1- Professor, Civil Engineering Faculty, Imam Khomeini International University, Qazvin, Iran.
2- Ph.D. Student, Civil Engineering Faculty. Imam Khomeini Intenational University, Qazvin, Iran.
3- Ph.D, Civil Engineering Faculty, Imam Khomeini International University, Qazvin. ,ali.saberi@edu.ikiu.ac.ir
2- Ph.D. Student, Civil Engineering Faculty. Imam Khomeini Intenational University, Qazvin, Iran.
3- Ph.D, Civil Engineering Faculty, Imam Khomeini International University, Qazvin. ,
Abstract: (23 Views)
Diffusion equations such as Darcy's equation which is used to measure the permeability coefficient of concrete has a one-dimensional limitation. If the water penetrates into the concrete in a multi-dimensional way. Therefore, there is a need for equations that measure the permeability coefficient of concrete either in a multi-dimensional way or without considering things like one-dimensional, two-dimensional or three-dimensional. Also, acute environmental conditions such as different cycles of ice and ice melting have a negative effect on concrete and especially on the surface of concrete. Therefore, in this article, according to the fractal theory, a new theoretical relationship has been presented that measures the permeability coefficient of concrete without the need for permeability dimensions. Also, the relationship between the surface resistance of concrete and its permeability coefficient in the conditions of ice and ice melting has been investigated by using pull tests from the surface and cylindrical chamber. Cylindrical chamber test is a new test invented by Mahoud Naderi. This test is very simple and has a portable device. The above test has the ability to measure the permeability of concrete in situ. Using this test, it is possible to measure the permeability of water into the concrete without breaking the concrete. To perform the above test, a steel plate must be glued on the concrete surface using epoxy resin glue. The desired adhesive must have the required compressive and shear strength so that no water leaks around it during the test. After that, the cylindrical container should be placed on the steel plate and water should be poured into it. Then, by using the handle on the device, the required pressure is applied to the water so that the water penetrates into the concrete. In the "direct tension" test to determine the surface resistance of concrete, first a metal cylinder with a diameter of 5 cm is attached to the place of the test using epoxy resin glue, then by using the "direct tension" device, the tensile force is applied to the cylinder. It is inserted to separate from the concrete surface. According to the existing relationship, the resistance value obtained by the "direct tension" method is obtained by dividing the tension force applied by the area of the cylinder. The direct tensile test can also be performed in situ. In addition, unlike the previous theories, the new theory has the ability to investigate the effect of processing time on the permeability coefficient. The obtained results show the high accuracy of the presented model for measuring the permeability coefficient of concrete. Also, the acute conditions of ice and ice melting have a negative effect on the permeability coefficient of concrete, and an inverse relationship between the permeability coefficient of concrete and the surface resistance obtained from the pull-out test was observed. With the increase in the number of acute cycles of ice and ice melting, the permeability of concrete also increases, which shows the negative effect of these conditions on concrete. Also, a great agreement between the theoretical and experimental results was observed.
Article Type: Original Research |
Subject:
Civil and Structural Engineering
Received: 2024/05/19 | Accepted: 2024/11/20
Received: 2024/05/19 | Accepted: 2024/11/20
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