CN-121977965-A - Method and device for testing vacuum saturation moisture content of light building material

CN121977965ACN 121977965 ACN121977965 ACN 121977965ACN-121977965-A

Abstract

The application belongs to the technical field of building material testing, and particularly relates to a testing device for vacuum saturated moisture content of a light building material, which comprises a water absorption module, a vacuum operation module and a test piece, wherein the water absorption module is used for providing a closed vacuum operation space for vacuum saturated water absorption of the light building material test piece; the buoyancy self-adaptive graded release module is in sealing connection with the water absorption module through a sealing piece and is used for dynamically adjusting the pressing limiting force and the height according to the buoyancy real-time change in the water absorption process of the test piece, so that the test piece is immersed in the whole process and does not shade the water absorption surface of the test piece. The application constructs a vacuum saturation test foundation structure adapting to the light building material, solves the core problems that a test piece is easy to float upwards and cannot be completely immersed in the traditional test, realizes the cooperation of whole-course pressing limit and bearing of the test piece, ensures that each module works independently, the vacuum environment is sealed and controllable, and the pressing structure does not shade the water absorption surface of the test piece, thereby laying a device foundation for testing the vacuum saturation moisture content of the light building material.

Inventors

SUN LIXIN
YANG HANYU
JIANG ZHAOCAI
QU JUNHUI
ZHANG SONGHAO
ZHAO LIANG
KAN JIANFENG
Bi Bingteng

Assignees

中国建筑科学研究院有限公司

Dates

Publication Date: 20260505
Application Date: 20260325

Claims (10)

1. The device for testing the vacuum saturated moisture content of the light building material is characterized by comprising the following components: The water absorption module (1) is used for providing a closed vacuum operation space for vacuum saturated water absorption of the light building material test piece (9); The buoyancy self-adaptive graded release module (2) is in sealing connection with the water absorption module (1) through a sealing piece (3) and is used for dynamically adjusting the pressing limiting force and the height according to the buoyancy real-time change in the water absorption process of the test piece (9), so that the test piece (9) is immersed in the whole process and does not shade the water absorption surface of the test piece (9); The vacuum module is communicated with the water absorption module (1) through an exhaust pipe (5) and is used for vacuumizing the water absorption module (1) to form a negative pressure environment; the water supply module is communicated with the water absorption module (1) through a transfusion tube (7) and is used for conveying water into the water absorption module (1) to enable the test piece (9) to be immersed gradually; the exhaust pipe (5) and the infusion pipe (7) are respectively and independently provided with a valve (8) for on-off control.
2. The testing device according to claim 1, wherein the water absorption module (1) comprises a vacuum box (101), a vacuum pressure reducing valve (102), a vacuum pressure gauge (103) and a supporting frame (104), the supporting frame (104) is arranged inside the vacuum box (101) and used for supporting a test piece (9), and the vacuum pressure reducing valve (102) and the vacuum pressure gauge (103) are assembled on the box wall of the vacuum box (101) and are communicated with the inner cavity of the vacuum box (101).
3. The testing device according to claim 1, wherein the buoyancy adaptive grading release module (2) comprises a limiting press net (201), a loading rod (202), a force sensor (203), a driving device (204) and a control unit (205), the driving device (204) is arranged at the outer top of the vacuum box (101), the loading rod (202) penetrates through the sealing element (3) to extend into the vacuum box (101), the lower end of the loading rod is connected with the limiting press net (201), the force sensor (203) is arranged on the rod body, the control unit (205) is electrically connected with the force sensor (203) and the driving device (204), the limiting press net (201) is of a hollowed-out net structure and is matched with the upper surface of the test piece (9), and the limiting press can be formed on the test piece (9) in a planar mode without obstructing moisture from contacting the surface of the test piece (9).
4. The testing device according to claim 1, wherein the vacuum module is a vacuum pump (4), the vacuum pump (4) is communicated with the interior of the vacuum box (101) through an exhaust pipe (5), the exhaust pipe (5) and the infusion pipe (7) are both in sealing connection with the box wall of the vacuum box (101), and the height of a port of the infusion pipe (7) extending into the interior of the vacuum box (101) is lower than the bearing surface of the supporting frame (104).
5. The testing device according to claim 1, wherein the water supply module is a water tank (6), the water tank (6) is communicated with the interior of the vacuum box (101) through a liquid conveying pipe (7), and water injection into the box is realized by utilizing negative pressure in the vacuum box (101).
6. The method for testing the vacuum saturated moisture content of the light building material is characterized in that the testing device of any one of claims 1-5 is adopted, the stable immersion and sufficient water absorption of the light building material test piece (9) are realized by means of vacuumizing to form a negative pressure environment, dynamically releasing the pressure to adapt to the water absorption buoyancy change of the test piece (9) and slowly immersing the test piece (9) by vacuum water injection, and then the vacuum saturated moisture content test is completed, and the method comprises the following steps: S1, placing a test piece (9) on a support frame (104) in a vacuum box (101) of a water absorption module (1), closing the vacuum box (101) to ensure the sealing of the box, starting a vacuum pump (4) of the vacuum module and opening a valve (8) on an exhaust pipe (5), vacuumizing the vacuum box (101) and monitoring through a vacuum pressure gauge (103), and keeping a preset vacuum state for a preset time; S2, a control signal is sent to a driving device (204) through a control unit (205), the driving device (204) drives a loading rod (202) to move downwards to enable a limiting pressing net (201) to press a test piece (9), and after a force sensor (203) detects the pressure signal and feeds the pressure signal back to the control unit (205), the driving device (204) is controlled to stop moving downwards to achieve initial pressing limiting of the test piece (9); S3, opening a valve (8) on a transfusion tube (7) connected with the water supply module and the water absorption module (1), sucking water in the water tank (6) into the vacuum tank (101) by utilizing negative pressure in the vacuum tank (101), controlling the water injection speed to slowly raise the liquid level, and closing the valve (8) on the transfusion tube (7) after the water body submerges the top of the test piece (9) to a preset height; S4, opening a vacuum relief valve (102) on the vacuum box (101) to enable the internal pressure of the vacuum box (101) to slowly recover to normal pressure, detecting initial buoyancy F0 received by the test piece (9) by a force sensor (203) at the moment, and transmitting the initial buoyancy F0 to a control unit (205) for recording; S5, controlling a force sensor (203) through a control unit (205) to record buoyancy data of the test piece (9) at intervals of preset time and feed back the buoyancy data in real time, and moving a limiting pressing net (201) upwards in a grading manner according to buoyancy change, so as to gradually release the pressing force until the test piece (9) is thoroughly released; s6, taking out the test piece (9) after soaking in the water body in the vacuum box (101) for a preset time, and measuring and calculating the vacuum saturated moisture content of the test piece.
7. The method according to claim 6, wherein in step S1, the air pressure in the vacuum box (101) is pumped to below 2000Pa and the vacuum is maintained for 4 hours to ensure adequate evacuation of air from the internal pores of the test piece (9).
8. The test method according to claim 6, wherein in step S3, the rising speed of the liquid level of the water injected into the vacuum box (101) is not more than 1mm/min, and the water is injected to the 5cm position at the top of the water body submerged test piece (9), so that the test piece (9) is fully and slowly submerged.
9. The test method according to claim 6, wherein in the step S5, the force sensor (203) records buoyancy data at intervals of half an hour, when the detected buoyancy is lower than 0.5 times of the initial buoyancy F0, the control unit (205) controls the driving device (204) to drive the loading rod (202) to move the limiting press net (201) upwards by 3cm, and when the detected buoyancy is lower than 0.1 times of the initial buoyancy F0, the control unit (205) controls the driving device (204) to drive the loading rod (202) to move the limiting press net (201) upwards to the initial position, so that the test piece (9) is thoroughly released.
10. The test method according to claim 6, wherein in step S6, the total immersion time of the test piece (9) is 24 hours, the saturated moisture mass is obtained by measuring the difference between the saturated wet weight and the dry weight of the test piece (9) in air, and the vacuum saturated moisture content of the test piece (9) is calculated by combining the volume of the test piece (9) measured according to archimedes' principle.

Description

Method and device for testing vacuum saturation moisture content of light building material Technical Field The invention belongs to the technical field of building material testing, and particularly relates to a method and a device for testing vacuum saturated moisture content of a light building material. Background The light building material has excellent heat preservation and insulation performance due to the structural characteristics of low dry density and high porosity, and the light building material such as rock wool, glass wool, foam concrete and the like is widely applied to the field of building energy conservation. When the energy-saving performance and durability evaluation work is carried out on the building components adopting the materials, the heat-moisture coupling transfer calculation is a core analysis means, the vacuum saturated moisture content is used as a key wet physical parameter of the light building materials, and the test precision directly determines the reliability of the heat-moisture coupling transfer calculation result, so that the method for accurately obtaining the vacuum saturated moisture content of the light building materials has important engineering practical significance. At present, a standard vacuum saturation experiment method is generally adopted in the industry to measure the vacuum saturation moisture content of a building material, the method discharges air in pores inside the material by vacuumizing, then the water body fills the pores of the material by utilizing negative pressure, and finally the vacuum saturation moisture content is calculated by measuring the difference value of the saturation wet weight and the dry weight of the material. However, aiming at the light building materials with lower dry density and higher porosity, the standard test method has the obvious technical defects in practical application that as the light building materials are light in weight, in the water injection stage of the vacuum saturation test, the test piece is subjected to obvious buoyancy generated by the water body, the condition that the test piece floats upwards or even partially exposes out of the water surface is very easy to occur, the test piece cannot be completely immersed in the water body in the whole process, and the internal pores of the material cannot be fully filled by the water body, so that the deviation between the vacuum saturation moisture content obtained by the test and the true value is larger, and the test precision is seriously influenced. In the existing research and engineering practice, no mature special solution exists for the problem of test piece floating of the vacuum saturation test of the light building material, part of testers can limit the test piece by adopting a mode of placing a heavy object above the test piece or arranging a fixed pressing plate, although the problem of test piece floating can be solved to a certain extent, the fixed pressing mode has obvious defects that firstly, a pressing device of a fixed structure cannot be adaptively adjusted according to buoyancy change in the water absorption process of the test piece, dead weight of the test piece can be gradually increased, the buoyancy is continuously reduced, continuous fixed pressing is not practically necessary, secondly, the heavy object or the fixed pressing plate can shield part of the water absorption surface of the test piece, prevent the water body from being fully contacted with pores of the test piece, further lead to insufficient water absorption of the material, further aggravate test errors of vacuum saturation moisture content, and cannot meet the requirement of accurate test of the vacuum saturation moisture content of the light building material. In summary, aiming at the vacuum saturated moisture content test of light building materials, a special test scheme for adapting the material characteristics of the light building materials is still lacking at present, and a test device and a method which can realize the whole-course stable immersion of a test piece and can dynamically adjust the pressing limit according to the buoyancy change are needed to solve the problems of floating of the test piece, shielding of a water absorption surface by a pressing structure and the like in the existing test, improve the test precision of the vacuum saturated moisture content and meet the actual engineering requirements of energy conservation and durability evaluation of building components. Disclosure of Invention The invention aims at providing a method and a device for testing the vacuum saturation moisture content of a light building material aiming at the technical problems. In view of this, the present invention provides a test device for vacuum saturation moisture content of a lightweight building material, comprising: The water absorption module is used for providing a closed vacuum operation space for vacuum saturated water absorption of the light bu