Kian Asghari; Saeed Mehrabi; Shahriar Tavousi Tafreshi
Abstract
Nowadays, concrete has received special attention due to reasons such as the ease of preparation of constituent components, low costs compared to other materials, favorable engineering properties, extraordinary durability, formability, and most importantly, positive interaction with the environment. ...
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Nowadays, concrete has received special attention due to reasons such as the ease of preparation of constituent components, low costs compared to other materials, favorable engineering properties, extraordinary durability, formability, and most importantly, positive interaction with the environment. Although the construction of concrete with the main components of cement, aggregate and water is very simple and conventional, but the addition of new materials such as fibers causes the fragility of concrete to be significantly reduced and it shows ductile behavior under different loads. Fibrous concrete is actually a type of composite that, with the use of reinforcing fibers in the concrete mixture, does not easily fall apart under the impact of impact loads, and its tensile strength increases above normal.Concrete gains very little strength at very low temperatures, so when the degree of saturation of the concrete is not sufficiently reduced by the dewatering action, it is necessary to protect the concrete against damage caused by freezing. The use of polyolefin fibers and the effect of appropriate granulation in the concrete mixing plan is one of the effective factors in reducing the effect of freezing. In this article, the reason for the use of polyolefin fibers, the manufacturing method, mechanical properties, fiber concrete applications, and the effect of mixing design granulation on the compressive strength and abrasion percentage of fiber concrete samples in the normal environment and freezing, according to the results of applications and researches has been discussed.
keramat mahdavi; hosein Hosein Janzadeh; Hassan Divandari
Volume 2, Issue 12 , March 2021, , Pages 11-25
Abstract
In the last two decades, the increase in quality and strength in new concrete technology has grown significantly. One of the new generation concretes that is considered as a powerful and efficient concrete in the construction industry today is fiber concrete, which has improved mechanical properties ...
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In the last two decades, the increase in quality and strength in new concrete technology has grown significantly. One of the new generation concretes that is considered as a powerful and efficient concrete in the construction industry today is fiber concrete, which has improved mechanical properties such as higher tensile strength and even improved compressive strength. This concrete, which has a compressive strength in a range of 15 to 200 MPa, is mainly used in the construction of structures resistant to dynamic loads and thin walls, and its use in new construction projects has a high potential. In the present study, the role of human hair as fibers in reinforcing concrete and the characteristics of hardened concrete have been investigated and its details have been studied from the point of view of mechanical characteristics. For this purpose, 6 types of mixing schemes with different percentages of crushed hair (0-1-2-3-4 and 5% by volume) were considered and the desired mixtures were reached and molded with the help of lubricant. Tests of compressive strength, tensile strength, modulus of elasticity, and water absorption were performed to evaluate the mechanical and physical properties of concrete. The results of compressive strength of the samples showed that 2% of the consumed hair caused a 9.8% increase in compressive strength compared to the control design. Tensile strength also increased by 34.3% in the same percentage of consumption compared to the control design. The modulus of elasticity increased by 8.65% in 1% of hair consumed and then decreased. Water absorption had an increasing trend and in 2% consumption, showed a 24.2% increase compared to the control.
Kian Asghari; Mehdi Vajdian
Volume 2, Issue 5 , August 2020, , Pages 55-68
Abstract
The use of fiber concrete can have a significant change in the quantity and quality of running structures or future plans of the country. Fiber concrete is actually a composite that increases the tensile strength by applying the reinforcing fiber inside the concrete mixture and is not easily break down ...
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The use of fiber concrete can have a significant change in the quantity and quality of running structures or future plans of the country. Fiber concrete is actually a composite that increases the tensile strength by applying the reinforcing fiber inside the concrete mixture and is not easily break down under the impact of impact loads. This composite combination has the proper integration and continuity and the possibility of using concrete as a possible material to produce wiggly-resistant surfaces. The use of macrosynthetic fibers increased the physical and chemical properties of concrete and reduced shrinkage of fresh and hardened concrete. Macrosynthetic fiber can be a suitable replacement for metal fiber and thermal rebars, so the use of this type of fiber has spread in recent years. Fiber concrete is currently widely used in various applications such as highways, foundations, military industries, protection walls, and other cases. In this research, the reason for the necessity of using kortta fiber, construction method, mechanical properties of fiber concrete samples according to the results of applications and research has been discussed.
Kian Asghari; Mehdi Vajdian
Volume 2, Issue 5 , August 2020, , Pages 69-86
Abstract
The destruction of concrete depends on the formation of cracks and cracks in the cracks. As the load increases, the cracks are connected together, forming the cracks. In order to overcome this problem as well as the creation of homogeneous conditions, in the last few decades, a series of thin strands ...
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The destruction of concrete depends on the formation of cracks and cracks in the cracks. As the load increases, the cracks are connected together, forming the cracks. In order to overcome this problem as well as the creation of homogeneous conditions, in the last few decades, a series of thin strands used in all the volume of concrete are used, which are called fibers. Fibers concrete is actually a composite that increases the tensile strength by applying the reinforcing fibers inside the concrete mixture. This composite combination has the proper integration and continuity and the possibility of using concrete as a possible material to produce wiggly - resistant surfaces. Fibers concrete is also highly capable of absorbing high energy and is not easily break down under the impact of impact loads. The historical witness of this technology is the great use of building buildings. As a matter of fact, fibers concrete is the advanced form of this technology, which is replaced by natural and synthetic fibres, replacement of straw, and cement replacement in the thatch. The fibers used in this study is of the type of polyolefin fiber and polyolefine. In this research, the reason for the necessity of using fibers, construction method, mechanical propeties and applications of fiber concrete and obtaining conversion coefficients of standard cubic samples of fiber concrete to standard cylindrical sample of fiber concrete according to the results of applications and research has been discussed.
Ghasem pachideh; amin moshtagh
Volume 1, Issue 7 , December 2019, , Pages 27-53
Abstract
Given the growing demand for lightweight concrete research to obtain optimal results from lightweight concrete is inevitable. In this study, the influence of steel fibers, polypropylene and glass on the tensile strength, compressive strength and water absorption (durability) of lightweight concrete is ...
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Given the growing demand for lightweight concrete research to obtain optimal results from lightweight concrete is inevitable. In this study, the influence of steel fibers, polypropylene and glass on the tensile strength, compressive strength and water absorption (durability) of lightweight concrete is investigated. For this purpose, initially 10 basic mixing schemes in which all the properties of the fixed materials and only the percentage of fibers were changed, and one design as the reference mixing scheme (concrete without fibers) were developed. After selecting the control design, the tests of compressive strength, tensile strength, percentage Water absorption (durability) was performed on the samples at 7 days and 28 days. According to the results, it can be concluded that steel fibers are very useful in increasing the compressive and tensile strength of lightweight plastic containing fiber, which in some stages of testing increases the compressive and tensile strength of concrete by more than 40% but poly fibers Propylene and glass, due to their physical and physical properties, are most effective in reducing the percentage of water absorption or increasing the durability of concrete in corrosive environments, although they have a slight effect on the compressive and tensile strength of concrete.
