2031 research outputs found
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Measurement Model for Determining the Disparity Factors of Intercity Railway Transportation
Get PDFCountries that are still developing experience significant disparities in access to railway services, as these nations also grapple with societal inequality issues that remain unaddressed. In developed countries, railway transportation systems serve as the primary mode of transportation for both passengers and goods. However, in recent years, studies on disparities in developed countries have increased, while literature concerning developing countries remains scarce. Therefore, this study takes place in Thailand, a developing country facing significant population disparities. The objective is to examine factors contributing to these disparities in access to railway transportation systems across cities, using Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) to identify user disparities. The sample group comprises 1,252 randomly selected railway users from various regions in Thailand, obtained through Stratified Random Sampling. The results reveal seven dimensions of disparities: cultural, spatial, societal, political, knowledge-based, economic, and environmental. The CFA results also highlight cultural disparities as a significant factor in explaining access disparities among railway users. These findings can inform relevant organizations, aiding them in better understanding the actual needs of railway users and aligning railway development plans accordingly. Ultimately, this contributes to policy development aimed at reducing access disparities and fostering a more equitable society. Doi: 10.28991/CEJ-2024-010-03-01 Full Text: PD
Behavior of Fire-damaged RC Beams After Strengthening with Various Techniques
Get PDFHigh temperatures during a fire can significantly degrade the structural capacity of concrete. However, in many cases, it is possible to restore and strengthen fire-damaged concrete rather than completely rebuild damaged structures. The study considered two types of concrete (normal 25 MPa and high-strength 65 MPa) with two types of strengthening techniques: carbon-fiber-reinforced polymers (CFRP) sheets with different thicknesses of 1.5 and 2.5 mm and slurry-infiltrated fibrous concrete (SIFCON) jacketing with different fiber sizes of 20 and 30 mm. The numerical simulations and analyses were conducted to capture the complex behavior of fire-damaged concrete members (beams). A fire-damaged concrete beam subjected to an extreme or critical fire Exposure time (2 hours) was evaluated and modified using a finite element simulation approach. The simulation process included three stages: the first, subjecting the concrete beam to thermal loading; the second, reflecting the fire distribution map to another model of applying mechanical loading; and the third, involving the application of strengthening to the damaged model. The results showed that the strengthening using CFRP with a thickness of 2.5 improved the load-carrying capacity compared with SIFCON in both types of concrete. 200% improvement for the normal-strength concrete beam and a 136% improvement for the high-strength concrete beam, compared to the damaged beams. Doi: 10.28991/CEJ-2024-010-01-012 Full Text: PD
Behavior of Axially Loaded Concrete Columns Reinforced with Steel Tubes Infilled with Cementitious Grouting Material
Get PDFThe paper presents a novel method of reinforcing concrete columns using small-diameter steel tubes instead of traditional steel bars. The researchers conducted experimental investigations on twelve mid-scale circular concrete column specimens, which were divided into two groups consisting of six specimens each: short and long columns. Two of the specimens in each group were reinforced with steel bars, while the remaining four were reinforced with steel tubes filled with cementitious grouting material. The study proposed two concepts for cementitious grouted steel-tube reinforcement. The first concept utilized steel tubes with equivalent net areas to the steel bar areas used in the reference column, while the second concept used steel-tube reinforcement with the same diameter as the steel bars in the reference column. Nonlinear Finite Element (FE) analyses were conducted on experimental specimens using ABAQUS software. The results showed that using steel tubes with an area equivalent to that of steel bars instead of conventional columns increased the bearing capacity of reinforced concrete columns by 17%. Moreover, using steel tubes whose area matched 30% of the steel bar area achieved a bearing capacity of about 81% of the conventional concrete columns. The experimental and FE analysis findings indicate that this methodology can increase the bearing capacity of reinforced concrete columns when compared to traditional methods. The axial load-axial displacement curves, axial load-axial strain curves, and failure load of the FE model all demonstrated good convergence with the experimental data. Doi: 10.28991/CEJ-2024-010-02-017 Full Text: PD
Evaluating the Impact of Material Selections, Mixing Techniques, and On-site Practices on Performance of Concrete Mixtures
Get PDFThis paper aims to evaluate the influence of sand quality, water-to-cement ratio, binder properties, mix design methods, and mixing techniques on the fresh and hardened properties of concrete. The physicochemical characteristics of coarse aggregates, sands, and binders were analyzed. The experimental results show that the binders and coarse aggregates met standard specifications. However, none of the sands meet construction standards. Corrections were necessary for the dune sands to meet construction standards in terms of grain size distribution and fineness modulus. The results also show that the concretes formulated using the Dreux-Gorisse method exhibited higher quality than the locally formulated concretes. Furthermore, it was found that hand mixing resulted in inadequate mixing, material wastage, lower strength, and increased porosity, whereas machine mixing produced concretes with a more homogeneous microstructure, uniform particle distribution, lower porosity, and higher strength. The batch variability and compressive strength of the hand-mixed concretes were also found to be influenced by the expertise level of the batch mixer and the number of successive hand batches. It was also found that both the soluble silica and the inert methods are reliable for determining binder content in machine-mixed concrete. However, the soluble silica method occasionally exhibited significant variations in hand-mixed concrete compared to the inert method. A combined approach utilizing the average of both methods enhances the overall reliability of the binder content values. Observations on construction sites revealed widespread deviations from recommended guidelines. Issues such as lack of material inspection, proper stockpiling, ingredient contamination, and inadequate batch mixing contributed to variations in concrete workability, porosity, and compressive strength. Doi: 10.28991/CEJ-2024-010-02-016 Full Text: PD
Influence of Maintenance Funds on Improve Road Steadiness with the Curva Expert Program
Get PDFSustainable road construction is instrumental in improving connectivity among regions and economies while also offering road users a diverse range of options within the traffic network. To ensure optimal road performance for users, it becomes essential to allocate adequate maintenance funds that correlate with the planned service life. This necessity originates from a profound understanding of the significant influence maintenance funds have on road steadiness. Therefore, this study aims to establish a comprehensive road steadiness model, investigating the influence of toll roads as new routes and the impact on maintenance funds. The analysis included national roads across 15 cities in Central Java Province, Indonesia, covering a distance of 759.75 km from 2018–2023. Using a quantitative approach, the study adopted the Curva Expert program to evaluate the values of road steadiness and maintenance funds. The results showed a 5.78% enhancement in road steadiness over the period from 2018 to 2023, underscoring the positive impact of sustainable road construction practices and the allocation of adequate maintenance funds. The establishment of relationship between road steadiness and maintenance funds was established through a regression value of R2=0.94. This statistical correlation is represented by the equation y= 90.521 + 0.022x, providing a quantitative understanding of how maintenance funds influence road steadiness. The insights obtained from the outcomes of road steadiness modeling reiterate the significance of investing in additional routes and ensuring sufficient maintenance funds to improve performance. Doi: 10.28991/CEJ-2024-010-02-014 Full Text: PD
Integrating Technology and Heritage Design for Climate Resilient Courtyard House in Arid Region
Get PDFThis research has investigated the sustainability and climate resilience of courtyard houses of adobe architecture in the UAE. It analyzed design effectiveness in terms of power consumption, CO2 emissions, thermal comfort, and daylight use, employing simulations to assess building structures and construction systems. Adopting a three-phase mixed-methods approach, the study began with a literature review on courtyard house design, construction, and environmental performance, emphasizing sustainable design and passive ventilation. The second phase involved a case study of a UAE courtyard house (Al Midfa), including site visits, interviews, and energy consumption and CO2 emission data collection. The final phase used building energy simulation software to model energy performance and evaluate passive ventilation's role in reducing energy consumption and CO2 emissions, with simulation results validated against real-world data. Advanced Sefaira simulations with the Energy Plus Engine identified one out of seven modified models (M5) as exceptionally thermally efficient, influencing the architectural design of the Al Midfa house. To transform the Al Midfa house into a sustainable climate-resistant structure, the research suggested retrofitting with new glazing and insulation on the inside of external walls and on the roof surface at a combined U-value of 0.4 W/m2to enhance energy efficiency without altering the exterior. A notable innovation was the use of injected cellulose insulation in wall systems, combining efficient insulation with architectural aesthetics, signifying a shift towards energy-efficient interior modifications. The study's findings contribute to the evolution of traditional house designs toward climate change resilience and a sustainable future. Doi: 10.28991/CEJ-2024-010-03-018 Full Text: PD
Influence of Sunflower Seed Husks Ash on the Structure Formation and Properties of Cement Concrete
Get PDFThe limitation of the application of non-renewable materials is one of the solutions to the problem of the sustainable evolution of civilization in the 21st century. Using additional binders in concrete obtained from plant waste will be economically and environmentally beneficial and will also allow us to move closer to achieving sustainable development goals. This study searches for rational composition components and a methodological approach regarding the technological characteristics to get the highest quality elements and prime concrete properties on the basis of sunflower seed husk ash (SSHA). Experimental concrete specimens were manufactured with partial Portland cement substitution with SSHA amounts ranging from 2% to 16% by weight in increments of 2%. This study focuses on investigating the density and workability of the concrete mixture, along with the compressive strength, concrete density, and water absorption. This article used granulometric, microscopic, and X-ray phase analysis methods. Including SSHA in all considered ranges reduces the slump in concrete mixtures. The optimal SSHA content in concrete is up to 12%. An 8% SSHA content has been found to deliver the most favorable mechanical characteristics of the concrete studied. The compressive strength of the investigated concrete has increased by 14.89%, and water absorption has decreased by 15.78%. Doi: 10.28991/CEJ-2024-010-05-08 Full Text: PD
Effect of Coal Combustion Waste on Cement-Treated Clay
Get PDFHigh 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
Local Scour around Different-Shaped Bridge Piers
Get PDFLocal scour around piers is the major cause of bridge failures, and its estimation is critical for safe design. The present study aims to identify a modified pier shape that can reduce local scour compared to a circular pier. In addition, M5 models are developed for maximum scour depth prediction and compared with the existing equations available in the literature. Thus, the effect of pier shape and alignment on local scour is experimentally investigated using three pier models with the same cross-sectional area placed in isolated and tandem arrangements under clear-water conditions. These are circular (M1) and two modified pier shapes (M2 and M3), where M2 is a combination of semi-circle and triangle oriented either way (M2a and M2b), and M3 is a further modification to M2a with a small protrusion on the semi-circular end. The results showed that the local scour depth for aligned (skew angle, α = 0°) M2a, M2b, and M3 piers is reduced by 23.5%, 50%, and 55%, respectively, compared to the M1 pier but not if α > 0°. In tandem arrangements, the least scour depths observed around M1 and M2a at X = 1.0D (X is clear-spacing between piers and D is pier diameter), and M3 and M1 at X = 1.75D placed as front and rear pier, respectively. It is observed that the developed M5 models are more accurate compared to the existing equations. Flow intensity (V/Vc) and αhave more influence on the scour depth prediction around tandem and isolated piers, respectively. Doi: 10.28991/CEJ-2024-010-06-019 Full Text: PD
GGBFS and Red-Mud based Alkali-Activated Concrete Beams: Flexural, Shear and Pull-Out Test Behavior
Get PDFGeopolymers and antacid-enacted fasteners have accumulated critical interest as promising development and fixing materials because of their exceptional properties. Also, they bring about less contamination contrasted with regular concrete cements. Geopolymers address a clever class of suggested restricting materials blended through the basic enactment of bountiful aluminosilicate materials. The usage of geopolymer materials from side effects offers a critical decrease in carbon impression and yields positive natural effects. Geopolymer is progressively recognized as a plausible substitute for OPC concrete. In this review, sodium-based antacid activators, especially sodium metasilicate (Na2SiO3), were used for different blend extents. The boundaries researched included NaOH arrangements with a grouping of 8 M, alongside a Na2SiO3/NaOH proportion of 1. This paper evaluates the fundamental characteristics of geopolymer cement beams, employing red mud and GGBFS in powdered form as complete replacements for traditional concrete. Six bar specimens are tested under a two-point static loading condition, all cured at room temperature under ambient conditions. Of the six beams, three were exposed to flexural conduct testing with a molarity of 8 M, while the excess three beams were tried for shear conduct. The outcomes of testing geopolymer beams subjected to shear and bending loads indicated that the beams incorporating aluminum slag performed better than those incorporating blast furnace slag. Both types also demonstrated promising results compared to beams incorporating OPC, highlighting their potential environmental benefits compared to cement use. Doi: 10.28991/CEJ-2024-010-05-09 Full Text: PD