Tarbiat Modares UniversityModares Civil Engineering journal2476-676326220260622Analytical Evaluation of the Effect of Geometry and Local Configuration of Diagrid Structures on the Robustness Component of Seismic ResilienceAnalytical Evaluation of the Effect of Geometry and Local Configuration of Diagrid Structures on the Robustness Component of Seismic Resilience19322404710.48311/mcej.2026.24047FAMaryamKhalajzadehKharazmi UniversitySafooraMorshed-ShekarchiKharazmi UniversityAfshinMeshkat-DiniKharazmi UniversityAliMassumiKharazmi UniversityJournal ArticleDiagrid structure is an extended resistant skeleton based on framed tube system which has been considered in high-rise buildings constructions due to its architectural aesthetics and configurational character. These general characteristics are demonstrated by reducing the consuming materials through removing columns and the application of a grid configuration of diagonal elements. The seismic behaviour of such a structure is affected by the configuration angle and the axial capacity of the diagonal members. With the dominance of axial function, the diagonal elements also resist lateral loads caused by wind and earthquake, and also play a key role in limiting the amplitude of inelastic behaviour. Therefore, the seismic performance of diagonal elements would reduce the process of formation and expansion of nonlinear zones in diagrid structures. According to the lack of guiding principles for the integrated design of diagrid structures, there is a high demand for extensive researches in collecting comprehensive and effective criteria for estimating stiffness and strength parameters, establishing dynamic stability and understanding how the resilience of these structures change due to dynamic loads caused by wind and earthquake. <br><br>In this study, the seismic performance of three 20-story studied diagrid buildings with the same structural system under a set of near-field records has been evaluated. The particular focus of this study is on evaluating the effect of the geometry and configuration of the resistant skeleton in the ground floor and the entrance section on the behavioural characteristics. In this paper, an analytical study has been run on the drift response parameter, the results of incremental dynamic analysis (IDA), fragility curve and the seismic resilience component under the selected earthquake records. The analytical results of this study show a close convergence between the behavioural characteristics of all three studied structures.Diagrid structure is an extended resistant skeleton based on framed tube system which has been considered in high-rise buildings constructions due to its architectural aesthetics and configurational character. These general characteristics are demonstrated by reducing the consuming materials through removing columns and the application of a grid configuration of diagonal elements. The seismic behaviour of such a structure is affected by the configuration angle and the axial capacity of the diagonal members. With the dominance of axial function, the diagonal elements also resist lateral loads caused by wind and earthquake, and also play a key role in limiting the amplitude of inelastic behaviour. Therefore, the seismic performance of diagonal elements would reduce the process of formation and expansion of nonlinear zones in diagrid structures. According to the lack of guiding principles for the integrated design of diagrid structures, there is a high demand for extensive researches in collecting comprehensive and effective criteria for estimating stiffness and strength parameters, establishing dynamic stability and understanding how the resilience of these structures change due to dynamic loads caused by wind and earthquake. <br><br>In this study, the seismic performance of three 20-story studied diagrid buildings with the same structural system under a set of near-field records has been evaluated. The particular focus of this study is on evaluating the effect of the geometry and configuration of the resistant skeleton in the ground floor and the entrance section on the behavioural characteristics. In this paper, an analytical study has been run on the drift response parameter, the results of incremental dynamic analysis (IDA), fragility curve and the seismic resilience component under the selected earthquake records. The analytical results of this study show a close convergence between the behavioural characteristics of all three studied structures.https://mcej.modares.ac.ir/article_24047_bad65e96c2c6456a4f82970601d39714.pdfTarbiat Modares UniversityModares Civil Engineering journal2476-676326220260622Assessing Experimental Relationships and Numerical Modeling for Predicting Discharge Coefficient of Rectangular Piano Key Weirs using Response Surface MethodologyAssessing Experimental Relationships and Numerical Modeling for Predicting Discharge Coefficient of Rectangular Piano Key Weirs using Response Surface Methodology7182781310.48311/mcej.2025.97991.0FAAkbarSafarzadehFaculty Member, Water Engineering Group, Faculty of Civil and Environmental Engineering, Tarbiat Modares UniversityHooshangVelayatiMsC of Civil Engineering, University of Mohaghegh ArdabiliJournal Article20180619This study examines the hydraulic relationships provided for piano-key weirs. The hydraulic relationships presented by researchers in various sources include multiple geometric parameters in some cases, while others focus only on a limited number of these parameters. In the first step, using the RSM-CCD method and data from Anderson's study (2011), the discharge coefficient relations were derived in the relative head ranges of 0.1-0.2 and 0.2-0.9, with a total of 18 data points. In the second step, through laboratory and numerical model designs, the derived relationship using the RSM-CCD method was compared and evaluated against other hydraulic relationships for piano-key weirs. This comparison was done using statistical indices and the discharge-head ratio charts. The statistical index values obtained from generalizing the discharge coefficient relation using the RSM-CCD method to Anderson's (2011) 115 laboratory data points were R² = 0.9985, MAE = 0.0034, and RMSE = 0.0041, indicating the accuracy of this method, despite using fewer data points. Evaluation of the hydraulic relationships presented for predicting the discharge coefficient of the physical model of the studied piano-key weir, using statistical indices, shows the good performance of the relationships by Liet-Ribeiro et al. (2012) and Michaels (2012). The R², MAPE, and RMSE values for these two relationships are 0.99, 5.05%, 0.063, and 0.96, 6.8%, 0.071, respectively. Comparison of the discharge-head ratio charts derived from the RSM-CCD method and laboratory models shows that the accuracy of this relationship increases with increasing relative flow head. The MAPE values for the relative head ranges of 0.1-0.3 and 0.3-0.8 were 11% and 1.25%, respectively, which can be considered when predicting discharge at high relative heads.This study examines the hydraulic relationships provided for piano-key weirs. The hydraulic relationships presented by researchers in various sources include multiple geometric parameters in some cases, while others focus only on a limited number of these parameters. In the first step, using the RSM-CCD method and data from Anderson's study (2011), the discharge coefficient relations were derived in the relative head ranges of 0.1-0.2 and 0.2-0.9, with a total of 18 data points. In the second step, through laboratory and numerical model designs, the derived relationship using the RSM-CCD method was compared and evaluated against other hydraulic relationships for piano-key weirs. This comparison was done using statistical indices and the discharge-head ratio charts. The statistical index values obtained from generalizing the discharge coefficient relation using the RSM-CCD method to Anderson's (2011) 115 laboratory data points were R² = 0.9985, MAE = 0.0034, and RMSE = 0.0041, indicating the accuracy of this method, despite using fewer data points. Evaluation of the hydraulic relationships presented for predicting the discharge coefficient of the physical model of the studied piano-key weir, using statistical indices, shows the good performance of the relationships by Liet-Ribeiro et al. (2012) and Michaels (2012). The R², MAPE, and RMSE values for these two relationships are 0.99, 5.05%, 0.063, and 0.96, 6.8%, 0.071, respectively. Comparison of the discharge-head ratio charts derived from the RSM-CCD method and laboratory models shows that the accuracy of this relationship increases with increasing relative flow head. The MAPE values for the relative head ranges of 0.1-0.3 and 0.3-0.8 were 11% and 1.25%, respectively, which can be considered when predicting discharge at high relative heads.https://mcej.modares.ac.ir/article_27813_fc2208d8522b90cf01368d83dbfe9906.pdfTarbiat Modares UniversityModares Civil Engineering journal2476-676326220260622Predicting the number of accidents in rail-road level crossings using the Poisson zero-adjusted model and demographic factors approachPredicting the number of accidents in rail-road level crossings using the Poisson zero-adjusted model and demographic factors approach33472781410.48311/mcej.2025.99117.0FASeyed AliMosayebiIran university of science and technologyMohammadHoseiniIran unviersity of science and technolgyRezaMohammad HasanyIran university of science and technologyJournal Article20241113Rail transport holds a special place among transportation methods due to its cost-effectiveness and high safety. However, the intersection of road and rail networks at grade crossings compromises railway safety and results in significant financial and human losses. This study aims to identify the factors influencing the number of accidents at these crossings and provide a method for prioritizing grade crossings in Iran with a focus on improving safety. Based on data from the last 10 years leading up to 2022, the 1385 Persian calendar population blocks, and the characteristics of 130 grade crossings, this research utilizes the Zero-Inflated Poisson model, which offers higher accuracy compared to previous studies in Iran. The study also seeks to diversify the variables influencing accidents and explore their relationships with grade crossing incidents. The model consists of two parts: the Poisson section, which analyzes the number of accidents based on influencing factors such as road usage type, the male-to-female population ratio within a 5-mile radius, distance to the nearest intersection, total passing trains, total population within the 5-mile radius, and the number of tracks at the crossing. An increase in these variables correlates with more accidents, while a higher number of tracks at a crossing lead to fewer accidents. The second part of the model is the logistic section, which assesses the probability of zero accidents occurring. Factors such as the availability of an alternative route when the crossing is closed, the male-to-female population difference within a 5-mile radius, and the average daily road traffic all affect this probability. Increasing the first two factors raises the likelihood of zero accidents, while increased traffic lowers this probabilityRail transport holds a special place among transportation methods due to its cost-effectiveness and high safety. However, the intersection of road and rail networks at grade crossings compromises railway safety and results in significant financial and human losses. This study aims to identify the factors influencing the number of accidents at these crossings and provide a method for prioritizing grade crossings in Iran with a focus on improving safety. Based on data from the last 10 years leading up to 2022, the 1385 Persian calendar population blocks, and the characteristics of 130 grade crossings, this research utilizes the Zero-Inflated Poisson model, which offers higher accuracy compared to previous studies in Iran. The study also seeks to diversify the variables influencing accidents and explore their relationships with grade crossing incidents. The model consists of two parts: the Poisson section, which analyzes the number of accidents based on influencing factors such as road usage type, the male-to-female population ratio within a 5-mile radius, distance to the nearest intersection, total passing trains, total population within the 5-mile radius, and the number of tracks at the crossing. An increase in these variables correlates with more accidents, while a higher number of tracks at a crossing lead to fewer accidents. The second part of the model is the logistic section, which assesses the probability of zero accidents occurring. Factors such as the availability of an alternative route when the crossing is closed, the male-to-female population difference within a 5-mile radius, and the average daily road traffic all affect this probability. Increasing the first two factors raises the likelihood of zero accidents, while increased traffic lowers this probabilityhttps://mcej.modares.ac.ir/article_27814_b1134631cfcd61e4c42f25102802c8f6.pdfTarbiat Modares UniversityModares Civil Engineering journal2476-676326220260622Implementation of an Advanced Modern System for Seawater Desalination and Transportation: A Case Study of Chalus CityImplementation of an Advanced Modern System for Seawater Desalination and Transportation: A Case Study of Chalus City49632781610.48311/mcej.2025.99129.0FAKooshaAghazadehuniversity of tehranREZAAttarnejaduniversity of tehranJournal Article20241229This article presents a comprehensive analysis of an innovative seawater desalination and transfer system, hereafter referred to as the "desalination pipeline system." This system seeks to provide an efficient solution for freshwater shortages, particularly in coastal regions. The proposed system is structured into three main stages: evaporation, transfer, and condensation. Each stage is intricately detailed, elucidating the processes and formulations involved, while underlining the system’s remarkable capabilities in achieving high transfer speeds and substantial desalination capacities. Focusing on the specific context of Chalus—a coastal city in Iran—and the adjacent heights of Kelardasht, the study underscores the unique geographical and climatic conditions of the region. The interplay between the marine environment and the mountainous terrain creates a potential opportunity for harnessing seawater through an effective desalination process. By exploring various pipe diameters within the system, the research challenges the conventional wisdom that larger diameters are inherently better for maximizing freshwater output and operational efficiency. Contrary to these assumptions, the findings indicate that utilizing smaller diameter pipes can result in significantly higher vapor speeds. Nevertheless, it is crucial to regulate these speeds to prevent vapor velocities from surpassing the speed of sound, which could lead to inefficiencies and operational issues. The methodology employs pipelines with diameters of 1 meter and 2 meters for the transfer of vapor over a distance of 15 kilometers, transporting it from the Chalus area to Alam Kuh, which is situated at an elevation of 1,800 meters. This distance and elevation present unique challenges and opportunities, as they require precise engineering to ensure the effective movement of desalinated water. The study reveals that the efficiency of sub-atmospheric vapor transfer is primarily influenced by three key factors: pipe diameter, transfer distance, and the temperature difference between the seawater and the receiving mountain peaks. These findings provide critical insights into the design and operation of the desalination pipeline system. Specifically, the research quantifies the performance of the two pipe diameters under investigation. The results demonstrate that a 2-meter diameter pipe can produce an average of 3,950 cubic meters of freshwater daily, of which 2,950 cubic meters are effectively transferred to the higher altitude. In contrast, the 1-meter diameter pipe yields 850 cubic meters of water per day, with 710 cubic meters successfully transferred. These figures highlight the balance between pipe diameter and transfer efficiency, emphasizing that various configurations can still lead to the effective delivery of freshwater resources. This characteristic minimizes the need for extensive pre-treatment processes or additional energy inputs, making the operation both environmentally friendly and economically viable. In conclusion, the proposed desalination pipeline system offers a progressive approach to addressing freshwater shortages, presenting a cost-effective and efficient alternative to many existing desalination methods. By leveraging the unique geological and climatic conditions of the Chalus and Kelardasht region, this system not only maximizes the potential of seawater resources but also contributes to sustainable water management practices. Future studies could expand upon these findings, exploring long-term operational viability, environmental impacts, and potential scalability to further enhance the system's applicability in other regions facing water scarcity.This article presents a comprehensive analysis of an innovative seawater desalination and transfer system, hereafter referred to as the "desalination pipeline system." This system seeks to provide an efficient solution for freshwater shortages, particularly in coastal regions. The proposed system is structured into three main stages: evaporation, transfer, and condensation. Each stage is intricately detailed, elucidating the processes and formulations involved, while underlining the system’s remarkable capabilities in achieving high transfer speeds and substantial desalination capacities. Focusing on the specific context of Chalus—a coastal city in Iran—and the adjacent heights of Kelardasht, the study underscores the unique geographical and climatic conditions of the region. The interplay between the marine environment and the mountainous terrain creates a potential opportunity for harnessing seawater through an effective desalination process. By exploring various pipe diameters within the system, the research challenges the conventional wisdom that larger diameters are inherently better for maximizing freshwater output and operational efficiency. Contrary to these assumptions, the findings indicate that utilizing smaller diameter pipes can result in significantly higher vapor speeds. Nevertheless, it is crucial to regulate these speeds to prevent vapor velocities from surpassing the speed of sound, which could lead to inefficiencies and operational issues. The methodology employs pipelines with diameters of 1 meter and 2 meters for the transfer of vapor over a distance of 15 kilometers, transporting it from the Chalus area to Alam Kuh, which is situated at an elevation of 1,800 meters. This distance and elevation present unique challenges and opportunities, as they require precise engineering to ensure the effective movement of desalinated water. The study reveals that the efficiency of sub-atmospheric vapor transfer is primarily influenced by three key factors: pipe diameter, transfer distance, and the temperature difference between the seawater and the receiving mountain peaks. These findings provide critical insights into the design and operation of the desalination pipeline system. Specifically, the research quantifies the performance of the two pipe diameters under investigation. The results demonstrate that a 2-meter diameter pipe can produce an average of 3,950 cubic meters of freshwater daily, of which 2,950 cubic meters are effectively transferred to the higher altitude. In contrast, the 1-meter diameter pipe yields 850 cubic meters of water per day, with 710 cubic meters successfully transferred. These figures highlight the balance between pipe diameter and transfer efficiency, emphasizing that various configurations can still lead to the effective delivery of freshwater resources. This characteristic minimizes the need for extensive pre-treatment processes or additional energy inputs, making the operation both environmentally friendly and economically viable. In conclusion, the proposed desalination pipeline system offers a progressive approach to addressing freshwater shortages, presenting a cost-effective and efficient alternative to many existing desalination methods. By leveraging the unique geological and climatic conditions of the Chalus and Kelardasht region, this system not only maximizes the potential of seawater resources but also contributes to sustainable water management practices. Future studies could expand upon these findings, exploring long-term operational viability, environmental impacts, and potential scalability to further enhance the system's applicability in other regions facing water scarcity.https://mcej.modares.ac.ir/article_27816_90c838391b2bb4cf27115449e681bf84.pdfTarbiat Modares UniversityModares Civil Engineering journal2476-676326220260622Solving Viscoelastic Problems Using Complex Fourier Boundary Element MethodSolving Viscoelastic Problems Using Complex Fourier Boundary Element Method65772781710.48311/mcej.2025.99145.0FAMahdiehBahrampourSalehHamzehei-JavaranShahid Bahonar University of Kerman0000-0002-7341-4314Journal Article20250313A complex Fourier boundary element method for two-dimensional numerical analysis of viscoelastic materials such as rubber, concrete, polymers, or biological substances using radial basis functions (RBF) is proposed in the current paper. This matter was considered due to the fact that the demand for a much more realistic vision is increasing as science proceeds towards optimized approaches. The classic reciprocal work theorem is reconsidered in the well-known boundary element method (BEM) when complex Fourier RBFs serve as shape functions instead of the customary ones. These functions can satisfy various areas such as exponential and trigonometric fields as well as polynomial fields. Afterwards, displacements and tractions are approximated and compared to both Lagrangian and analytical procedures for three benchmark problems to determine the validity and stability of the proposed method. The results show magnificent accuracy and efficiency for the Fourier method in comparison with the classic approach, and by considering the fact that more accurate results are gained while incorporating fewer degrees of freedom in the analysis procedure, it was concluded that the suggested method is both economical and more efficient.A complex Fourier boundary element method for two-dimensional numerical analysis of viscoelastic materials such as rubber, concrete, polymers, or biological substances using radial basis functions (RBF) is proposed in the current paper. This matter was considered due to the fact that the demand for a much more realistic vision is increasing as science proceeds towards optimized approaches. The classic reciprocal work theorem is reconsidered in the well-known boundary element method (BEM) when complex Fourier RBFs serve as shape functions instead of the customary ones. These functions can satisfy various areas such as exponential and trigonometric fields as well as polynomial fields. Afterwards, displacements and tractions are approximated and compared to both Lagrangian and analytical procedures for three benchmark problems to determine the validity and stability of the proposed method. The results show magnificent accuracy and efficiency for the Fourier method in comparison with the classic approach, and by considering the fact that more accurate results are gained while incorporating fewer degrees of freedom in the analysis procedure, it was concluded that the suggested method is both economical and more efficient.https://mcej.modares.ac.ir/article_27817_67ba8120f499c6706644ce234fc5ee1c.pdfTarbiat Modares UniversityModares Civil Engineering journal2476-676326220260622Experimental investigation on mechanical and durability properties of twisted basalt fiber reinforced concreteExperimental investigation on mechanical and durability properties of twisted basalt fiber reinforced concrete79932781810.48311/mcej.2025.99146.0FAHesammodinNasaj MoghadamPh.D. Student, Department of Civil Engineering, Shahrood University of Technology, Shahrood, IranFarshidJandaghi AlaeeAssociate Professor, Department of Civil Engineering, Shahrood University of Technology, Shahrood, IranJournal Article20250315The corrosion of steel reinforcement is a major challenge for concrete structures in marine environments, reducing their durability and structural integrity. While steel fibers are commonly used in Fiber Reinforced Concrete (FRC), their susceptibility to corrosion and pitting has led researchers to explore non-metallic alternatives. Basalt fiber, a non-metallic material, offers numerous advantages, including high tensile strength, non-toxicity, and excellent resistance to acidic and corrosive environments. This study investigates the mechanical and durability properties of Basalt Fiber Reinforced Concrete (BFRC) with twisted basalt fibers at different volume fractions. Four mixtures containing 0%, 0.5%, 1%, and 1.8% fiber content were prepared and compared to Normal Concrete (NC). Mechanical properties, including compressive strength, splitting tensile strength, and modulus of rupture (MOR), were assessed. The results indicated that compressive strength marginally increased from 48.4 MPa for NC to 51.3 MPa for BFRC-1.8, representing a 6% improvement attributed to the crack-bridging action of the fibers. More notable were the enhancements in splitting tensile strength, which increased from 2.8 MPa in NC to 4.1 MPa in BFRC-1.8, reflecting a 46% gain. The incorporation of twisted basalt fibers also shifted the failure mode from brittle to ductile, enabling the concrete to absorb and dissipate more energy before failure. Flexural performance, measured via MOR, improved by 15%, 40%, and 81% for fiber additions of 0.5%, 1%, and 1.8%, respectively, with corresponding increases in toughness values reaching up to 364%. These results demonstrate the superior energy absorption and resilience of BFRC under loading. Durability properties, including water penetration depth, water absorption, electrical resistivity, and performance under accelerated corrosion testing, were also evaluated. Durability assessments showed marked improvements with increased fiber content. Water penetration depth decreased substantially (by 18–53%), while water absorption dropped from 2.3% in NC to 1.28% for BFRC-1.8, confirming the ability of fibers to reduce porosity and fill microcracks, thereby protecting internal steel from ion ingress. Electrical resistivity tests revealed that greater fiber content produced higher electrical resistance, further impeding the initiation and progression of corrosion. Results from accelerated corrosion testing demonstrated that twisted basalt fibers are highly effective in mitigating steel rebar corrosion. Corrosion rates were substantially reduced from 0.55 mm/year in NC to 0.25, 0.16, and 0.09 mm/year for BFRC-0.5, BFRC-1, and BFRC-1.8, respectively. Similarly, rebar weight loss decreased from 49.9% in NC to 22.7%, 14.1%, and 8.6% in the respective BFRC mixtures. The time to the first visible crack caused by corrosion was delayed, increasing from 55 days in NC to 74 days in BFRC-1.8. These findings indicate that twisted basalt fibers effectively impede the passage of aggressive ions, markedly improving the durability of reinforced concrete in severe environments. In summary, incorporating twisted basalt fibers into concrete blends offers measurable benefits in both mechanical and durability properties, with a pronounced effect in suppressing steel reinforcement corrosion, making BFRC a highly promising, sustainable material for marine infrastructureThe corrosion of steel reinforcement is a major challenge for concrete structures in marine environments, reducing their durability and structural integrity. While steel fibers are commonly used in Fiber Reinforced Concrete (FRC), their susceptibility to corrosion and pitting has led researchers to explore non-metallic alternatives. Basalt fiber, a non-metallic material, offers numerous advantages, including high tensile strength, non-toxicity, and excellent resistance to acidic and corrosive environments. This study investigates the mechanical and durability properties of Basalt Fiber Reinforced Concrete (BFRC) with twisted basalt fibers at different volume fractions. Four mixtures containing 0%, 0.5%, 1%, and 1.8% fiber content were prepared and compared to Normal Concrete (NC). Mechanical properties, including compressive strength, splitting tensile strength, and modulus of rupture (MOR), were assessed. The results indicated that compressive strength marginally increased from 48.4 MPa for NC to 51.3 MPa for BFRC-1.8, representing a 6% improvement attributed to the crack-bridging action of the fibers. More notable were the enhancements in splitting tensile strength, which increased from 2.8 MPa in NC to 4.1 MPa in BFRC-1.8, reflecting a 46% gain. The incorporation of twisted basalt fibers also shifted the failure mode from brittle to ductile, enabling the concrete to absorb and dissipate more energy before failure. Flexural performance, measured via MOR, improved by 15%, 40%, and 81% for fiber additions of 0.5%, 1%, and 1.8%, respectively, with corresponding increases in toughness values reaching up to 364%. These results demonstrate the superior energy absorption and resilience of BFRC under loading. Durability properties, including water penetration depth, water absorption, electrical resistivity, and performance under accelerated corrosion testing, were also evaluated. Durability assessments showed marked improvements with increased fiber content. Water penetration depth decreased substantially (by 18–53%), while water absorption dropped from 2.3% in NC to 1.28% for BFRC-1.8, confirming the ability of fibers to reduce porosity and fill microcracks, thereby protecting internal steel from ion ingress. Electrical resistivity tests revealed that greater fiber content produced higher electrical resistance, further impeding the initiation and progression of corrosion. Results from accelerated corrosion testing demonstrated that twisted basalt fibers are highly effective in mitigating steel rebar corrosion. Corrosion rates were substantially reduced from 0.55 mm/year in NC to 0.25, 0.16, and 0.09 mm/year for BFRC-0.5, BFRC-1, and BFRC-1.8, respectively. Similarly, rebar weight loss decreased from 49.9% in NC to 22.7%, 14.1%, and 8.6% in the respective BFRC mixtures. The time to the first visible crack caused by corrosion was delayed, increasing from 55 days in NC to 74 days in BFRC-1.8. These findings indicate that twisted basalt fibers effectively impede the passage of aggressive ions, markedly improving the durability of reinforced concrete in severe environments. In summary, incorporating twisted basalt fibers into concrete blends offers measurable benefits in both mechanical and durability properties, with a pronounced effect in suppressing steel reinforcement corrosion, making BFRC a highly promising, sustainable material for marine infrastructurehttps://mcej.modares.ac.ir/article_27818_7d4a64abdf664973b622937d6f83d078.pdfTarbiat Modares UniversityModares Civil Engineering journal2476-676326220260622Investigating the mechanical properties of sprayable fiber reinforced cementitious composites containing limestone calcined clay cementInvestigating the mechanical properties of sprayable fiber reinforced cementitious composites containing limestone calcined clay cement951092855710.48311/mcej.2025.99160.0FASajjadMirzamohammadiPh.D/ Department of structural Engineering, Tarbiat Modares University, Tehran, Iran0000-0002-0797-2377SajjadMirzamohammadiProfessor / Department of structural Engineering, Tarbiat Modares University, Tehran, IranJournal Article20250511The construction industry is particularly cost-sensitive, thus new materials should be justified, and their economic advantages should be satisfactory. Over the last 50 years, using fiber-reinforced cement base materials has significantly increased. Among them, a particularly malleable category includes engineered cementitious composites (ECC), strain hardening cementitious composites (SHCC), and ultra-high toughness cementitious composites (UHTCC). These high-performance fiber reinforced cementitious based materials (HPFRCC) show considerable strain hardening capacity. Meanwhile, it is crucial to consider how these new materials (HPFRCC) will affect the environment. Indeed, the quantity of cement or cementitious materials used in their manufacturing may sometimes approach 1000 kg/m3. Substituting supplemental materials with cementitious properties for clinker is one of the greatest ways to reduce carbon dioxide emissions from HPFRCC manufacture (supplementary cementitious materials). Clays-containing kaolinite is one of the acceptable auxiliary ingredients for cement with good accessibility. These clays are among the substances that are widely distributed over the globe. When heated to 700-850°C, clays with at least 40% kaolinite produce metakaolin and become significantly pozzolanic. The simultaneous addition of calcined clay, and limestone to replace with part of the clinker in the mixed design results in LC3 or cement consisting of calcined clay and limestone, which reduces carbon emissions by roughly 30% turns into dioxide (CO2). The optimal substitution ratio of OPC by LC3 is 50% clinker, 30% calcined clay (MK), 15% limestone powder, and 5% gypsum. Therefore, the optimal OPC substitution ratio by LC3 is 45% (55% OPC, 30% metakaolin, and 15% limestone powder) with kaolin content of around 40-50% in the clay. This study developed a sprayable HPFRCC using local materials such as limestone calcined clay cement (LC3) and ordinary polypropylene (PP) fiber to increase the durability of structures (as a material for repairing) without harming the environment. The developed composite's sprayability and mechanical performance were investigated through a flow table, compressive strength, uniaxial tension, and three-point flexural tests. Moreover, the material sustainability index (MSI) was used to evaluate the performance of the mixes in terms of consumed energy and carbon emissions. Finally, using LC3 and ordinary polypropylene fibers, it was possible to achieve sprayable HPFRCC with a tensile strain capacity of 3.5%. Furthermore, this composite exhibits low carbon production, low cost, and high ductility, promoting its use in infrastructure repairs. The compressive strength of cast specimens was 11% higher than that of the sprayed specimens. The reason for this was their apparent density difference and porosity (i.e. the compressive strength of the cast specimens was higher due to their lower porosity). The bending and tensile strengths of the cast specimens were, respectively, 14% and 22% lower than those of the sprayed specimens due to pneumatic compaction during the spraying process; the distribution of fibers in the sprayed specimens was more uniform, resulting in greater bending and tensile strengths. However, the flexural deformation and tensile strain capacity of the sprayed and cast specimens were almost equal. Moreover, A superplasticizer/binder (LC3 mass) ratio of 2.5% must be chosen for spraying HPFRCC containing calcined clay.The construction industry is particularly cost-sensitive, thus new materials should be justified, and their economic advantages should be satisfactory. Over the last 50 years, using fiber-reinforced cement base materials has significantly increased. Among them, a particularly malleable category includes engineered cementitious composites (ECC), strain hardening cementitious composites (SHCC), and ultra-high toughness cementitious composites (UHTCC). These high-performance fiber reinforced cementitious based materials (HPFRCC) show considerable strain hardening capacity. Meanwhile, it is crucial to consider how these new materials (HPFRCC) will affect the environment. Indeed, the quantity of cement or cementitious materials used in their manufacturing may sometimes approach 1000 kg/m3. Substituting supplemental materials with cementitious properties for clinker is one of the greatest ways to reduce carbon dioxide emissions from HPFRCC manufacture (supplementary cementitious materials). Clays-containing kaolinite is one of the acceptable auxiliary ingredients for cement with good accessibility. These clays are among the substances that are widely distributed over the globe. When heated to 700-850°C, clays with at least 40% kaolinite produce metakaolin and become significantly pozzolanic. The simultaneous addition of calcined clay, and limestone to replace with part of the clinker in the mixed design results in LC3 or cement consisting of calcined clay and limestone, which reduces carbon emissions by roughly 30% turns into dioxide (CO2). The optimal substitution ratio of OPC by LC3 is 50% clinker, 30% calcined clay (MK), 15% limestone powder, and 5% gypsum. Therefore, the optimal OPC substitution ratio by LC3 is 45% (55% OPC, 30% metakaolin, and 15% limestone powder) with kaolin content of around 40-50% in the clay. This study developed a sprayable HPFRCC using local materials such as limestone calcined clay cement (LC3) and ordinary polypropylene (PP) fiber to increase the durability of structures (as a material for repairing) without harming the environment. The developed composite's sprayability and mechanical performance were investigated through a flow table, compressive strength, uniaxial tension, and three-point flexural tests. Moreover, the material sustainability index (MSI) was used to evaluate the performance of the mixes in terms of consumed energy and carbon emissions. Finally, using LC3 and ordinary polypropylene fibers, it was possible to achieve sprayable HPFRCC with a tensile strain capacity of 3.5%. Furthermore, this composite exhibits low carbon production, low cost, and high ductility, promoting its use in infrastructure repairs. The compressive strength of cast specimens was 11% higher than that of the sprayed specimens. The reason for this was their apparent density difference and porosity (i.e. the compressive strength of the cast specimens was higher due to their lower porosity). The bending and tensile strengths of the cast specimens were, respectively, 14% and 22% lower than those of the sprayed specimens due to pneumatic compaction during the spraying process; the distribution of fibers in the sprayed specimens was more uniform, resulting in greater bending and tensile strengths. However, the flexural deformation and tensile strain capacity of the sprayed and cast specimens were almost equal. Moreover, A superplasticizer/binder (LC3 mass) ratio of 2.5% must be chosen for spraying HPFRCC containing calcined clay.https://mcej.modares.ac.ir/article_28557_87c04785ed9bce046df7b17642eed05a.pdf