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Gas permeability testing method used for high-compactness solid concrete

A technology of gas permeability and testing method, which is applied in the field of gas permeability testing of high-density concrete, which can solve the problems of small gas flow rate of concrete, inability to accurately measure gas flow rate, and insufficient test accuracy of high-density concrete, achieving a breakthrough technology bottleneck effect

Inactive Publication Date: 2020-01-17
SHANGHAI RES INST OF BUILDING SCI CO LTD +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] "High Integrity Containers for Low and Intermediate Level Radioactive Waste - Concrete Containers" (GB36900.2-2018) mentioned the gas permeability test method of differential pressure stabilization method in the national standard for the first time, but this method also exists for high-density concrete The problem of insufficient test accuracy is mainly manifested in the fact that when the concrete density is high, the gas flow through the concrete is extremely small, and the existing test parameters and metering equipment cannot accurately measure the gas flow through the concrete test block

Method used

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  • Gas permeability testing method used for high-compactness solid concrete
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  • Gas permeability testing method used for high-compactness solid concrete

Examples

Experimental program
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Effect test

Embodiment 1

[0051] In this example, the gas permeability of C30 and C50 high-performance concrete was tested by the original test method in the national standard, and the gas permeability of C80 high-performance concrete was tested by the improved test method in the present invention. When the C80 high-density concrete is used, the gas flow rate when the inlet pressure is 0.15MPa and 0.2MPa is increased.

[0052] Table 1: Test results of gas permeability of concrete with different strength grades

[0053]

[0054] Note: Ka is the apparent gas permeability of concrete under different pressures, K V is the inherent permeability of concrete

[0055] Table 2: Test time required for one test with soap film flowmeter for different gas flow rates

[0056] Gas flow Q(mL / min) 0.12 0.2 0.6 3 10 20 40 Required time / s 516 310 103 21 6 3 1.5 Soap film breakage probability / % 70 20 5 0 0 0 0

[0057] Referring to Table 1 and Table 2, from the test resul...

Embodiment 2

[0060] In this example, the gas permeability of ultra-high performance concrete with a compressive strength greater than 120 MPa is tested, and the test results using the conventional range soap film flowmeter and the improved range soap film flowmeter are compared. The pressure of the air nozzle is 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa.

[0061] Table 3: Test time required for one test with soap film flowmeter for different gas flow rates

[0062]

[0063] Combined with Table 3, from the test results of ultra-high performance concrete:

[0064] C120 strength grade ultra-high performance concrete, when the inlet pressure is 0.15MPa, 0.2MPa, 0.3MPa, the gas flow rate through the concrete is 0.021mL / min, 0.045mL / min and 0.096mL / min, which is beyond the conventional The range of the soap film flowmeter, even when the air inlet pressure is 0.4MPa, the gas flow is only 0.132mL / min. It is extremely time-consuming to test with a conventional soap film flowmeter and the test success rate...

Embodiment 3

[0067] This example is used to verify the air tightness between the test block and the silicone sleeve of the gas permeation unit under different air inlet pressures when the gas pressure of the inflatable oil bag is 0.8 MPa.

[0068] The C80 high-strength and high-performance concrete test block is processed according to the method of the present invention and then loaded into the gas permeation unit, the plexiglass plate is improved in the middle of the top cover, and the PVC circular backing plate between the top cover and the concrete test block is removed to form an air outlet cavity. Water with half the volume of the cavity was added to the cavity, and the air intake pressures of 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, and 0.7 MPa were applied to the air inlet, and the gas leakage on the concrete surface was observed with water as the medium.

[0069] The observation results show that when the inlet pressure is 0.3MPa, 0.4MPa, 0.5MPa and 0.6MPa, a series of small bubbles emer...

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Abstract

The invention discloses a gas permeability testing method used for high-compactness solid concrete. The method includes: A, forming a cylindrical concrete test piece, and obtaining a round cake test block by cutting after curing, wherein round cake thickness is 30 mm; B, drying the round cake, placing the same in a constant temperature and humidity environment until constant weight of the test block is achieved, coating a side surface of the round cake with epoxy resin, and carrying out drying; C, assembling a gas permeation unit, and connecting a gas permeation testing device gas path, wherein the unit includes a base seat, a steel sleeve of a middle section and a top cover of an upper part, the round cake-shaped concrete test block is placed in the steel sleeve, a silicone sleeve and aninflatable rubber oil bag are sequentially arranged from an inside to an outside between the test block and the steel sleeve, a gas input mouth is arranged at the base seat to connect a high-pressurenitrogen source, a gas output mouth is arranged at the top cover to connect a soap film flow meter, the inflatable rubber oil bag elastically seals a side edge of the round cake concrete test block through squeezing the silicone sleeve after inflation, inflation pressure of the inflatable rubber oil bag is 0.8 MPa, an inner diameter of a glass tube of the soap film flow meter is 3 mm, and a rangeof the soap film flow meter is 0.01 ml / min-10 ml / min; and D, carrying out gas permeability testing of the concrete test block and result calculation.

Description

technical field [0001] The invention belongs to the technical field of concrete durability testing, and particularly relates to a gas permeability testing method for high-density concrete. Background technique [0002] The impermeability of concrete has long been the key content of the durability research and design of concrete structures. The existing concrete impermeability test methods can be divided into three categories according to different permeable media: water permeation method, chloride ion permeation method and gas permeation method. At present, the water infiltration method and chloride ion infiltration method are mainly used at home and abroad to study the impermeability of concrete. [0003] With the development of high-strength, high-performance and ultra-high-performance concrete materials, the water-binder ratio of concrete has been greatly reduced, and the use of ultra-fine admixtures such as silica fume has made high-strength and high-performance concret...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N7/10G01N15/08
CPCG01N7/10G01N15/0826
Inventor 樊俊江於林锋韩建军王琼沈贵阳孙丹丹李华良
Owner SHANGHAI RES INST OF BUILDING SCI CO LTD
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