Dr. Nagy is a Professor in Structural and Geotechnical Engineering and currently he is the Head of the Civil & Arch Eng. Division. MTC Prof. Nagy received the B.Sc. and M.Sc. in Civil Engineering from MTC , in 1994, 2000 respectively, and Ph.D. degree in Geotechnical Engineering from University of Bradford, UK in 2008. He became an Associate Professor and then Professor in Geotechnical Engineering, in 2013, and 2018 respectively. He was a visiting Professor in Western University Canada 2016
In concrete applications. Major/critical applications of such concrete are radiation-shielding fa... more In concrete applications. Major/critical applications of such concrete are radiation-shielding facilities. Both steel slag and silica fume are examples of common by-product materials that can be used as a replacer of aggregates and cement. Thus, in this research work, steel slag was utilized as heavy aggregate in concrete production besides silica fume to present sustainable concrete mixtures probably with better radiation-shielding properties. Different cementitious plasters were applied on the conducted sustainable concrete mixture using different powdery materials; hematite, magnetite, barite, bentonite, and steel slag powders in addition to nano-titanium dioxide as full replacers for sand. The proposed plasters were presented to determine the optimum plaster technique in terms of static performance and attenuation capability against gamma and neutron radiations. The results exhibited that utilizing steel slag and silica fume in concrete mixtures enhanced compressive strength by up to 9.09 % compared to conventional concrete, while the addition of nano-titanium to conventional plaster led to superior enhancement in the compressive strength by up to 38.65 % relative to traditional plaster. Conversely, fully replacing conventional silica sand with the abovementioned powdery materials generally reduced the compressive strength of cementitious plasters by up to 30.83 %. However, the radiation shielding properties against Cs-137, and Co-60 energies have been enhanced by up to 20 % and 26 %, respectively.
Catastrophic disasters caused by hard/high-speed projectiles represent a significant threat to th... more Catastrophic disasters caused by hard/high-speed projectiles represent a significant threat to the integrity of concrete structures. Therefore, the impact resistance of concrete structures must be a critical consideration in its design procedures. This research assessed green concrete mixtures incorporating steel slag and silica fume as byproducts that fulfill sustainability criteria, and geogrid reinforcement as reinforcing contenders, tested against modified hard M8 armor-piercing incendiaries at velocities up to 930 m/s. The compressive, tensile, and flexural strength of the proposed green concretes was evaluated. While, the projectile impact resistance was evaluated in terms of the energy absorption capacity, perforation resistance, crack trajectory, projectile deviation length and angle, and fracture diameter at front and rear faces of concrete panels. The results indicated slight static performance improvements and substantial impact resistance enhancements. It was revealed as a 96 % increase in energy absorption, up to 50 % better-cracking resistance, up to 12 % reduction in impact diameter, and up to 200 % improvement in deviation angle and distance compared to normal concrete. A superior impact resistance was achieved by the multiple geogrid-reinforced green concrete panels by fully preventing the perforation of the aforementioned high-speed projectile. The concluded optimum design for overall mechanical properties is steel slag concrete mixtures reinforced by biaxial geogrid meshes. This research achievements pave the way for utilizing such sustainable concrete in critical infrastructures.
Egypt's national highway network expanded by an astounding 98.78% between 2013 and 2024 (from 65.... more Egypt's national highway network expanded by an astounding 98.78% between 2013 and 2024 (from 65.7 thousand km to 130.6 thousand km). The California Bearing Ratio (CBR) test is a crucial test for both road design and maintenance procedures. Also, a tried-and-true, simple technique, CBR test uses in Egyptian highway construction to assess the strength of base course materials and soil subgrades. While adding conventional materials like fly ash, cement, and lime to improve mechanical properties is thought to be environmentally harmful, the new science of the nanotechnology revolution has positive ecological and economic feedback. The strength of the tested soil varies in each sample depending on the percentage of nano-white cement (N-WCem) alone or combined with the nano-silica (N-Si) additive. The resulting difference in soil strength depends mainly on increasing the percentage of additions, which in turn increases the amount of water for each sample, especially with high percentages of nanomaterials. Thus, the present study tried to evaluate CBR Test in many varying degrees of soaking. Various percentages of the additives N-Si and activator N-WCem were added to the tested soil, namely (0.3, 0.6, 0.9, and 1.2%) and (0.5, 1, and 1.5%), respectively. The improvement in the CBR test values continued when the two materials were mixed, even at low percentages of N-WCem.
IOP Conference Series: Earth and Environmental Science, 2024
Alkali-activated materials (AAM) have gained popularity in research because of their lower carbon... more Alkali-activated materials (AAM) have gained popularity in research because of their lower carbon dioxide emissions than Portland cement. Electric arc furnace slag (EAFS) exceeds landfills. Moreover, electric arc furnaces emit less CO2 than oxygen-blast furnaces. This research is the first to suggest that mixing EAFS and metakaolin (MK) as AAM precursors could compensate for the deficiency of SiO2 and Al2O3 in the EAFS and CaO in the MK, which would produce better AAM properties than using either of them singularly. Furthermore, the utilization of EAFS aggregate instead of natural aggregate in alkali-activated concrete (AAC) reduces waste materials, consumes fewer natural resources, and solves the problem of natural aggregate scarcity. This study's main objectives were to evaluate the effects of varying ratios of EAFS and MK as precursors and EAFS aggregate to natural aggregate ratios on the AAC's fresh and hardened properties. The properties under consideration are workability and cube compressive strength. The outcomes showed that increasing EAFS with decreasing MK content increased AAC workability and cube compressive strength while increasing EAFS aggregate over natural aggregate improved AAC workability and decreased cube compressive strength.
IOP Conference Series: Earth and Environmental Science, 2024
Concrete is widely recognized as a primary structural material worldwide and is extensively emplo... more Concrete is widely recognized as a primary structural material worldwide and is extensively employed across diverse construction sectors. It ranks as the second most consumed material by humans, following water. While past research has predominantly focused on assessing the static and dynamic performance of concrete, there has been a noticeable lack of discussion regarding its torsional resistance, primarily due to challenges associated with testing methodologies. This study investigates the torsional resistance of concrete elements confined with various durable geogrid types using four distinct concrete mixtures. Experimental evaluations were conducted to assess the compressive strength, indirect tensile strength, and torsional resistance of each group. Findings reveal that all concrete mixtures achieved the targeted compressive strength of 30 MPa. Furthermore, the incorporation of different geogrid reinforcements notably enhanced the tensile strength and torsional resistance of the concrete elements by up to 87% and 43.75%, respectively. Notably, among the tested specimens, those reinforced with tri-axial geogrid demonstrated superior tensile and torsional resistance properties.
IOP Conference Series: Earth and Environmental Science, 2024
As the economy advances, there is a growing need for energy. Harnessing hydroelectric energy has ... more As the economy advances, there is a growing need for energy. Harnessing hydroelectric energy has emerged as a crucial strategy for addressing the energy crisis. To promote hydropower development, numerous tall concrete dams are either under construction or in the planning stages. These dams are frequently situated in areas with elevated water levels and face the challenge of being located in regions with high seismic intensity. An accident resulting from the failure of concrete dams can pose significant threats to both economic development and public safety. Therefore, it is of crucial importance to investigate the stability of such dams, particularly under conditions of high water levels and seismic activity. The finite element program Geostudio is being undertaken to evaluate a complete numerical analysis of the dam. In this paper, Longtan Dam has been selected as the case study for the research. This study is applied in two cases: seismic and static conditions. A two-dimensional seismic numerical analysis was carried out using the Koyna earthquake acceleration time records in 1976. The results of the FEM model concluded that the dam is unsafe under sesmic conditions. The concrete-rock interface, particularly susceptible to sliding, was identified as the most critical part of the dam, presenting the most likely failure mode. The study highlights the significance of its methodology in investigating earthquake effects on dams, prioritizing it over the achieved results. The aim is for the conclusions and recommendations to provide valuable guidance for future studies and initiatives focused on enhancing safety at hydropower dams.
Soft clayey soils present a geotechnical challenge due to their low shear strength and high compr... more Soft clayey soils present a geotechnical challenge due to their low shear strength and high compressibility. The finite element package, ABAQUS, is used to perform a comprehensive numerical analysis on stone columns. The study investigates the bearing capacity and vertical and lateral deformations of soft clayey soils due to installing stone columns in them. The numerical model using the unit cell concept investigates the influence of varying two main physical parameters, i.e. the stone column material strength (Ļ), and the native soil cohesion (c). Moreover, this study utilizes variable numerical models to study the effect of the ratio between column length and its diameter, (L/d), on the efficiency of stone columns as a soil-enhancing method for weak clayey soil conditions. The influence of the stone column length on the occurred failure mode was studied. The outcomes demonstrated that using stone columns improves the behaviour of soft clayey soil, where the bearing capacity is enhanced and the soil surface settlement is reduced. Furthermore, using stone column filling materials with higher friction angles enhanced the stability of the system, and the optimum values of native soil cohesion and stone column materials friction angle are 30 kPa and 40Ā°, respectively. Also, the outcomes illustrated that increasing the applied pressure controls the bulging length of SC, where the bulging length was 2.5d, 3d, and 3.5d for the applied pressure of 50.0 kPa, 100.0kPa, and 150.0 kPa, respectively.
Weak soil is a major obstacle facing the urban development of any site with other exceptional mer... more Weak soil is a major obstacle facing the urban development of any site with other exceptional merits. The current study aims to investigate the utilization of nano-silica in enhancing the mechanical properties of weak kaolin soils. Design mixes using different percentages of nano-silica were investigated in the range between 0.25-1.20% from the dry weight of the kaolin soil. Various chemical, physical, and mechanical properties of each mixture have been investigated. The obtained results indicated that nano-silica addition to such kaolin soils decreased the plasticity index and the maximum dry density while increasing the plastic limit, the Liquid limit, and the optimum moisture content. In different curing days of the tested mixtures, maximum dry density was decreased, while the optimum moisture content increased. The optimum value of added nano-silica was less than 1% of the soil dry weight. In the modified kaolin soil with 0.9% nano-silica, the plastic limit was increased by 29%, while the liquid limit decreased by 13% in comparison with the untreated sample. After 28 days of the cured sample, the unconfined compressive strength readings increased by almost 14% compared to its reading on day one. Also, the California bearing ratio results recorded significant enhancement with nano-silica additives in comparison with the untreated kaolin soil. After 28 curing days, the sonicated samples recorded enhancement in the unconfined compressive strength readings by more than 5% and 9% with the additive N-Si (0.3% and 0.9%), respectively, when compared with the unsonicated samples.
Aircraft shelter is a structure or a reinforced hanger that has many uses in military aspects. It... more Aircraft shelter is a structure or a reinforced hanger that has many uses in military aspects. It is used to protect military aircraft from different dangers such as enemy chemical attacks. Also, it provides housing, permitting aircraft maintenance and it can be storage for different weapons. therefore, optimum design of aircraft shelter is of a great importance. It may take several shapes to be suitable for its usage. It can be made from concrete, steel or composite materials. The foundations of an airplane shelter must be designed as best as possible. Design objectives are greatly impacted by the contact pressure between the earth and the foundation surface. Classical method in design assumes maximum uniform linear distribution of pressure under contact surface of footing. So, considering real contact pressure has a great interest for many authors. In this article, a new analytical method is proposed to study the effect of moments and load inclination on the design of rectangular isolated footing. The model proposed takes into consideration the real soil pressure. A parametric study was conducted and data obtained from classical model were larger than those from proposed model. Seven Rectangular isolated footings were designed using traditional method and proposed method. The proposed method is more economic since it provides less concrete dimensions. Results obtained from the new model were compared with FEM and achieved reasonable agreement.
In recent years, the use of drones to monitor various types of smart constructions has attracted ... more In recent years, the use of drones to monitor various types of smart constructions has attracted more attention. Unmanned Aerial Vehicles (UAV) have a number of potential benefits over manual methods for Analyzing construction due to their permit scalable, quick, and affordable solutions to tasks that would otherwise be unsuitable for individuals who are subject to fatigue and measurement uncertainty. In order to better understand how drones can be used in dam monitoring and construction for situation assessment, early warning, and image processing, the current study is studying this topics. High resolution Ierial images that captured by UAV is used to detect the cracks in the dam body structure. Drone-shot images are analyzed by using MATLAB software in order to assess the crack in the dam body and make the correct maintenance.The finite element program Geostudio is undertaken to evaluate a complete numerical analysis of the dam to find out the cause of cracks in the dam body and give solutions to prevent these cracks from happening again depending on the outcome results. This study is applied under two cases seismic and static condition. The results of FEM model concluded that cracks starts to appear at slope change point at downstream and in upstream at dam heel during earthquake action. The current work shows that using drones in dam monitoring is a very effective and fast way to detect cracks in the dam body.
View the article online for updates and enhancements. You may also like Study on winter indoor th... more View the article online for updates and enhancements. You may also like Study on winter indoor thermal environment of temporary shelters built in Nepal after massive earthquake 2015 Rita Thapa, Hom Bahadur Rijal, Masanori Shukuya et al.-Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
One of the problems, which would affect airport runways is the settlement of soil. Such settlemen... more One of the problems, which would affect airport runways is the settlement of soil. Such settlement would be controlled by enhancing the performance of the soil underneath the airport runway. The composite system consists of graded stone-reinforced soil and reinforcing layers. This system is defined as stone column, which is widely used to improve weak soils as one of the soil stabilization methods due to its simple construction and economic cost. It is used to reduce settlement and enhance soil-bearing capacity. By using such technique, part of the high-compressibility and low-shear strength soil is replaced with coarse filler materials with high-shear strength and extremely low compressibility. In this study, a 3D numerical model of a unit cell is created to examine the impact of changing the controlling parameters in the model, i.e. spacing between columns (S), weak soil cohesion (c), and angle of internal friction for stone column material (Ļ). It was established that the use of stone columns improves the soil-bearing capacity and reduces settlement, strengthening the stability of airport runways. The efficiency of the system is improved by increasing the column material's internal friction angle and the cohesion of the surrounding soil. The ultimate bearing capacity of soil without SC and SC-soil systems were 150 kPa, and 460 kPa, respectively, which illustrates that the bearing capacity was increased by 306.7%.
Alkali-activated materials (AAM) have become popular in research due to their considerable decrea... more Alkali-activated materials (AAM) have become popular in research due to their considerable decrease in CO2 emissions compared with Portland cement. Despite efforts, electric arc furnace slag (EAFS) as an AAM precursor has been the topic of comparatively fewer studies than other most investigated precursors. Additionally, some countries are suffering from a shortage of ground-granulated blast furnace slag, which is the most used precursor because these countries only produce steel in electric arc furnaces. Consequently, this is a study among the first that delves into the viability of utilizing a combination of EAFS and metakaolin (MK) as precursors in alkali-activated paste (AAP). This research proposes that mixing MK with EAFS could result in better AAM properties than using one of them as a sole precursor. The objectives of this study were to assess the effect of precursor composition and the alkaline-to-precursor ratios (A/P) on the fresh and hardened properties and microstructure of the AAP. The properties studied were setting times, flowability, compressive strength, and shrinkage strain. Furthermore, energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) were applied. The results demonstrated that increasing EAFS with decreasing MK content increased flowability, decreased setting times, increased compressive strength, and increased shrinkage strain. The optimum mix design in terms of compressive strength was at 100% EAFS and 0.35 A/P, which achieved 32.13 MPA after 56 days of curing at ambient temperature. The results indicated reliable performance of EAFS with MK alkali activation, leading to a wider usage of EAFS as an AAM precursor.
In Egypt, the Kaolin soil is the most widespread dispersion. So, it has appeared to the necessary... more In Egypt, the Kaolin soil is the most widespread dispersion. So, it has appeared to the necessary to investigate new techniques for improving the performance properties of these soils, especially for highway construction. This study aims to assess and compare the efficiency of nano-white cement in enhancing the mechanical properties of kaolin alone and kaolin mixed with nano-silica. The results of the compaction tests of the kaolin soil treated with different percentages of nano-white cement revealed a decrement in the maximum dry density, the plasticity index, and the workability. While they had elevated the optimum moisture content, plastic limit, Liquid limit, and unconfined compressive strength. The tested samples treated only with nano-silica reached their maximum strength properties with a concentration of 0.9% nano-silica then declined. The samples treated with the lowest percent of nano-silica and the different percentages of nano-white cement recorded higher readings in the unconfined compressive strength compared with the result of the sample treated with the highest percent of nano-white cement individually. Furthermore, the SEM images of treated samples represented the physical and chemical bonds between soil particles, nano-white cement, and nano-silica. In conclusion, the nano-white cement and nano-silica additive mixtures have a powerful improving effect on the mechanical properties of kaolin soil than the nano-white cement additive only. From the results, the nano-additive (nano-silica) in tested clay blended with nano-white cement had a significant positive effect on the behavior of clay soil. So, using additives and activators on a nanoscale has economic feedback with a positive ecological effect.
Constructing dams is one of the human achievements in developing urban societies. In the last few... more Constructing dams is one of the human achievements in developing urban societies. In the last few decades, rapid growth in developing the Red Sea coast and Sinai in Egypt has taken place. According to the UN Nexus definition, water, energy, and food are the main sources of sustainable development. The dam gives the best structure that can fulfill these requirements. The geology of Egypt in the concerning areas in both the Red Sea and Sinai shows that both areas are mountainous areas. The wadies in these mountains suffer from being exposed to severe weathering conditions. Flash floods and wind blowing are the main causes of exposing sedimentary rocks in these Wadies to different degrees of weathering. The present paper focuses on studying the effect of weathering on the engineering behavior of dams intended to be constructed in these areas. The examined rock foundations cover mud-stone, Sandstone , and limestone. A published numerical model for Longtan Dam was utilized as a reference case to construct a verified numerical model that was later employed in a parametric study to clear the effect of weathering on the studied sediment rock. The verification and parametric study were carried out using GeoStudio software. The results show the clear effect of the variation in weathering on the engineering parameters of the examined sedimentary rock deposits.
In recent years, the use of drones to monitor various types of smart constructions has attracted ... more In recent years, the use of drones to monitor various types of smart constructions has attracted more attention. Unmanned Aerial Vehicles (UAV) have a number of potential benefits over manual methods for Analyzing construction due to their permit scalable, quick, and affordable solutions to tasks that would otherwise be unsuitable for individuals who are subject to fatigue and measurement uncertainty. In order to better understand how drones can be used in dam monitoring and construction for situation assessment, early warning, and image processing, the current study is studying this topics. High resolution Ierial images that captured by UAV is used to detect the cracks in the dam body structure. Drone-shot images are analyzed by using MATLAB software in order to assess the crack in the dam body and make the correct maintenance.The finite element program Geostudio is undertaken to evaluate a complete numerical analysis of the dam to find out the cause of cracks in the dam body and give solutions to prevent these cracks from happening again depending on the outcome results. This study is applied under two cases seismic and static condition. The results of FEM model concluded that cracks starts to appear at slope change point at downstream and in upstream at dam heel during earthquake action. The current work shows that using drones in dam monitoring is a very effective and fast way to detect cracks in the dam body.
In concrete applications. Major/critical applications of such concrete are radiation-shielding fa... more In concrete applications. Major/critical applications of such concrete are radiation-shielding facilities. Both steel slag and silica fume are examples of common by-product materials that can be used as a replacer of aggregates and cement. Thus, in this research work, steel slag was utilized as heavy aggregate in concrete production besides silica fume to present sustainable concrete mixtures probably with better radiation-shielding properties. Different cementitious plasters were applied on the conducted sustainable concrete mixture using different powdery materials; hematite, magnetite, barite, bentonite, and steel slag powders in addition to nano-titanium dioxide as full replacers for sand. The proposed plasters were presented to determine the optimum plaster technique in terms of static performance and attenuation capability against gamma and neutron radiations. The results exhibited that utilizing steel slag and silica fume in concrete mixtures enhanced compressive strength by up to 9.09 % compared to conventional concrete, while the addition of nano-titanium to conventional plaster led to superior enhancement in the compressive strength by up to 38.65 % relative to traditional plaster. Conversely, fully replacing conventional silica sand with the abovementioned powdery materials generally reduced the compressive strength of cementitious plasters by up to 30.83 %. However, the radiation shielding properties against Cs-137, and Co-60 energies have been enhanced by up to 20 % and 26 %, respectively.
Catastrophic disasters caused by hard/high-speed projectiles represent a significant threat to th... more Catastrophic disasters caused by hard/high-speed projectiles represent a significant threat to the integrity of concrete structures. Therefore, the impact resistance of concrete structures must be a critical consideration in its design procedures. This research assessed green concrete mixtures incorporating steel slag and silica fume as byproducts that fulfill sustainability criteria, and geogrid reinforcement as reinforcing contenders, tested against modified hard M8 armor-piercing incendiaries at velocities up to 930 m/s. The compressive, tensile, and flexural strength of the proposed green concretes was evaluated. While, the projectile impact resistance was evaluated in terms of the energy absorption capacity, perforation resistance, crack trajectory, projectile deviation length and angle, and fracture diameter at front and rear faces of concrete panels. The results indicated slight static performance improvements and substantial impact resistance enhancements. It was revealed as a 96 % increase in energy absorption, up to 50 % better-cracking resistance, up to 12 % reduction in impact diameter, and up to 200 % improvement in deviation angle and distance compared to normal concrete. A superior impact resistance was achieved by the multiple geogrid-reinforced green concrete panels by fully preventing the perforation of the aforementioned high-speed projectile. The concluded optimum design for overall mechanical properties is steel slag concrete mixtures reinforced by biaxial geogrid meshes. This research achievements pave the way for utilizing such sustainable concrete in critical infrastructures.
Egypt's national highway network expanded by an astounding 98.78% between 2013 and 2024 (from 65.... more Egypt's national highway network expanded by an astounding 98.78% between 2013 and 2024 (from 65.7 thousand km to 130.6 thousand km). The California Bearing Ratio (CBR) test is a crucial test for both road design and maintenance procedures. Also, a tried-and-true, simple technique, CBR test uses in Egyptian highway construction to assess the strength of base course materials and soil subgrades. While adding conventional materials like fly ash, cement, and lime to improve mechanical properties is thought to be environmentally harmful, the new science of the nanotechnology revolution has positive ecological and economic feedback. The strength of the tested soil varies in each sample depending on the percentage of nano-white cement (N-WCem) alone or combined with the nano-silica (N-Si) additive. The resulting difference in soil strength depends mainly on increasing the percentage of additions, which in turn increases the amount of water for each sample, especially with high percentages of nanomaterials. Thus, the present study tried to evaluate CBR Test in many varying degrees of soaking. Various percentages of the additives N-Si and activator N-WCem were added to the tested soil, namely (0.3, 0.6, 0.9, and 1.2%) and (0.5, 1, and 1.5%), respectively. The improvement in the CBR test values continued when the two materials were mixed, even at low percentages of N-WCem.
IOP Conference Series: Earth and Environmental Science, 2024
Alkali-activated materials (AAM) have gained popularity in research because of their lower carbon... more Alkali-activated materials (AAM) have gained popularity in research because of their lower carbon dioxide emissions than Portland cement. Electric arc furnace slag (EAFS) exceeds landfills. Moreover, electric arc furnaces emit less CO2 than oxygen-blast furnaces. This research is the first to suggest that mixing EAFS and metakaolin (MK) as AAM precursors could compensate for the deficiency of SiO2 and Al2O3 in the EAFS and CaO in the MK, which would produce better AAM properties than using either of them singularly. Furthermore, the utilization of EAFS aggregate instead of natural aggregate in alkali-activated concrete (AAC) reduces waste materials, consumes fewer natural resources, and solves the problem of natural aggregate scarcity. This study's main objectives were to evaluate the effects of varying ratios of EAFS and MK as precursors and EAFS aggregate to natural aggregate ratios on the AAC's fresh and hardened properties. The properties under consideration are workability and cube compressive strength. The outcomes showed that increasing EAFS with decreasing MK content increased AAC workability and cube compressive strength while increasing EAFS aggregate over natural aggregate improved AAC workability and decreased cube compressive strength.
IOP Conference Series: Earth and Environmental Science, 2024
Concrete is widely recognized as a primary structural material worldwide and is extensively emplo... more Concrete is widely recognized as a primary structural material worldwide and is extensively employed across diverse construction sectors. It ranks as the second most consumed material by humans, following water. While past research has predominantly focused on assessing the static and dynamic performance of concrete, there has been a noticeable lack of discussion regarding its torsional resistance, primarily due to challenges associated with testing methodologies. This study investigates the torsional resistance of concrete elements confined with various durable geogrid types using four distinct concrete mixtures. Experimental evaluations were conducted to assess the compressive strength, indirect tensile strength, and torsional resistance of each group. Findings reveal that all concrete mixtures achieved the targeted compressive strength of 30 MPa. Furthermore, the incorporation of different geogrid reinforcements notably enhanced the tensile strength and torsional resistance of the concrete elements by up to 87% and 43.75%, respectively. Notably, among the tested specimens, those reinforced with tri-axial geogrid demonstrated superior tensile and torsional resistance properties.
IOP Conference Series: Earth and Environmental Science, 2024
As the economy advances, there is a growing need for energy. Harnessing hydroelectric energy has ... more As the economy advances, there is a growing need for energy. Harnessing hydroelectric energy has emerged as a crucial strategy for addressing the energy crisis. To promote hydropower development, numerous tall concrete dams are either under construction or in the planning stages. These dams are frequently situated in areas with elevated water levels and face the challenge of being located in regions with high seismic intensity. An accident resulting from the failure of concrete dams can pose significant threats to both economic development and public safety. Therefore, it is of crucial importance to investigate the stability of such dams, particularly under conditions of high water levels and seismic activity. The finite element program Geostudio is being undertaken to evaluate a complete numerical analysis of the dam. In this paper, Longtan Dam has been selected as the case study for the research. This study is applied in two cases: seismic and static conditions. A two-dimensional seismic numerical analysis was carried out using the Koyna earthquake acceleration time records in 1976. The results of the FEM model concluded that the dam is unsafe under sesmic conditions. The concrete-rock interface, particularly susceptible to sliding, was identified as the most critical part of the dam, presenting the most likely failure mode. The study highlights the significance of its methodology in investigating earthquake effects on dams, prioritizing it over the achieved results. The aim is for the conclusions and recommendations to provide valuable guidance for future studies and initiatives focused on enhancing safety at hydropower dams.
Soft clayey soils present a geotechnical challenge due to their low shear strength and high compr... more Soft clayey soils present a geotechnical challenge due to their low shear strength and high compressibility. The finite element package, ABAQUS, is used to perform a comprehensive numerical analysis on stone columns. The study investigates the bearing capacity and vertical and lateral deformations of soft clayey soils due to installing stone columns in them. The numerical model using the unit cell concept investigates the influence of varying two main physical parameters, i.e. the stone column material strength (Ļ), and the native soil cohesion (c). Moreover, this study utilizes variable numerical models to study the effect of the ratio between column length and its diameter, (L/d), on the efficiency of stone columns as a soil-enhancing method for weak clayey soil conditions. The influence of the stone column length on the occurred failure mode was studied. The outcomes demonstrated that using stone columns improves the behaviour of soft clayey soil, where the bearing capacity is enhanced and the soil surface settlement is reduced. Furthermore, using stone column filling materials with higher friction angles enhanced the stability of the system, and the optimum values of native soil cohesion and stone column materials friction angle are 30 kPa and 40Ā°, respectively. Also, the outcomes illustrated that increasing the applied pressure controls the bulging length of SC, where the bulging length was 2.5d, 3d, and 3.5d for the applied pressure of 50.0 kPa, 100.0kPa, and 150.0 kPa, respectively.
Weak soil is a major obstacle facing the urban development of any site with other exceptional mer... more Weak soil is a major obstacle facing the urban development of any site with other exceptional merits. The current study aims to investigate the utilization of nano-silica in enhancing the mechanical properties of weak kaolin soils. Design mixes using different percentages of nano-silica were investigated in the range between 0.25-1.20% from the dry weight of the kaolin soil. Various chemical, physical, and mechanical properties of each mixture have been investigated. The obtained results indicated that nano-silica addition to such kaolin soils decreased the plasticity index and the maximum dry density while increasing the plastic limit, the Liquid limit, and the optimum moisture content. In different curing days of the tested mixtures, maximum dry density was decreased, while the optimum moisture content increased. The optimum value of added nano-silica was less than 1% of the soil dry weight. In the modified kaolin soil with 0.9% nano-silica, the plastic limit was increased by 29%, while the liquid limit decreased by 13% in comparison with the untreated sample. After 28 days of the cured sample, the unconfined compressive strength readings increased by almost 14% compared to its reading on day one. Also, the California bearing ratio results recorded significant enhancement with nano-silica additives in comparison with the untreated kaolin soil. After 28 curing days, the sonicated samples recorded enhancement in the unconfined compressive strength readings by more than 5% and 9% with the additive N-Si (0.3% and 0.9%), respectively, when compared with the unsonicated samples.
Aircraft shelter is a structure or a reinforced hanger that has many uses in military aspects. It... more Aircraft shelter is a structure or a reinforced hanger that has many uses in military aspects. It is used to protect military aircraft from different dangers such as enemy chemical attacks. Also, it provides housing, permitting aircraft maintenance and it can be storage for different weapons. therefore, optimum design of aircraft shelter is of a great importance. It may take several shapes to be suitable for its usage. It can be made from concrete, steel or composite materials. The foundations of an airplane shelter must be designed as best as possible. Design objectives are greatly impacted by the contact pressure between the earth and the foundation surface. Classical method in design assumes maximum uniform linear distribution of pressure under contact surface of footing. So, considering real contact pressure has a great interest for many authors. In this article, a new analytical method is proposed to study the effect of moments and load inclination on the design of rectangular isolated footing. The model proposed takes into consideration the real soil pressure. A parametric study was conducted and data obtained from classical model were larger than those from proposed model. Seven Rectangular isolated footings were designed using traditional method and proposed method. The proposed method is more economic since it provides less concrete dimensions. Results obtained from the new model were compared with FEM and achieved reasonable agreement.
In recent years, the use of drones to monitor various types of smart constructions has attracted ... more In recent years, the use of drones to monitor various types of smart constructions has attracted more attention. Unmanned Aerial Vehicles (UAV) have a number of potential benefits over manual methods for Analyzing construction due to their permit scalable, quick, and affordable solutions to tasks that would otherwise be unsuitable for individuals who are subject to fatigue and measurement uncertainty. In order to better understand how drones can be used in dam monitoring and construction for situation assessment, early warning, and image processing, the current study is studying this topics. High resolution Ierial images that captured by UAV is used to detect the cracks in the dam body structure. Drone-shot images are analyzed by using MATLAB software in order to assess the crack in the dam body and make the correct maintenance.The finite element program Geostudio is undertaken to evaluate a complete numerical analysis of the dam to find out the cause of cracks in the dam body and give solutions to prevent these cracks from happening again depending on the outcome results. This study is applied under two cases seismic and static condition. The results of FEM model concluded that cracks starts to appear at slope change point at downstream and in upstream at dam heel during earthquake action. The current work shows that using drones in dam monitoring is a very effective and fast way to detect cracks in the dam body.
View the article online for updates and enhancements. You may also like Study on winter indoor th... more View the article online for updates and enhancements. You may also like Study on winter indoor thermal environment of temporary shelters built in Nepal after massive earthquake 2015 Rita Thapa, Hom Bahadur Rijal, Masanori Shukuya et al.-Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
One of the problems, which would affect airport runways is the settlement of soil. Such settlemen... more One of the problems, which would affect airport runways is the settlement of soil. Such settlement would be controlled by enhancing the performance of the soil underneath the airport runway. The composite system consists of graded stone-reinforced soil and reinforcing layers. This system is defined as stone column, which is widely used to improve weak soils as one of the soil stabilization methods due to its simple construction and economic cost. It is used to reduce settlement and enhance soil-bearing capacity. By using such technique, part of the high-compressibility and low-shear strength soil is replaced with coarse filler materials with high-shear strength and extremely low compressibility. In this study, a 3D numerical model of a unit cell is created to examine the impact of changing the controlling parameters in the model, i.e. spacing between columns (S), weak soil cohesion (c), and angle of internal friction for stone column material (Ļ). It was established that the use of stone columns improves the soil-bearing capacity and reduces settlement, strengthening the stability of airport runways. The efficiency of the system is improved by increasing the column material's internal friction angle and the cohesion of the surrounding soil. The ultimate bearing capacity of soil without SC and SC-soil systems were 150 kPa, and 460 kPa, respectively, which illustrates that the bearing capacity was increased by 306.7%.
Alkali-activated materials (AAM) have become popular in research due to their considerable decrea... more Alkali-activated materials (AAM) have become popular in research due to their considerable decrease in CO2 emissions compared with Portland cement. Despite efforts, electric arc furnace slag (EAFS) as an AAM precursor has been the topic of comparatively fewer studies than other most investigated precursors. Additionally, some countries are suffering from a shortage of ground-granulated blast furnace slag, which is the most used precursor because these countries only produce steel in electric arc furnaces. Consequently, this is a study among the first that delves into the viability of utilizing a combination of EAFS and metakaolin (MK) as precursors in alkali-activated paste (AAP). This research proposes that mixing MK with EAFS could result in better AAM properties than using one of them as a sole precursor. The objectives of this study were to assess the effect of precursor composition and the alkaline-to-precursor ratios (A/P) on the fresh and hardened properties and microstructure of the AAP. The properties studied were setting times, flowability, compressive strength, and shrinkage strain. Furthermore, energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) were applied. The results demonstrated that increasing EAFS with decreasing MK content increased flowability, decreased setting times, increased compressive strength, and increased shrinkage strain. The optimum mix design in terms of compressive strength was at 100% EAFS and 0.35 A/P, which achieved 32.13 MPA after 56 days of curing at ambient temperature. The results indicated reliable performance of EAFS with MK alkali activation, leading to a wider usage of EAFS as an AAM precursor.
In Egypt, the Kaolin soil is the most widespread dispersion. So, it has appeared to the necessary... more In Egypt, the Kaolin soil is the most widespread dispersion. So, it has appeared to the necessary to investigate new techniques for improving the performance properties of these soils, especially for highway construction. This study aims to assess and compare the efficiency of nano-white cement in enhancing the mechanical properties of kaolin alone and kaolin mixed with nano-silica. The results of the compaction tests of the kaolin soil treated with different percentages of nano-white cement revealed a decrement in the maximum dry density, the plasticity index, and the workability. While they had elevated the optimum moisture content, plastic limit, Liquid limit, and unconfined compressive strength. The tested samples treated only with nano-silica reached their maximum strength properties with a concentration of 0.9% nano-silica then declined. The samples treated with the lowest percent of nano-silica and the different percentages of nano-white cement recorded higher readings in the unconfined compressive strength compared with the result of the sample treated with the highest percent of nano-white cement individually. Furthermore, the SEM images of treated samples represented the physical and chemical bonds between soil particles, nano-white cement, and nano-silica. In conclusion, the nano-white cement and nano-silica additive mixtures have a powerful improving effect on the mechanical properties of kaolin soil than the nano-white cement additive only. From the results, the nano-additive (nano-silica) in tested clay blended with nano-white cement had a significant positive effect on the behavior of clay soil. So, using additives and activators on a nanoscale has economic feedback with a positive ecological effect.
Constructing dams is one of the human achievements in developing urban societies. In the last few... more Constructing dams is one of the human achievements in developing urban societies. In the last few decades, rapid growth in developing the Red Sea coast and Sinai in Egypt has taken place. According to the UN Nexus definition, water, energy, and food are the main sources of sustainable development. The dam gives the best structure that can fulfill these requirements. The geology of Egypt in the concerning areas in both the Red Sea and Sinai shows that both areas are mountainous areas. The wadies in these mountains suffer from being exposed to severe weathering conditions. Flash floods and wind blowing are the main causes of exposing sedimentary rocks in these Wadies to different degrees of weathering. The present paper focuses on studying the effect of weathering on the engineering behavior of dams intended to be constructed in these areas. The examined rock foundations cover mud-stone, Sandstone , and limestone. A published numerical model for Longtan Dam was utilized as a reference case to construct a verified numerical model that was later employed in a parametric study to clear the effect of weathering on the studied sediment rock. The verification and parametric study were carried out using GeoStudio software. The results show the clear effect of the variation in weathering on the engineering parameters of the examined sedimentary rock deposits.
In recent years, the use of drones to monitor various types of smart constructions has attracted ... more In recent years, the use of drones to monitor various types of smart constructions has attracted more attention. Unmanned Aerial Vehicles (UAV) have a number of potential benefits over manual methods for Analyzing construction due to their permit scalable, quick, and affordable solutions to tasks that would otherwise be unsuitable for individuals who are subject to fatigue and measurement uncertainty. In order to better understand how drones can be used in dam monitoring and construction for situation assessment, early warning, and image processing, the current study is studying this topics. High resolution Ierial images that captured by UAV is used to detect the cracks in the dam body structure. Drone-shot images are analyzed by using MATLAB software in order to assess the crack in the dam body and make the correct maintenance.The finite element program Geostudio is undertaken to evaluate a complete numerical analysis of the dam to find out the cause of cracks in the dam body and give solutions to prevent these cracks from happening again depending on the outcome results. This study is applied under two cases seismic and static condition. The results of FEM model concluded that cracks starts to appear at slope change point at downstream and in upstream at dam heel during earthquake action. The current work shows that using drones in dam monitoring is a very effective and fast way to detect cracks in the dam body.
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Papers by Nabil M Nagy
from a shortage of ground-granulated blast furnace slag, which is the most used precursor because these countries only produce steel in electric arc furnaces. Consequently, this is a study among the first that delves into the viability of utilizing a combination of EAFS and metakaolin (MK) as precursors in alkali-activated paste (AAP). This research proposes that mixing MK with EAFS could result in better AAM properties than using one of them as a sole precursor. The objectives of this study were to assess the effect of precursor composition and the alkaline-to-precursor ratios (A/P) on the fresh and hardened properties and microstructure of the AAP. The properties studied were setting times, flowability, compressive strength, and shrinkage strain. Furthermore, energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) were applied. The results demonstrated that increasing EAFS with decreasing MK content increased flowability, decreased setting times, increased compressive strength, and increased shrinkage strain. The optimum mix design in terms of compressive strength was at 100% EAFS and 0.35 A/P, which achieved 32.13 MPA after 56 days of curing at
ambient temperature. The results indicated reliable performance of EAFS with MK alkali activation, leading to a wider usage of EAFS as an AAM precursor.
from a shortage of ground-granulated blast furnace slag, which is the most used precursor because these countries only produce steel in electric arc furnaces. Consequently, this is a study among the first that delves into the viability of utilizing a combination of EAFS and metakaolin (MK) as precursors in alkali-activated paste (AAP). This research proposes that mixing MK with EAFS could result in better AAM properties than using one of them as a sole precursor. The objectives of this study were to assess the effect of precursor composition and the alkaline-to-precursor ratios (A/P) on the fresh and hardened properties and microstructure of the AAP. The properties studied were setting times, flowability, compressive strength, and shrinkage strain. Furthermore, energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) were applied. The results demonstrated that increasing EAFS with decreasing MK content increased flowability, decreased setting times, increased compressive strength, and increased shrinkage strain. The optimum mix design in terms of compressive strength was at 100% EAFS and 0.35 A/P, which achieved 32.13 MPA after 56 days of curing at
ambient temperature. The results indicated reliable performance of EAFS with MK alkali activation, leading to a wider usage of EAFS as an AAM precursor.