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Designing Climate-Adaptive Buildings: Impact of Courtyard Geometry on Microclimates in Hot, Dry Environments
No full textDesigning climate-adaptive buildings is crucial for mitigating the adverse effects of climate change by enhancing energy efficiency and reducing greenhouse gas emissions. Additionally, such designs improve thermal comfort and resilience in urban environments, particularly in regions with extreme climates, thereby promoting sustainable living conditions. This study aims to mitigate climate change through strategic urban and building design, focusing on the impact of building geometry and courtyard configurations on enhancing microclimates and thermal comfort in the UAE's hot arid climate. Utilizing ENVI-met software for qualitative analysis, the research examines design modifications in a school building's layout and courtyards. The analysis and findings reveal that strategic alterations can reduce outdoor air temperatures by up to 1.45°C and average building temperatures by approximately 1.89°C. Additionally, these modifications significantly improve thermal comfort perceptions on the PMV scale. The findings underscore the potential of architectural design to contribute to climate change mitigation efforts, highlighting the importance of thoughtful building and courtyard designs in promoting sustainable architecture and urban planning. This study offers novel insights into the role of design in enhancing thermal environments, providing a practical approach for developing climate-adaptive buildings in hot, dry environments. Doi: 10.28991/CEJ-2024-010-08-017 Full Text: PD
Comparative Study of UPV and IE Results on Concrete Cores from Existing Structures
No full textDynamic non-destructive methods (NDT) are particularly attractive owing to their time and cost efficiency when compared to conventional uniaxial compressive strength tests. However, the results of these methods are highly scattered; therefore, they are primarily used for qualitative material characterization. One of the most important NDT results is the calculation of the dynamic Young's modulus, which is associated to the uniaxial compressive strength (UCS) of concrete. The ultrasonic pulse velocity (UPV) is the most commonly used NDT. The limitation of this method is that it directly depends on knowledge of the Poisson's ratio, and an assumption of its value must be made. This assumption results in highly scattered results. In contrast, the impact echo method (IE) can result in a dynamic Young's modulus calculation without knowing the Poisson's ratio. The limitation of this method is that it is dependent on the specimen's slenderness, which in turn depends on the Poisson's ratio. This study investigates the IE method's applicability to short cylinders. A comparison of the UPV and IE methods is made, and the error in the dynamic Young's modulus value derived by assuming Poisson's ratio value in the UPV method is calculated. The authors conducted a numerical analysis and recently proposed the use of a shape correction factor (SCF) to apply the IE results for short cylinders, considering the influence of the slenderness (L/D) of the samples. For the first time worldwide, an extensive experimental study on 232 concrete samples with L/D ≈ 1.0 confirmed the wide spread of UPV test results and showed that it can lead to an error on Young's Modulus determination by up to 50% owing to the adoption of an arbitrary Poisson's ratio value. In contrast, using the SCF yields IE results with a ±2% error. A new methodology, ultrasonic pulse impact echo synergy (UPIES), is proposed by performing both UPV and IE tests on the specimens and using the SCF. The Poisson's ratio and, consequently, the Young's modulus can be accurately determined. Doi: 10.28991/CEJ-2024-010-09-03 Full Text: PD
Global Buckling Strength of Girts with Inner Flange in Compression
No full textThe objective of this paper is to provide guidance on improving the lateral-torsional buckling strength of cold-formed, channel-section wall girts subjected to leeward wind loads, which cause the inner flange to compress. Additionally, it aims to identify the cross-sectional dimensions that most affect this strength. This is necessary due to the observation that the lateral-torsional buckling strength, with the inner flange in compression, of those members is significantly lower than that of the outer flange due to the difference in lateral bracing lengths, which leads to material waste. The available methods for improving the lateral-torsional buckling of girts when the inner flange is in compression were first summarized. Then, a parametric study was performed on three typical channel cross-sections. Sixty-three cases were created by varying flange width, lip length, cross-sectional depth, and thickness within practical ranges. These cases were solved manually for lateral-torsional buckling strengths using Microsoft Excel. The results showed that increasing the flange width is the most effective way to improve the flexural strength without considering the bracing effect of sheathings, Mnl, while increasing the cross-section thickness is the best for the strength considering the sheathing effect, Mn. Therefore, a new asymmetrical section with a larger inner flange width is recommended for girts when Mnlgoverns the strength. Doi: 10.28991/CEJ-2024-010-11-05 Full Text: PD
Evaluating the Rutting Resistance of Asphalt Mixtures Containing Waste Steel and Treated Recycled Concrete Aggregate
No full textUsing treated recycled concrete aggregate (RCA) in asphalt with waste steel reinforcement benefits the economy and the environment while delaying asphalt pavement deterioration. This study examined the impact of using RCA in several percentages reinforced by three dosages of waste steel: 0.3, 0.6, and 0.9 added as a proportion of mixture weight. The RCA was immersed in a 0.1M Hydrochloric acid solution for one day to treat the weak cement mortar in RCA and reduce the thickness of this layer. The assessment was carried out in a laboratory using the typical Marshall test to determine the optimum quantity of asphalt contents, the volumetric properties of asphalt mixtures, and the wheel tracking test; the study involved ten rectangular slabs measuring 30í—40í—5 cm, and they were repeatedly subjected to 700 N wheel loads at 55°C to test their rut resistance. According to the study, while Marshall's stability increased, adding waste steel and RCA did not significantly alter the volumetric properties of asphalt mixes. The greatest improvement in Marshall stability, 45.18% over the conventional mix, was seen in the mix, including 75% RCA and 0.9% waste steel. The rutting performance decreased with the addition of RCA and rose with the inclusion of waste steel. The results indicate that adding waste steel to asphalt mixtures effectively increases the rutting resistance. The mixture with 50% RCA and 0.9% waste steel showed less rutting depth of 25.01% than the conventional mix. Doi: 10.28991/CEJ-2024-010-11-011 Full Text: PD
Evolution and Implications of Changes in Seismic Load Codes for Earthquake Resistant Structures Design
No full textSeismic load is a critical load that can trigger damage or collapse of structures, especially in earthquake-prone areas. The susceptibility of structures to seismic loads is influenced by factors related to soil characteristics and structural behavior. This paper comprehensively examines the development of Indonesian seismic code design parameters and their comparison with the current seismic code. The results of the analysis showed that the design spectral acceleration of short-period AD and long-period A1 SKBI 1987 and SNI 2002 increased with increasing PGA values, with a consistent pattern of SC < SD < SE. Unlike the previous two codes, design spectral acceleration AD and A1 SNI 2012 and SNI 2019 experience fluctuations in all types of soil. The ratio design spectral acceleration of AD and A1 SNI 2019 to KBI 1987 and SNI 2002 varies; there are up, fixed, and down for SC, SD, and SE soil conditions. The ratio of design spectral acceleration AD and A1 SNI 2019 to SNI 2012 designs also varies; this condition is due to changes in site coefficients. There were significant changes to the SKBI 1987 and SNI 2002 structural systems, especially the low and medium seismic levels. The increase in the seismic influence coefficient ratio of some cities varies for each type of soil and code. The increase in the 1970 PMI seismic coefficient was < 30% for all soil types, and the highest percentage increase occurred in SC soil types. The increase in seismic coefficient in SKBI 1987, SNI 2002, and SNI 2012 is more dominant in SE soil types. Doi: 10.28991/CEJ-2024-010-01-04 Full Text: PD
Cost Efficiency of Retrofitting Green Chemical Industrial Buildings
No full textClimate change is a threat and crisis that hit the world today. The green industry is widely implemented in the manufacturing sector as an effort to reduce negative impacts on the environment. The implementation of the green industry is influenced by various factors. The Chemical Industry is one sector that faces challenges in implementing green industry practices. The objective of this paper is to create an innovative conceptual framework that combines blockchain technology and building information modeling. This research examines the concept of green retrofitting in the chemical industry using an assessment based on the Ministry of Public Works and Housing Regulation No. 21 of 2021. The study was conducted in a chemical industry located in Cilegon, Banten, Indonesia. The research method combines Blockchain-Building Information Modeling (BIM) to analyze the cost efficiency of green retrofitting and Structural Equation Modeling-Partial Least Squares (SEM-PLS) as a tool to process data from questionnaires and identify influential factors. The results indicate that the use of Blockchain-BIM can reduce retrofitting costs by 4.42% for low-level, 4.45% for medium-level, and 4.40% for high-level categories. This demonstrates that Blockchain-BIM has a significant impact on improving cost performance in the retrofitting process. Doi: 10.28991/CEJ-2024-010-03-04 Full Text: PD
Novel Ni/ZnO Nanocomposites for the Effective Photocatalytic Degradation of Malachite Green Dye
No full textWater scarcity threatens human civilization because of rapid industrialization's damage to freshwater sources. Pollutants like dyes, which are frequently found in the paper, leather, food, plastics, textile, and cosmetics industries, must be removed to preserve water. In the present study, Zinc oxide nanocomposites impregnated with nickel (Ni/ZnO) were prepared using a wet impregnation technique. These novel materials were investigated for their ability to photocatalytically degrade malachite green (MG) under the irradiation of visible. The synthesized nanocomposite catalyst was characterized by various analytical techniques, including SEM, EDX, XRD, and BET methods of surface analysis, and revealed a high surface area of 192.88 m2g-1 with an average size range from 88-354 nm. EDX results showed efficient doping of Ni (28.9%). The composites were then used under the influence of a visible light source to degrade MG dye. The investigation also assessed the degradation of MG using a photo-Fenton reagent. Factors such as catalyst dosage, H2O2 levels, pH, and duration were optimized to understand their impact in both degradation studies. The synthesized catalyst showed stunning photocatalytic activities, as 99.4% of the 60 µg.ml-1of MG was degraded in 40 min with 100 mg of Ni/ZnO at pH 8. Ni/ZnO had a good application prospect for MG degrading and can be used as a potential photocatalyst. Doi: 10.28991/CEJ-2024-010-08-011 Full Text: PD
Evaluating the Impact of Material Selections, Mixing Techniques, and On-site Practices on Performance of Concrete Mixtures
No full textThis 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
Vulnerability Index Assessment for Mapping Ground Movements Using the Microtremor Method as Geological Hazard Mitigation
No full textVarious geological disasters, such as landslides and ground movements, occur annually in Srimulyo Village, Malang District, with varying levels of damage. Ground movements can affect structures built above, causing sinking, cracking, and collapse. Research into landslides and ground movements triggered by vibrations is generally conducted using the microtremor method, which has proven effective. This study uses the microtremor method to map the soil condition that is potentially prone to movement or landslides based on the observed soil vulnerability index. Data was collected using a TDL 303s Digital Portable Seismograph instrument; the measurement points were established in the form of a grid distributed across the research area, with a recording duration of approximately 45 minutes at each point. The analysis technique utilizes the Horizontal Vertical Spectrum Ratio (HVSR) based on the Fast Fourier Transform (FFT) principle. The study's results found that the research location's seismic vulnerability index varies between 6.5 and 16.5. Areas with high seismic vulnerability index values, specifically those with Kg>11.5, are scattered on the west, south, and southeast sides of the research location. Based on field observations, these areas are dominated by relatively thick sediment layers, leading to lower dominant frequency values and higher amplification values; consequently, the seismic vulnerability index in the southern region is also high. Doi: 10.28991/CEJ-2024-010-05-017 Full Text: PD
Optimizing Alkali-Concentration on Fresh and Durability Properties of Defected Sanitary Ware Porcelain based Geopolymer Concrete
No full textIntroducing defective sanitaryware porcelain as a low-calcium binder for geopolymer mix concrete was regarded as green concrete. Four alkali concentrations (8M, 10M, 12M, and 14M) mixes involving four initial curing temperatures (60°C, 75°C, 90°C, and 105°C) were investigated for porosity, rapid chloride penetration, compressive and abrasive resistance. Tests on geopolymer paste for consistency and initial and final setting times were also assessed. For all the mixes, consistency and setting time decreased with increased alkali concentration levels. An increment in curing temperature increased the setting time rate. Microstructural studies such as X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were carried out, and the results were presented. The compressive and abrasive resistance of the specimen performance increased with an increase in the initial curing temperature and alkali concentration level. Majorly, the mechanical strength of porcelain-based geopolymer specimens increased by increasing the alkali concentration level. Applying 105°C for the initial curing temperature to the specimen, compressive strength, abrasive resistance, and resistibility to chloride ingress of the specimen enhanced. At the 28-days curing period, the ultimate compressive strength was 68.03 N/mm2, the lowest weight loss from abrasive motion was 0.09%, and the lowest passing charge was 1,440.91 coulombs were recorded respectively. As a result, porcelain-based geopolymers required a high initial curing temperature and a high alkali concentration level. It was found that 14M porcelain-based specimens heated at 105°C curing temperature for 24 hours led to an eco-friendly concrete mix with prominent positive results for engineering properties. Doi: 10.28991/CEJ-2024-010-04-05 Full Text: PD