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Evaluation of Alkali-Activated Mortar Incorporating Combined and Uncombined Fly Ash and GGBS Enhanced with Nano Alumina
Get PDFThe present research focuses on assessing the fresh and hardened properties as well as the durability performance of alkali-activated mortar in an ambient environment and the impact of integrating nano-alumina (NA) at a 2% ratio as a substitute for binder materials in alkali-activated mortar (AAM). Additionally, it assesses the effectiveness of alkali-activated mortar employing different blends of ground granulated blast furnace slag (GGBS) and fly ash as environmentally friendly substitute building materials. Fly ash (FA), ground granulated blast slag (GGBS), and an equal mixture of GGBS and FA make up these binder ingredients. As a result, the main binders contain GGBS, FA, or a 50/50 mixture of GGBS and FA. The sodium hydroxide (NaOH) concentration is fixed at a 12-molarity level, and the alkali activator solution to binder ratio is kept at 0.5. In the alkali solution, the ratio of sodium silicate to sodium hydroxide is always 2.5. The study evaluates various properties of AAM, such as compressive strength, flowability, unit weight, flexural tensile strength, and durability, under ambient conditions at a steady room temperature of 23±3°C. Results indicate that AAM mixtures devoid of NA exhibit a higher flow rate compared to those containing NA. Nonetheless, the flowability of AAM mixtures aligns well with standard requirements, being modest yet adequate. Significantly, the inclusion of NA enhances the mechanical properties and durability of AAM, demonstrating its beneficial effects. Doi: 10.28991/CEJ-2024-010-03-016 Full Text: PD
Effectiveness of Grouting and GFRP Reinforcement for Repairing Spalled Reinforced Concrete Beams
Get PDFCorrosion of steel reinforcement from chloride exposure can compromise the strength of reinforced concrete structures. Rust formation expands, applying pressure on concrete, resulting in cracks and spalling. Prompt repair is crucial for severe cases of spalling. This research assessed the efficacy of repair strategies for reinforced concrete beams post-spalling, including grouting and different techniques involving Glass Fiber Reinforced Polymer (GFRP) reinforcement. The research examined four variations of reinforced concrete beams, each sized at 150 mm í— 200 mm í— 3300 mm. Results showed that the standard beam (BK) had an average maximum load capacity of 29.74 kN. In contrast, the grouted beam (BGR) demonstrated a reduced maximum load of 14.39 kN, along with decreased steel and concrete strain compared to BK. This suggests that the grouting repair did not fully restore the beam's flexural capacity after spalling. Incorporating GFRP strips (BGRS) led to a marginal increase in the beam's maximum load, albeit remaining below BK, with lower steel and concrete strain than BK. However, the steel and concrete approached their yield points, indicating enhanced flexural performance. The full-wrap GFRP beam (BGRSF) experienced an 8.08% increase in maximum load compared to BK, with concrete strain surpassing BK, suggesting an enhancement in flexural stiffness. Doi: 10.28991/CEJ-2024-010-07-05 Full Text: PD
Strength and Deformability of Structural Steel for Use in Construction
Get PDFThe purpose of the study is an experimental determination of the stress-related characteristics of the structural steel produced in the Republic of Kazakhstan for use in conventional and earthquake-resistive construction. Since 2015, the construction industry has been using European regulatory documents”Eurocodes”as a statutory framework. In particular, the Eurocode 1993 for steel structures and the Eurocode 1998 for the design of earthquake-resistant structures However, the study of stress-related properties of structural steel using experimental methods of ISO standards has not been performed. Therefore, in the construction industry of the Republic of Kazakhstan, steel-work structures have been used in fairly limited volume since 2015. The experimental studies were conducted on 7 types of structural steel with thicknesses of 8, 10, and 20 mm manufactured by Arcelor Mittal. The yield strength, ultimate tensile strength (breaking stress), and tensile strength at break were studied. The experimental studies were carried out on the basis of ISO standards. In each test run, 5 samples were used. In two series, 20 samples each were tested, which made it possible to estimate the yield strength and strength distribution functions. The correlation relationships between Brinell hardness and yield and strength limits have been studied. As a result of experimental studies, it was found that the strength and deformability parameters fully comply with the requirements of Eurocode 1993. Based on the application of the Student's test, it is revealed that the distribution functions of yield strength and resistance correspond to the normal law (Gaussian function). The calculation of a three-story, two-span residential building with box section columns for construction in an area with a seismicity of 8 points is performed by the finite element method. The work results will significantly increase the scope of Kazakhstani structural steel use in seismic and conventional areas of the Republic of Kazakhstan. Doi: 10.28991/CEJ-2024-010-03-09 Full Text: PD
Investigating Barriers to the Adoption of Energy Management Practices for Sustainable Construction Projects: SEM and ANN Approaches
Get PDFThis research addresses the critical challenges hindering the integration of Energy Management Practices (EMPs) within the construction industry, impeding its progress toward sustainability. Recognizing the pivotal role of EMPs in fostering sustainable practices, this study aims to fill a notable research gap by conducting a meticulous survey involving 100 industry professionals. Through the application of Partial Least Squares Structural Equation Modeling (PLS-SEM) and Artificial Neural Network (ANN) analyses, this study provides a comprehensive exploration of the intricate barriers and their interrelated dynamics within the construction sector. The findings reveal significant financial obstacles, including higher initial costs and limited financing options, underscoring the need for interventions to alleviate financial constraints. Additionally, policy and regulatory challenges, such as limited government incentives and shifting energy management rules, are identified, highlighting the necessity for stable and supportive regulatory environments to foster EMP adoptions. This research provides unique insights into the barriers hindering EMP adoption within the construction sector. The implications of this study extend beyond EMP adoption, offering a foundation for advancing sustainable practices in the construction industry. The insights gained can inform both academic research and practical decision-making, contributing to the ongoing discourse on sustainability in construction. Doi: 10.28991/CEJ-2024-010-04-015 Full Text: PD
Corrosion Resistance of Reinforcing Steel in Concrete Using Natural Fibers Treated with Used Engine Oil
Get PDFThe addition of natural fibers in the elaboration of concrete pastes has increased as an innovative alternative for the development of more ecological and environmentally friendly constructions. The objective of this research is to incorporate natural fiber residues from palm leaves and mango stone impregnated with used engine oil (UEO) in the cement matrix to improve the mechanical and electrochemical properties of reinforced concrete. Samples with fiber percentages of 0.2% and 0.4% with respect to the weight of the sand with a length of 10 mm were fabricated. Their properties, such as workability, air content, porosity, and compressive and flexural strength, were analyzed. To understand the corrosion rate of the steel bars, electrochemical techniques of corrosion potential, electrochemical noise, linear polarization resistance, and electrochemical impedance spectroscopy were applied to cubic samples exposed in a 3% sodium chloride saline environment for 365 days. The experimental results showed a positive effect on the corrosion phenomenon with the UEO and mango fiber treatment, decreasing the corrosion rate due to the formation of a protective film at the steel/concrete interface. Doi: 10.28991/CEJ-2024-010-04-02 Full Text: PD
Performance Index Model of Small Dam in Semi-Arid Area
Get PDFThe aim of this research is to build a model of small dam performance index in semi-arid areas by considering 4 aspects that are physical, institution, service, and operation and maintenance aspects. Research locations are 85 small dams that spread to 8 islands and 5 SWS in 22 regencies in Nusa Tenggara Timur Province. The data consists of secondary data from BWS NT II and primary data from survey results and survey blank filling to 85 locations of small dams in the field. The methodology consists of Structural Equation Modeling Partial Least Squares (SEM-PLS) and Generalized Reduced Gradient (GRG). The analysis result shows that physical; institution; service; and operation and maintenance aspects are significantly influenced by the performance index of small dams. The structural analysis expresses that physical; institution; service; and operation and maintenance aspects are positively and significantly influenced by the performance index of small dams. The novelty in this research is the performance index of small dams that is successfully developed and tested by using field data and GRG. In addition, this model gives accurate value to the performance index of small dams in semi-arid areas in Nusa Tenggara Timur Province. However, the performance index model of small dams in semi-arid areas is formulated as follows: IK physical = 0.093 KT + 0.128 KTE + 0.159 KBS + 0.087 BPL + 0.155 JD + 0.145 KBLY + 0.233 KBP; IK institution = 0.58 DOP + 0.42 RA; IK service = 0.56 KBL + 0.09 AM + 0.12 VG + 0.09 WK + 0.14 PA; IKOM = 0.360 PKOP + 0.515 PPE + 0.125 KSOP. The general formulation for performance index of small dams is I IDK-Pentewati = 0.15 IK physical + 0.12 IK institution + 0.20 IK service + 0.53 IK OM. Doi: 10.28991/CEJ-2024-010-08-014 Full Text: PD
Artificial Intelligence for Application in Water Engineering: The Use of ANN to Determine Water Quality Index in Rivers
Get PDFTo improve water quality, total daily loads must be established, and this requires determining the quality of the water in rivers, storage tanks, ponds, and coastal areas. Current methods to evaluate water quality involve the collection of water samples for subsequent laboratory analysis. Although these technologies offer precise measurements for a specific location and time, they are expensive, time-consuming, and do not provide the continuous, temporal, or spatial conditions of water quality that are required for managing, assessing, and monitoring water quality. In order to calculate the water quality, the water quality index is modeled using artificial neural network models that incorporate feedforward neural network backpropagation neural networks and radial neural networks. The water quality index of Malaysia's Klang River was determined by training the artificial network using six major sub-quality parameters. Compared to the current method, the artificial neural network simplifies and expedites the computation of the water quality index. The artificial neural network method could provide a significant saving in terms of money and time while offering a robust assessment of water quality. The proposed method could also be used as an early warning system for pollution of water bodies. The best artificial neural network was the feedforward neural network with one hidden layer containing 5 neurons. Furthermore, conventional approaches for calculating the water quality index rely on empirical equations, often introducing a high degree of approximation and uncertainty into the results. Moreover, these equations cannot be applied when some parameters are not measured. In contrast, the artificial neural network methods and technique offer an efficient and straightforward process for estimating and creating prediction models for water quality index. Doi: 10.28991/CEJ-2024-010-07-012 Full Text: PD
Performance of NSM GFRP Retrofitted Postfire RC Slabs Under Monotonic and Cyclic Loadings
Get PDFThis study investigated the performance and mechanical properties of NSM GFRP retrofitted postfire RC slabs under monotonic and cyclic loadings. Experiments were conducted for eight RC slabs exposed to different fires. These postfire slabs were retrofitted with NSM GFRP bars, which were then monotonically and cyclically loaded until failure. The results indicated that the control slab failed in flexure, with steel yielding and a main mid-span crack. NSM GFRP retrofitted postfire slabs failed by either crushing of compressive concrete or rupture of GFRP bars. The tested slabs were characterized by bi-linear behavior. NSM GFRP retrofitting improved the yield and ultimate loads of postfire slabs by 47.2% and 116.4% on average, respectively. Fire duration was confirmed to be a main factor that significantly reduced the elastic stiffness of NSM GFRP retrofitted postfire slabs by 60.9% for 60 min of fire. The average plastic-to-elastic stiffness of NSM GFRP retrofitted postfire slabs was 0.132, which was 32 times that of the control slab. The cyclic loading effect caused substantial stiffness degradation of NSM GFRP retrofitted postfire slabs. The average stiffness degradations were 10.6% and 7.2% for original and NSM GFRP retrofitted postfire slabs, respectively. However, the cyclic loading effect caused negligible strength degradation. The combination of increasing fire duration and the cyclic loading effect significantly decreased ductility. Theoretical analyses were carried out to estimate the yield moments of slabs. The analytical equation demonstrated its accuracy in estimating the yield moment capacity of postfire RC slabs without and with NSM GFRP retrofitting. Doi: 10.28991/CEJ-2024-010-06-017 Full Text: PD
Natural Rubber Latex-Modified Concrete with Bottom Ash for Sustainable Rigid Pavements
Get PDFThis article investigates the viability of using natural rubber latex (NRL)-modified concrete with bottom ash (BA) as a partial replacement for river sand in sustainable rigid pavements. Concrete mixes with 10% and 20% BA replacement ratios and varying NRL dosages (0%, 1.0%, 1.5%, and 2.0% by weight of cement) were prepared and evaluated for their mechanical and microstructural characteristics. Results showed that BA substitution decreased the compressive strength of concrete. However, the addition of NRL at an optimal dosage of 1.0% significantly improved both the compressive and flexural strengths. The 10%BA+1.0%NRL and 20%BA+1.0%NRL mixes exhibited mechanical properties surpassing the control mix and meeting the minimum requirements for rigid pavement materials. However, excessive NRL content (1.5% and 2.0%) led to a reduction in mechanical strength. Scanning electron microscopy analysis exhibited a denser and more compact matrix in NRL-modified BA concrete, with NRL films enhancing the interfacial bonding and crack-bridging mechanism. Nonetheless, excessive NRL content resulted in the formation of abundant and thicker NRL films, which disrupted the continuity of the cement matrix and created weak zones. X-ray diffraction analysis confirmed the existence of crucial crystalline phases and their optimal balance in the 20%BA+1.0%NRL mix, contributing to its superior performance. Mixes with excessive NRL contents exhibited lower intensities of quartz, calcite, and portlandite peaks, indicating a disturbance in the proper formation and growth of essential crystalline phases. The findings demonstrated the potential of NRL-modified BA concrete as an eco-friendly and high-performance alternative for sustainable rigid pavements when using an optimal NRL dosage, promoting the employment of waste resources and reducing the environmental impact of the construction industry. Doi: 10.28991/CEJ-2024-010-08-05 Full Text: PD
Evaluation of GPM IMERG Product Against Ground Station Rainfall Data in Semi-Arid Region
Get PDFBenanain River is the longest and largest river on Timor Island, with a length of 132 km and an area of 6,460.12 km². In this region, a significant factor affecting the presence of surface water sources is rainfall. To compensate for the lack or unavailability of automatic Rainfall Data (RD) in the Benanain River Basin (BRB), Global Rainfall Measurement (GPM) data from 1998 to 2018 (20 years) were used. The accuracy of GPM rainfall analysis was obtained when parameter conformity and compatibility with data recorded at Rainfall Station (RS) were maintained. The difficulty of predicting rainfall values, spatially and temporally, in the field led to data gaps and unreliable data for analysis needs. Additionally, RD obtained from observation stations contributed to measuring rainfall because there was insufficient RD for analysis in a few regions. The challenge of accurately predicting rainfall values in the field led to differences in data, rendering it unreliable for analysis. To address this issue, satellite data was required as an alternative method to estimate rainfall. Among a total of 7 RS, only 2 passed rainfall characteristic tests. Following this discussion, Lahurus station showed a correlation coefficient of 0.7046, an RMSE of 25.89, and an NSE of 0.476. In addition, the rainfall characteristic test result for Haliwen Station was 1.66 (R100/R2). The second station that passed was Kaubele Station, signifying a correlation coefficient of 0.7907, RMSE of 25.28, and NSE of 0.604. Additionally, the rainfall characteristic test result for Haliwen Station was 3.04 (R100/R2) and the daily performance of the GPM product in the rainy season with low rainfall (≤ 50 mm) was better compared to extreme rainfall (≥ 100 mm). In this study, corrected GPM daily RD in the range >100 mm was underestimated. This analysis implied that the GPM IMERG Final Run product on daily and monthly rainfall timescales had strong detection capabilities and provided data support for long-time series investigations on Timor Island. Doi: 10.28991/CEJ-2024-010-12-09 Full Text: PD