2031 research outputs found
Sort by
Analysis of Rock Quarry Sand and Bottom Ash Reinforced by Randomly Distributed PET Rings
Get PDFThe study presented deals with determining the shear strength and deformation properties of coarse-grained waste materials, such as rock quarry sand (RQS) and bottom ash (BA), which can be improved using randomly distributed reinforcements made of polyethylene terephthalate (PET) rings. The tests were executed for a degree of reinforcement n, i.e., a ratio of a PET ring weight to the weight of the dry parent materials, which equals about n = 0.25%, 0.5%, and 1.0% in the case of RQS, and n = 0.5%, 1.0%, and 1.5% in the case of BA. The results showed that the most effective improvement in the shear strength properties can be achieved for n = 0.25 - 0.5% in the case of RQS and n = 0.5 - 1.0 % in the case of BA. Reinforcing RQS by n = 1.0% or BA by n = 1.5% led to a significant decrease in the 1D deformation modulus. The positive effect of randomly distributed PET ring reinforcements on the properties of RQS and BA materials was also demonstrated using physical modeling. An embankment model made of RQS and reinforced by PET rings (n = 0.25 %) can carry up to a 2.8 times greater load than an embankment model made of the parent RQS. An embankment model made of BA with PET rings (n = 0.5%) can carry up to a 2.3 times greater load than an embankment model made of the parent BA. Doi: 10.28991/CEJ-2025-011-05-06 Full Text: PD
Statistical Estimation of Reliability Values for Large-Panel Buildings Based on Passportization Results
Get PDFIn 2017-2018 and 2023-2024, a full passportization of the housing stock of apartment buildings in the city of Almaty (Republic of Kazakhstan) was carried out for the first time. The database includes 2666 multi-story large-panel buildings of different numbers of stories, from 2 to 9 floors. The aim of this study is to assess the reliability of standard-series large-panel buildings based on previous experimental research and passportization results, as well as to evaluate their seismic resistance and reliability using passportization data. The latest earthquakes in Almaty have allowed for refinements in seismic impact models. Therefore, the reliability assessment has been conducted considering this information using the Monte Carlo method. The technical condition of large-panel buildings has been assessed. The earthquake recurrence is taken into account according to the current "Map of seismic zoning of the Republic of Kazakhstan". Reliability value for the whole group of large-panel buildings has been obtained. It is revealed that large-panel buildings with the first flexible or brick floor are not earthquake-resistant. For the first time, the theoretical analysis of reliability and failure values for 2 types of large-panel buildings with the use of experimental data is performed. Regional peculiarities of seismic impact for Almaty City are taken into account. The results of reliability and failure values estimations are used for practical recommendations on risk reduction and expected losses in case of possible earthquakes. The novelty lies in the reliability and failure assessment based on the large-scale passportization of the housing stock in Almaty. It is established that the main types of large-panel buildings are earthquake-resistant. Estimates of earthquake resistance according to the results of passportization and the results of reliability calculations coincided. It is proposed to reinforce large-panel buildings with the first flexible or brick floor (33 buildings). The method of reinforcement should be determined by special studies. Doi: 10.28991/CEJ-2025-011-05-019 Full Text: PD
Innovative Advancements in Construction: The Sustainable Promise of Aerated Concrete Incorporating Fly Ash and River Sand
No full textAerated Concrete, or lightweight concrete, is primarily used in construction work for non-load-bearing structures and is typically produced with cement as a primary binding material. Cement production accounts for 7 to 8% of the environmental CO2 emissions. Furthermore, the dumping of industrial waste and the consumption of aggregates disrupt the environment and ecosystem. This research aims at developing sustainable AC by partially substituting cement with FA and hill sand with IRS while maintaining the fundamental properties of aerated concrete. The study was conducted to investigate the physical and chemical properties of the materials and the physical and mechanical properties of aerated concrete. Variations of fly ash, i.e., 10%-70%, were incorporated as a CRM to get optimum FA usage in terms of density and compressive strength. Optimum FA was incorporated as CRM and IRS as sand replacement, used in four variations, i.e., 10% - 25%. Specimens were cured using the conventional curing method and autoclaving for NAAC and AAC, considering both manufacturing processes, CO2 emissions and time limitations in respective curing methods. Conventional curing was performed at 7, 14, and 28 days, while autoclaving was performed at various pressures, i.e., 0.5 bar, 1 bar, and 1.5 bar. The optimum compressive strength of AAC and NAAC was achieved when 20% of the IRS and 50% of FA were replaced with hill sand and cement, respectively, for both AAC and NAAC. Additionally, approximately 32% and 39.3% of CO2 emissions were reduced with 50% FA and 20% river sand replacement with cement for AAC and NAAC specimens. Although AAC demonstrated slightly lower water absorption due to densification through autoclaving, NAAC performed satisfactorily in offering a more cost-effective and energy-efficient alternative
Factors Influencing Performance, Durability, and Environmental Impact of Hydraulic Structures Using Waste Composite
Get PDFThis research explores the crucial elements influencing the impact of hydraulic structures constructed using waste-based composites, emphasizing sustainable material integration in infrastructure. A conceptual model comprising five constructs—Design and Structural Performance, Durability, Environmental Impact, Material Characteristics, and Waste Composites—was established and analyzed utilizing Partial Least Squares Structural Equation Modeling (PLS-SEM). Data was combined from 260 construction professionals across the key construction industry. G*Power analysis confirmed the lowest required sample size of 150; the larger sample enhanced statistical robustness. All constructs demonstrated strong reliability, convergent validity, and discriminant validity, with significant path relationships supporting the proposed hypotheses. Material Characteristics (β = 0.568) and Environmental Impact (β = 0.353) emerged as the most influential predictors of hydraulic structure performance. Empirical correlation, cross-loadings, HTMT, and VIF analyses confirmed model stability and construct independence. The results provide precious information for engineers, construction managers, and policymakers aiming to optimize structural integrity and environmental sustainability through the adoption of recycled composite materials. This research contributes to theoretical advancements in sustainable construction and provides practical implications for material selection, policy formulation, and infrastructure design. The study recommends future research on real-time performance monitoring, expanded geographic validation, and inclusion of cost-efficiency and technological integration variables
A Comparative Study of PCA and KPCA for Groundwater Quality Index Estimation
Get PDFGroundwater quality assessment is crucial for ensuring human welfare and promoting sustainable economic development. This study evaluates the effectiveness of linear Principal Component Analysis (PCA) and nonlinear Kernel PCA (KPCA) in developing a reliable Groundwater Quality Index (GWQI) for Qena, Egypt. Using ten hydrochemical parameters from seventy-three groundwater samples, we compare the performance of four kernel functions within the KPCA framework. The PCA-based GWQI classified 71.0% of samples as suitable for irrigation, closely aligning with the Wilcox Diagram classification (76.7%). In contrast, KPCA with linear, polynomial, sigmoid, and radial basis function kernels yielded suitability rates of 58.9%, 52.1%, 63.0%, and 58.9%, respectively. These values are consistent with USSL (53.4%) and Na% (53.4%) classifications. Notably, the sigmoid kernel in KPCA demonstrated stronger correlations with Key hydrochemical parameters, effectively capturing nonlinear data structures. These findings underscore the importance of accounting for nonlinearity in groundwater quality assessment and demonstrate the potential of KPCA to improve GWQI accuracy. This comparative analysis highlights KPCA’s superiority over PCA for nonlinear datasets, providing enhanced tools for groundwater management and more reliable quality evaluations
Impact-Echo Method on Short Cylinders: A Numerical and Experimental Investigation
Get PDFDespite the widespread use of Ultrasonic Pulse Velocity (UPV) to estimate the dynamic properties of materials, the accuracy of its results for concrete and rock cylinders, even though it does not depend on cylinder slenderness, is directly affected by the a priori assumption of a specific value of the Poisson's ratio ( ), which can lead to errors of up to 50% in the calculation of the dynamic modulus of elasticity (Ed). In contrast, the Impact Echo (IE) method allows the calculation of Ed without the need-to-know Poisson’s ratio, with an error of approximately 2%, but its results are affected not only by the slenderness ratio (L/D) but also by the inertia effect and the mass of the sensor. In this study, both UPV and IE—longitudinal and torsional—tests were carried out on cylindrical steel and aluminium specimens for six different slenderness values and L/D values ranging from 1-5. The experimental results fully confirm the authors’ proposed shape correction factor (SCF). A numerical analysis of short cylinders is conducted to examine how the mass of the accelerometer used on the IE affects the results. Specifically, aluminium and steel specimens with six different slenderness values were simulated via the finite element method (FEM) via experimental evaluation. Inertia and mass interactions significantly affect the results. Two new correction factors were proposed for steel and aluminium cylinders to address this issue, and three different combinations of NDTs were tested to find that the dynamic properties are very sensitive to these parameters. Poisson’s ratio has been accurately calculated for steel and aluminium cylinders and can be calculated for concrete and rock cores by applying the proposed correction factors
Leaching-Permeability Behavior of Collapsible Gypseous Soils Treated with Nano-Titanium Dioxide
No full textAs a result of the limited studies that have been conducted on the utilization of nano titanium dioxide as a nanomaterial for stabilizing gypseous soils in geotechnical works, this study is directed to predict the changes in the coefficient of permeability k, the leaching strain, the total dissolved salts TDS, and the pH values with the changes in the percentages of nano titanium dioxide NTD. The gypseous soil samples were obtained from three sites located north of Baghdad, the capital of Iraq, with different gypsum contents of about 34%, 50%, and 60%. Tests have identified the mechanical and physical characteristics of the studied gypseous soils. In addition, oedometer permeability leaching tests were conducted using an oedometer cell apparatus. The results of the tested gypseous soils presented a significant effect of NTD on reducing the coefficient of permeability k and cost-effectively, especially at 0.3 and 0.5% for the three tested soils. For S1 tested soil, the reduction percentages of the k values were 79.02% and 80.0% when treated with 0.3% and 0.5% of NTD, respectively. While for S2 tested gypseous soil, the reduction percentages were 75.9% and 79.1%, and 66.04% and 73.6% for S3 tested gypseous soil when treated with 0.3% and 0.5% of NTD, respectively. The treated gypseous soils are exposed to less gypsum dissolution, as the NTD material forms an impermeable layer to prevent direct contact between water and gypsum. This reduces gypsum dissolution and, thus, reduces leaching strain. For S1 tested soil, the percentage of reduction of the leaching strain was 90.5%, while for S2 and S3 tested soils, it was 91.2% and 89.9%, respectively, when 0.3% of NTD was applied. As the percentage of the NTD increased for S1, S2, and S3, the pH values decreased due to decreased TDS in the leached water, and it is clear that 0.3% of NTD gives a reliable pH value for the three tested soils. Considering these results, it appears that even small amounts of nano titanium dioxide have the potential to be an effective agent for reducing permeability and stabilizing collapsible gypseous soils in civil engineering projects, compared with other nano or traditional materials
Geodynamic Processes Monitoring of Subway Infrastructure Using Geodetic and Remote Sensing Methods
No full textThis article examines the development of a methodology for monitoring geodynamic processes during the construction of the Almaty metro using an integrated approach that incorporates geodetic methods, laser scanning, and aerospace technologies. The study aims to enhance the safety of underground structures in the context of complex engineering-geological conditions and high-density urban environments. Monitoring was conducted at the "Saryarka" and "Bauyrzhan Momyshuly" stations, employing underground polygonometry, aerial surveys with unmanned aerial vehicles (DJI Mavic 3 multispectral), laser scanning (Faro Focus 3D X), and finite element numerical modeling (PHASE 2, AutoCAD Civil 3D). The geodetic work covered a 3201-meter section with the installation of 34 benchmarks, ensuring a relative measurement error of no more than 1:30,000. Laser scanning achieved an average point cloud density of 7 mm, enabling the creation of precise 3D tunnel models, identification of deviations from the design axis, and determination of critical stress zones. The study revealed that at a depth of 32.28 m, the maximum vertical stress reached 11.2 MPa, and horizontal stress was 2.7 MPa. At a depth of 19.58 m, the vertical stress reached 10.5 MPa, while the horizontal stress was 2.47 MPa. The maximum concentration of stresses in critical zones reached 20 MPa. The use of UAVs and aerospace technologies facilitated the creation of a highly accurate digital terrain model and the identification of potential deformation zones. The findings confirm the necessity of regular monitoring in dense urban and seismically active areas and demonstrate the potential of integrating modern technologies to improve the precision and efficiency of geodynamic assessments. The proposed methodology can be applied not only to metro construction but also to other underground structures, including mining industry facilities, both in Kazakhstan and internationally
Behavior of Full-Scale One-Way Semi-Precast Concrete Slabs with Varying Sizes and Shear Connectors
Get PDFThis study investigates the structural performance of semi-precast concrete slabs (SPCSs), an innovative hybrid construction system that integrates factory-produced precast concrete units with a cast-in-place (CIP) concrete topping to create a composite structural element. This system offers notable advantages in terms of construction acceleration, improved quality control, and reduced labor requirements, as the precast unit serves as both a load-bearing component and a permanent formwork. To evaluate the structural behavior of the SPCSs, an experimental program was conducted on seven full-scale, one-way slab specimens with varying span lengths (4.75 m and 6.0 m), precast unit thicknesses (80 mm and 100 mm), and shear connector geometries (rectangular and triangular). A control slab without shear connectors was also tested to establish a baseline for comparison. The results demonstrated that the inclusion of shear connectors significantly enhanced structural performance. Specifically, the ultimate load capacity increased by 186.4%, and the cracking load increased by 220% compared to the control specimen. Rectangular connectors proved more effective than triangular ones in minimizing interface slip and enhancing ductility. The initial stiffness increased by 163.95%, while the energy dissipation capacity improved by 411.35%. Although variations in span length and topping thickness had relatively minor effects, the presence and geometry of shear connectors played a decisive role in ensuring effective composite action. All reinforced slabs exhibited flexural failure modes, indicating strong bonding and interaction between the precast and cast-in-place (CIP) concrete layers, whereas the control slab experienced premature failure due to interlayer debonding. Theoretical equations based on ACI 318-19 were used to estimate the nominal flexural capacities of the hybrid SPCS slabs, showing reliable agreement with the experimental results. These findings demonstrated the importance of shear connector design in maximizing the load-bearing capacity, ductility, and structural stiffness of SPCS systems under both service and extreme loading conditions
Probabilistic Reliability Framework for Nanomaterial-Stabilized Soft Clays: Model Calibration and Geometry Effects
No full textThe stabilization of soft clay soils using nanomaterials offers a promising alternative to conventional additives such as lime and cement, yet most studies remain deterministic, neglecting soil variability and treatment geometry. This study proposes an experimental–probabilistic framework combining triaxial shear and model footing tests with Monte Carlo simulations to evaluate nano-SiO₂, nano-MgO, and nano-clay. Dosages from 1% to 5% were examined, and 3% was selected as optimal based on strength improvement and economic feasibility. Classical bearing capacity models (Terzaghi, Meyerhof, Hansen) were applied and calibrated using regression factors, with input variability modeled under normal and lognormal distributions. Results indicate that nano-MgO achieved the lowest probability of failure ( < 0.1), nano-SiO₂ showed intermediate but geometry-sensitive performance, and nano-clay provided limited reliability. The calibrated Terzaghi model (R² = 0.742) yielded the most consistent predictions. Enlarged treatment zones improved stress redistribution and reduced failure risk. The study also identifies priorities for future work: durability under cyclic loading, hybrid nanomaterial blends (e.g., SiO₂ + MgO), and scalability for large infrastructure projects. Collectively, the findings establish a reliability-based framework that integrates probabilistic modeling, calibration, and material geometry optimization for resilient geotechnical design