Civil Engineering Journal
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2007 research outputs found
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Numerical Investigation of Oil Shale in Asphalt for Road Surfacing Using COMSOL Multiphysics
No full textThis study introduces a sustainable, performance-driven approach to asphalt pavement design by incorporating oil shale-modified bitumen into hot-mix asphalt (HMA) and evaluating four performance grade (PG) binders. The research provides a comprehensive evaluation of mechanical and rheological behaviors across varying thermal and loading conditions. A key innovation lies in the integration of oil shale, which significantly reduces voids in mineral aggregates (VMA), leading to improved aggregate contact and material densification. This microstructural enhancement directly translates into increased dynamic modulus (E*) and shear modulus (G*), reinforcing the mixture’s stiffness and deformation resistance without the need for costly chemical additives. The results demonstrate that oil shale improves the load-bearing capacity of asphalt mixtures, particularly under high-frequency loading where elastic responses are favored. Moreover, the optimized mixtures maintain a favorable balance between rigidity and flexibility, typically prone to compressive deformation, and benefit from oil shale integration through enhanced stress dissipation characteristics. The study offers a novel pathway for valorizing oil shale, a locally abundant, underutilized material, as a functional asphalt modifier. The findings validate its potential to extend pavement service life, optimize stiffness–temperature profiles, and reduce dependency on virgin bitumen. These results position oil shale as a viable, cost-effective, and environmentally advantageous additive for future-proof pavement engineering
Reliability Design of a New Masonry Bridge: An Approach Based on RBDO and Rigid Block Analysis
No full textThe objective of this study is to establish a reliability-based design framework for new masonry arch bridges, providing a rational alternative to the empirical rules that traditionally governed their construction. The proposed methodology integrates Reliability-Based Design Optimization (RBDO) with the rigid block limit analysis method to optimize key geometric parameters under uncertain loading conditions. The probabilistic formulation incorporates the variability of geometric and load parameters, which are identified as the dominant sources of uncertainty during the design phase of new masonry bridges. Two RBDO strategies are employed: the Performance Measure Approach (PMA) and Sequential Optimization with Reliability Assessment (SORA), both coupled with a linear programming formulation of equilibrium and yield constraints. The approach is applied to the reconstruction of the historical Dar El Makina bridge in Fes, Morocco, to determine the optimal geometric configuration that satisfies target reliability requirements. The results indicate that the optimized design achieves a 27% reduction in arch thickness and a 13% increase in rise compared to the existing structure, leading to a safer and more material-efficient configuration. Compared with classical empirical formulas, the proposed approach provides a rational and quantitative basis for the design of masonry bridges, combining structural safety, material efficiency, and heritage preservation
A Multivariate Analysis of Smartphone Use Behavior Among Motorcyclists at Urban Intersections
No full textThe increasing use of smartphones while riding motorcycles poses significant safety risks, particularly in urban environments of middle-income countries with high motorcycle usage. Despite growing global concerns, limited research has examined the combined influence of individual, behavioral, and environmental factors on smartphone use among motorcyclists at signalized intersections. This study investigates the determinants of smartphone use behavior—both hand-held and hands-free—among motorcyclists in Khon Kaen City, Thailand. A total of 31,648 riders were observed using video surveillance across eight intersections with varying geometric and land-use characteristics. As part of the methodological approach, binary and multinomial logistic regression models were applied to analyze factors associated with smartphone use. The results show that 7.7% of motorcyclists used smartphones while riding, with 6.2% using hand-held and 1.5% using hands-free modes. Significant predictors included riding alone, being male, not wearing a helmet, riding during nighttime or weekdays, and stopping at red lights. Delivery riders were particularly likely to use smartphones, especially in hands-free mode. These findings highlight the multifaceted nature of distracted riding and suggest the need for comprehensive, context-sensitive policy interventions. The insights gained from this study can inform strategic planning and safety enforcement not only in Thailand but also in other urban areas across middle-income countries where motorcycles remain a dominant mode of transport
Evaluation of Fresh Properties of Cement Pastes: Part II-Modelling via Central Composite Design
No full textThis study investigates how variations in constituent materials affect the fresh properties of cement-based pastes using a statistically driven experimental approach. A Central Composite Design (CCD) was implemented to examine the influence of three key input parameters: water-to-cement ratio (w/c), superplasticizer-to-powder ratio (Sp/p), and water-to-powder ratio (w/p). Fifteen mix compositions were produced and tested using the mini-slump test and Marsh funnel flow time, both immediately after mixing and after 60 minutes. Response Surface Methodology (RSM) was applied to develop predictive models for each property. The results showed that the water-to-powder ratio was the most influential factor on workability, followed by the superplasticizer-to-powder ratio. The statistical models successfully captured main, interaction, and quadratic effects, enabling accurate prediction of flow and time measurements. These models were further used to optimize mix compositions according to targeted fresh-state performance. Compared with conventional one-variable-at-a-time approaches, the CCD method substantially reduces the number of tests required while providing deeper analytical insights. The proposed methodology improves the understanding of complex interactions among mix parameters and supports the efficient design of cement-based materials for performance-critical applications
Spatial Prediction of Soil Index Properties Using GIS and Empirical Bayesian Kriging
No full textThe purpose of this study is to assess the possible use of Empirical Bayesian Kriging (EBK) combined with Geographic Information Systems (GIS) to map and analyze geotechnical index properties in Thi Qar Province in southern Iraq. The aim of this objective is to describe the spatial variability of soil limits of the consistency and define areas with expansive soils, which may influence infrastructure development. Data on 550 boreholes and 862 observations per soil property, including Liquid Limit (LL), Plastic Limit (PL), and Plasticity Index (PI), were analyzed. To test the predictive accuracy of the EBK model and thus assure its statistical validation, RMSE, MSD, RMSSD, and correlation coefficients were used to test the model. The findings show that the LL was between 32% and 69%, the PL between 9% and 36%, and the PI between 1% and 39%, with most of the soils being CL and CH, which signifies moderate-high plasticity. The results indicate that there are good spatial patterns, and plasticity is more dense in the north and central areas. The originality of this work is the use of EBK to create detailed digital soil maps of a semi-arid area, where the available geotechnical data is sparse, which is used to form a dependable base to support engineering design, land-use planning, and regional geotechnical modelling
Effect of Cu and SiO₂ on a Remelted-Recycled Piston Alloy Under Vertical Centrifugal Casting Conditions
No full textFunctionally graded aluminum matrices produced by means of centrifugal casting offer a route to location-specific properties, yet sustainable feedstocks and dual-density reinforcements are less well explored. In this work, we evaluate vertical centrifugal casting (VCC) of a remelted, recycled piston alloy reinforced with silica (SiO₂) and copper (Cu) particulates selected for their contrasting densities relative to the matrix. Castings were produced at 1000 rpm for 5 minutes using a 500 °C preheated mold and an 800 °C pour temperature. Cu was added at 1–4 wt.% and SiO₂ was added at 0–9 wt.%. Bulk density/porosity measurements, Vickers hardness testing, and optical/SEM microstructural analysis were employed to characterize the resulting gradients. The density increased with the radial distance from the rotation axis, accompanied by a monotonic decrease in porosity, consistent with centrifugal separation. Microstructurally, SiO₂ concentrated toward the inner region near the rotation center; in comparison, Cu was enriched at the outer periphery. Correspondingly, hardness exhibited a spatial gradient: SiO₂-reinforced zones were hardest near the inner region, whereas Cu-rich outer zones were hardest at the external rim. These results demonstrate that VCC of a recycled Al–Si feedstock can be used to reliably tailor its microstructure and properties through density-driven particle segregation, enabling controllable, bidirectional functional grading using environmentally friendly starting materials
Mechanical Properties and Structural Behavior of Sustainable Ferrock Concrete for Green Construction Applications
No full textThis study aims to develop a sustainable alternative to Ordinary Portland Cement (OPC) by investigating the mechanical and structural properties of Ferrock concrete, an iron carbonate-based binder composed largely of industrial by-products. An experimental program was conducted, testing over 114 concrete cubes, 18 cylinders, and 6 full-scale reinforced concrete beams with Ferrock replacing OPC at 5%, 10%, 15%, 20%, and 25% by weight. The results demonstrate that a 15% replacement ratio yields a 25% increase in 28-day compressive strength, while splitting tensile strength improves consistently with Ferrock content. Most notably, reinforced beams with 20% Ferrock exhibited up to a 33% increase in flexural capacity, with failure modes shifting toward more ductile behavior and experimental capacities exceeding predictions from ACI 318, CSA A23.3, and Eurocode 2 by up to 62%. This research confirms that Ferrock is not only a carbon-negative material but also a technically superior partial replacement for OPC, offering enhanced strength, ductility, and structural performance for green construction applications
Numerical Analysis of Lateral and Vertical Deformation of the Embedded Length of Monopile in a Sandy Soil
No full textA monopile is a large-diameter steel cylinder partially inserted into seabeds; thus, it is one of the major selections of offshore wind and tower foundations. This study aimed to investigate the effect of monopile diameter, thickness, and ratio of soil embedded depth to height of water on the lateral and vertical displacements of the embedded part of the pile. In the study, the monopile was subjected to a lateral displacement equivalent to 10% of the pile diameter at the pile head in order to examine the lateral and vertical deformations of the embedded length of the pile. The three-dimensional finite element software PLAXIS 3D was used to simulate the study. The soil layer used consisted of one layer of medium-dense sandy soil. The study involved investigating the location along the embedded depths that exhibit zero lateral and vertical displacements; that location was found to depend on the monopile diameter, wall thickness, and ratio of embedded depth to water height. The depth of zero lateral displacement was found to increase as pile rigidity and wall thickness increase. The study shows that increasing the L/H ratio on the embedded depth of zero lateral displacement, LHzero, diminishes with increasing monopile diameter for the same wall thickness. Also, the variation of lateral displacement along pile length demonstrates a constant trend behavior regardless of pile thicknesses and diameters, but the depth of zero lateral displacement, LHzero, was varied. Furthermore, the monopile diameter effect on the vertical displacement shows that as the monopile diameter increases, the depth of zero vertical displacement decreases. Also, as L/H decreased, the depth of zero vertical displacement declined
Development of Fiber-Reinforced Concrete for Road Pavement Surfaces Enhanced with Complex Additives
No full textThis study aims to develop high-performance road pavement concrete capable of withstanding increasing traffic loads while ensuring long service life and reduced maintenance needs. The research focuses on enhancing the mechanical characteristics of fine-grained concrete used in the outer pavement layer through the incorporation of complex additives and dispersed reinforcement. The methodology involved modifying the concrete matrix using the superplasticizer Melflux 5581F, microsilica MK-85, and varying percentages of basalt fibers introduced through different preparation techniques. Mechanical testing, including compressive and flexural strength evaluations, was performed on 40×40×160 mm specimens cured under standard conditions and tested at 7 and 28 days. The analysis showed that Melflux 5581F significantly enhanced strength without increasing cement content, while MK-85 further improved compressive and flexural strengths by up to 50.59% and 46.28%, respectively. The addition of basalt fibers increased flexural strength, with optimal formulations achieving 89.49 MPa in compressive strength and 11.14 MPa in flexural strength. These findings demonstrate that the combined use of chemical, mineral, and fiber additives, together with appropriate technological approaches, substantially improves the performance of road concrete. The proposed modified concrete exhibits enhanced durability, offering a promising solution for extending pavement service life and reducing repair frequency
Comparison Between the Calcium-Based Stabilizer and Non-Organic Agents on the Stabilization of Contaminated Soil
No full textThis study was conducted to investigate the properties of nickel- and copper-contaminated soil and to determine the potential use of calcium stabilizers and inorganic agents as soil improvement methods. The soil was classified as loamy sand (SM) with a low plasticity index (PI = 4%), medium permeability, and high silica content (>33%). X-ray fluorescence (XRF) testing revealed nickel oxide concentrations of 1.5% and copper oxide concentrations of 2.5% in the soil. Nickel and copper contamination based on added nitrate salts was estimated at 1,500 ppm and 2,500 ppm, respectively. X-ray Diffraction (XRD) results showed that quartz and kaolinite were the most abundant, and the contaminants were likely present in an amorphous or surface-adsorbed manner. Unconfined Compressive Strength (UCS) results indicated a significant improvement in compressive strength: from 96 kPa (2% cement, 7 days) to over 12,445 kPa (7% cement, 28 days). The 20% fly ash yielded a strength of 934.5 kPa after 28 days, due to natural pozzolanic reaction and mineral adsorption. Overall, strength improved, and stability was achieved with increased curing time. These results demonstrate that cement and fly ash improved both the mechanical properties and environmental performance of sandy soils contaminated with heavy metals. However, the accelerated strength improvement for cement was significantly greater (over 12,445 kPa) than for fly ash (934.5 kPa, with 20% fly ash) after 28 days of curing. This result suggests that cement-based materials have superior load-bearing performance in applications, but fly ash may be less effective and potentially more environmentally friendly