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Keywords: concrete

Prediction of concrete nonlinear creep using machine learning methods

https://doi.org/10.58224/2618-7183-2026-9-1-2
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Abstract
Based on the experimental data of concrete nonlinear creep under high stress levels (40-80% of prismatic strength), this study explores the application of machine learning methods for predicting creep deformation. A recurrent artificial neural network (ANN) and the CatBoost algorithm were employed to model the time-dependent creep strain, using stress and time as input parameters. The ANN demonstrated high predictive accuracy, with training achieving a mean square error of 0.000154, and its generated creep curves showed an excellent fit with the experimental data. In contrast, the CatBoost algorithm, while effectively capturing the physical trend that creep strain increases nonlinearly with stress and decelerates over time, exhibited lower prediction accuracy than the ANN. Feature importance analysis within the CatBoost model highlighted the significant influence of lagged stress parameters and time-squared terms, aligning with the nonlinear physical nature of concrete creep. The results confirm the strong potential of machine learning, particularly recurrent neural networks, for modeling complex nonlinear creep in concrete, even with limited datasets. Future work is suggested to incorporate concrete strength class and loading age as additional parameters to enhance model generalizability.
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Improving the performance of concrete for bridge structures

https://doi.org/10.58224/2618-7183-2025-8-6-2
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Abstract
Concrete for ambitious engineering projects, including bridges, must meet certain requirements related to strength, water resistance, frost resistance and plasticity. The objective of the article is to improve the efficiency of concrete for bridge structures. The compositions of high-strength building composites have been optimized with a reduction in the proportion of the clinker component. The densest packing of filler particles has been achieved, providing a self-compacting effect during hardening. The compositions of building composites have been optimized at the macro-, micro- and nanolevels to obtain a high-density matrix packing and increase the strength of the composite (including taking into account the granulometric analysis of fillers and the choice of superplasticizer). New properties of high-strength building composites (rheology of highly concentrated dispersed systems, shrinkage deformations, workability, setting time, etc.) have been studied. The results of fresh properties of the developed mixtures showed their compliance with the P5 grade, which indicates that they have good transportability to the place of manufacture of bridge structures. The study of the physical and mechanical characteristics of cement composites (average density, porosity, compressive and bending strength, elastic modulus, frost resistance, shrinkage, Poisson's ratio) showed that the obtained materials can be effectively used for the construction of critical structures, including bridges.
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Fine-grained cement concrete with compressed structure, modified with basalt technogenic highly dispersed powder

https://doi.org/10.58224/2618-7183-2025-8-4-2
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Abstract
At present, improving the performance properties of concrete for dry and hot climates due to changing climatic conditions is of increasing interest to a wide range of researchers from the point of view of their practical application in the production of construction products. The paper investigates the possibility of synthesizing a spatially reinforced fine-crystalline structure of cement concrete for dry and hot climates, modified with basalt dust. The introduction of basalt dust waste into the composition of cement concrete forms the structure of artificial stone with the most dense packing. This is achieved by using a complex modifier based on basalt production dust removal waste together with a plasticizing additive in the composition of concrete for dry and hot climates. The introduction of these additives allows creating the best conditions for the process of forming the structure of cement stone from the standpoint of water content. Providing water content at all stages of the synthesis of modified stone allows for the acceleration and more complete flow of hydration and structure formation processes. The combined use of additives, as studies have shown, improves the performance properties of cement concrete, and therefore its use in the production of an expanded range of building products.
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Influence of carbon black additives and finely ground waste from stone wool production on characteristics of cement systems

https://doi.org/10.58224/2618-7183-2025-8-4-8
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Abstract
The object of research is cement composites with additives of carbon black and finely ground waste stone wool production. The work aims to design a mix of a cement composite with the additives of carbon black and finely ground waste from stone wool production, which achieves the best strength characteristics. The results show that carbon black is represented on average by particles of 155 microns with inclusions of large agglomerates up to 1-2 mm in size, consisting of almost homogeneous nanoparticles 10-20 nm in size. Carbon black is distinguished by high hydrophobic properties with a true powder density of 900 kg/m3 and a bulk density of 300 kg/m3. The chemical composition of black carbon is 70-80% carbon and 10-15% oxygen, and it also contains impurity compounds of zinc, iron, sulfur, silicon, and other elements. Carbon additives acquire hydrophilic properties in the presence of a plasticizer, and the degree of their influence on hydration becomes less pronounced. The contraction of the binder during the first three hours of hardening is reduced when carbon black is introduced into the cement system in an amount of 8%. A composition with the best strength characteristics was obtained: the content of finely ground waste from stone wool production is 6% by weight of the binder; carbon black content is 4-5%; W/C = 0.2. However, there is difficulty in mixing the mixture at such a low W/C. With a water-cement ratio of 0.3, this problem is solved, and the strength characteristics remain quite high.
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Optimization of concrete composition with polypropylene fiber to improve their crack resistance in road construction conditions

https://doi.org/10.58224/2618-7183-2025-8-2-5
Abstract
The study included a detailed examination of the crack resistance of heavy concrete and foam concrete that were not subjected to autoclave curing. An important aspect of this study was the use of polypropylene fiber as a reinforcing material, which made it possible to identify differences in the characteristics between reinforced and unreinforced samples. The purpose of the work was to evaluate the mechanical properties of the materials under study, as well as their behavior during destruction. For this purpose, the criteria of fracture mechanics were used, which made it possible to establish not only the strength and deformation characteristics, but also the force and energy indicators of crack resistance. The experimental results showed that the addition of polypropylene fiber significantly improves the strength characteristics of both heavy concrete and foam concrete. This improvement was especially noticeable in the case of foam concrete, which, due to reinforcement, demonstrated increased crack resistance. This is due to the fact that polypropylene fiber promotes a more uniform distribution of stress in the material, which in turn reduces the likelihood of cracking and improves resistance to destruction. In addition, the study confirmed that the use of polypropylene fiber not only increases strength, but also improves the durability of concrete, making them more suitable for use in construction, especially in conditions where materials are subject to significant mechanical loads and adverse environmental factors.
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Heat transfer from a cylindrical heater to a medium with variable thermophysical characteristics and heat source power

https://doi.org/10.58224/2618-7183-2024-7-6-8
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The formulation and solution of the problem of non-stationary thermal conductivity in a composite material with variable thermophysical characteristics are considered. Density, heat capacity, thermal conductivity, as well as the power of the heat source due to the hydration reactions of the binder components change during the concrete hardening process. The heat transfer problem is formulated for the general case when there are no calculation formulas for thermophysical transfer coefficients. The “microprocess method” was used to calculate the dynamics of the temperature field. According to this method, the space from the outer surface of the heater is modeled by a system of successively located “rings”. When moving from the previous “ring” to the next one, the charge in the transfer coefficients and the power of the volumetric heat source were taken into account. At the same time, the initial and boundary conditions were corrected. The boundary value problems are formulated in the form of a differential equation of non-stationary heat transfer with an arbitrary initial distribution of transfer potentials, Dirichlet boundary conditions, and a heat source in the form Po=f(Fo).The obtained solutions are analyzed for some particular cases. Prospects for further theoretical and experimental research are determined.
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Influence of corn cob ash additive on the structure and properties of cement concrete

https://doi.org/10.58224/2618-7183-2024-7-3-2
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Abstract
In accordance with the Sustainable Development Goals (SDGs) concept, there is a need to find technologies that would help make concrete production less energy intensive and more environmentally friendly. One technology involves substituting some mineral components in concrete with rapidly renewable plant-based alternatives. This study aims to establish the essential patterns among the concrete composition, micro-structure, and properties of cementitious composites modified with corn waste. Additionally, it seeks to explore the potential for producing high-quality composites using this waste material. To assess the effectiveness of this kind of waste, the strength of the cement-sand mortar, several characteristics like compressive strength, flexural durability and water absorption of hardened concrete were studied. It is established that introducing corn cob ash (CCA) to substitute a part of the cement up to 16% is justified and allows to obtain mortar and concrete with enhanced properties. CCA has a beneficial impact on the properties of Cement Sand Mortar (CSM) when replacing cement by no more than 15%. The maximum effect was achieved at 10% CCA, and the rise of compressive and flexural strength were 6.06% and 6.32%. In concrete with a CCA amount of 8%, the most impressive growth of compressive strength was 7.14%, and the lowest value of water absorption, which is 10.31% lower compared to the ordinary composition. Including CCA reduces the properties like workability, density of concrete mixtures, and the hardened composite density. The scientific results obtained prove the possibility of using CCA as an effective mineral pozzolanic additive that improves the properties of concrete.
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Processing of nonlinear concrete creep curves using nonlinear optimization methods

https://doi.org/10.58224/2618-7183-2024-7-1-2
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Abstract
The article proposes a method for determining the rheological parameters of concrete based on creep curves at various stress levels using the theory of V.M. Bondarenko. Using the proposed methodology, the experimental data presented in the work of A.V. Yashin is processed. The problem of searching for rheological parameters is posed as a nonlinear optimization problem. The sum of squared deviations of the experimental values of creep strains from the theoretical ones is minimized. The interior point method is used as a nonlinear optimization method. Four different expressions for the creep measure are considered, including the creep measure by N.Kh. Harutyunyan, creep measure by A.G. Tamrazyan, a creep measure in the form of a sum of two exponentials, and McHenry’s creep measure. It has been shown that the best agreement with experimental data is provided by the McHenry’s creep measure. An expression has been selected for the nonlinearity function, which describes the nonlinear relationship between stresses and creep strains. It is shown that the instantaneous nonlinearity of deformation and the nonlinearity that manifests itself over time cannot be described by a single function.
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Structure and properties of modified shungite concrete during electrode heating

https://doi.org/10.58224/2618-7183-2023-6-6-1
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Concrete composition modifying by different electrically conductive components is one of less laborious but relatively effective methods between wide variety of electrode concrete heating effectiveness improvement methods. The purpose of this study is investigation of special aspects of cement systems modified by powdered shungite (Ssp 400 m2/kg) in combination with active mineral and plasticizing admixtures that harden under electrode heating at below zero temperatures. By the method of differential thermal analysis anomaly of exothermic reaction of cement stone specimens was discovered, that is due to formation of hydrated calcium silicate С2SH (A) discovered by the method of quantitative XRDA, and is verified by results received from scanning electron microscopy method, which among other factors provides higher strength and low permeability to these composites. Stabil-ity of cement systems modified by shungite and curing under electrode heating has been proved.
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