity, while its influence on yield stress depends on dispersion conditions and superplasticizer efficiency. In contrast, FA reduces both yield stress and viscosity, improving flowability due to its spherical particle shape. Thermal analysis indicates that SF modifies hydration by reducing and slightly delaying the main exothermic peak at higher dosages, whereas FA mainly lowers the peak temperature with limited effect on its timing. Microstructural analysis reveals that SF contributes to a denser, more homogeneous matrix through pore refinement and increased C–S–H formation, whereas FA systems exhibit a more heterogeneous structure with slower early-age development. The results demonstrate a clear relationship between rheology, hydration, and microstructure. The combined use of SF and FA has been shown to be an effective approach to improving the performance and sustainability of SCC.

The performance of fine-grained concrete strongly depends on chemical admixtures, yet the combined effect of superplasticizers and air-entraining agents on early hydration and strength remains insufficiently understood. This study evaluates the influence of a polycarboxylate-ether superplasticizer (PS) and an air-entraining admixture (AER), applied separately and in combination, on the hydration kinetics, compressive strength, and microstructure of fine-grained concrete. PS (0.5–1.5 % by mass of cement) and AER (0.10–0.30 %) and their combinations were tested against a control paste at W/C = 0.28. Early-age hydration was assessed by temperature-evolution monitoring, determining the maximum hydration temperature (Tmax) and the time to peak (tmax); compressive strength was measured at 7 and 28 days, and the microstructure was examined by SEM. AER progressively reduced Tmax (by up to 17.8 %) and delayed hydration (tmax up to +52.7 %). PS at an optimal dosage of 1.0 % produced the highest Tmax (87.5 °C), while combined PS–AER systems showed the strongest retardation (tmax up to 18.89 h). PS increased compressive strength by up to 33.2 % at 7 days, whereas AER alone markedly reduced it. The optimal combination SA0.1 (1.0 % PS + 0.10 % AER) reached 27.3 MPa at 7 days and 34.0 MPa at 28 days. SEM revealed a denser C–S–H network for PS-modified samples and characteristic spherical air voids in AER-modified ones. Overall, a superplasticizer at 1.0 % combined with a low AER dosage (0.10 %) optimally balances hydration, strength, and microstructure.

This study examines how mechanically activated fly ash (TF), a polycarboxylate superplasticizer (PC), and an air-entraining admixture (AE) affect the hydration, microstructure, pore structure, mechanical properties, and freeze–thaw resistance of fine-grained concrete. Mechanical activation increased the specific surface area of the untreated ash (UF) from 3710 to 6450 cm²/g and reduced its mean particle size to 6.06 μm. Replacing 5 wt.% of cement with TF accelerated the nucleation of hydration products and densified the microstructure, as confirmed by exothermic profiling, XRD, and SEM. PC delayed the exothermic peak yet produced the highest heat-release intensity, indicating more efficient wetting and dispersion of reactive surfaces. The TF–PC system reached 39.3 MPa at 28 days, while the ternary TF–PC–AE composition achieved 33.2 MPa with a refined pore-size distribution (mercury intrusion porosimetry). The combined use of PC and AE tripled the pore volume in the 0.01–0.10 μm range and increased it by 28.7% (0.1–1 μm) and 46.21% (1.0–10 μm). The calculated potential freeze–thaw resistance rose from 54.25 to 61.97 and 72.83, confirming the beneficial role of 3–10 μm pores. After 110 accelerated freeze–thaw cycles, the optimized ternary composition lost only 0.55% of its mass.

The problem of designing mix compositions for fine-grained self-compacting concrete is addressed. The relevance of the study is associated with the limitations of conventional approaches based on the principle of densely packed aggregate systems. It has been established that existing methods, including those proposed by Okamura, are not sufficiently effective for high-strength multicomponent systems. In this study, a new mathematical model is proposed based on the criterion of excess of the cement-dispersed matrix over the sand volume (Ipcd) and the criterion of excess of the cement-dispersed-sand rheological matrix over the coarse aggregate volume (Ishchcdp). A fine-grained self-compacting concrete mix incorporating stone powder and microsilica has been developed. Experimental results demonstrated intensive strength development kinetics: more than 60% of the compressive strength is achieved within the first 3 days, frost resistance in aggressive environments reaches the F200 level, and a linear increase in transverse deformations is observed up to medium load levels. The research was conducted within the framework of the scientific project IRN AP27511185 «Energy-saving technology for the production of non-prestressed reinforced concrete products using fine-grained self-compacting concrete».

The integration of modern computer technologies into the construction industry is transforming design and building processes, offering professionals numerous advantages. One of the most significant advancements is the adoption of virtual modeling tools, which enhance design accuracy, improve project quality, and reduce implementation time. These technologies also optimize material costs, making construction more efficient and cost-effective. A major milestone in this digital transformation is the widespread use of Building Information Modeling (BIM) technologies, such as Revit and Archicad. These programs create a unified software environment that streamlines project management across all stages, from initial design to construction and operation. Additionally, they enable the development of complex architectural forms through 3D printing, further expanding the potential of modern construction methods. The success of 3D printing in construction depends heavily on advanced materials, particularly fine-grained concrete with inorganic binders. While these materials enhance durability and structural integrity, their development remains a challenge due to strict technical requirements. Overcoming these challenges requires a scientifically grounded approach to optimizing material composition and ensuring seamless integration into additive manufacturing processes. In conclusion, the fusion of digital tools with construction methodologies significantly improves efficiency, precision, and sustainability. These innovations not only advance the design and building processes but also pave the way for the successful realization of complex and economically viable projects, shaping the future of the construction industry.