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2007 research outputs found
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Shear Performance of ULCC and PCC: Experimental and Numerical Insights Using DIC and FEM
No full textThis study investigates the shear behavior of reinforced concrete beams constructed with high-calcium fly ash-based Ultra-Low Carbon Concrete (ULCC) as a sustainable alternative to conventional Portland Cement Concrete (PCC). The objective is to assess ULCC’s structural performance under shear and its potential as a low-carbon substitute. Using a dry-mix method with dry activators, six beams (five ULCC, one PCC) of identical dimensions (150 × 250 × 1800 mm) were tested under four-point bending, with variations in shear reinforcement, flexural reinforcement, and shear span-to-depth (a/d) ratios. Digital Image Correlation (DIC) was employed to monitor crack propagation and strain development, while Finite Element Modeling (FEM) provided numerical validation. Results show that increasing shear reinforcement enhanced capacity by 12.05%, whereas higher (a/d) ratios decreased it by 22.63%; increased flexural reinforcement improved shear resistance by 31.27%. FEM closely matched experimental outcomes, with a load-deflection ratio of 1.01. ULCC outperformed PCC in shear capacity and exceeded ACI 318-19 predictions. The integration of DIC and FEM offers a comprehensive analysis framework, and the findings demonstrate ULCC’s viability as a structurally efficient, environmentally sustainable alternative for shear-critical applications
Impact-Echo Method on Short Cylinders: A Numerical and Experimental Investigation
No full textDespite 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
Tracking Process and Benefit-Ability of Reflection Spectrum of TQM in Construction Industry
No full textTotal Quality Management is an important journey in developing the construction industries. Construction firms are working to achieve the aspirations of clients in terms of quality systems, and through adopting a total quality management tracking system, it contributes significantly to achieving the objectives of projects and aspirations of clients too. The primary objective of this research paper is to develop a tracking process for total quality management by identifying restrictions and a model of required actions to overcome these restrictions to ensure the successful implementation of TQM as a basic system in the construction industry. Therefore, the research is divided into two phases. The first phase included identifying and analyzing restrictions by using a questionnaire to survey 102 expert engineers in the construction industry and quality laboratories. The second phase involved developing the main hypothesis and analyzing required actions through analysis using the assumption of Kruskal-Wallis. The opinions of three groups of experts were also relied upon to complete this tracking phase. To evolve a tracking system that includes the actions that are coded in this research paper under (A-TQM). The proposed patch model carries the symbol (MPP) for tracking TQM and has been presented. The MPP consists of three figures that indicate the wheel of TQM, tracking of the required scope of TQM, and packages of scope to meet with TQM pillars
Adaptive Stilt Housing and Socio-Ecological Resilience in Coastal Settlements Under Urbanization Pressure
No full textThe water-based settlement of Cambayya, Makassar, represents a spatial adaptation by coastal communities facing urbanization, land scarcity, and dynamic marine conditions. High population density has driven the organic growth of informal stilt housing over coastal waters. This study examines spatial adaptation strategies that foster socio-ecological resilience in densely populated coastal environments. Utilizing a mixed-methods approach within a constructivist paradigm, the research combines spatial analysis, participatory observation, field surveys, interviews, and socio-ecological data interpretation. The findings reveal key adaptive responses, including the conversion of underfloor stilt areas into domestic space, the use of hybrid timber-concrete structures, and horizontal expansion into shallow waters. While adaptive, these practices exacerbate ecological degradation, such as tidal flooding, pollution, and inadequate sanitation. The study highlights the need for inclusive, sustainable spatial planning and proposes an innovative strategy: integrating stilt housing with waterfront development and cultural seascape tourism. This approach not only enhances resilience but also unlocks economic potential—estimated at over IDR 3.5 billion annually—through heritage-based ecotourism and creative industries. The study contributes a context-sensitive, community-driven spatial model for resilient coastal urbanism, positioning Cambayya as a reference for sustainable development in similar tropical coastal settlements
Study on Shear Behavior of Reinforced Concrete Beams Confined with Reinforcing Meshes
No full textThis study reveals the results of a numerical simulation performed using the ABAQUS/CAE finite element program. The study aimed to provide a simulation model that can forecast the shear behavior of reinforced concrete beams confined with reinforcing meshes. Limited numerical studies have been conducted using geogrid or FRP mesh as shear reinforcement, with limited representation accuracy and limited material quality. The results were compared to published experimental findings in the literature. The finding of the finite element model and the experimental results were highly comparable; consequently, the model was determined to be valid. Following this, the domain of numerical analyses was broadened to include the investigation of many aspects, like the material of reinforcement mesh, the angle of inclination of mesh strip, and the number of mesh strips. The results show that the inclined strip beams gave ultimate loads greater than the beams with vertical strips, where the ultimate load for beams with inclined strips was higher than that for beams with vertical strips by 5.6, 2.5, and 9.4% for beams with geogrid, geotextile, and GFRP mesh, respectively. The smaller the strip width and the larger the number, the better. Beams with inclined strips (45°) gave higher ductility indexes than similar beams with vertical strips. Beams with six strips (width of 50 mm) gave higher ductility indexes than similar beams with four strips (width of 75 mm)
The Role of Recycled Plastic Bottles in Enhancing Asphalt Longevity
No full textProducing “green” pavement is important in decreasing the negative effects of plastic on the environment and ensuring sustainable resource management. Because many worldwide strategies are aimed at reducing the use of plastic, this work studies a recycled polymer concrete modified by a defined amount of recycled plastic waste in asphalt. The specimens were prepared with a maximum optimal asphalt content using ±0.5% of the optimum level. The logic indicated that 11% plastic waste can be used as an alternative to the coarse aggregate. Experimental tests were carried out to examine moisture damage, short- and long-term aging, and compressive strength (rutting resistance). The measured properties were ITS, resilient modulus, and permanent deformation of the first load cycle and after 1200 load cycles using the PRLS device. In aging experiments, the resilient modulus was found to increase by 118% during the first cycle and by 40% after 1200 cycles. The decrease in permanent deformation was 40% and 48.5% after the first load cycle and after 1200 cycles, respectively. The results obtained in the moisture susceptibility test were within the required limit. Finally, the compressive strength of samples with asphalt content of 4.0%, 4.5%, and 5% was found to be 3660, 4120, and 2900 kPa, respectively. This achievement indicates the advantages of utilizing plastic waste in road construction to develop sustainable asphalt concrete with improved mechanical properties and reduced environmental impact, especially in hot climates such as Iraq, where it would be beneficial for rutting-sensitive roads
Numerical Investigation for Selection the Optimal Flexural Strengthening Strategy of Reinforced Concrete Beams
No full textReinforced concrete is the most widespread material that is used in structural applications. In structural systems, concrete beams can become damaged due to aging and increased design loads. Furthermore, for architectural purposes, specific dimensions may be imposed on concrete beams. For these reasons, it always needed to strengthen these beams. In this study, a numerical study was conducted to simulate the strengthening and improving of the flexural strength of reinforced concrete beams using three techniques: carbon fiber (CFRP sheets), steel plate, and external bars. The numerical analysis was verified with previous experimental studies. For the parametric study, the thickness, number of layers, and tensile strength were adopted for the CFRP strengthening technique. For the steel plates, the effect of changing the thickness and number of layers and yield stress was studied. Finally, for the additional external bars, different ratios of longitudinal reinforcement were investigated. After conducting numerical analysis of the studied models, the results showed a clear increase in the ultimate load and stiffness of the beams when strengthened with carbon fiber and steel plate, especially when increasing the tensile strength and yield strength, which was the most influential parameter, compared to a very limited effect of the number of layers due to the separation between the layers, especially for CFRP. However, both strategies showed brittle failure without clear ductility. Using additional external bars or increasing the ratio of longitudinal reinforcement was the most influential strengthening strategy in terms of increasing the beams’ capacity for bending and ductility
Spatial Variation of Shallow Soil Bearing Capacity Using SPT Data and MATLAB Analysis
No full textThe current research examines the spatial distribution of shallow bearing capacity in Al-Najaf City through the use of Standard Penetration Test (SPT) data supplemented with advanced computational tools in MATLAB. A high-quality geotechnical survey of 464 boreholes was carried out, with drilling performed at depths ranging from 18 m to 35 m below the current ground surface. To assess the shallow foundations, the top 12 m of the soil profile was analyzed. To measure in-situ soil resistance, SPT measurements were taken at specified depth intervals in every borehole. The raw SPT N-values were adjusted for overburden pressure, an energy-correction parameter, and groundwater effects; other minor adjustments were considered negligible based on their minimal impact on the final dataset. These corrected N-values formed the basis for calculating both ultimate and allowable bearing capacities using empirically developed correlations. MATLAB surface-interpolation procedures were used to generate georeferenced thematic maps that depict the lateral variation of bearing capacity within the 0–12 m depth interval. The resulting spatial analysis shows a significant increase in the bearing capacity of the northern and western regions of Al-Najaf, correlating with increases in urbanization and infrastructure density. The predictive geotechnical maps developed in this study can be considered a highly robust, cost-effective, and timely tool for initial subsurface engineering surveys to guide sustainable city development, infrastructure design, and optimization of foundation engineering
Combined Effect of Basalt Fibers and Bentonite Clay on Complex Mortar Properties
No full textThis study examined the effects of basalt microfibers and amorphous-structured bentonite clay on the properties of complex mortar mixtures composed of cement and quicklime, utilizing locally sourced raw materials. Bentonite clay was subjected to thermal treatments at 400, 600, and 1000°C, and a technogenic pozzolanic additive was incorporated to investigate its influence on mortar performance. Optimal results were observed for the clay treated at 600°C, which was subsequently used in the mortar formulations. The primary objective was to assess the effects of varying basalt microfiber dosages (0.5%, 1%, and 2%) and thermally treated bentonite clay concentrations (5%, 15%, and 25%) on the chemical composition, physico-mechanical properties, and structural development of the resulting multi-component systems. Advanced analytical techniques, including SEM/EDS, XRD, FTIR, XRF, DLS, and thermochemical analyses (TG/DTG, TG/DSC, and TG/MS), were used to evaluate the mineralogical composition, particle size distribution, microstructure, and thermal behavior. The findings show that the combined use of basalt microfibers and thermally treated bentonite clay significantly enhanced the mechanical strength and structural formation of the mortars. This study provides novel insights into the synergistic effects of these components, offering a promising approach for enhancing mortar performance using locally sourced materials
Assessment of Sulfur Dioxide Levels in Atmospheric Air Over the Period 2019–2024
No full textThis study investigates the spatiotemporal distribution and dynamics of atmospheric sulfur dioxide (SO₂) over the Crimean Peninsula during the period 2019–2024, employing protected natural areas as background reference sites for air quality assessment. The primary objective is to determine the variability in SO₂ concentrations in the atmosphere over Crimea. Methodologically, the study involves selecting background sites across diverse landscape levels throughout the peninsula, and applying Z-analysis to categorize ambient air pollution into four levels: conditionally low, average, elevated, and high. The analysis encompasses annual mean SO₂ levels, assessment of temporal trends, and localization of pollution hotspots. Results indicate a peak in SO₂ levels in 2020, predominantly at mid-mountain landscape level, and a minimum in 2019. Overall, a decreasing trend of 25.4 µmol/m² per year in SO₂ concentrations is observed, despite localized zones of high pollution, including areas northeast of the regional center, Simferopol. In 2022, the low-mountain landscape level of the northern macroslope exhibited the most extensive conditionally high pollution zone, covering nearly half of its territory. The novelty of this work lies in integrating protected natural areas as reference sites within the Z-analysis framework, enabling more precise identification of anthropogenic influences and the spatial distribution patterns of sulfur dioxide concentrations in the region’s atmosphere