2031 research outputs found
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A Novel Process for Decolmatation of Wells During In Situ Leach Mining of Uranium
Get PDFThe objective of this research is to enhance the efficiency of geotechnical wells by using a low-toxicity ammonium fluoride substance in neutral, acidic, and alkaline environments to dissolve colmatants. The research methodology includes X-ray spectral analysis, semi-quantitative X-ray phase analysis of the colmatants, laboratory experiments, and pilot-scale tests. The study results indicate that the use of ammonium fluoride combined with soda increases the dissolution of colmatants, particularly quartz, thereby improving the flow rate and extending the inter-repair cycle of process wells. When ammonium fluoride is used with sulfuric acid, it leads to a decrease in the oxidation-reduction potential (ORP), whereas its combination with soda ash increases the ORP, both of which positively affect the efficiency of in situ leaching technology for uranium mining. The practical significance and novelty of this work lie in the development of an effective and environmentally friendly decolmatation technology using a low-toxicity reagent”ammonium fluoride in combination with soda. For the first time, this research established the dependence of the degree of quartz colmatant dissolution on the concentration of ammonium fluoride in both acidic and alkaline environments, along with observed changes in ORP and pH values over time during treatment with alkaline and acidic solutions of ammonium fluoride. Doi: 10.28991/CEJ-2025-011-04-011 Full Text: PD
Shear Strength and Serviceability of GFRP-Reinforced Concrete Beams: A Study on Varying Reinforcement Ratios
Get PDFThis study investigates the behavior of GFRP-reinforced concrete beams with varying reinforcement ratios. The experimental program consists of five concrete beams tested under a simply supported four-point bending setup with a section of (250í—300) mm and a clear span of 1800 mm with a span-to-depth ratio of 2.3. The beams were reinforced longitudinally with GFRP bars with varying reinforcement ratios (Ï = 0.5, 0.9, 1.35, 1.8, and 2.25) for B1-B5, respectively. GFRP stirrups were used for the transverse direction with a spacing of 240 mm for all the beams. The results showed that raising the GFRP longitudinal reinforcement ratio to 1.35 enhanced load-carrying capacity performance and dropped at higher reinforcement ratios (1.8, 2.25) while offering better performance in controlling crack widths and deflection, which could be due to the limit of bonding with concrete. Increasing the GFRP longitudinal reinforcement ratio reduced the deflection at both service and ultimate loads with enhanced crack control. Lower reinforcement ratios of (Ï= 0.5) resulted in a brittle failure, wider cracks, and poor stiffness. Conversely, a 1.8 reinforcement ratio led to delayed crack initiation, smaller crack widths, and a balanced stiffness-to-ductility ratio being achieved. It was found that the dowel action of longitudinal GFRP bars greatly contributes to the shear strength of concrete beams, with a ratio of (Ï= 1.35) having the maximum load capacity along the tested beams. The ductility index ranged from 1.7 to 2.49. Higher reinforcement ratio beams resulted in a deeper neutral axis up to (Ï = 1.35), demonstrating improved stress distribution and reduced deformations. Doi: 10.28991/CEJ-2025-011-03-04 Full Text: PD
Shear Behavior of Random Rockfill in Dam Construction via Large-Scale In-Situ Testing
No full textDam construction commonly demands a massive amount of random material. This material offers practical material collection, minimum environmental impact, and economical cost. Unfortunately, shear strength assessment of random material is difficult because of large particle presence. Regular laboratory tests cannot accommodate these large particles. Misevaluation of random material shear strength may induce disastrous collapse. A large-scale direct shear apparatus, with a 70 cm by 70 cm shear plane, was developed and proposed for testing random fill material in-situ. This manuscript presents an experimental study using this device in Rukoh Dam construction, Indonesia. Test results captured variations between normal stress and shear stress to determine shear strength parameter models. Volume changes during shearing were also observed. Random materials in Rukoh Dam could be categorized as random rock. This study was also compared to other relevant rockfill studies. The proposed method offers an impressive approach for assessing and verifying the shear strength of compacted random material as well as compaction quality on site. It can be used to decide if the ongoing design and compaction method have to be modified or continued. Since the proposed direct shear test is reliable, fast, simple, and inexpensive, it is strongly recommended for dam construction
Experimental and Numerical Analysis of the Behavior of Steel Scaffolding
Get PDFIn recent days, due to the reduction in the labor force, investment in construction equipment has become increasingly common to compensate for the shortage of workers. Among other equipment, scaffolding”both external and internal”plays a crucial role during the construction phase of buildings. Scaffolds are among the components that require special attention, as they are directly linked to the health and safety of workers. For this reason, they have received significant attention in recent years following frequent collapse incidents. Any defect in the construction or use of scaffolding can pose serious, even fatal, risks to workers. Therefore, the safety and stability of scaffolds are essential for preventing accidents and protecting the lives of those working on construction sites, especially those working at great heights. This study analyzes scaffolding with a height of 200 cm, treating it in a spatial manner to calculate the maximum load-bearing capacity, lateral and vertical displacements, as well as to assess the stress and deformation states in the vertical elements (columns). This process was carried out by applying the rules of Eurocode EN 1993-1-1, along with experimental analysis and calculations using the SEIMOSOFT application software. Doi: 10.28991/CEJ-2025-011-05-014 Full Text: PD
Sustainable Interlocking Blocks Containing Sugarcane Bagasse Ash: Structural Integrity, Cost Efficiency, and Environmental Benefits
Get PDFThis study aimed to evaluate the potential use of sugarcane bagasse ash (SCBA) as a partial replacement for Portland cement in interlocking blocks to enhance sustainability, reduce costs, and mitigate environmental impacts. The research objectives included assessing the compressive strength, water absorption, durability, microstructural characteristics, cost-effectiveness, and carbon footprint of SCBA-modified interlocking blocks. Experiments followed established standards, using various SCBA replacement levels (5–30%), with performance evaluated through mechanical testing, SEM analysis, cost assessment, and life cycle carbon footprint calculation. The findings demonstrated that interlocking blocks with 20% SCBA substitution maintained structural integrity, achieving a compressive strength of over 7 MPa, with acceptable water absorption and excellent durability. Cost analysis showed savings of up to 7.53%, while environmental assessment revealed carbon emission reductions of 17.99%. Microstructural analysis confirmed the presence of calcium silicate hydrate, supporting strength development. The study also introduced the SCOPEC framework (Selection of materials, Composition and mix optimization, Operational performance, Production consistency, Economic feasibility, and Carbon reduction), offering practical guidance for SCBA utilization in sustainable block production. This research contributes a novel, scalable solution to reduce cement consumption, enhance resource efficiency, and promote eco-friendly construction materials for affordable housing projects. Doi: 10.28991/CEJ-2025-011-05-024 Full Text: PD
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
Experimental and Bearing Capacity Research on Prestressed Shape Memory Alloy Strips Confined Concrete Column
Get PDFThe prestressed shape memory alloy (SMA) strips confined columns are a novel reinforcement method, which not only exerts active confinement stress on the core concrete but also avoids the common stress hysteresis problem in reinforcement. This paper performed axial compression tests on eight sets of concrete columns with varying SMA strip width, net spacing, and pre-strain, and the impacts of these variables regarding the failure pattern, bearing capacity, and deformability of the specimens were investigated. A calculation model for the bearing capacity of SMA strips actively confined to concrete columns was established and contrasted with the prediction performance of the BP neural network. The results indicate that compared to the unconfined column, SMA strip-confined columns exhibit obvious ductile failure under compression, with the highest increase of bearing capacity and deformability reaching up to 20.27% and 24.96%, respectively. The confinement effect becomes better and better with the increasing strip width or the decreasing strip net spacing. When the strip pre-strain gradually increases, the bearing capacity of confined columns gradually improves, while the deformability first enhances and then weakens. The experimental data of other scholars is used to verify that the calculation results accord with the experimental results well, and the prediction precision of the proposed calculation model exceeds that of the BP neural network. Meanwhile, it is confirmed that the BP neural network exhibits a high fitting level in bearing capacity prediction (R2training=0.990 and R2test=0.965), offering a novel approach for predicting the bearing capacity of structures
Performance of Soil Biogrouting as a Subgrade Material of the Road Pavement
No full textSoft clay subgrade is unsuitable for road pavement because it has low bearing capacity and CBR value. Therefore, the soil needs stabilization, but with a sustainable stabilization method. One of these methods is biogrouting, namely grouting, which uses bacteria. Thus, the main objective of this study was to determine the performance of Bacillus subtilis and Bacillus amyloliquefaciens bacteria in stabilizing the soil. The performance of these bacteria was quantified by the CBR value and soil-bearing capacity experimentally in a laboratory model test with each soil thickness of 0-30 cm. The CBR value of the soil improved by the biogrouting method by about 4 times the CBR value of untreated soil. The increase in bearing capacity was obtained about 4 times for treated soil with Bacillus subtilis and about 5 times for treated soil with Bacillus amyloliquefaciens. The layer thickness significantly improves the performance of the subgrade at a layer thickness of 20 cm. The new result of this study is that both bacteria are native Indonesian bacteria, so they are suitable for use in Indonesia. In addition, Bacillus amyloliquefaciens has never been used in research to increase soil-bearing capacity
Numerical Analysis of Load-Bearing Capacity in Contaminated and Uncontaminated Soils Treated with Nanomaterials
Get PDFConstruction of load-bearing structures requires both a strong foundation and stable soil. For projects located on weak or contaminated soils, stabilization techniques are a prerequisite. Nanotechnology holds promise for improving soil strength and stability, offering innovative solutions for enhancing site conditions in geotechnical engineering. This numerical study explores the potential application of nano-clay (NC) and nano-silica (NS) in improving the overall load-bearing performance of a strip footing resting on clean and kerosene-contaminated soils. The objectives are to assess the impact of varying nanoparticle contents and curing durations on soil performance. Results suggested that adding NC and NS substantially enhances the bearing capacity ratio (BCR) up to a maximum of 4.76 and 4.33 at 1% NC and 1.5% NS, respectively, compared to untreated soil. Overdosing, however, resulted in reduced effectiveness, emphasizing the significance of optimal contents. Conversely, the BCR improvement was less noticeable in kerosene-contaminated soils until it peaked at 2.5% NS and 2% NC. However, results of both clean and contaminated soils revealed that nanomaterials negatively impact settlement behavior. Curing age was found to be a major factor affecting BCR, in which treated soils showed a consistent increase in BCR over time. These findings endorse the potential of nanomaterials for stabilizing soil used in geotechnical engineering. Careful selection of dosages and consideration of soil contamination are critical to optimizing performance in complex geotechnical conditions
The Role of Recycled Plastic Bottles in Enhancing Asphalt Longevity
Get PDFProducing “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