Journal of Materials and Engineering Structures
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316 research outputs found
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Temperature-wind interactions and implications for civil engineering in the Congolese tropics
Full text linkTemperature has a strong influence on wind modelling, acting on pressure gradients and convective movements, which directly affect the loads on structures. In Central Africa, this climatic interaction must be taken into account to ensure the stability and durability of structures. This study analyzes the correlation between maximum temperatures and maximum wind speeds in several Congolese localities, based on data from meteorological stations. The approach combines descriptive statistics, visualizations (whisker boxes, histograms), simple linear regressions as well as the examination of possible transformations to optimize the quality of the fit, and residual analysis. The results show considerable regional variability: some cities (e.g. Pointe-Noire) show significant correlations, while others (Dolisie, Makoua) reveal weak or inverse relationships. These differences can be explained by geographical or microclimatic factors. The low coefficients of determination highlight the limitations of linear models, underlining the interest of non-linear or artificial intelligence-based methods to improve wind speed prediction. In terms of civil engineering, these results call for the design of infrastructures adapted to increasing climatic hazards
To study the metallurgical and mechanical properties of SMAW dissimilar weld joints between AISI 1020 carbon steel and AISI 410 martensitic stainless steel using three distinct fillers
Full text linkThis study investigates the metallurgical and mechanical properties of dissimilar weld joints between AISI 1020 carbon steel and AISI 410 martensitic stainless steel, fabricated using three distinct filler metals: austenitic AWS 309L and AWS 316L, and martensitic AWS 410. The weldments were comprehensively evaluated through tensile testing, Charpy V-notch impact testing, microhardness profiling, and microstructural analysis to determine the optimal consumable for this application. The results demonstrated the superior performance of the AWS 309L filler, which yielded the highest ultimate tensile strength (410.5 MPa) and greatest impact toughness (24.2 J). This enhanced performance was attributed to the formation of a desirable duplex microstructure of austenite and distributed delta ferrite in the fusion zone. Conversely, the weldment made with the matching AWS 410 filler, despite exhibiting the highest hardness (peak 532 HV), showed low impact toughness (18.7 J) and moderate tensile strength (371.3 MPa), indicating a brittle, untempered martensitic structure susceptible to failure. The AWS 316L filler produced the lowest mechanical properties overall. The findings conclude that AWS 309L is the most suitable filler metal, producing a robust and damage-tolerant joint, whereas the AWS 410 filler is inappropriate for this application in the as-welded condition due to its inherent brittleness
Improving the essential characteristics of Lake Chad diatomaceous earth for the ecological construction.
Full text linkIn the Lake Chad region, diatomaceous earth is the type of soil that is easily accessible, but its use for construction presents challenges due to its specific characteristics. This study aims to characterize the physico-chemical and mechanical properties of these soils after adaptive treatment, consisting to add a small amount of lime. The X-ray diffraction reveals a composition of 73% quartz, 2.3% kyanite, 21% carbon and 1.58% of other minerals. The measured pH is 8.3, indicating this diatomite soil can be stabilize. Stabilized and Compressed Earth Blocks (SCEBs) were molded using six formulations (0% of lime added, 2%, 4%, 6%, 8% and 10%) and cured in three groups (groups of 7, 14 days and 30 days). The measure of their compressive strength denotes the SCEBs without lime, after 30 days of curing, show strength of 2 MPa and the SCEBs with 10% of lime exhibit a high compressive strength of 4.27 MPa, according to several standards of Compressed Earth Blocks. Thus, the addition of lime allow for the production of quality SCEB for construction. Regarding thermal properties, experiments on SCEBs show that thermal conductivity decrease with the addition of lime, from 0.194 W/m.°C to 0.370W/m.°K, and remain widely above 0.065 W/m.°K which is good value for thermal insulation. Finally, above 4% of lime, the mass loss (0.24%) is negligible
Cool Pavement Technologies for Urban Heat Island Mitigation: A Comprehensive Review with Future Research Directions for Developing Cities
Full text linkCool pavement technologies have emerged as an effective solution to mitigate urban heat island (UHI) effects by reducing pavement surface temperatures and enhancing urban thermal comfort. This study reviews three major categories of cool pavements—reflective, evaporative, and thermal energy storage systems—based on their mechanisms, effectiveness, benefits, and limitations. Results show that reflective pavements provide the most immediate cooling performance, with temperature reductions typically ranging from 5 °C to 15 °C, depending on materials and application. In contrast, thermal energy storage systems such as hydronic pavements or thermoelectric technologies may achieve reductions of up to 20 °C. Evaporative pavements offer added value through water retention and stormwater management, although their performance is highly dependent on local climate and water availability. While these technologies offer substantial environmental and societal benefits, challenges remain in terms of long-term durability, cost, and standardization. In the context of Hanoi, Vietnam, ongoing research and pilot implementations are actively exploring light-colored asphalt, porous and water-retentive pavements, microsurfacing, and innovative materials like TiO₂-based asphalt. These initiatives reflect the growing commitment to sustainable and climate-adaptive infrastructure solutions in urban settings
A high-performance and low cost nitrogen-containing gray cast iron
Full text linkTo meet the demand for high-strength gray iron castings while lowering casting production costs, nitrogen micro alloyed gray cast iron with manganese nitride inoculant was developed, and the effects of manganese nitride addition on its microstructure, mechanical properties, and casting cost were investigated. The test results show that with different manganese nitride additions, the graphite flakes have round and blunt ends and short, thick, and slightly curved shapes; as the nitrogen content in the iron increases, the graphite forms become shorter and curved, and the pearlite content increases, which is conducive to improving the strength and hardness of gray cast iron. Excess nitrogen content in castings causes nitrogen porosity defects, which significantly degrades the material properties. The addition of alloying elements such as Cu and Sn can be reduced by adding an appropriate amount of manganese nitride to the process, and the casting cost can be reduced by 180 RMB/ton to realize low-cost production of high-performance gray cast iron
Predicting the Compressive Strength of UHPFRC Using Machine Learning and Soft Computing Models: Optimization of Fiber Content and Additives
Full text linkUltra-high-performance fiber-reinforced concrete (UHPFRC) is a relatively new material known for its superior mechanical properties, particularly its compressive strength (CS), making it suitable for advanced structural applications. Traditional experimental methods for predicting CS are time-consuming and costly. In this study, a dataset of 276 samples with 12 input parameters was compiled from existing literature to develop predictive analytical models. The input variables include cement, sand, water, superplasticizer, silica fume, fiber content, water–binder ratio, water–cement ratio, curing age, fiber aspect ratio, temperature, and fiber volume. The reported CS values range from 90 to 186 MPa. Five modeling techniques—Linear Regression (LR), Log Base Regression (LBR), Nonlinear Regression (NLR), M5P-tree, and Artificial Neural Network (ANN)—were employed to predict the compressive strength of UHPFRC. Among these models, ANN demonstrated the highest prediction accuracy across all evaluation criteria, followed by the M5P-tree model. Residual error analysis confirmed that the ANN produced the lowest prediction error. Sensitivity analysis revealed that temperature, curing age, and superplasticizer content significantly influence CS. Optimization results indicated that a fiber content between 2.05% and 2.09% yields maximum compressive strength. These findings provide valuable insights for optimizing UHPFRC mix design using machine learning approaches
Smart expressways in Vietnam: An architectural proposal
Full text linkSmart expressways represent an emerging direction in modern transportation, where digital technologies are embedded into road infrastructure to improve mobility, safety, and sustainability. By integrating advanced communication, sensing, and automation systems, they aim to meet the rising demands of urbanization and future mobility trends. Vietnam’s expressway network, though expanding, remains conventional and continues to face congestion, safety concerns, and limited readiness for digital transformation. This study evaluates how smart expressway concepts can be adapted and implemented within the nation’s socio-economic context. The research combines a review of Vietnam’s current infrastructure with an assessment of digitalization initiatives in the transport sector. It also draws on international case studies, adapting relevant lessons to identify technological opportunities—such as IoT, AI, V2X communication, and ITS—while acknowledging challenges in financing, governance, and institutional capacity. The results emphasize both the benefits of smart expressway adoption, including greater efficiency, reduced environmental impacts, and enhanced safety, and the barriers that must be addressed. The study concludes by proposing a practical roadmap and architectural framework suited to Vietnam’s developmental stage, providing strategic guidance for sustainable and future-ready mobility
A Data-Driven Approach for Estimation and Multi-Objective Optimization of Concrete Mix Design
Full text linkThe study focuses on establishing the optimum concrete mix of ratios through a comprehensive analysis of experimental results. For this purpose, 62 numbers of concrete mixtures have been considered by varying the level of key ingredients- cement, water, fine aggregate and coarse aggregate. Using experimental data, Genetic Expression Programming (GEP) has been used to develop predictive equations for compressive strength and slump with cement, water, and coarse aggregates and fine aggregates as inputs. These equations are useful to estimate compressive strength and workability of concrete for particular ingredients. Moreover, mathematical multi objective optimization has been conducted by Genetic Algorithm (GA) using these equations as basic functions and optimum content of cement, water, fine aggregate and coarse aggregate have been determined for obtaining maximum compressive strength, maximum slump at lowest cost. Further, multi objective optimizations of different grades of concrete with slump and cost separately have also been carried out to determine these ingredients. Thus, by implementing the present results a more accurate number of mixed proportions with desired compressive strength, and slump can be obtained at minimum cost
Influence of Fine Aggregates and Specimen Geometry on Mortar Compressive Strength
Full text linkThe characterisation and comparison of mortars prepared with different standardised sands are essential to ensure the equivalence of results obtained under distinct national and international testing standards. The performance of mortars is heavily dependent on the physical and mechanical properties of the sand used as fine aggregates, such as particle size distribution, grain geometry, and water absorption. This study compared the standardised sand from Brazil (IPT), European sand (EN), and local sand from Porto União (Brazil), aiming to assess differences in their physical and chemical properties, their effects on mortar consistency and compressive strength, and the influence of specimen geometry (prismatic and cylindrical) on strength outcomes. The fine aggregates were characterised using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and other tests for organic matter content, humidity, and water absorption. Results showed no significant differences in aggregate morphology, except for minor variations in sphericity. Chemical composition was comparable across samples, though absorption rates were higher for European sands. Mortar consistency was also affected, with European mortars showing significant differences compared to others, and statistical distinctions between the mortars using Porto União sand and IPT sand. Specimen geometry had no significant influence on compressive strength. This research underscores the importance of understanding fine aggregate characteristics in optimising mortar performance
Effects of Waste Turmeric Oil on the Rheology and Structural Performance of Modified Bitumen
Full text linkFlexible pavements face continual degradation due to traffic and environmental stresses. Concurrently, waste materials like Waste Turmeric Oil (WTO) pose sustainability challenges. This study explores the WTO as a bio-modifier for VG30 bitumen, aiming to enhance binder performance while addressing waste disposal concerns. WTO-modified binders (WTOMB) were evaluated through physical tests (penetration, softening point, flash point) and rheological tests using a Brookfield viscometer and Dynamic Shear Rheometer (DSR). Results showed that increasing WTO content raised penetration and reduced softening points, indicating improved flexibility. Viscosity decreased by 20–25% at WTO contents above 3%, enhancing workability and reducing mixing temperatures. Short-term aging was simulated using the Rolling Thin Film Oven (RTFO) test, with all samples showing low mass loss and good thermal stability. DSR-based Performance Grade (PG) and Multiple Stress Creep Recovery (MSCR) tests indicated a significant reduction in non-recoverable creep compliance (Jnr) to 1.8 kPa¹ at 3% WTO, identifying it as the optimal dosage for rutting resistance. Although 4% WTO also achieved Jnr 2.0 kPa¹, benefits plateaued. Recovery results suggested that binders with 1–2% WTOMB are suitable for high-traffic conditions. Overall, WTO effectively enhances the performance and sustainability of bitumen binders, offering a cost-efficient and environmentally responsible solution for flexible pavement construction