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Method for determining gas permeability coefficient of concrete

A technology of gas permeation and gas permeability, which is applied in the field of construction engineering, can solve the problems of large errors and no consideration of the gas slip effect, and achieve the effect of high precision

Inactive Publication Date: 2013-08-14
NANJING INST OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to propose a method based on Darcy's law, and aiming at the problem that the existing concrete gas permeability test method does not consider the slip effect of gas in the process of pore migration, and the deduced result has a large error with the actual value. Test Method for Inherent Gas Permeability of Concrete Corrected to Account for Slip Effects

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  • Method for determining gas permeability coefficient of concrete

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Embodiment 1

[0025] Example 1: After sealing the side of the concrete specimen (with a size of Φ100mm×50mm) formed and maintained for 28 days with epoxy resin, place it in the test tank of the gas permeability test device, fix it, and then, in the figure 1 Enter N into the test tank in the left direction 2 , adjust the outlet air pressure P through the pressure regulator and the pressure gauge 2 0.1N / m 2 . Then enter N on the lower side 2 , and the pressure regulator and pressure gauge to adjust the inlet air pressure P 1 0.3N / m respectively 2 , 0.5N / m 2 , 0.7N / m 2 , 0.9N / m 2 , 1.1N / m 2 . After waiting for the gas flow to be constant, measure the inlet air pressure P through the flowmeter 1 0.3N / m respectively 2 , 0.5N / m 2 , 0.7N / m 2 , 0.9N / m 2 , 1.1N / m 2 When, the outlet gas flow rate Q 2 7.9×10 -13 m 3 / s, 1.5×10 -12 m 3 / s, 2.5×10 -12 m 3 / s, 3.7×10 -12 m 3 / s, 4.9×10 -12 m 3 / s. Put μ=17.58×10 -6 Ns / m 2 、L=0.05m、P 2 =0.1N / m 2 ,P 1 , Q2 and A=7.85×10 -3 ...

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Abstract

The invention discloses a method for determining a gas permeability coefficient of concrete. The method comprises the following specific steps of: (1) sealing the side surface of a cylindrical concrete test specimen which is then placed in a test flume of a gas permeability testing device; (2) inputting N2 into the test flume of the gas permeability testing device, and regulating a pressure to a constant value by a pressure regulating meter and a pressure meter, which are connected with the test flume, thus obtaining an outlet pressure P2 remained unchanged; (3) inputting N2 into the bottom of the concrete test specimen, regulating a pressure by a pressure regulating meter and a pressure meter, which are connected with the concrete test specimen, thus obtaining, an inlet pressure P1; and (4) measuring the volume flow rate of gas at different inlet pressures P1 through a flowmeter connected with the concrete test specimen, recording the reading number Q2 of the flowmeter, and then calculating to obtain the revised gas permeability coefficient K. The gas permeability coefficient of concrete derived by the method is relatively close to an actual value and high in accuracy.

Description

technical field [0001] The invention belongs to the field of construction engineering, and in particular relates to a method for measuring the gas permeability coefficient of concrete, which is mainly used for evaluating the gas permeability of on-site concrete structures and concrete test pieces in laboratories. Background technique [0002] Concrete is a porous material, and the existence of pores strongly affects its durability such as strength, toughness, impermeability, air tightness, and corrosion resistance. Permeability is one of the main indicators of concrete durability. At present, two types of permeable media are mainly used in the determination of this property: water and gas. When water is used as the infiltration medium, due to factors such as continuous hydration of cement, migration of substances, and changes in capillary structure, it is difficult to achieve a steady state in the infiltration process, so it is difficult to accurately measure the permeabilit...

Claims

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Application Information

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IPC IPC(8): G01N13/04
Inventor 张士萍宗兰张厚先董良峰费正岳
Owner NANJING INST OF TECH
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