Seyed Fathollah Sajedi | Azad Islamic University of Ahvaz Branch (original) (raw)
Papers by Seyed Fathollah Sajedi
Journal of Structural and Construction Engineering, Oct 23, 2020
Cement and Concrete Research, 2016
This paper reports an investigation of the recycled concrete (RC) microstructure using synchrotro... more This paper reports an investigation of the recycled concrete (RC) microstructure using synchrotron microtomography (μCT) at the Advanced Light Source combined with Scanning Electron Microscopy analysis. The study evaluated the influence of 50% of recycled concrete aggregate (RCA) and its water absorption compensation on the RC microstructure. The following variables were studied: a) the compressive strength of the original concrete used to obtain the RCA (40 and 80MPa) and b) the initial moisture condition of the RCA (Saturated Surface Dry and Oven Dry). The microtomographic images showed the mixtures cast with RCA in the dry condition developed an evident macropore network surrounding the RCA particle that was not observed in the mixtures using RCA in the SSD condition. SEM images confirmed the initial findings from CT and showed that the thickness of the interfacial transition zone in RC is in the same order of magnitude as the reference concrete.
Journal of Structural and Construction Engineering, Dec 22, 2019
Today, restrictions on access to natural aggregate resources in concrete production have become o... more Today, restrictions on access to natural aggregate resources in concrete production have become one of the problems in many countries. Concrete, as one of the most widely used human products, is a factor in consuming a large amount of aggregate. To meet this need, today many developed countries use different types of recycled aggregates as a suitable alternative to natural aggregates. The present study investigates the effect of complete replacement of recycled concrete coils instead of coarse natural aggregates in concrete. In order to improve the quality of recycled concrete, the pozzolans like as micro-silica, natural zeolite and fly ash were used in different percentages. In order to determine and compare the mechanical properties of concrete, 11 mixing designs were made and compressive strength tests at 7, 28 and 91 days, indirect tensile strength (SPT), modulus of elasticity and ultrasound velocity tests at 28 days of age were performed. The results showed that micro-silica, especially at the 10% replacement level, has a dramatic effect on the improvement of the compressive strength of fully recycled concrete compared to other pozzolans. The results of the application of natural zeolite in fully recycled concrete showed that this pozzolan, especially in the 10% substitution, act as a cementitious reducing agent and play a lesser role in improving the mechanical properties of recycled concrete compared to recycled concrete without pozzolan. On the other hand, pozzolanic materials, in a way that improves the compressive strength of recycled concrete, are not able to improve the tensile strength and the modulus of elasticity of the recycled concrete compared to conventional concrete.
هدیکچ هزورما دربراک اب نلاوزوپ ندوزفا و اه ی ،اه نف رد یمیظع ینوگرگد یروآ تلام اه یارب بسک تمواقم... more هدیکچ هزورما دربراک اب نلاوزوپ ندوزفا و اه ی ،اه نف رد یمیظع ینوگرگد یروآ تلام اه یارب بسک تمواقم و ،لااب ماود هدش داجیا .تسا زا فده قیقحت نیا ماجنا تلام تخاس ئزجود یاه ی هس و ئزج ی اقم و هسی ژولوئر صاوخ ی ناکم و یکی نآ اه یم .دشاب ا رد نی قیقحت امزآ شی یاه تمواقم یاه راشف ،ی شمخ ی و ششک ی ور رب ی عجرم تلام ، تلام یئزجود یاه نیمه و روط تلام هس یاه زج یئ تروص یفرصم هرابرس .تفرگ تلام تخاس رد هدش دیلوت راوها دلاوف هناخراک رد قیقحت یاه نینس رد یراشف تمواقم شیامزآ .تسا 7 ، 28 ، 56 و 91 شیامزآ و هزور یاه تمواقم نینس رد یششک و یشمخ یاه 28 و 91 شیامزآ رد .دندش ماجنا هزور تمواقم یاه هنومن زا بیترت هب روکذم یاه دعب هب یبعکم یاه 50 یلیم هنومن ،رتم داعبا هب یروشنم یاه 160 × 40 × 40 یلیم هنومن و رتم ه ینیزگیاج هک داد ناشن جیاتن .تسا هدش هدافتسا درادناتسا ینویپاپ یا م سیلیسورکی ات % 10 س نزو ،نامی ازفا ثعاب شی تمواقم یاه راشف ی شمخ ، ی و ششک ی رد تلام یئزجود یاه دیدرگ ا هک نی ازفا شی اه مامت رد نس نی هنومن هب تبسن دقاف م سیلیسورکی لباق هدوب هجوت .تسا غت تاریی تمواقم یاه راشف ،ی شمخ ی ششک و ی اب ش...
The effect of pure axial pressure on elliptical reinforced concrete columns made of normal (NC) a... more The effect of pure axial pressure on elliptical reinforced concrete columns made of normal (NC) and high-strength concretes (HSC) enclosed by a glass-fiber reinforced pipes (GRP) as well as a carbon-FRP was investigated. Behavior refers to the compressive capacity (CC). The effect of concrete type, casing, wrapping and its layers were investigated. Totally 12 columns with 200*120 and 600 mm height were constructed; they were divided into 2 groups of NC and HSC; each group was divided into two parts of 3. The first part had a casing and the second part did not. From each part, first column lacked a reinforcing layer, second with one layer and third with two twisted layers. The wrapping and casing improved the columns behavior. Using one and two wrapping layers increased the CC by 19.7% and 28.7% on average in the first and 11.0% and 28.7% in the second groups, respectively; use of casing resulted in an average increase in the CC of the columns in the first group by 4.15 times and in ...
Australian Journal of Civil Engineering
This paper presents the results of a laboratory study on the mechanical performance of recycled c... more This paper presents the results of a laboratory study on the mechanical performance of recycled concretes prepared with incorporation of two mineral admixtures including silica fume (SF) and fly ash (FA). The recycled aggregates concrete (RAC) was prepared by using 0, 25, 50 and 100% coarse aggregate replacement. The compressive strength, splitting tensile strength (SPT) and ultrasonic pulse velocity (UPV) of concrete mixes were completed. The results showed that the pozzolanic materials cannot have a significant effect on compressive strength loss trend. In contrast, the ultimate compressive strength of recycled concretes strongly effected by pozzolanic materials. The SPT and UPV test results showed that compare with FA, the use of SF reduced the negative effect of high replaced percentage of recycled aggregates.
Neural Computing and Applications
Today, the tendency to use self-compacting concrete (SCC) is expanding because of its significant... more Today, the tendency to use self-compacting concrete (SCC) is expanding because of its significant benefits. In this study, SCC was made by using native materials and then different pozzolans were replaced instead of a part of cement and the rheological and mechanical properties and microstructure of the concrete were investigated. The pozzolans containing of metakaolin (15%, 25% and 35%), silica fume (6%, 12% and 18%) and fly ash (20%, 35% and 50%) were replaced instead of a part of cement separately or simultaneously. Self-compaction tests including slump flow, T500, L-box, U-box, and J-ring as well as mechanical tests including compressive strength, splitting tensile strength, and static modulus of elasticity were performed on the specimens. The results showed that the pozzolans improved the microstructure of the SCC and the secondary reactions improved the mechanical properties of the concrete containing the pozzolans at older ages than the reference concrete. At 15% replacement,...
The use of ground granulated blast furnace slag (ggbfs) as a replacement material instead of ceme... more The use of ground granulated blast furnace slag (ggbfs) as a replacement material instead of cement has many advantages from environmental and economic viewpoints. Ggbfs improves the mechanical properties, but it is a material with latent potential whereas mortars and concretes incorporating ggbfs have lower early strength compared to cement mortars and concretes. This is a major loss and in order to overcome, it needs to be activated. Prior to activation, the optimum level of cement replaced with slag was determined within the range of 40-50% and subsequently an optimum level of 50% was adopted for all the test mixes. Following this, seven methods of activation were used as chemical, thermal, mechanical, chemical-thermal, chemical-mechanical, thermal-mechanical and chemical-thermal-mechanical. The most effective method thermal-mechanical gave the strength levels 3 and 7 days as 62 and 68 MPa. It was proven that some of the activation methods do not have significant effects on stren...
Smart Structures and Systems, May 1, 2019
Smart Structures and Systems, Feb 1, 2019
The use of high strength concrete (HSC) has been studied for many years in developed and developi... more The use of high strength concrete (HSC) has been studied for many years in developed and developing countries. Although, HSC has a few disadvantages, it has many advantages. The concrete with compressive strength (CS) levels in the range of 50 to100 MPa, is called HSC. The most important property of HSC is 28-day CS as a criterion. Sometimes due to time limitations and construction project problems, estimation of 28- day CS based on 7-day CS can be useful. Based on many experimental tests and analysis of the results, three sets of equations are determined with ANN and Regression techniques are compared and the best is recommended.
There is a long history of occurrences for events and natural &/ un-natural crisis in Iran. Some ... more There is a long history of occurrences for events and natural &/ un-natural crisis in Iran. Some natural crisis are as earthquake, flood, storm, reaper, landslide and fire. Generally, in every crisis the homes and accommodations of majority of people are damaged and some people getting into financial and psychological damages. Temporary accommodation of injured people in every crisis is the main task for the authorities of each country. Temporary accommodation operation should be conducted with due observance on the rules such as time, cost and operation of the site. Nowadays, much progresses has been conducted in the world in building of the temporary accommodations and then construction velocity and quality were improved. In this research, Iran’s country conditions were studied and optimization of time and cost of building of temporary accommodations were investigated using both of particle size optimization algorithm (PSOA) and MATLAB software. The aim of research was optimal dis...
Nowadays, strengthening of the column using fiber-reinforced polymer (FRP) composites is consider... more Nowadays, strengthening of the column using fiber-reinforced polymer (FRP) composites is considered as the strengthening technics of these loading elements in a structure. In this technique, increasing the surrounding pressure on radial levels of the concrete column increases the compressive and tensile strengths of the concrete element, reduces slenderness, and increases the buckling load and ductility of this element. Moreover, using glass-fiber reinforced plastic pipes (GRP) as the concrete column casing in addition to the independence of the need for framing leads to confinement effect on the concrete, high ductility and energy absorption, reduction in shrinkage and creep of concrete, lack of contact of the concrete with the corrosive factors, high construction speed, and proper loading capacity. In this research, a compressive capacity test was conducted on 6 cylinders reinforced concrete columns (RCC) of 150 mm and diameter 600 mm height, with and without GRP casing, and the e...
Smart Structures and Systems, 2018
Pavements porous concrete is a noble structure design in the urban management development general... more Pavements porous concrete is a noble structure design in the urban management development generally enabling water to be permeated within its structure. It has also capable in the same time to cater dynamic loading. During the technology development, the quality and quantity of waste materials have led to a waste disposal crisis. Using recycled materials (secondary) instead of virgin ones (primary) have reduced landfill pressure and extraction demanding. This study has reviewed the waste materials (Recycled crushed glass (RCG), Steel slag, Steel fiber, Tires, Plastics, Recycled asphalt) used in the pavement porous concretes and report their respective mechanical, durability and permeability functions. Waste material usage in the partial cement replacement will cause the concrete production cost to be reduced; also, the concretes\'s mechanical features have slightly affected to eliminate the disposal waste materials defects and to use cement in Portland cement (PC) production. Wh...
The large volume of unrecoverable waste glass has recently been considered as an alternative to s... more The large volume of unrecoverable waste glass has recently been considered as an alternative to some concrete components. In the previous studies, the replacement of sand with crumb glass at high ratios resulted in a significant reduction in the mechanical properties of concrete. In this research, the sand was replaced with waste fractures with ratios of 5%, 8% and 12%, and 3 mixing designs were cast. Three mixes were also made by replacing glass powder with cement at 4%, 8% and 12%. Combined designs with a constant replacement of 8% glass crumbs with sand and cement with glass powder in ratios of 4%, 8% and 12% were also prepared. A total of 230 sampling was done. The compressive strength of samples at the age of 7, 28, 56 and 91 days, and tensile strength at 28 days were also measured. Static modulus test was performed on cylindrical specimens. Experiments results in fresh and hardened concretes compounds decreased compared to mixed glass containing glass powder, which is indicati...
The use of high strength concrete (HSC) has been studied for many years in developed and developi... more The use of high strength concrete (HSC) has been studied for many years in developed and developing countries. Although, HSC has a few disadvantages, it has many advantages. The concrete with compressive strength (CS) levels in the range of 50 to100 MPa, is called HSC. The most important property of HSC is 28-day CS as a criterion. Sometimes due to time limitations and construction project problems, estimation of 28-day CS based on 7-day CS can be useful. Based on many experimental tests and analysis of the results, three sets of equations are determined with ANN and Regression techniques are compared and the best is recommended.
The present investigation is studied the effect of the replacement of different percentages of na... more The present investigation is studied the effect of the replacement of different percentages of natural zeolite (Ze) pozzolan powder on the mechanical properties of recycled concrete made from coarse masonry recycled aggregates. In made concretes, natural aggregates were replaced with recycled coarse masonry aggregates at 25%, 50% and 100% levels. For improve the mechanical properties, natural zeolite was replaced by cement at 10%, 20% and 30% levels. In total, 195 standard cubic and cylindrical concrete samples in the 16 mixing designs were made and compressive strength tests at 7, 28 and 91 days, splitting tensile strength, modulus of elasticity and ultrasonic pulse velocity at 28 days of age were evaluated. the results showed that, at replacement levels of 20% natural zeolite with cement was had the greatest improvement in the mechanical properties of natural concrete but in combination with recycled aggregates, the replacement of 10% natural zeolite by cement was improved the mec...
Journal of Structural and Construction Engineering, Oct 23, 2020
Cement and Concrete Research, 2016
This paper reports an investigation of the recycled concrete (RC) microstructure using synchrotro... more This paper reports an investigation of the recycled concrete (RC) microstructure using synchrotron microtomography (μCT) at the Advanced Light Source combined with Scanning Electron Microscopy analysis. The study evaluated the influence of 50% of recycled concrete aggregate (RCA) and its water absorption compensation on the RC microstructure. The following variables were studied: a) the compressive strength of the original concrete used to obtain the RCA (40 and 80MPa) and b) the initial moisture condition of the RCA (Saturated Surface Dry and Oven Dry). The microtomographic images showed the mixtures cast with RCA in the dry condition developed an evident macropore network surrounding the RCA particle that was not observed in the mixtures using RCA in the SSD condition. SEM images confirmed the initial findings from CT and showed that the thickness of the interfacial transition zone in RC is in the same order of magnitude as the reference concrete.
Journal of Structural and Construction Engineering, Dec 22, 2019
Today, restrictions on access to natural aggregate resources in concrete production have become o... more Today, restrictions on access to natural aggregate resources in concrete production have become one of the problems in many countries. Concrete, as one of the most widely used human products, is a factor in consuming a large amount of aggregate. To meet this need, today many developed countries use different types of recycled aggregates as a suitable alternative to natural aggregates. The present study investigates the effect of complete replacement of recycled concrete coils instead of coarse natural aggregates in concrete. In order to improve the quality of recycled concrete, the pozzolans like as micro-silica, natural zeolite and fly ash were used in different percentages. In order to determine and compare the mechanical properties of concrete, 11 mixing designs were made and compressive strength tests at 7, 28 and 91 days, indirect tensile strength (SPT), modulus of elasticity and ultrasound velocity tests at 28 days of age were performed. The results showed that micro-silica, especially at the 10% replacement level, has a dramatic effect on the improvement of the compressive strength of fully recycled concrete compared to other pozzolans. The results of the application of natural zeolite in fully recycled concrete showed that this pozzolan, especially in the 10% substitution, act as a cementitious reducing agent and play a lesser role in improving the mechanical properties of recycled concrete compared to recycled concrete without pozzolan. On the other hand, pozzolanic materials, in a way that improves the compressive strength of recycled concrete, are not able to improve the tensile strength and the modulus of elasticity of the recycled concrete compared to conventional concrete.
هدیکچ هزورما دربراک اب نلاوزوپ ندوزفا و اه ی ،اه نف رد یمیظع ینوگرگد یروآ تلام اه یارب بسک تمواقم... more هدیکچ هزورما دربراک اب نلاوزوپ ندوزفا و اه ی ،اه نف رد یمیظع ینوگرگد یروآ تلام اه یارب بسک تمواقم و ،لااب ماود هدش داجیا .تسا زا فده قیقحت نیا ماجنا تلام تخاس ئزجود یاه ی هس و ئزج ی اقم و هسی ژولوئر صاوخ ی ناکم و یکی نآ اه یم .دشاب ا رد نی قیقحت امزآ شی یاه تمواقم یاه راشف ،ی شمخ ی و ششک ی ور رب ی عجرم تلام ، تلام یئزجود یاه نیمه و روط تلام هس یاه زج یئ تروص یفرصم هرابرس .تفرگ تلام تخاس رد هدش دیلوت راوها دلاوف هناخراک رد قیقحت یاه نینس رد یراشف تمواقم شیامزآ .تسا 7 ، 28 ، 56 و 91 شیامزآ و هزور یاه تمواقم نینس رد یششک و یشمخ یاه 28 و 91 شیامزآ رد .دندش ماجنا هزور تمواقم یاه هنومن زا بیترت هب روکذم یاه دعب هب یبعکم یاه 50 یلیم هنومن ،رتم داعبا هب یروشنم یاه 160 × 40 × 40 یلیم هنومن و رتم ه ینیزگیاج هک داد ناشن جیاتن .تسا هدش هدافتسا درادناتسا ینویپاپ یا م سیلیسورکی ات % 10 س نزو ،نامی ازفا ثعاب شی تمواقم یاه راشف ی شمخ ، ی و ششک ی رد تلام یئزجود یاه دیدرگ ا هک نی ازفا شی اه مامت رد نس نی هنومن هب تبسن دقاف م سیلیسورکی لباق هدوب هجوت .تسا غت تاریی تمواقم یاه راشف ،ی شمخ ی ششک و ی اب ش...
The effect of pure axial pressure on elliptical reinforced concrete columns made of normal (NC) a... more The effect of pure axial pressure on elliptical reinforced concrete columns made of normal (NC) and high-strength concretes (HSC) enclosed by a glass-fiber reinforced pipes (GRP) as well as a carbon-FRP was investigated. Behavior refers to the compressive capacity (CC). The effect of concrete type, casing, wrapping and its layers were investigated. Totally 12 columns with 200*120 and 600 mm height were constructed; they were divided into 2 groups of NC and HSC; each group was divided into two parts of 3. The first part had a casing and the second part did not. From each part, first column lacked a reinforcing layer, second with one layer and third with two twisted layers. The wrapping and casing improved the columns behavior. Using one and two wrapping layers increased the CC by 19.7% and 28.7% on average in the first and 11.0% and 28.7% in the second groups, respectively; use of casing resulted in an average increase in the CC of the columns in the first group by 4.15 times and in ...
Australian Journal of Civil Engineering
This paper presents the results of a laboratory study on the mechanical performance of recycled c... more This paper presents the results of a laboratory study on the mechanical performance of recycled concretes prepared with incorporation of two mineral admixtures including silica fume (SF) and fly ash (FA). The recycled aggregates concrete (RAC) was prepared by using 0, 25, 50 and 100% coarse aggregate replacement. The compressive strength, splitting tensile strength (SPT) and ultrasonic pulse velocity (UPV) of concrete mixes were completed. The results showed that the pozzolanic materials cannot have a significant effect on compressive strength loss trend. In contrast, the ultimate compressive strength of recycled concretes strongly effected by pozzolanic materials. The SPT and UPV test results showed that compare with FA, the use of SF reduced the negative effect of high replaced percentage of recycled aggregates.
Neural Computing and Applications
Today, the tendency to use self-compacting concrete (SCC) is expanding because of its significant... more Today, the tendency to use self-compacting concrete (SCC) is expanding because of its significant benefits. In this study, SCC was made by using native materials and then different pozzolans were replaced instead of a part of cement and the rheological and mechanical properties and microstructure of the concrete were investigated. The pozzolans containing of metakaolin (15%, 25% and 35%), silica fume (6%, 12% and 18%) and fly ash (20%, 35% and 50%) were replaced instead of a part of cement separately or simultaneously. Self-compaction tests including slump flow, T500, L-box, U-box, and J-ring as well as mechanical tests including compressive strength, splitting tensile strength, and static modulus of elasticity were performed on the specimens. The results showed that the pozzolans improved the microstructure of the SCC and the secondary reactions improved the mechanical properties of the concrete containing the pozzolans at older ages than the reference concrete. At 15% replacement,...
The use of ground granulated blast furnace slag (ggbfs) as a replacement material instead of ceme... more The use of ground granulated blast furnace slag (ggbfs) as a replacement material instead of cement has many advantages from environmental and economic viewpoints. Ggbfs improves the mechanical properties, but it is a material with latent potential whereas mortars and concretes incorporating ggbfs have lower early strength compared to cement mortars and concretes. This is a major loss and in order to overcome, it needs to be activated. Prior to activation, the optimum level of cement replaced with slag was determined within the range of 40-50% and subsequently an optimum level of 50% was adopted for all the test mixes. Following this, seven methods of activation were used as chemical, thermal, mechanical, chemical-thermal, chemical-mechanical, thermal-mechanical and chemical-thermal-mechanical. The most effective method thermal-mechanical gave the strength levels 3 and 7 days as 62 and 68 MPa. It was proven that some of the activation methods do not have significant effects on stren...
Smart Structures and Systems, May 1, 2019
Smart Structures and Systems, Feb 1, 2019
The use of high strength concrete (HSC) has been studied for many years in developed and developi... more The use of high strength concrete (HSC) has been studied for many years in developed and developing countries. Although, HSC has a few disadvantages, it has many advantages. The concrete with compressive strength (CS) levels in the range of 50 to100 MPa, is called HSC. The most important property of HSC is 28-day CS as a criterion. Sometimes due to time limitations and construction project problems, estimation of 28- day CS based on 7-day CS can be useful. Based on many experimental tests and analysis of the results, three sets of equations are determined with ANN and Regression techniques are compared and the best is recommended.
There is a long history of occurrences for events and natural &/ un-natural crisis in Iran. Some ... more There is a long history of occurrences for events and natural &/ un-natural crisis in Iran. Some natural crisis are as earthquake, flood, storm, reaper, landslide and fire. Generally, in every crisis the homes and accommodations of majority of people are damaged and some people getting into financial and psychological damages. Temporary accommodation of injured people in every crisis is the main task for the authorities of each country. Temporary accommodation operation should be conducted with due observance on the rules such as time, cost and operation of the site. Nowadays, much progresses has been conducted in the world in building of the temporary accommodations and then construction velocity and quality were improved. In this research, Iran’s country conditions were studied and optimization of time and cost of building of temporary accommodations were investigated using both of particle size optimization algorithm (PSOA) and MATLAB software. The aim of research was optimal dis...
Nowadays, strengthening of the column using fiber-reinforced polymer (FRP) composites is consider... more Nowadays, strengthening of the column using fiber-reinforced polymer (FRP) composites is considered as the strengthening technics of these loading elements in a structure. In this technique, increasing the surrounding pressure on radial levels of the concrete column increases the compressive and tensile strengths of the concrete element, reduces slenderness, and increases the buckling load and ductility of this element. Moreover, using glass-fiber reinforced plastic pipes (GRP) as the concrete column casing in addition to the independence of the need for framing leads to confinement effect on the concrete, high ductility and energy absorption, reduction in shrinkage and creep of concrete, lack of contact of the concrete with the corrosive factors, high construction speed, and proper loading capacity. In this research, a compressive capacity test was conducted on 6 cylinders reinforced concrete columns (RCC) of 150 mm and diameter 600 mm height, with and without GRP casing, and the e...
Smart Structures and Systems, 2018
Pavements porous concrete is a noble structure design in the urban management development general... more Pavements porous concrete is a noble structure design in the urban management development generally enabling water to be permeated within its structure. It has also capable in the same time to cater dynamic loading. During the technology development, the quality and quantity of waste materials have led to a waste disposal crisis. Using recycled materials (secondary) instead of virgin ones (primary) have reduced landfill pressure and extraction demanding. This study has reviewed the waste materials (Recycled crushed glass (RCG), Steel slag, Steel fiber, Tires, Plastics, Recycled asphalt) used in the pavement porous concretes and report their respective mechanical, durability and permeability functions. Waste material usage in the partial cement replacement will cause the concrete production cost to be reduced; also, the concretes\'s mechanical features have slightly affected to eliminate the disposal waste materials defects and to use cement in Portland cement (PC) production. Wh...
The large volume of unrecoverable waste glass has recently been considered as an alternative to s... more The large volume of unrecoverable waste glass has recently been considered as an alternative to some concrete components. In the previous studies, the replacement of sand with crumb glass at high ratios resulted in a significant reduction in the mechanical properties of concrete. In this research, the sand was replaced with waste fractures with ratios of 5%, 8% and 12%, and 3 mixing designs were cast. Three mixes were also made by replacing glass powder with cement at 4%, 8% and 12%. Combined designs with a constant replacement of 8% glass crumbs with sand and cement with glass powder in ratios of 4%, 8% and 12% were also prepared. A total of 230 sampling was done. The compressive strength of samples at the age of 7, 28, 56 and 91 days, and tensile strength at 28 days were also measured. Static modulus test was performed on cylindrical specimens. Experiments results in fresh and hardened concretes compounds decreased compared to mixed glass containing glass powder, which is indicati...
The use of high strength concrete (HSC) has been studied for many years in developed and developi... more The use of high strength concrete (HSC) has been studied for many years in developed and developing countries. Although, HSC has a few disadvantages, it has many advantages. The concrete with compressive strength (CS) levels in the range of 50 to100 MPa, is called HSC. The most important property of HSC is 28-day CS as a criterion. Sometimes due to time limitations and construction project problems, estimation of 28-day CS based on 7-day CS can be useful. Based on many experimental tests and analysis of the results, three sets of equations are determined with ANN and Regression techniques are compared and the best is recommended.
The present investigation is studied the effect of the replacement of different percentages of na... more The present investigation is studied the effect of the replacement of different percentages of natural zeolite (Ze) pozzolan powder on the mechanical properties of recycled concrete made from coarse masonry recycled aggregates. In made concretes, natural aggregates were replaced with recycled coarse masonry aggregates at 25%, 50% and 100% levels. For improve the mechanical properties, natural zeolite was replaced by cement at 10%, 20% and 30% levels. In total, 195 standard cubic and cylindrical concrete samples in the 16 mixing designs were made and compressive strength tests at 7, 28 and 91 days, splitting tensile strength, modulus of elasticity and ultrasonic pulse velocity at 28 days of age were evaluated. the results showed that, at replacement levels of 20% natural zeolite with cement was had the greatest improvement in the mechanical properties of natural concrete but in combination with recycled aggregates, the replacement of 10% natural zeolite by cement was improved the mec...