Ehsan Mohsenian Fard; Meysam Memar; Davood Ghaedian
Abstract
Concrete and rebars should have a good bond behavior so that there is no slip between rebars and concrete under the service loads. On the other hand, one of the major disadvantages of steel bars is their vulnerability to corrosion. Covering bars as a solution is also costly and cannot be implemented ...
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Concrete and rebars should have a good bond behavior so that there is no slip between rebars and concrete under the service loads. On the other hand, one of the major disadvantages of steel bars is their vulnerability to corrosion. Covering bars as a solution is also costly and cannot be implemented in all projects. So one of the most suitable alternative methods is the use of GFRP bars. Other ways to compensate for the weakness of the concrete tensile strength as well as its low ductility are the use of different fibers. Concrete with polypropylene fibers is highly ductiled compared to conventional concrete and is completely scattered in concrete and creates isotropetic conditions and can prevent cracks. Therefore, in this study, the effect of polypropylene fibers on concrete compressive strength and bonding strength between concrete and GFRP rebar was investigated experimentally. For this purpose, the amount of this type of fiber is selected 0.15, 0.30 and 0.45 % volume of concrete, and 15cm cubic concrete samples were made in three types of 350, 400 and 450 grade and were cured at 7- and 28-day ages. In this study, the rebar diameter of GFRP was chosen 8 mm and rebars were embedded inside the concrete in a length five times the rebar diameter, and 28-day concrete samples were tested through pull-out and compressive resistance tests. Finally, the compressive strength of the samples and the force-time curves from the pull-out test were assessed. Average compressive strength values, slump values, maximum force and other important parameters were discussed. The results showed that the bond resistance between the polypropylene fiber-reinforced concrete and GFRP rebar increased with the increase in the amount of fibers. Adding fibers also has a relatively good effect on enhancement of the compressive strength of the concrete.
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.
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.
