Stel’makh S.A.

Candidate of Engineering Sciences (Ph.D.), Associate Professor, Head of the Department Construction of Unique Buildings and Structures, Don State Technical University

Variatropic concrete compressive strength prediction under freeze-thaw conditions using machine learning methods

https://doi.org/10.58224/2618-7183-2025-8-6-10
Аннотация
The introduction of intelligent models, in particular using machine learning methods, opens up prospects for the development of the construction industry. The construction of regression models for predicting the physical and mechanical properties of various types of building materials is a promising and relevant area. The use of such models makes it possible to take into account complex and multifactorial dependencies, while minimizing the influence of the human factor. In the present study, variatropic concrete B30, obtained by centrifugation, acts as the test material. The dataset (351 objects) was assembled during laboratory studies to study the effect of freeze-thaw cycles on the strength characteristics of the material. Using the computer vision method based on the convolutional neural network U-Net, the damage on each of the concrete layers was assessed on different cycles. 4 machine learning models for predicting compressive strength were trained and tested on the collected dataset: Ridge Regression (RR), Random Forest (RF), CatBoost (CB) and Multi-layer Perceptron (MLP). The hyperparameters of the models were optimized using Grid Search + 3-fold cross-validation. As a result of testing the algorithms on a test sample, the best quality metrics were demonstrated by tree architectures: MAE for RF and CB 0.09 and 0.17 MPa, respectively, R2 = 0.99. The results are supplemented by SHAP analysis. The results obtained are a useful tool for optimizing the composition of variatropic concretes used under aggressive conditions.
PDF

Eco-Friendly Foam Concrete with Improved Physical and Mechanical Properties, Modified with Fly Ash and Reinforced with Coconut Fibers

https://doi.org/10.58224/2618-7183-2025-8-1-1
Аннотация
The development of new types of environmentally friendly and cost-effective building materials is currently a relevant topic and is actively developing throughout the world. In modern construction materials science, the most popular direction is the development of new concrete compositions using waste of various origins. The objective of this study is to develop new compositions of foam concrete using local waste from the fuel and energy complex and plant natural fibers. To determine the optimal amount of the modifying additive fly ash (FA), 7 experimental concrete compositions with different percentages of cement replacement by FA were made. The content was established as optimal. Foam concrete with 15% FA has the lowest density of 1075 kg/m3 and a minimum thermal conductivity coefficient of 0.248 W/m × °C, as well as increases in compressive and bending strength of 23.3% and 21.7%, respectively. The effect of coconut fiber (CF) was assessed on the composition of foam concrete modified with the optimal amount of FA 15%. The optimal dosage of CF was 0.6%. As a result of FA modification and CF dispersed reinforcement, a complex effect was obtained. The increase in compressive and bending strength was 30.14% and 72.83%, respectively, compared to conventional foam concrete. The density and thermal conductivity coefficient decreased by 9.8% and 8.34%, respectively. The results obtained during the experimental studies prove the effectiveness of the proposed formulation solutions and allow obtaining an energy-efficient foam concrete composite with improved characteristics.
PDF