Seleem Ahmad | Zagazig University (original) (raw)
Papers by Seleem Ahmad
The Egyptian International Journal of Engineering Sciences and Technology (Print), Mar 1, 2023
This study presents experimental work to evaluate the efficiency of using the biaxial geogrid as ... more This study presents experimental work to evaluate the efficiency of using the biaxial geogrid as a shrinkage reinforcement for RC slabs instead of using upper shrinkage steel reinforcement. Geogrid distinguish from steel reinforcement in its low cost and it doesn't rust. The present work studies and assesses the shrinkage strain of RC slabs considering different parameters, slab thickness, number of geogrid layers, and thickness of the upper concrete cover. The shrinkage strain is measured, while shrinkage strain reduction SSR% is determined considering plastic and dry shrinkages, along with temperature and humidity are recorded weekly for 15 specimens of 50*50 cm slabs over 91 days. All specimens have lower steel reinforcement with/without upper geogrid reinforcement. The results prove the efficiency of geogrids reinforcement to resist the shrinkage stains in RC slabs, where, two layers of geogrids with 3 cm of upper cover gives the lowest shrinkage stain, i.e., largest shrinkage resistance. The results also show that as the RC slab thickness decrease as the shrinkage strain and SSR% value increase and vice versa. But there is no noteworthy effect of geogrid on the SSR% value.
The Egyptian International Journal of Engineering Sciences and Technology
International Conference on Aerospace Sciences & Aviation Technology, May 1, 1999
Mode I fatigue crack growth behaviour was experimentally investigated under constant and followin... more Mode I fatigue crack growth behaviour was experimentally investigated under constant and following the application of a single spike overload. Different specimen thicknesses were investigated at different overload ratios. A previously developed crack tip deformation model to correlate fatigue crack growth behaviour following k • a single overload cycle was used to correlate that behaviour for different specimen thicknesses. It was found that the effect of specimen thickness on the fatigue crack growth behaviour under constant amplitude of loading is marginal especially at growth rates greater than le mm/cycle. The retardation due to the application of a tensile single overload decreases with the increase in specimen thickness. Good agreement between relevant experimental results and those predicted using three dimensional crack tip deformation parameter was found.
In this work the effect of recycled concrete aggregate modified with mineral admixtures and Nano-... more In this work the effect of recycled concrete aggregate modified with mineral admixtures and Nano-silica on the mechanical properties and performance of the concrete was investigated after curing in tap water for 28 and 90 days. The compressive, ƒc, indirect tensile, ƒt, and flexural, ƒb, strengths for cured concrete specimens were measured and concrete strength ratios were analyzed. The water and rapid chloride permeability were measured. SEM analysis of microstructure was, also, investigated. The coarse aggregates used were dolomite (control) and recycled concrete aggregate with the incorporation of different mineral admixtures including ground granulated blast slag and granite as well as Nano-silica. It was found that, the slump values of the dolomite concrete decreases compared with recycle aggregate concrete. The results indicate that, the concrete mix containing recycle aggregate have the highest compressive strength, tensile strength and flexural strength compered to concrete mix containing dolomite aggregate. As far as the compressive strength is concerned, the addition 1 % NS and 15 % of slag improved the physico-mechanical properties of the recycled aggregate concretes compared to the other mixes after curing in tap water.
The International Conference on Civil and Architecture Engineering (Print), Apr 1, 2018
Nano technology application has added the effort to improve its properties by altering the micros... more Nano technology application has added the effort to improve its properties by altering the microstructure. Nano materials, by virtue of their very small particle size can affect the concrete properties. The use of amorphous Nano silica at different cement contents 500, 600 and 700 Kg/m3 was studied to improve the compressive strength and tensile strength of high strength concrete. An experimental investigation has been carried out by replacing the cement with Nano silica of 0.5%, 1% and 1.5% by weight of cement at the different cement contents. The experimental test results showed that concrete prepared with 1% Nano silica showed a higher strength than those of the 0.5% and 1.5% Nano silica at the different cement contents and at 28 and 56 days.
Elsevier eBooks, 1995
Publisher Summary This chapter analyzes the deformation behavior and the stress–strain field exis... more Publisher Summary This chapter analyzes the deformation behavior and the stress–strain field existing near the front of a stationary crack under cyclic loading to predict the site of fatigue crack initiation. 3D elastic–plastic finite element model is developed to simulate the deformation behavior of a stationary crack under cyclic loading. Relevant kinematic parameters corresponding to loading–unloading–reloading phases of a cycle were computed and correlated. The variation of stresses and strains through the plate thickness was analyzed. The monotonic and cyclic crack tip plastically deformed zones and opening displacements both at the surface and at the midsection of the plate were compared with 2D finite element analyses under plane stress and plane strain conditions. The plastic zone size from the 3D analysis for both the specimen surface and the specimen interior is bounded by its 2D plane stress and plane strain calculations.
The Egyptian International Journal of Engineering Sciences and Technology (Print), Jun 1, 2018
Application of elastomers in concrete industry has been successful in the last few years perhaps ... more Application of elastomers in concrete industry has been successful in the last few years perhaps due to some properties of these substances, which make it possible for the elastomers such as rubber aggregates to save the tougher cementitious compounds. This paper investigates the mechanical properties and fracture toughness of rubberized modified concrete under static loading. The natural aggregate was replaced partially with different rubber contents of (5-10-15-20-25-30-40 %) replacement of fine rubber aggregate with size of (1-4)mm, and contents of (5-15-25 %) as a replacement of coarse rubber aggregates with size of (4-20)mm. Laboratory tests include compression and indirect tension were conducted, static flexural test was carried out using square slab specimens. The results from laboratory testing on all concrete specimens were analyzed. It was found that the inclusion of rubber aggregates into concrete will reduce the strength of concrete. The usage of fine aggregate sizes of rubber up to specified dosage, gives better strength of concrete compared that of greater sizes of rubber aggregates.The rubberized modified concrete can absorb fracture energy and has more suitable usage in roads, bridges, airports runways and some of the military defensive constructions such as shelters and fortifications.
Materials, Jul 21, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Scientific Review Engineering and Environmental Sciences, Jun 1, 2022
DergiPark (Istanbul University), Dec 31, 2021
The durability and mechanical properties of HPFRC are experimentally investigated in this study a... more The durability and mechanical properties of HPFRC are experimentally investigated in this study after being exposed to four different media. Those media were air, water, sodium chloride, and magnesium sulfate with 7% concentration for both chloride and sulfate. Hooked-end galvanized steel fiber 50 mm length with three different fiber volume fractions, Vf, as follows 0.5%, 1.0% and 1.5% and polypropylene fiber with, Vf, 0.1%, 0.3%, and 0.5% were invoked in concrete containing macro silica fume, SF. Compressive, indirect tensile, and flexural tests were conducted on HPFRC specimens after exposing them to previous media after 28 and 180 days of exposure. The test results in the present work indicated that the HPFRC containing steel fiber is more durable than the other one containing polypropylene fiber, especially when exposed to sodium chloride and magnesium sulfate media. Moreover, the optimum values for compressive strength of HPFRC are obtained when Vf equals 1.0% for steel fiber and 0.3% for polypropylene fiber. On the other hand, the optimum values for indirect tensile and flexural strengths of HPFRC are obtained when Vf equals 1.5% for steel fiber and 0.5% for polypropylene fiber.
Frattura ed Integrità Strutturale
This work introduces an experimental study to evaluate the effect of elevated temperatures on the... more This work introduces an experimental study to evaluate the effect of elevated temperatures on the mechanical properties of high-performance concrete (HPC) mix with changes in Water-Cementitious ratios, W/(C+SF), Silica Fume percent, SF, and Polypropylene, PP, fiber contents. This mix was typically designed to satisfy the requirements of tunnel concrete. The compressive and indirect tensile strengths were measured at room temperature, RT, and after exposure to 400°C and 800°C. Moreover, SEM micrograph and EDS spot analysis tests were done to evaluate the effect of elevated temperatures. Fifteen mixes of HPC with different ratios of W/(C+SF), SF, and PP fiber were tested. According to the test results, the compressive strength values of design mixes increased significantly after exposure to 400°C. Moreover, using SF = 10%, the results indicated remarkable improvements in the compressive strength at 400°C and 800°C, in the case of the W/(C+SF) ratio of 0.31. On the other hand, the high...
Frattura ed Integrità Strutturale, 2021
The creation of cracks, which are the most common cause of structural failure, has a significant ... more The creation of cracks, which are the most common cause of structural failure, has a significant impact on the structure's strength and durability. As a result, effective repair and maintenance are vital and unavoidable for treating any of these issues. Self-healing mortar holds promising benefits for reducing the cost of repair as cracks are autonomously repaired without any human intervention. This study investigated the effect of bacteria type, bacteria content, bacteria concentration, and nutrient type on the properties of the self-healing mortar. Three types of bacteria, Bacillus sphaericus, Bacillus Megaterium, and Bacillus subtilis encapsulated in calcium alginate beads, were introduced into the mortar. Two concentrations of bacteria, 2× 108 and 2× 109 Colony Forming Units per milliliter, and different percentages of bacteria of cement weight were selected for the study. In addition, calcium lactate and calcium acetate were used at 0.5% of cement weight as nutrition for...
Arabian Journal for Science and Engineering, 2021
In this study, the strength reduction of high-strength concrete (HSC) integrating silica fume (SF... more In this study, the strength reduction of high-strength concrete (HSC) integrating silica fume (SF) and nano-silica (NS) exposed to elevated temperatures besides its mass loss is evaluated. Cubes and cylinders were cast and tested at 28 and 56 d to evaluate the concrete compressive and tensile strengths (fcu and ftu), respectively. The prepared cubes and cylinders were subjected to elevated temperatures (T = 200, 400, 600, 800, and 1000 °C), cooled in air, and tested in compression and tension, respectively. For the cement paste and aggregate, spot analysis was performed through scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Furthermore, SEM between aggregate and cement paste was performed. The obtained results indicated that for concrete mixes incorporating NS, compressive strength increased as temperature was raised to 400 °C and decreased as temperature increased from 400 to 800 °C. In addition, a remarkable reduction in the concrete tensile str...
Journal of Al-Azhar University Engineering Sector, 2017
Recently there is a strong trend in engineering researches in the field of engineering materials ... more Recently there is a strong trend in engineering researches in the field of engineering materials for the production of high and ultra-high strength concrete. Using different additives which are added to the concrete mix reduced the water cement ratio and caused an increase in the concrete strength. As well as the use of ultra-fine materials such as Nano-silica increase the strength of concrete dramatically. In spite of the success of this research to get to compressive strength up to 150 MPa or more, however, many problems have found in the mechanical behavior of these concretes, which turned into a decrease in the fracture toughness significantly. An experimental program was designed to investigate the effect of cement content, silica fume and Nano silica percent, and curing on the compressive strength of concrete at different curing ages. The results of the present work clearly showed an increase in the value of 28-day concrete compressive strength with existence of silica and Nano silica. Steam curing, also, led to an improvement in compressive strength as compared to water curing.
Frattura ed Integrità Strutturale
In this work, an experimental and numerical program was designed to evaluate the role of compress... more In this work, an experimental and numerical program was designed to evaluate the role of compressive strength, Fc, and area of reinforcing steel, As, on the flexural behavior of functionally graded reinforced concrete beams. Eighteen layered sections of reinforced concrete beams were tested with different compressive strengths arrangement and area of main steel. The result showed that the minimum steel reinforcement with higher compressive strength in the compression zone increases load capacity and ductility. The average steel reinforcement with higher strength in the compression zone increases load capacity and decreases ductility. The results also approved that; higher strength in the compression zone can be used in beams with a high tensile steel ratio for decreasing compression steel as an economic side. 3D finite element was executed using ABAQUS to simulate experimental beams. The numerical result showed variation from the experimental but still, the behavior of numerical bea...
Scientific Reports
Due to the rapid increase of pollution around the world, the disposal of waste materials such as ... more Due to the rapid increase of pollution around the world, the disposal of waste materials such as granite powder (GP), iron powder (IP), brick powder (BP), and waste plastic particles (PP) is a major environmental problem in the entire world. Utilizing these industrial waste materials has many advantages for the construction industry regarding cost-effectiveness and the sustainability of natural resources. This investigation examined the addition of GP, IP, BP, and PP as a fine aggregate with ratios of 5%, 10%, 15%, and 20% of sand in producing and assessing sustainable concrete. The static properties, i.e., compressive, tensile, flexural strength, and dynamic properties using the drop-weight impact test, were evaluated of such materials. The results showed that using IP as a partial replacement enhances both static and dynamic properties of concrete; the enhancement kept increasing up to 20% of IP, and the compressive, tensile, flexural strength, and impact energy increased by 8.4%,...
IOP Conference Series: Earth and Environmental Science
The goal of this study is to see how the effect of recycled concrete aggregate admixed with miner... more The goal of this study is to see how the effect of recycled concrete aggregate admixed with mineral admixtures and Nano-silica on concrete's durability after being exposed to aggressive media attacks. The coarse aggregates applied in the concrete were dolomite (control) and recycled concrete aggregate with the addition of various mineral admixtures such as ground granulated blast slag (GGBFS), granite, and Nano-silica. To lower the water/cement ratio, a superplasticizer (SP)-type (F) was used. The physical and mechanical properties of commonly used raw materials such as aggregates and other various concrete kinds were investigated. The effects of saltwater and 3% sodium chloride on concrete mechanical and microstructures properties were investigated. The slump values of dolomite concrete were found to be lower than those of recycled aggregate concrete. The concrete mix using recyclable aggregate has the highest compressive strength, according to the results. In terms of compress...
Journal of Sustainable Cement-Based Materials
Buildings
This research aims to illustrate and express the impact of analytical techniques such as TOPSIS- ... more This research aims to illustrate and express the impact of analytical techniques such as TOPSIS- and FTOPSIS-based Taguchi models on obtaining the optimum design of fiber-reinforced concrete (FRC).Three levels of silica fume content, fly ash content, water-to-cementitious (W/C) ratio, and superplasticizer content were examined in the present work. However, the steel fiber content (1%) and the maximum aggregate size of 14 mm were kept constant for all mixes. Once the experimental results were obtained following Taguchi’s method, it was used as input data to the TOPSIS and FTOPSIS models. The optimum set of mixture factor levels was determined by identifying the two modules. The optimal FRC mix proportions obtained from the TOPSIS- and FTOPSIS-based Taguchi model were 5% silica fume content, 0% fly ash content, 0.27 W/C ratio, and 0.5% superplasticizer. Multi-response optimization approaches are essential to optimize the concrete mix proportions to achieve the required strengths, work...
The Egyptian International Journal of Engineering Sciences and Technology (Print), Mar 1, 2023
This study presents experimental work to evaluate the efficiency of using the biaxial geogrid as ... more This study presents experimental work to evaluate the efficiency of using the biaxial geogrid as a shrinkage reinforcement for RC slabs instead of using upper shrinkage steel reinforcement. Geogrid distinguish from steel reinforcement in its low cost and it doesn't rust. The present work studies and assesses the shrinkage strain of RC slabs considering different parameters, slab thickness, number of geogrid layers, and thickness of the upper concrete cover. The shrinkage strain is measured, while shrinkage strain reduction SSR% is determined considering plastic and dry shrinkages, along with temperature and humidity are recorded weekly for 15 specimens of 50*50 cm slabs over 91 days. All specimens have lower steel reinforcement with/without upper geogrid reinforcement. The results prove the efficiency of geogrids reinforcement to resist the shrinkage stains in RC slabs, where, two layers of geogrids with 3 cm of upper cover gives the lowest shrinkage stain, i.e., largest shrinkage resistance. The results also show that as the RC slab thickness decrease as the shrinkage strain and SSR% value increase and vice versa. But there is no noteworthy effect of geogrid on the SSR% value.
The Egyptian International Journal of Engineering Sciences and Technology
International Conference on Aerospace Sciences & Aviation Technology, May 1, 1999
Mode I fatigue crack growth behaviour was experimentally investigated under constant and followin... more Mode I fatigue crack growth behaviour was experimentally investigated under constant and following the application of a single spike overload. Different specimen thicknesses were investigated at different overload ratios. A previously developed crack tip deformation model to correlate fatigue crack growth behaviour following k • a single overload cycle was used to correlate that behaviour for different specimen thicknesses. It was found that the effect of specimen thickness on the fatigue crack growth behaviour under constant amplitude of loading is marginal especially at growth rates greater than le mm/cycle. The retardation due to the application of a tensile single overload decreases with the increase in specimen thickness. Good agreement between relevant experimental results and those predicted using three dimensional crack tip deformation parameter was found.
In this work the effect of recycled concrete aggregate modified with mineral admixtures and Nano-... more In this work the effect of recycled concrete aggregate modified with mineral admixtures and Nano-silica on the mechanical properties and performance of the concrete was investigated after curing in tap water for 28 and 90 days. The compressive, ƒc, indirect tensile, ƒt, and flexural, ƒb, strengths for cured concrete specimens were measured and concrete strength ratios were analyzed. The water and rapid chloride permeability were measured. SEM analysis of microstructure was, also, investigated. The coarse aggregates used were dolomite (control) and recycled concrete aggregate with the incorporation of different mineral admixtures including ground granulated blast slag and granite as well as Nano-silica. It was found that, the slump values of the dolomite concrete decreases compared with recycle aggregate concrete. The results indicate that, the concrete mix containing recycle aggregate have the highest compressive strength, tensile strength and flexural strength compered to concrete mix containing dolomite aggregate. As far as the compressive strength is concerned, the addition 1 % NS and 15 % of slag improved the physico-mechanical properties of the recycled aggregate concretes compared to the other mixes after curing in tap water.
The International Conference on Civil and Architecture Engineering (Print), Apr 1, 2018
Nano technology application has added the effort to improve its properties by altering the micros... more Nano technology application has added the effort to improve its properties by altering the microstructure. Nano materials, by virtue of their very small particle size can affect the concrete properties. The use of amorphous Nano silica at different cement contents 500, 600 and 700 Kg/m3 was studied to improve the compressive strength and tensile strength of high strength concrete. An experimental investigation has been carried out by replacing the cement with Nano silica of 0.5%, 1% and 1.5% by weight of cement at the different cement contents. The experimental test results showed that concrete prepared with 1% Nano silica showed a higher strength than those of the 0.5% and 1.5% Nano silica at the different cement contents and at 28 and 56 days.
Elsevier eBooks, 1995
Publisher Summary This chapter analyzes the deformation behavior and the stress–strain field exis... more Publisher Summary This chapter analyzes the deformation behavior and the stress–strain field existing near the front of a stationary crack under cyclic loading to predict the site of fatigue crack initiation. 3D elastic–plastic finite element model is developed to simulate the deformation behavior of a stationary crack under cyclic loading. Relevant kinematic parameters corresponding to loading–unloading–reloading phases of a cycle were computed and correlated. The variation of stresses and strains through the plate thickness was analyzed. The monotonic and cyclic crack tip plastically deformed zones and opening displacements both at the surface and at the midsection of the plate were compared with 2D finite element analyses under plane stress and plane strain conditions. The plastic zone size from the 3D analysis for both the specimen surface and the specimen interior is bounded by its 2D plane stress and plane strain calculations.
The Egyptian International Journal of Engineering Sciences and Technology (Print), Jun 1, 2018
Application of elastomers in concrete industry has been successful in the last few years perhaps ... more Application of elastomers in concrete industry has been successful in the last few years perhaps due to some properties of these substances, which make it possible for the elastomers such as rubber aggregates to save the tougher cementitious compounds. This paper investigates the mechanical properties and fracture toughness of rubberized modified concrete under static loading. The natural aggregate was replaced partially with different rubber contents of (5-10-15-20-25-30-40 %) replacement of fine rubber aggregate with size of (1-4)mm, and contents of (5-15-25 %) as a replacement of coarse rubber aggregates with size of (4-20)mm. Laboratory tests include compression and indirect tension were conducted, static flexural test was carried out using square slab specimens. The results from laboratory testing on all concrete specimens were analyzed. It was found that the inclusion of rubber aggregates into concrete will reduce the strength of concrete. The usage of fine aggregate sizes of rubber up to specified dosage, gives better strength of concrete compared that of greater sizes of rubber aggregates.The rubberized modified concrete can absorb fracture energy and has more suitable usage in roads, bridges, airports runways and some of the military defensive constructions such as shelters and fortifications.
Materials, Jul 21, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Scientific Review Engineering and Environmental Sciences, Jun 1, 2022
DergiPark (Istanbul University), Dec 31, 2021
The durability and mechanical properties of HPFRC are experimentally investigated in this study a... more The durability and mechanical properties of HPFRC are experimentally investigated in this study after being exposed to four different media. Those media were air, water, sodium chloride, and magnesium sulfate with 7% concentration for both chloride and sulfate. Hooked-end galvanized steel fiber 50 mm length with three different fiber volume fractions, Vf, as follows 0.5%, 1.0% and 1.5% and polypropylene fiber with, Vf, 0.1%, 0.3%, and 0.5% were invoked in concrete containing macro silica fume, SF. Compressive, indirect tensile, and flexural tests were conducted on HPFRC specimens after exposing them to previous media after 28 and 180 days of exposure. The test results in the present work indicated that the HPFRC containing steel fiber is more durable than the other one containing polypropylene fiber, especially when exposed to sodium chloride and magnesium sulfate media. Moreover, the optimum values for compressive strength of HPFRC are obtained when Vf equals 1.0% for steel fiber and 0.3% for polypropylene fiber. On the other hand, the optimum values for indirect tensile and flexural strengths of HPFRC are obtained when Vf equals 1.5% for steel fiber and 0.5% for polypropylene fiber.
Frattura ed Integrità Strutturale
This work introduces an experimental study to evaluate the effect of elevated temperatures on the... more This work introduces an experimental study to evaluate the effect of elevated temperatures on the mechanical properties of high-performance concrete (HPC) mix with changes in Water-Cementitious ratios, W/(C+SF), Silica Fume percent, SF, and Polypropylene, PP, fiber contents. This mix was typically designed to satisfy the requirements of tunnel concrete. The compressive and indirect tensile strengths were measured at room temperature, RT, and after exposure to 400°C and 800°C. Moreover, SEM micrograph and EDS spot analysis tests were done to evaluate the effect of elevated temperatures. Fifteen mixes of HPC with different ratios of W/(C+SF), SF, and PP fiber were tested. According to the test results, the compressive strength values of design mixes increased significantly after exposure to 400°C. Moreover, using SF = 10%, the results indicated remarkable improvements in the compressive strength at 400°C and 800°C, in the case of the W/(C+SF) ratio of 0.31. On the other hand, the high...
Frattura ed Integrità Strutturale, 2021
The creation of cracks, which are the most common cause of structural failure, has a significant ... more The creation of cracks, which are the most common cause of structural failure, has a significant impact on the structure's strength and durability. As a result, effective repair and maintenance are vital and unavoidable for treating any of these issues. Self-healing mortar holds promising benefits for reducing the cost of repair as cracks are autonomously repaired without any human intervention. This study investigated the effect of bacteria type, bacteria content, bacteria concentration, and nutrient type on the properties of the self-healing mortar. Three types of bacteria, Bacillus sphaericus, Bacillus Megaterium, and Bacillus subtilis encapsulated in calcium alginate beads, were introduced into the mortar. Two concentrations of bacteria, 2× 108 and 2× 109 Colony Forming Units per milliliter, and different percentages of bacteria of cement weight were selected for the study. In addition, calcium lactate and calcium acetate were used at 0.5% of cement weight as nutrition for...
Arabian Journal for Science and Engineering, 2021
In this study, the strength reduction of high-strength concrete (HSC) integrating silica fume (SF... more In this study, the strength reduction of high-strength concrete (HSC) integrating silica fume (SF) and nano-silica (NS) exposed to elevated temperatures besides its mass loss is evaluated. Cubes and cylinders were cast and tested at 28 and 56 d to evaluate the concrete compressive and tensile strengths (fcu and ftu), respectively. The prepared cubes and cylinders were subjected to elevated temperatures (T = 200, 400, 600, 800, and 1000 °C), cooled in air, and tested in compression and tension, respectively. For the cement paste and aggregate, spot analysis was performed through scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Furthermore, SEM between aggregate and cement paste was performed. The obtained results indicated that for concrete mixes incorporating NS, compressive strength increased as temperature was raised to 400 °C and decreased as temperature increased from 400 to 800 °C. In addition, a remarkable reduction in the concrete tensile str...
Journal of Al-Azhar University Engineering Sector, 2017
Recently there is a strong trend in engineering researches in the field of engineering materials ... more Recently there is a strong trend in engineering researches in the field of engineering materials for the production of high and ultra-high strength concrete. Using different additives which are added to the concrete mix reduced the water cement ratio and caused an increase in the concrete strength. As well as the use of ultra-fine materials such as Nano-silica increase the strength of concrete dramatically. In spite of the success of this research to get to compressive strength up to 150 MPa or more, however, many problems have found in the mechanical behavior of these concretes, which turned into a decrease in the fracture toughness significantly. An experimental program was designed to investigate the effect of cement content, silica fume and Nano silica percent, and curing on the compressive strength of concrete at different curing ages. The results of the present work clearly showed an increase in the value of 28-day concrete compressive strength with existence of silica and Nano silica. Steam curing, also, led to an improvement in compressive strength as compared to water curing.
Frattura ed Integrità Strutturale
In this work, an experimental and numerical program was designed to evaluate the role of compress... more In this work, an experimental and numerical program was designed to evaluate the role of compressive strength, Fc, and area of reinforcing steel, As, on the flexural behavior of functionally graded reinforced concrete beams. Eighteen layered sections of reinforced concrete beams were tested with different compressive strengths arrangement and area of main steel. The result showed that the minimum steel reinforcement with higher compressive strength in the compression zone increases load capacity and ductility. The average steel reinforcement with higher strength in the compression zone increases load capacity and decreases ductility. The results also approved that; higher strength in the compression zone can be used in beams with a high tensile steel ratio for decreasing compression steel as an economic side. 3D finite element was executed using ABAQUS to simulate experimental beams. The numerical result showed variation from the experimental but still, the behavior of numerical bea...
Scientific Reports
Due to the rapid increase of pollution around the world, the disposal of waste materials such as ... more Due to the rapid increase of pollution around the world, the disposal of waste materials such as granite powder (GP), iron powder (IP), brick powder (BP), and waste plastic particles (PP) is a major environmental problem in the entire world. Utilizing these industrial waste materials has many advantages for the construction industry regarding cost-effectiveness and the sustainability of natural resources. This investigation examined the addition of GP, IP, BP, and PP as a fine aggregate with ratios of 5%, 10%, 15%, and 20% of sand in producing and assessing sustainable concrete. The static properties, i.e., compressive, tensile, flexural strength, and dynamic properties using the drop-weight impact test, were evaluated of such materials. The results showed that using IP as a partial replacement enhances both static and dynamic properties of concrete; the enhancement kept increasing up to 20% of IP, and the compressive, tensile, flexural strength, and impact energy increased by 8.4%,...
IOP Conference Series: Earth and Environmental Science
The goal of this study is to see how the effect of recycled concrete aggregate admixed with miner... more The goal of this study is to see how the effect of recycled concrete aggregate admixed with mineral admixtures and Nano-silica on concrete's durability after being exposed to aggressive media attacks. The coarse aggregates applied in the concrete were dolomite (control) and recycled concrete aggregate with the addition of various mineral admixtures such as ground granulated blast slag (GGBFS), granite, and Nano-silica. To lower the water/cement ratio, a superplasticizer (SP)-type (F) was used. The physical and mechanical properties of commonly used raw materials such as aggregates and other various concrete kinds were investigated. The effects of saltwater and 3% sodium chloride on concrete mechanical and microstructures properties were investigated. The slump values of dolomite concrete were found to be lower than those of recycled aggregate concrete. The concrete mix using recyclable aggregate has the highest compressive strength, according to the results. In terms of compress...
Journal of Sustainable Cement-Based Materials
Buildings
This research aims to illustrate and express the impact of analytical techniques such as TOPSIS- ... more This research aims to illustrate and express the impact of analytical techniques such as TOPSIS- and FTOPSIS-based Taguchi models on obtaining the optimum design of fiber-reinforced concrete (FRC).Three levels of silica fume content, fly ash content, water-to-cementitious (W/C) ratio, and superplasticizer content were examined in the present work. However, the steel fiber content (1%) and the maximum aggregate size of 14 mm were kept constant for all mixes. Once the experimental results were obtained following Taguchi’s method, it was used as input data to the TOPSIS and FTOPSIS models. The optimum set of mixture factor levels was determined by identifying the two modules. The optimal FRC mix proportions obtained from the TOPSIS- and FTOPSIS-based Taguchi model were 5% silica fume content, 0% fly ash content, 0.27 W/C ratio, and 0.5% superplasticizer. Multi-response optimization approaches are essential to optimize the concrete mix proportions to achieve the required strengths, work...