2031 research outputs found
Sort by
Effect of Waste Tire Rubber Particles on the Properties of Rubberized Concrete
No full textMillions of waste tires accumulate annually worldwide, posing environmental and public health challenges. Recycling these tires in concrete production presents a sustainable and practical solution. The present study was intended to investigate the effects of waste tire particles of varying sizes and shapes; specifically granular, short fiber, and mixed fine crumb rubber, along with coarse shredded rubber; on the characteristics of rubberized concrete. Fine rubber particles replaced sand, while shredded rubber replaced stone aggregates at 5%, 10%, and 15% substitution levels by weight. Results revealed that increasing rubber content reduced density, compressive strength, modulus of elasticity, and tensile strength. However, workability, Poisson’s ratio, ductility, and toughness improved significantly in comparison with conventional concrete. This study compares the effects of particle size and shape of rubber used in rubberized concrete. Notably, the newly introduced short fiber-type rubber particles exhibited superior mechanical properties compared to the granular and shredded rubber forms, revealing their potential for structural applications
The ITB Unit Hydrograph Method: A Novel Approach to User-Defined Unit Hydrograph Development (Part I)
Get PDFAll synthetic unit hydrographs can be considered user-defined to some degree, reflecting the inherent influence of user input in their development. This paper constitutes the first part of a two-part series titled The ITB Unit Hydrograph Method: A Novel Approach to User-Defined Unit Hydrograph Development. It focuses on foundational concepts, the verification of existing SUH methods, and the creation of simple user-defined Synthetic and Natural Unit Hydrographs. The verification process involves reproducing established hydrographs, including the SCS-Triangular, SCS-Curvilinear, and SCS-Delmarva models, by computing their Peak Rate Factor (Kp) and Peak Discharge (Qp) values using ITB-UH formulas. Results demonstrate high accuracy, with discrepancies in Kp values consistently below 1%, confirming the reliability of the ITB-UH Method in replicating existing models. Furthermore, the study highlights the ITB-UH Method's capability to develop user-defined synthetic hydrographs, as exemplified by the Double Triangle Synthetic Unit Hydrograph and the HKR Natural Unit Hydrograph. The Double Triangle model introduces a simple unit hydrograph with distinct geometric properties, while the HKR model effectively represents a natural unit hydrograph derived from rainfall-runoff dynamics in a watershed. Both models were applied to flood discharge simulations in the Pinamula Watershed using consistent steps for effective rainfall excess distribution and convolution. The results demonstrate that all hydrographs, despite differences in shape and peak characteristics, yield consistent total flood volumes. These findings underscore the ITB-UH Method's potential to generate unit hydrographs based on user-defined models”whether defined by equations or tables. It should be noted that the simple user-defined unit hydrographs presented in this paper do not include calibration capabilities, a topic that will be explored in Part II of the series. Doi: 10.28991/CEJ-2025-011-04-021 Full Text: PD
The Effect of Additional Baffle Plates on Double-Stage Gravitational Water Vortex Turbine
Get PDFA Gravitational Vortex Water Turbine (GWVT) is an appropriate device to harness the kinetic energy of water to convert it into rotational mechanical energy in low-head. The water flow is directed into a circular basin, which can produce a vortex and can rotate the turbine blades. Turbine performance is influenced by the shape of the blade, so an optimal blade shape is required. Turbine performance is influenced by the shape of the blades, which can rotate optimally. This study aims to determine the effect of adding baffle plates in the blade on the performance of two-stage GWVT using experimental methods. The variation used is the proportion of baffle plate on the runner in the first stage with variations without baffle plate, 25%, 50%, 75%, and 100%. The data taken in the test is the torque and rotation at each additional blade plate. Torque measurement uses a rope brake system, and rotation measurement uses a tachometer. The results of the study showed that the addition of a 50% baffle plate in the first stage can capture the energy of the water vortex more optimally. A baffle plate can increase efficiency by up to 23.15% compared to the blade without the addition of a baffle plate. Doi: 10.28991/CEJ-2025-011-02-011 Full Text: PD
The Crack Propagation in Different Rock Types: A Comparative Seismic Simulation
Get PDFThe presence of a preexisting crack in a rock can affect its stability during seismic events, leading to reduced strength and stiffness. This study, which aims to examine how different types of preexisting fracture angles and the mechanical properties of the rock impact real-time cracking propagation modes and crack propagation shape, has practical implications. The researchers used ABAQUS software to apply simulated seismic loading to their model and studied crack propagation using the extended finite element method (XFEM). They found that the crack propagation shape and real-time cracking propagation vary based on the preexisting fracture angles and the mechanical properties of the rock. Additionally, they observed a significant relationship between strain leading to nonlinear deformations and the mechanical properties and fracture seismic toughness mechanism. These findings can be applied to improve the prediction of failure mechanisms in rocks with different crack shapes and could potentially enhance seismic response simulation and geotechnical earthquake engineering codes. The numerical simulation results were validated and compared to existing literature, further highlighting the practical applications of this study's findings. Doi: 10.28991/CEJ-2025-011-01-01 Full Text: PD
Downscaling GRACE Data for Improved Groundwater Forecasting Using Artificial Neural Networks
Get PDFThis study introduces a dual-phase approach utilizing Artificial Neural Networks (ANNs) to overcome the challenges of groundwater monitoring at regional scales. Traditional well-based methods provide limited spatial coverage, while GRACE satellite data, despite its value for large-scale hydrological analysis, suffers from low spatial resolution (~300 km), limiting its application for local-scale assessments. Existing downscaling methods such as geographically weighted regression and Random Forests are computationally intensive and often lack adaptability to complex groundwater systems. In this study, Phase 1 refines GRACE data using ANNs to achieve a 4í—4 km spatial resolution, addressing the resolution challenge for regional applications. Phase 2 integrates the downscaled GRACE data with groundwater well observations and climatic factors to predict groundwater levels with high accuracy (R² = 0.9885). This dual-phase framework demonstrates significant improvements over existing methods, providing an efficient and scalable solution for groundwater monitoring in hydrologically complex regions. The findings highlight the potential of machine learning to enhance groundwater resource management, particularly in addressing water scarcity and climate variability challenges. Doi: 10.28991/CEJ-2025-011-02-01 Full Text: PD
Development and Validation of a Seismic Index for Assessing the Vulnerability of Low-Rise RC Buildings
Get PDFThis research develops a comprehensive framework for evaluating the seismic vulnerability of Afghanistan's low-rise reinforced concrete (RC) structures, aiming to enhance urban resilience and mitigate seismic risks. The primary objective is to improve structural safety and reduce economic losses and casualties during devastating earthquakes. Utilizing a database of low-rise RC buildings constructed between 2001 and 2022 by the Ministry of Urban Development and Housing (MUDH) and the Ministry of Education (MOE), the study analyzes structures with varying materials, architectural styles, construction years, and number of stories. The methodology integrates a modified Japanese Is Index, refined using statistical techniques to incorporate local seismic data and building characteristics across diverse seismic zones. Advanced analyses, including the Capacity Spectrum Method (CSM) and dynamic analysis using STERA 3D software, support the development of the Afghanistan Seismic Index (ASI). Findings confirm ASI's reliability by comparing it to existing seismic assessment methods, demonstrating its suitability for region-specific evaluations. The research proposes a novel, tailored seismic index (ASI) for assessing seismic vulnerability and addressing gaps in Afghanistan's building code (ABC) and standards. This framework enhances structural performance and informs future policy, providing a foundation for safer urban environments and sustainable infrastructure development in earthquake-prone regions. Doi: 10.28991/CEJ-2025-011-03-016 Full Text: PD
Mechanical Properties of Sustainable Base Course Binder Incorporating GGBFS and Spent FCC Catalyst
Get PDFThis study investigates the feasibility of utilizing ground granulated blast furnace slag (GGBFS) and spent fluid catalytic cracking (FCC) catalyst as partial cement replacements in pavement base course materials. Various blends of GGBFS and FCC catalyst were evaluated as binders for unbound granular base (UGB) material, with total binder content fixed at 10% by weight. Mechanical properties were assessed through unconfined compressive strength (UCS) and splitting tensile strength tests at 3, 7, 28, and 56 days. Microstructural analysis was conducted using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results indicate that an optimal blend of 60% FCC and 40% GGBS achieved the highest UCS of 9.6 MPa at 56 days, exceeding typical requirements for cement-treated base materials. All investigated mix proportions surpassed the minimum 28-day strength requirement of 4 MPa for pavement base applications. Splitting tensile strength results corroborated compressive strength trends, with enhanced tensile-to-compressive strength ratios suggesting improved crack resistance potential. Microstructural analysis revealed a dense, well-reacted cementitious system supporting the observed mechanical performance. These findings demonstrate the technical feasibility and potential environmental benefits of incorporating high volumes of GGBS and spent FCC catalyst in pavement base materials, offering a sustainable alternative to conventional cement-based binders. Doi: 10.28991/CEJ-2025-011-03-012 Full Text: PD
Stability Analysis of Dike Pond Due to Pore-Water Pressure Changes
Get PDFThe Brigif retention pond not only serves to temporarily store rainwater for groundwater reserving but also reduces the risk of flooding in the Southern Jakarta area. Research was purposed to study two critical conditions of a dike made from clayey material from before to after water impounding stages correlating with its stability. The research will investigate pore-water pressure (u) parameter changes at any stage in both conditions. The parameter of (u) can be predicted (upre) using the laboratory consolidation or oedometer test and measured (uact) completely with hydrostatic pressure (u0) directly in the field. Actual measurements using a piezometer were also conducted on the body of the dike. The prediction analysis used the self-developed program and conventional geotechnical software. The critical peak depth of (u) was found at 3.0 to 4.0 m. The actual settlement potential values reached -0.10 to -1.42 m and matched the prediction result. Safety factor (SF) was around 2.0 to 4.0, or in stable condition. Research results found that the magnitude parameter of (u) could be influenced by groundwater flow and porosity or void ratio fluctuations. The consolidation process also would affect the physical soil pore, contributing to the change of (SF) the dike pond
On the Impact of Lacing Reinforcement Arrangement on Reinforced Concrete Deep Beams Performance
Get PDFThe optimum design is characterized by structural concrete components that can sustain loads well beyond the yielding stage. This is often accomplished by a fulfilled ductility index, which is greatly influenced by the arrangement of the shear reinforcement. The current study investigates the impact of the shear reinforcement arrangement on the structural response of the deep beams using a variety of parameters, including the type of shear reinforcement, the number of lacing bars, and the lacing arrangement pattern. It was found that lacing reinforcement, as opposed to vertical stirrups, enhanced the overall structural response of deep beams, as evidenced by test results showing increases in ultimate loads, yielding, and cracking of 30.6, 20.8, and 100%, respectively. There was also a 53.6% increase in absorbed energy at the ultimate load. The shear reinforcement arrangement had a greater impact and a significant effect on the structural response than the number of lacing bars. For lacing reinforcement with a phase difference equivalent to the half-lacing cycle (i.e., phase lag lacing), the percentage of improvement under different loading stages was 6.7-27.1% and 20.8-113.3%, respectively. The structural responses are significantly impacted by the lacing arrangement; members with two and three lacing bars, respectively, exhibited improvements in ultimate load of 30.6% and 47%. Beyond the yielding stage, the phase lag lacing specimens deviated from those without phase lag lacing and normal shear stirrups because of the lacing contribution. Phase lag specimens showed more strain than specimens without phase lag lacing, meaning that the lacing reinforcement contributed more to the beam strength. It was found that the first shear cracking load of all the laced reinforced specimens was higher than that of the conventional shear stirrup specimens. Phase lag lacing produced the greatest improvement, with two bars achieving 92.44% and three bars achieving 217.07%. For the aforementioned number of bars, lacing shear reinforcement without phase lag was less successful, with 36.91% and 46.53%, respectively. Doi: 10.28991/CEJ-2025-011-02-019 Full Text: PD
Fire Resistance of Crushed Brick-Based Alkali-Activated Mortars
Get PDFThis study investigates the fire resistance of alkali-activated mortar incorporating crushed brick as both a precursor and aggregate. The optimal alkaline activator was identified as a combination of KOH and Na₂SiO₃, with a curing period of 3 days at 70 °C. Two mortar series were produced, each exhibiting different workability: on series comprised cement mortar, while the other included three alkali-activated mortars, with variations in the molarity of the KOH solution. The mortar samples were subsequently heated to 600°C, and their mechanical properties and mass were measured to determine residual values/losses. The best-performing alkali-activated and cement mortars underwent visual assessments of cross-sections to evaluate the impact of mortar consistency on fire resistance. Additionally, changes in mineralogy and microstructure were followed by instrumental techniques to clarify the results before and after heating. While cement mortars had superior mechanical properties at room temperature, alkali-activated mortars retained a higher percentage of their mechanical properties post-heating, demonstrating better fire resistance. Mortars with plastic consistency showed better fire resistance than those with fluid consistency. These findings suggest that brick-based alkali-activated mortars could be developed into fire protection boards for structural members. Doi: 10.28991/CEJ-2025-011-04-05 Full Text: PD