civil engineering
farhad pirmohammadi alishah; mehdi Mohammadrezaei
Abstract
Nowadays, improving problematic soils is considered as one of the geotechnical engineering challenges. Since the problematic soils have a secondary origin that are the results of chemical weathering, they have a wide range of dispersive characteristics. One of these types of soils is clay that causes ...
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Nowadays, improving problematic soils is considered as one of the geotechnical engineering challenges. Since the problematic soils have a secondary origin that are the results of chemical weathering, they have a wide range of dispersive characteristics. One of these types of soils is clay that causes many problems in the engineering project. These problems are related to their specifications, such as week strength, settlement, and dispersivity problems. One of the treatment methods of the mentioned problems is chemical soil stabilization. One of the ways to improve soil quality is to use additives. Due to the widespread use of nanomaterials in different sciences, the impact of these materials as a novel additive can be investigated. In this study, the effect of nanosilica additive on bond strength of clay soils was investigated. In this study, we investigated the effect of nanosilica on unconfined compressive strength of clay soils in Jolfa region using in vitro and uniaxial experiments. Cohesive soil samples were tested by adding different percentages of nanosilica. The results indicate that nanosilica increased the uniaxial compressive strength of the clay soil. The results showed that the percentage of nanosilica additive for optimum compressive strength in clay soil was about 0.8%. Comparison of three series of clay compressive strengths in different percentages of nanosilica additives shows a minimum resistance of about 6 kg / cm2 and maximum resistance of about 9 kg / cm2.
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.
Mehrdad Abdi Moghadam; Amirreza Abbasi Oshaghi
Abstract
The expansion of the planet's population and the need for the construction industry has caused a shortage of primary materials. On the other hand, the process of making and using these materials causes harmful damage to the environment and causes the pollution of natural resources and the release of ...
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The expansion of the planet's population and the need for the construction industry has caused a shortage of primary materials. On the other hand, the process of making and using these materials causes harmful damage to the environment and causes the pollution of natural resources and the release of carbon dioxide (CO2) in nature. In addition to this, plastic polymers used in various industries are one of the most consumed items that cause environmental pollution and the waste recycling process is costly and time-consuming. One of the most widely used polymers is polyvinyl chloride (PVC), which is used in the industry of making wires, electric cables, and all kinds of mobile phone chargers as a cover for their conductors.Limited studies have been done in the field of reusing this polymer as a member of the concrete structure as fibres and improving its mechanical properties in the past. This study deals with a comprehensive review of these studies in the field of using these types of fibres that have been used as reinforcing and reinforcing properties of concrete and focuses on a detailed investigation of the effect of different percentages and various dimensions of these types of fibres on the mechanical characteristics of concrete.
AliMohammad Sazegar; roozbeh aghamajidi; mehdi rezaei
Abstract
The use of rubber crumb as an additive in the production of concrete has been studied as a means of improving compressive strength while also addressing the environmental impact of non-degradable ingredients. In this research, the effects of adding 5%, 7.5%, and 10% rubber crumb by weight to 2% cement ...
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The use of rubber crumb as an additive in the production of concrete has been studied as a means of improving compressive strength while also addressing the environmental impact of non-degradable ingredients. In this research, the effects of adding 5%, 7.5%, and 10% rubber crumb by weight to 2% cement were analyzed. The results showed that the addition of 5% rubber crumb resulted in the highest increase in compressive strength, with a 45% increase at 7 days and 8% increase at 28 days compared to the control concrete. However, the addition of 10% rubber crumb resulted in a decrease in compressive strength, with a 3% reduction at 28 days, 5% reduction at 90 days, and 1% reduction at 120 days. The price of self-compacting concrete also increased by 16.4%, 20.5%, and 24.5% for the 5%, 7.5%, and 10% rubber crumb samples, respectively. Overall, this research suggests that the use of rubber crumb as an additive in concrete production can potentially improve compressive strength while also contributing to environmental sustainability, though the optimal percentage of rubber crumb for this purpose may vary.
Roozbeh Aghamajidi; Rahim Hajibagheri
Abstract
Increasing study and research on the components of concrete structures has led to the availability of materials, the use of which in turn has been able to have a tremendous impact on concrete production. Concrete is undoubtedly the most important building material, the production and consumption of which ...
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Increasing study and research on the components of concrete structures has led to the availability of materials, the use of which in turn has been able to have a tremendous impact on concrete production. Concrete is undoubtedly the most important building material, the production and consumption of which is increasing day by day and it is used in almost all structures. The performance of cement as one of the main components of concrete products has always been considered and with the increasing development of Iran's cement industry in terms of quantity in the production of cement, cement quality control by examining physical and chemical properties is very important. In this study, we tried to investigate the factors affecting the strength of hydrated cement used in concrete structures in Shiraz and the results indicate a decrease in concrete strength due to increasing the ratio of water to cement and also C3S and C2S are the two main compounds causing cement strength are hydrated.
farhad pirmohammadi alishah; Navid Mahmoudzadeh
Volume 2, Issue 5 , August 2020, , Pages 87-109
Abstract
Plastic concrete have been used for some four decades in watertight structures. In these four decades, plastic concrete has been successfully used in engineering control projects for seepage. Plastic concrete is produced by mixing of cement, bentonite, aggregates and water. Presence of bentonite and ...
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Plastic concrete have been used for some four decades in watertight structures. In these four decades, plastic concrete has been successfully used in engineering control projects for seepage. Plastic concrete is produced by mixing of cement, bentonite, aggregates and water. Presence of bentonite and high water-cement ratio is difference between plastic concrete and conventional concrete. These two factor cause plastic concrete, besides possession of water tighting property, have a very lesser comperssive strength and modulus of elasticity in comparsion with conventional concrete and therefore be more deformable. Researches that fulfilled on this type of concrete in the word and especially in Iran, were not extensive and most of done works have been typical studies on relative projects. In order to make more economical plastic concrete, it is necessary to evaluate the effects of changes in the properties of bentonite, and in particular the effect of its plastic index change, and given that there is no extensive research in this field in our country, we try to move toward this goal in this these. Therefore after primary stduies and test, 51 mix designs were teseted and compressive strength, modulus of elasticity and workability of them were determined. Based on the results, with increasing amount of plastic index of bentonite, compressive strength, elasticity modulus and workability decrease.
Mohamad Reza Bahadori
Volume 2, Issue 1 , April 2020, , Pages 18-30
Abstract
Today, concrete plays important role in civil engineering and construction industry. From the past until now, increasing compressive strength, durability and workability have been among the most important components considered by concrete technology researchers. Due to the fact that water is one of the ...
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Today, concrete plays important role in civil engineering and construction industry. From the past until now, increasing compressive strength, durability and workability have been among the most important components considered by concrete technology researchers. Due to the fact that water is one of the most important components of concrete mixes and forms a volume of 15 to 25% of concrete, its quality plays a key role in concrete. One way to increase workability and strength in countries such as China and Russia is to use magnetic technology in concrete construction. In this way, using magnetic technology, magnetic water is produced and used in mixing concrete. In the present paper, an attempt is made to review the studies and experiments performed in connection with the use of magnetic water in concrete mixes.
