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2007 research outputs found
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Effect of Coal Combustion Waste on Cement-Treated Clay
No full textHigh plasticity clay is soil with poor material characteristics; one of them is the large shrinkage condition due to its high plasticity. Therefore, it is necessary to improve the soil using cement and coal-combustion waste (CCW). The purpose of this research is to determine the effect of mixture addition on the CBR value of the specimen on stabilization. Variations of 6%, 9%, 12%, and 15% of CCW and cement content vary by 3% and 5%. Based on the test results, there is an increment in the CBR bearing capacity, which was initially 0.80% to 18.75% to 42.90% by adding cement and CCW between 6% and 15%, respectively, after 7 days of curing. This increment is the largest of all variations in the CBR test. The percentage of increment in CBR value is quite large, i.e., a multiple of 200. This proves that the mixture is able to work effectively in increasing the bearing capacity of the soil. Based on microscopic testing of CBR samples, it is obtained that the higher the levels of Bottom Ash Fly Ash (BAFA) and cement, the rougher and paler the samples became as the structure changed. And vice versa, the lower CCW content and cement content made the sample structure become smoother and brighter in color, closer to the original color of natural clay. Doi: 10.28991/CEJ-2024-010-11-010 Full Text: PD
The Effectiveness of Inclined Pile Breakwater on the Transmission Coefficient
No full textA breakwater is a structure designed to protect coastal areas by breaking and reducing the force of incoming waves. Waves that propagate through a wave dampening building will have some of their energy reflected (reflection), some of their energy transmitted (transmission), and some of their energy destroyed (dissipation). The effectiveness of wave-breaking structures in protecting coastal and harbor waters can be seen from how much wave energy the building can reduce. In this research, the performance of the wave breaker will be seen from the values of wave transmission (Kt) and wave reflection (Kr) with an inclined pile building structure. Reflection and transmission analysis of the results of 2D physical model testing of wave breakers with inclined pile structures are needed to optimize their use. Laboratory test results prove that this Inclined Pile Structure breakwater is quite effective in scenarios that have smaller Kt values and larger Kr values. In this experiment, testing was carried out with several parameters, namely the slope of the pile, the distance between the piles in one row (or distance between pillars), the distance between the tops of the piles (or distance between rows of piles), and the depth of the water. The Kt value in the model α=45°; D=1.69 cm; b=5 cm is 0.603 compared to the model α=60°; D=1.69cm; b=5 cm, Kt value is 0.652. This shows that the inclined pile structure of breakwater is more effective with a pile slope of 45° than with a pile slope of 60°. Doi: 10.28991/CEJ-2024-010-06-09 Full Text: PD
Seismic Resilience of Steel-Braced Frames Incorporating Steel Slit Dampers: A Review and Comparative Numerical Analysis
No full textSteel dampers, specifically steel slit dampers (SSDs), are crucial for enhancing the seismic resilience of buildings by absorbing energy and mitigating damage. SSDs are celebrated for their ability to produce stable hysteretic behavior, owing to the inelastic deformation of their strips, alongside benefits such as lightness, ease of manufacture, and straightforward post-earthquake replacement. This research extensively examines SSD applications, design principles, and innovations in their modeling, optimization, and production processes. The literature highlights SSDs' consistent performance in resisting both compression and tension, their adaptability in strength, ductility, and energy dissipation through modifications in strip configurations and the superiority of non-prismatic and hourglass-shaped designs over traditional options. Numerical analyses have been conducted to assess the effectiveness of non-prismatic slit dampers in comparison to their prismatic counterparts within braced frames. Three distinct braced frame configurations have been analyzed: one with a diagonal brace without a damper, another featuring a uniform prismatic slit damper, and a third incorporating a non-prismatic slit damper with an hourglass shape. The analysis primarily compared these systems' hysteresis behavior, ductility, and energy dissipation capacities. Results indicate a significant enhancement in performance when utilizing non-prismatic slit dampers. Notably, these dampers exhibited a remarkable 69% increase in cumulative energy dissipation compared to prismatic ones. Furthermore, the study reveals that a steel slit damper-braced frame, when equipped with optimally designed slit geometries, can tolerate inter-story drifts in excess of 2% while simultaneously achieving a greater than 12% increase in energy dissipation efficiency. Doi: 10.28991/CEJ-2024-010-04-019 Full Text: PD
Pulsed-Bed Column Adsorption for Triclosan Removal Using Macadamia Nut Shell Activated Carbon
No full textTriclosan (TCS), a common antibacterial agent found in numerous personal care products, has been detected in wastewater and surface water and is now of significant environmental concern due to its health impacts. To mitigate this issue, various treatment methods have been explored. This study investigated the efficacy of Macadamia nut shell activated carbon (MAC) as an economical adsorbent for triclosan removal. A pulsed-bed column adsorption technique was applied to enhance adsorption capacity and prolong the operational lifespan of the column. Batch experiments were conducted to explore various parameters and adsorption capacity. Column experiments were carried out to investigate breakthrough curves and various associated parameters. In batch experiments, MAC exhibited a high TCS adsorption capacity of 119.05 mg/g, and optimal adsorption conditions were determined. Adsorption kinetics followed the pseudo-second-order model, and equilibrium data were well-fitted by both the Langmuir and Freundlich isotherm models. A pulsed-bed column adsorption showed superior performance compared to a fixed-bed column under specific conditions (flow rate: 10 mL/min, TCS initial concentration: 60 mg/L, bed column height: 10 cm) and removal bed height of only 6 cm, successfully enhancing TCS adsorption capacity to 53.40 mg/g and extending the operational lifespan of the column to 5,280 minutes. Adapting pulsed-bed columns for TCS removal from wastewater in the personal care product industry led to the extension of column life with increased adsorption capacity and minimized the use of adsorbents as a practical and environmentally friendly method. Doi: 10.28991/CEJ-2024-010-05-019 Full Text: PD
Investigating the Hydraulic Behaviours of an Alluvial Meandering River Reach Between Two Barrages
No full textThe Abassia-Shammia is a meandering stream in Najaf province. Predicting and estimating the flow behavior of meandering rivers is crucial for designing hydraulic structures in an accurate manner in the vicinity and conducting environmental and ecological studies. The hydraulic properties of an alluvial stream are typically subject to change due to its location between two barrages. In this study, HEC RAS 2D, developed by the Hydrologic Engineering Center's River Analysis System, was employed to simulate the hydraulic performance of the Euphrates River reach between two series of barrages, i.e., Abbassia and Shammia. Reliable input data, such as Digital Elevation Models (DEMs), land cover classification, and data for the 2023 hydrograph as a boundary condition, were utilized to develop the hydraulic model. The model was calibrated by using the observed water surface elevation from field measurements downstream of Abbassia to match the ones calculated by the model. Hence, the hydraulic model of the Euphrates River was created using an appropriate Manning roughness coefficient value (n = 0.04) based on the most suitable values of statistical indices, correlation coefficient (R²), and root mean squared error (RMSE) to assess the agreement between the observed and simulated data throughout the calibration and validation phases. To visualize the HECRAS2D output, the hydraulic maps for the study region were presented. The ten cross-sections from the field study (investigated at the same period of flow hydrograph) were presented for modeling to emphasize the river's hydraulic behaviors. Based on the results, the water surface elevation ranged between 19.1–29.2 m.a.s.l., and the flow velocity was 2.50 m/s. Meanwhile, the values of bed shear stress (Pa) and the water depth (m) ranged between 0.1 Pa and 8.93 m for the entire river. The results also proved the superiority of the HEC RAS2D model to reliably represent the hydraulic performance of the Euphrates River reach located between the two barrages. Doi: 10.28991/CEJ-2024-010-05-013 Full Text: PD
Experimental Study on Seismic Performance of Kancingan Timber Frame Infill Walls Building
No full textThis study was carried out to examine the seismic performance of Kancingan house walls and the behavior of their timber frames, brick infill, and anchor nails during cyclic loading tests. Kancingan House, a timber frame building with brick infill walls, is a cost-effective and efficient method of wall construction commonly used in houses in Merauke, Indonesia. The experimental method was used to determine the seismic performance of the walls built using buswood with a module width of 100 cm and a height of 130 cm through cyclic load testing. The result showed a maximum lateral load of 26.43 kN with a displacement of 19.08 mm under compression loading and 28.78 kN under tensile loading with 15.6 mm displacement. The initial stiffness was measured at 5.03 kN and 9.59 kN/mm for compressive and tensile loading, respectively. Furthermore, ultimate load and displacement of 21.14 kN and 23.02 kN were obtained at a displacement of 30.68 mm under compressive loading and 25.23 mm under tensile loading. The ductility values of 10.76 and 9.78 were obtained under compressive and tensile loading. In conclusion, the study found that each wall element supports the seismic performance of the structure. As opposed to the timber frame, the infill walls have not suffered much damage except a hair crack because of the presence of anchor nails that keep the infill wall from collapsing when it loses its bond with the timber frames. Doi: 10.28991/CEJ-2024-010-08-06 Full Text: PD
Leak Detection in Urban Hydraulic Systems Using the K-BiLSTM-Monte Carlo Dropout Model
No full textUtility companies lose approximately 35 liters of water for every 100 produced due to incorrect, illegal connections and the poor condition of pipes. This study develops an intelligent model to detect leaks using the Kalman filter, BiLSTM neural networks, and the Monte Carlo Dropout algorithm. Using data from the Empresa de Acueductos y Alcantarillados de Bogotá (EAAB), Colombia, autocorrelation analysis, PCA, cluster analysis, ADF and Durbin-Watson tests, Hurst exponent, spectral analysis, and wavelet transform were performed. Then, Kalman filtering techniques were applied, and a BiLSTM architecture controlled with Monte Carlo dropout was implemented. The results showed an accuracy of 87.48% in training and 80.48% in validation. Temporal analysis revealed a stationary behavior in the flow series, and the decrease in spectral intensity around 0.25 Hz was related to pressure perturbations caused by leaks. A detailed evaluation of pressure and flow signals identified leak patterns with high precision, demonstrating the effectiveness of the wavelet spectrogram in detecting energy disturbances. The novelty of the study lies in the integration of advanced artificial intelligence and combinatorial optimization techniques to improve water resource management, allowing early and accurate detection of leaks, significantly improving compared to traditional methods. Doi: 10.28991/CEJ-2024-010-07-01 Full Text: PD
Development of Pavement Deterioration Models Using Markov Chain Process
No full textA common phenomenon in developing countries is that the function of the pavement in the road network will experience structural damage before the completion of life is reached, and the uncertainty of pavement damage is difficult to predict. Planning for maintenance treatment depends on the accuracy of predicting future pavement performance and observing current conditions. This study aims to apply the Markovian probability operational research process to develop a decision support system predicting future pavement conditions. Furthermore, it determines policies and effectiveness in managing and maintaining roads. A standard approach that can be used by observing the history of pavement damage from year to year is to estimate the transition probability as a Markovian-based performance prediction model. The results show that the application of the model is quite optimal, changes in pavement conditions after repair can be easily compared with an increase in good condition, reaching 92.8%. Routinely and consistently handling road deterioration will give favorable results regarding pavement condition value. This will ease in the management of the road network and the accomplishment of the optimal maintenance and repair policies. Doi: 10.28991/CEJ-2024-010-09-012 Full Text: PD
Unfired Bricks Mixed with Para Rubber Latex for Sustainable Construction Materials
No full textThis paper aims to study the development of bricks without burning, mixing para rubber latex, and compressing them with the technology of interlocking block production. The ratio of cement, lateritic soil, and water used in the mix was 1:6:11, while the percentage of para rubber latex (PRL) added was 2.5, 5, 7.5, 10, and 12.5% of the cement weight. The optimal PRL content (2.5%–7.5% by cement weight) enhances compressive strength, reduces water absorption, and improves durability, meeting the Thai industrial standard (TIS 77-2545). The PRL7.5 mixture achieved the highest performance, with a compressive strength of 21.42 MPa and a water absorption rate of 7.55%. These advancements are credited to the polymer film network formed from PRL during the hydration process, which strengthens particle bonds and reduces porosity. However, PRL content exceeding 7.5% leads to performance reductions, attributed to thicker polymer films and particle aggregation, which create larger voids within the material. Furthermore, the modified unfired bricks demonstrated enhanced crack resistance, increased ductility, and superior thermal insulation properties. Thermal tests of masonry walls confirmed that unfired bricks provide better thermal insulation. Temperature measurements revealed that houses constructed with unfired bricks consistently maintained cooler indoor temperatures compared to those made with fired bricks, indicating improved thermal efficiency. Environmentally, unfired bricks eliminate carbon emissions from firing processes and offer simpler, more energy-efficient production methods. These bricks provide sustainable alternatives to fired bricks, promoting both environmental and economic benefits for brick-making communities. Doi: 10.28991/CEJ-2024-010-12-05 Full Text: PD
Numerical Modeling the Rock Mass Stress-Strain State Near Vertical Excavations in Combined Mining
No full textIn recent years, the development of the mining industry in the Republic of Kazakhstan has been accompanied by the commissioning of new underground levels for many existing mineral deposits, which were initially developed through open-pit mining. As the depth of open-pit mining increases, the volume of overburden rises sharply, making open-pit mining unprofitable due to the significant amount of additional mining work required. For this reason, most open-pit mines in Kazakhstan are transitioning to underground mining, or combined mining. Many researchers have examined the timing of this transition and have worked on optimizing it to determine the best economic efficiency and manage risks. However, there is limited information available on how to determine the optimal location for a vertical mine shaft when transitioning from open-pit to underground mining. The purpose of this study is to identify a safe location for a vertical shaft in combined mining operations. Specifically, the study assesses the impact of the open-pit mine on the selection of the mine shaft's location, considering the stress-strain state of the rock mass during combined mining methods. To address these objectives, numerical modeling of the stress-strain state around vertical excavations during combined mining was performed. The results provide a solution to the critical issue of determining the location of the mine shaft in combined geotechnology and lay the groundwork for further research on shaft placement in Kazakhstan. The novelty of this study lies in identifying the shaft location by considering the geometric shape of the open-pit mine and the depth of development. Doi: 10.28991/CEJ-2024-010-09-010 Full Text: PD