civil engineering
Reza Bazrgary; Saeideh Ziyadidegan; Mehdi Bahmanzadeh
Abstract
Today, the role of concrete as the most widely used building material in the development of the civil and economic infrastructure of societies is undeniable. On the other hand, the production of cement requires the consumption of natural resources and the release of a significant amount of carbon dioxide ...
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Today, the role of concrete as the most widely used building material in the development of the civil and economic infrastructure of societies is undeniable. On the other hand, the production of cement requires the consumption of natural resources and the release of a significant amount of carbon dioxide into the environment, so the need to revise and change the ingredients of concrete in such a way as to meet the needs of construction and to minimize risks and damage to the environment. It is necessary that pozzolans are among the materials that can be used to improve this.Iran is one of the countries that can be a leader in this matter due to its diverse geographical areas and the availability of various mines. Therefore, this research presents the effect of using nano-silica (NS) and micro-silica (SF) of Hamadan city on the mechanical properties of ultra-high-strength concrete (UHPCs).For this purpose, two groups of concrete with and without silica fume (SF) were made. Also, nano silica (NS) was used as an additive to cement in amounts of 0%, 0.5%, 1%, 2% and 3%. In general, the results show the appropriate effect of pozzolanic materials produced in Iran in improving the properties of concrete in a way that gives that among the different contents of NS, UHPC containing 2% NS has the best results in terms of compressive strength, tensile strength, modulus of elasticity, and bending strength. Showed in 90 days. Also, UHPC samples containing dual cement materials (NS and SF) showed better results than concretes containing only NS
Mehdi Mokhtari; Reza Fatemian
Abstract
Todays, concrete is one of the common materials in construction industry. The dependence of concrete properties on various parameters such as constituent materials, production and generation process, execution method and concrete treating condition made it a complex material. However, it has more advantages ...
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Todays, concrete is one of the common materials in construction industry. The dependence of concrete properties on various parameters such as constituent materials, production and generation process, execution method and concrete treating condition made it a complex material. However, it has more advantages in the construction industry. In this case, these materials of mechanical properties such as tensile and compressive strength is discussed by civil engineers and researchers identified many ways to improving these properties which one of the is using of additive materials such as micro silica and polypropylene fibers. Therefore, in this research tensile and compressive strength tests performed on 40 models with the aim of investigating the effect of using micro silica with 0.04, 0.06 and 0.08 percentages and the mixture of these two materials on mechanical properties. The results showed that in the compressive test of 7-day concrete micro silica models and some of models of micro silica and polypropylene fiber mixture had acceptable response, as well as in 28-days concrete mixture models showed acceptable response. In the tensile test of 7-day models, all of the models showed lower strength than the original model, while in 28-day concrete models with micro silica 3% and polypropylene 0.04% increased tensile strength.
مدیریت ساخت و مدیریت پروژه
Hossein SamadYar
Abstract
Conventional concretes, which are designed, mixed, transported and processed by traditional methods, cannot be used to achieve the desired specifications for special applications or to achieve specific requirements. Strength alone cannot answer all the properties related to concrete, especially its durability, ...
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Conventional concretes, which are designed, mixed, transported and processed by traditional methods, cannot be used to achieve the desired specifications for special applications or to achieve specific requirements. Strength alone cannot answer all the properties related to concrete, especially its durability, and it is necessary to consider its reliability and durability in addition to the issue of resistance and bearing loads during the service life of concrete for different areas. In recent years, on the reinforcement used in reinforced concrete structures, developments in concrete have been placed at the top of the research programs of some countries of the world. The opinion of most experts and practitioners of concrete works has been drawn to this issue that strength alone cannot answer all the properties of concrete, especially its durability, and it is necessary to design concrete for different areas in addition to the issue of resistance and bearing loads during the service life. Its reliability and durability should also be considered. In recent years, there has been a huge change in concrete technology and the emergence of new concretes.
Ali Tavakoli
Volume 2, Issue 10 , December 2021, , Pages 55-76
Abstract
Due to the high consumption of concrete in the instruments and the need to use high-strength concrete, the use of ready-mixed concrete became mandatory. Limitations From making concrete to draining and despite the long distances and traffic and economic efficiency there was a need for large projects ...
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Due to the high consumption of concrete in the instruments and the need to use high-strength concrete, the use of ready-mixed concrete became mandatory. Limitations From making concrete to draining and despite the long distances and traffic and economic efficiency there was a need for large projects build a concrete factory in a suitable place in all parts of the city.
Batching plant with accessories as a concrete manufacturer is a "concrete factory"
Batching are classified into different types in terms of type of loading, method of transportation and handling, and type of material mix (mixer).
Ramzan Alizadeh Lasaki
Volume 1, Issue 6 , December 2019, , Pages 25-33
Abstract
The expansion of knowledge on how fibers affect mortar has led to recommendations for structural design. In this study, the effect of HPFRCC on the performance of reinforced concrete beams with and without polypropylene fibers on the energy absorption and hardness of the specimens was investigated. In ...
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The expansion of knowledge on how fibers affect mortar has led to recommendations for structural design. In this study, the effect of HPFRCC on the performance of reinforced concrete beams with and without polypropylene fibers on the energy absorption and hardness of the specimens was investigated. In this regard, a reference beam and four beams reinforced with a thin layer of HPFRCC in the lower part of the beams with polypropylene fibers were tested under a four-point bending test and the effect of reinforcement on energy absorption and hardness was investigated and compared.
Mohammad Reza Asadi
Volume 1, Issue 6 , December 2019, , Pages 34-44
Abstract
The study was conducted using a laboratory approach in which five full reinforced concrete beams were subjected to four-point loading tests. One of the beams is selected as a reference sample and the other four beams are reinforced at the lower surfaces of the concrete beams with a layer of HPFRCC material, ...
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The study was conducted using a laboratory approach in which five full reinforced concrete beams were subjected to four-point loading tests. One of the beams is selected as a reference sample and the other four beams are reinforced at the lower surfaces of the concrete beams with a layer of HPFRCC material, and the bending behavior and the ductility of the beams are compared. The highest plasticity occurs in beams reinforced with HPFRCC 1-2 samples (BH-1 sample) and (BH-2 with a 41% increase over the reference sample) due to the higher ultimate tensile strain of these reinforced materials than conventional concrete and utility system performance. In samples with 1% fibers an average of 23% increase in flexural capacity and in 3% of fibers an average of 26% increase in flexural capacity.
fereshteh Ghomi Avili; marzieh Makaremi; Mojtaba Amini
Volume 1, Issue 6 , December 2019, , Pages 77-83
Abstract
Concrete structures Projects under construction near wetlands cause harmful substances to enter the wetland and thereby escape or death of animals, wetland accumulation from artificial sediments, chemical change of water, etc. Using pozzolans as well as environmentally friendly concrete is a good way ...
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Concrete structures Projects under construction near wetlands cause harmful substances to enter the wetland and thereby escape or death of animals, wetland accumulation from artificial sediments, chemical change of water, etc. Using pozzolans as well as environmentally friendly concrete is a good way to reduce harmful substances.. In this research conducted in Anzali International Wetland, the effect of constructing concrete foundations along the road of Anzali port on the pollution of the wetland was investigated and the amount of chemical changes of the sample prepared in the wetland water by different concrete, one concrete made with Portland cement and another Portland blend concrete and fused micro-silica gel. The results of this study showed that by reducing the concrete content of 8% and adding the same percentage of fused micro-silica gel to the concrete volume of the bridge bridges, while increasing the bridge's resistance, Biodiversity and pollution of the wetland water also occurred in the environmental assessment of the bridges Concrete and metal found that it is more suitable to produce less pollutants in the process of manufacturing metal bridges. Addition of fiber-reinforced silica gel resulted in less change in the chemical quality of water than in cement-based concrete, and only due to the presence of silica, the amount of silicon element was greater than that of cement-based concrete.
Ramzan Alizadeh Lasaki
Volume 1, Issue 5 , October 2019, , Pages 71-80
Abstract
In this study, the cracking force in HPFRCC reinforced beams was compared to reference beams. In this regard, a reference beam and four beams reinforced with a thin layer of HPFRCC in the lower part of the beams were subjected to four-point pure bending experiment and finally the impact of reinforcement ...
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In this study, the cracking force in HPFRCC reinforced beams was compared to reference beams. In this regard, a reference beam and four beams reinforced with a thin layer of HPFRCC in the lower part of the beams were subjected to four-point pure bending experiment and finally the impact of reinforcement on the resulting forces is investigated and compared. In the reference concrete beam, the cracks are coupled with the tensile stress-strain curvature softening and the structural bearing capacity decreases with increasing cracks. Therefore, relying on reinforcement is essential to maintain the structure. However, in the lower layer beams of the HPRFCC the microtracks allow the material to enter the hardening stage and increase the bearing capacity. This increase is more noticeable in specimens with more fibers.
