Device and method for detecting the water vapor permeability coefficient of concrete and determining the minimum contact area

Abstract

The application provides a device and method for detecting water and gas permeability coefficients of concrete and measuring minimum contact area, which comprises the following steps: measuring the minimum permeation contact area of the concrete; measuring the gas permeability of the concrete; and measuring the water permeability of the concrete. The device and method for detecting water and gas permeability coefficients of concrete and measuring minimum contact area have high concentration, a wide experimental pressure range and high practicability. The permeability of the concrete is expressed in real time, accurately, quickly and intuitively.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of concrete performance measurement, in particular to a device and method for detecting the water and air permeability coefficient of concrete and determining the minimum contact area. TECHNICAL BACKGROUND

[0002] The water and air permeability of concrete refers to the performance of water or gas penetrating or penetrating concrete under the action of gradient pressure, which is an important indicator of the durability of concrete. It is generally measured by the permeability coefficient, which mainly depends on the pore structure of concrete, the number of harmful pores (including the number of non-microscopic pores and the number of large microscopic pores). Currently, two types of permeation media are mainly used to measure this performance: water and gas. The pore structure inside the concrete not only relates to its durability performance such as permeability, air tightness, corrosion resistance, but also affects the toughness and compressive strength of the concrete.

[0003] During the experimental process of concrete permeability test, it is found that when the permeation contact area of gas, water and concrete is small, the permeability is unstable, mostly showing less than the actual permeability coefficient of concrete. With the increase of the permeation contact area, the permeability tends to be stable. The reason is that there are large seepage channels on the surface and inside the concrete, and the permeation movement of gas and water is mainly through large seepage channels. When the contact area of gas, water and concrete is small, the probability of containing large seepage channels will also be small. Regardless of whether it contains or does not contain large seepage channels, the large seepage porosity on the cross section of the concrete test block with small contact area will differ more from the overall large seepage porosity. Only when the contact area reaches a certain size, the large seepage channel rate tends to be stable, and the measured permeability coefficient is representative. Therefore, it is of great significance to calculate and determine the minimum permeation contact area of concrete.

[0004] In the traditional concrete water permeability experiment, the concrete impermeability instrument is used to measure the permeability coefficient of concrete according to the industry standard SL / T352-2020 "Experimental procedure for hydraulic concrete". This method is based on the water height of the cross-sectional area under a certain pressure to obtain the impermeability grade and impermeability coefficient of concrete. The permeability grade obtained by the experiment is the average value of the entire permeation process. The permeation process cannot be observed in real time, and the experimental process is intermittent with missing data, which cannot prove that the permeation height and time are linearly related during the permeation process. According to the research, the water permeation process of concrete is a non-steady process. In the initial stage of permeation, the seepage of water is promoted, and in the later stage of permeation, the seepage of water is hindered due to the capillary pore siphon effect. Therefore, the traditional concrete impermeability instrument for calculating the permeability coefficient of concrete cannot meet the current demand, and a new experimental method and equipment are urgently needed to observe the permeation of water in concrete in real time and make a reasonable analysis of the permeation process of concrete.

[0005] The present application adopts steady seepage flow method, and the volume of seepage water of the concrete test block is obtained under a constant pressure gradient during the test process, the water permeability coefficient of the concrete is calculated according to the Darcy formula through the change of the water permeation amount in the concrete with time. -3 ml / min, the water pressure needs to be increased by 0.1 Mpa step by step until the seepage water amount is stable and greater than or equal to 1.7*10 -3 ml / min, the maximum pressure cannot exceed 1.5 Mpa, the pressure of the pressure gauge 5 is observed, the reading of the pressure gauge is stable and the seepage is stable, then the test is started, the reading is recorded every 15-30 min, and the reading is ended after 16 h, and the water permeability related value is calculated.

[0006] There is no certain and unified standard for the measurement method of the gas permeability coefficient of the concrete. At present, the method mostly refers to the Shulin air permeability test, adopts a negative pressure mode, the cavity air is extracted to below 99 kpa under normal pressure by a vacuum pump, then the valve is closed, the time when the vacuum pressure reaches 95 kpa is taken as the starting time of the test. The time required for measuring the vacuum pressure reaching 70 kpa is measured. According to the volume of the cavity and the change of the pressure, the gas permeability coefficient of the concrete is calculated according to the Darcy formula. The Shulin air permeability test can reflect the gas permeability of the concrete during the test process, but there are problems of sealing difficulty and low negative pressure intensity.

[0007] The present application refers to the Shulin air permeability method, adopts a positive pressure and extrusion sealing mode to carry out the gas permeability test of the concrete. According to the change of the gas pressure in the cavity with time, the gas permeation in the concrete is reflected, and the high limit value of the gas pressure is greatly improved compared with the Shulin air permeability method. Therefore, it is necessary to design a concrete water and gas permeability coefficient detection and minimum contact area measurement device and method. SUMMARY

[0008] The present application aims to provide a concrete water and gas permeability coefficient detection and minimum contact area measurement device and method, which has high concentration, wide experimental pressure range, and conforms to the actual situation. The permeation performance of the concrete is expressed in real time, accurately, quickly and intuitively.

[0009] To achieve the above-mentioned purpose, the present application provides the following scheme:

[0010] The utility model provides a kind of concrete water gas permeability coefficient detection and minimum contact area determination device, including: upper machine body part, test block placement part, lower machine body, rack and computer, the lower machine body is set in the outside of the upper machine body part, the test block placement part is located lower machine body and the inside of upper machine body part, the lower machine body is placed on the rack, and the upper machine body part is electrically connected with computer;

[0011] The upper machine body part includes air inlet water part, upper machine body and liquid level detection device, the top of the upper machine body is provided with the air inlet water part, the inside of the upper machine body is provided with upper cavity, the side of the upper machine body is provided with liquid level detection device, and the liquid level detection device is communicated with the upper cavity, and the liquid level detection device is electrically connected with the computer;

[0012] The inside of the lower machine body is provided with lower cavity, and the bottom of the lower machine body is provided with air-water outlet, which is communicated with the lower cavity.

[0013] The test block placement part includes test block placement cavity, test block fixing part, gasket adjusting part and temperature control device, the bottom of the upper cavity is provided with the test block fixing part on the upper part of the gasket adjusting part, and the upper cavity is communicated with the gasket adjusting part, the bottom of the gasket adjusting part is provided with the test block placement cavity, the bottom of the test block placement cavity is provided with the lower cavity, the test block fixing part is arranged at the junction of the test block placement cavity and the lower cavity, the upper machine body and the lower machine body are connected through the test block fixing part, the inside of the placement cavity is provided with the test block, and the temperature control device is arranged on the outside of the lower part of the upper machine body.

[0014] The air inlet water part includes air inlet part and water inlet part.

[0015] The water inlet part includes water tank, water pressure pump and water inlet pipe, the water pressure pump is arranged on the water tank, the water pressure pump is connected with the water inlet pipe, the water inlet pipe is communicated with the upper cavity, and the water inlet pipe is provided with water seal valve, water pressure gauge, water pressure gauge protection valve and water pressure transmitter, and the water pressure transmitter is electrically connected with the computer.

[0016] The air inlet part includes air pressure pump and air inlet pipe, the air pressure pump is connected with the air inlet pipe, the air inlet pipe is communicated with the upper cavity, and the air inlet pipe is provided with gas seal valve, gas pressure gauge, gas pressure gauge protection valve and gas pressure transmitter, and the gas pressure transmitter is electrically connected with the computer.

[0017] The test block fixing part includes a gasket adjusting baffle, a fixing plate, a nut and a screw rod, the gasket adjusting part is provided with the gasket adjusting baffle at the junction with the upper cavity, the test block placing cavity is provided with the fixing plate at the junction with the lower cavity, the gasket adjusting baffle and the fixing plate are correspondingly provided with a plurality of screw holes, the screw rod passes through the screw holes and is fixed through the nut;

[0018] The gasket adjusting part includes a gasket and a gasket adjusting area, the gasket is placed inside the gasket adjusting area, and the gasket is arranged between the lower part of the gasket adjusting baffle and the upper part of the test block;

[0019] The diameter of the test block is smaller than the diameter of the test block placing cavity, the side surface of the test block is coated with a paraffin and rosin mixture, the inside of the gasket adjusting baffle, the gasket and the fixing plate is hollow, and the upper and lower contact surfaces of the gasket are coated with a paraffin and rosin mixture.

[0020] The liquid level detection device includes a liquid level meter and a liquid level meter automatic reader, the liquid level meter is arranged on the outside of the upper cavity and communicates with the inside of the upper cavity, the liquid level meter is provided with the liquid level meter automatic reader, and the liquid level meter automatic reader is in communication connection with a computer;

[0021] The temperature control device includes a heating band and a temperature control box, the heating band is arranged on the outside of the lower half of the upper machine body, and the temperature control box is electrically connected with the heating band.

[0022] A concrete water and gas permeability coefficient detection and minimum contact area measurement method, including the following contents:

[0023] Content 1: measuring the minimum permeation contact area of concrete;

[0024] Content 2: measuring the gas permeability of concrete;

[0025] Content 3: measuring the water permeability of concrete.

[0026] Measuring the minimum permeation contact area of concrete, specifically:

[0027] Step 101: pretreating the test block before testing;

[0028] Step 102: inverting the upper machine body on the rack, placing the gasket on the gasket adjusting baffle, coating a layer of paraffin and rosin mixture on the surface of the gasket, inverting the test block in the test block placing cavity, and pressing the gasket;

[0029] Turning on the power supply of the temperature control box to make the temperature of the heating band rise, injecting the rosin and paraffin solution along the inner wall of the upper machine body, and making the paraffin and rosin mixture flush with the bottom of the upper machine body;

[0030] Using multiple bolts through the screw hole to connect the upper and lower body nut, make it tight, after 30 min, the body is placed;

[0031] Step 103: open the water seal valve, water pressure gauge protection valve, gas seal valve and gas pressure gauge protection valve, open the water pressure pump, make the water fill 2 / 3 of the upper cavity volume, close the water pressure pump, connect the air pressure pump;

[0032] Step 104: close the water seal valve, use the air pressure pump to increase the pressure, the initial pressure is 0.8Mpa, observe the water leakage amount of the gas water outlet, if the water leakage amount is less than 1.7*10 -3 ml / min, the water pressure needs to be increased by 0.1Mpa step by step, until the water leakage amount is stable and greater than or equal to 1.7*10 -3 ml / min, the maximum pressure cannot exceed 1.5Mpa, keep the pressure stable;

[0033] Step 105: according to the change of water pressure gauge with time, calculate the water permeability of concrete;

[0034] Step 106: according to the above test method, respectively place the gasket with different inner diameters in the gasket adjusting area, repeat steps 104 and 105 to test and measure;

[0035] Step 107: according to the different contact areas and permeability coefficients, draw a graph, when the permeability coefficient no longer changes with the increase of the contact area, the contact area at this time is the minimum permeation contact area;

[0036] The water permeability of concrete is measured, specifically:

[0037] Step 201: pretreat the test block before testing;

[0038] Step 202: according to the minimum permeation contact area test, determine the appropriate gasket, place the upper body upside down on the rack, place the gasket on the gasket adjusting baffle, coat a layer of paraffin and rosin mixture on the surface of the gasket, and place the test block upside down in the test block placing cavity and press the gasket;

[0039] Turn on the power of the temperature control box, make the temperature of the heating band rise, inject the rosin and paraffin solution along the inner wall of the upper body, until the paraffin and rosin mixture is flush with the bottom of the upper body;

[0040] Using multiple bolts through the screw hole to connect the upper and lower body nut, make it tight, after 30 min, the body is placed, connect the air pressure pump;

[0041] Step 203: open the water seal valve, water pressure gauge protection valve, gas seal valve and gas pressure gauge protection valve, open the water pressure pump, make the water fill 2 / 3 of the upper cavity volume, close the water pressure pump, connect the air pressure pump;

[0042] Step 204: Close the water sealing valve and use the air booster pump to increase the pressure. The initial pressure is 0.8 MPa. Observe the amount of water seepage from the air and water outlet. If the amount of water seepage is less than 1.7*10 -3 ml / min, the water pressure should be increased step by step by 0.1Mpa until the amount of seepage water is stable and greater than or equal to 1.7*10 -3 ml / min, the maximum pressure should not exceed 1.5Mpa, and the pressure should be kept stable;

[0043] Step 205: Observe the water pressure gauge reading. The experiment starts when the water pressure gauge reading and the gas-water outlet seepage volume are stable. Click the Start button on the computer software. Record the gas-water outlet seepage volume at regular intervals. The experiment ends after 16 hours. Click the End button on the computer.

[0044] Step 206: Calculate the concrete water permeability based on the change in the water pressure gauge reading over time:

[0045]

[0046] ΔP=P i -P a

[0047]

[0048] Where: Q is the average flow, V w is the liquid seepage of the test block, Δt is the test time, ΔP is the pressure difference value, P i The stable air pressure in the cavity is the water pressure gauge reading, Pa is the atmospheric pressure, K w is the water permeability coefficient, μ2 is the water viscosity coefficient, which is 0.8949×10 -6 (kPa·S), L is the height of the concrete specimen, and A represents the cross-sectional area of ​​the specimen.

[0049] Measures concrete gas permeability, specifically:

[0050] Step 301: pre-treating the test block before testing;

[0051] Step 302: Determine a suitable gasket based on the minimum permeation contact area, invert the upper body onto the stand, place the gasket on the gasket adjustment baffle, apply a layer of paraffin wax and rosin mixture on the gasket surface, invert the test block into the test block placement cavity, and press the gasket tightly;

[0052] Turn on the power of the temperature control box to increase the temperature of the heating tape, and inject the rosin and paraffin solution along the inner wall of the upper body until the paraffin and rosin mixture is flush with the bottom of the upper body;

[0053] Use multiple bolts to connect the nuts of the upper and lower bodies through the screw holes and tighten them. After standing for 30 minutes, turn the body upright and connect the air booster pump.

[0054] Step 303: Close the water sealing valve and the water pressure gauge protection valve, open the gas sealing valve and the gas pressure gauge protection valve, and start the air booster pump. When the gas pressure gauge reading is greater than 770 kPa, close the gas sealing valve and turn off the air booster pump.

[0055] Step 304: Observe the gas pressure gauge reading. When the gas pressure gauge reading drops to 750 kPa, the experiment begins. Click the Start button on the computer software. When the gas pressure gauge reading decreases to 650 kPa, the experiment ends. Click the End button on the computer software.

[0056] Step 305: Calculate the concrete gas permeability based on the change in the gas pressure gauge reading over time:

[0057] ΔP=P i -P f

[0058]

[0059] ΔP m =P m -P a

[0060]

[0061]

[0062]

[0063] Where: P i is the starting pressure in the test, P f is the pressure when it drops to a certain value, ΔP is the pressure difference, P m is the average pressure of the upper cavity within a certain period of time, ΔP m P is the pressure difference between the upper and lower parts of the test block, n is the average pressure in the test block, P a is atmospheric pressure, Q m is the average gas flow rate in the test block, V t is the volume of the upper cavity, Δt is the test time, μ1 is the gas viscosity coefficient, and the viscosity of air is 2.2×10 -5 (Pa·S), L is the height of the concrete test block, A is the cross-sectional area of ​​the test block, K g is the gas permeability coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below only constitute some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0065] Figure 1 It is a whole structure schematic view of the concrete water and gas permeability coefficient detection and minimum contact area determination device.

[0066] Figure 2 It is a permeability coefficient minimum contact area curve diagram.

[0067] The figure reference: 1, gas sealing valve; 2, gas pressure gauge; 3, gas pressure gauge protection valve; 4, water pressure gauge protection valve; 5, water pressure gauge; 6, water sealing valve; 7, air inlet pipe; 8, water inlet pipe; 9, water pressure transmitter; 10, air booster pump; 11, water tank; 12, water pressure pump; 13, upper machine body; 14, upper cavity; 15, liquid level gauge; 16, liquid level gauge automatic reader; 17, gasket adjusting baffle; 18, gasket adjusting area; 19, gasket; 20, test block placement cavity; 21, test block; 22, lower machine body; 23, lower cavity; 24, gas and water outlet; 25, screw hole; 26, nut; 27, screw rod; 28, computer; 29, rack; 30, heat tracing band; 31, temperature control box; 32, fixed plate; 33, gas pressure transmitter. DETAILED DESCRIPTION

[0068] The technical solutions in the embodiments of the present application will be described clearly and completely below with the drawings in the embodiments of the present application. Obviously, the described embodiments only constitute some of the embodiments of the present application, and for those skilled in the art, all other embodiments obtained without creative labor based on the embodiments in the present application also belong to the scope of protection of the present application.

[0069] The purpose of the present application is to provide a concrete water and gas permeability coefficient detection and minimum contact area determination device and method, which has high concentration, wide experimental pressure range, and conforms to the actual situation. Real-time, accurate, fast and intuitive expression of the permeability of concrete.

[0070] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the following will further describe the present application in combination with the drawings and specific embodiments.

[0071] As Figure 1As shown, the concrete water gas permeability coefficient detection and minimum contact area determination device provided by the present application comprises an upper machine body 13, a test block 21 placement part, a lower machine body 22, a rack 29 and a computer 28, the lower machine body 22 is sleeved outside the upper machine body, the test block 21 placement part is located inside the lower machine body 22 and the upper machine body part, the lower machine body 22 is placed on the rack 29, and the upper machine body is electrically connected with the computer 28;

[0072] The upper machine body comprises an air inlet water part, the upper machine body 13 and a liquid level detection device, the top of the upper machine body 13 is provided with the air inlet water part, the inside of the upper machine body 13 is provided with an upper cavity 14, the side of the upper machine body 13 is provided with the liquid level detection device, the liquid level detection device is in communication with the upper cavity 14, and the liquid level detection device is electrically connected with the computer 28;

[0073] The lower machine body 22 is in a reverse convex cylindrical structure, the lower inside is provided with a lower cavity 23, the bottom of the lower machine body 22 is provided with an air-water outlet 24, and the air-water outlet 24 is in communication with the lower cavity 23;

[0074] The test block 21 placement part comprises a test block placement cavity 20, a test block fixing piece, a gasket adjusting part and a temperature control device, the bottom of the upper cavity 14 is provided with the test block fixing piece on the upper part of the gasket adjusting part, the upper cavity 14 is in communication with the gasket adjusting part, the bottom of the gasket adjusting part is provided with the test block placement cavity 20, the bottom of the test block placement cavity 20 is provided with the lower cavity 23, the test block fixing piece is arranged at the junction of the test block placement cavity 20 and the lower cavity 23, the upper machine body 13 and the lower machine body 22 are connected through the test block fixing piece, the inside of the placement cavity is provided with the test block 21, and the lower outside of the upper machine body 13 is provided with the temperature control device.

[0075] The air inlet water part comprises an air inlet part and a water inlet part;

[0076] The water inlet part comprises a water tank 11, a water pressure pump 12 and a water inlet pipe 8, the water pressure pump 12 is arranged on the water tank 11, the water pressure pump 12 is connected with the water inlet pipe 8, the water inlet pipe 8 is in communication with the upper cavity 14, and the water inlet pipe 8 is provided with a water sealing valve 6, a water pressure gauge 5, a water pressure gauge protection valve 4 and a water pressure transmitter 9, and the water pressure transmitter 9 is electrically connected with the computer 28;

[0077] The air inlet part includes an air pressure pump 10 and an air inlet pipe 7, the air pressure pump 10 is connected to the air inlet pipe 7, the air inlet pipe 7 is communicated with the upper cavity 14, the air inlet pipe 7 is provided with the gas sealing valve 1, a gas pressure gauge 2, a gas pressure gauge protection valve 3 and a gas pressure transmitter 33, the gas pressure transmitter 33 is electrically connected to the computer 28, and one embodiment of the application is that the water inlet pipe 8 and the air inlet pipe 7 are Y-shaped two branches, the diameters of the air inlet pipe 7 and the water inlet pipe 8 are different.

[0078] The test block fixing part includes a gasket adjusting baffle 17, a fixing plate 32, a nut 26 and a screw rod 27, the gasket adjusting part is provided with the gasket adjusting baffle 17 at the junction with the upper cavity 14, the inside of the adjusting baffle 17 is hollow, the test block placing cavity 20 is provided with the fixing plate 32 at the junction with the lower cavity 23, the inside of the fixing plate 32 is hollow, the gasket adjusting baffle 17 and the fixing plate 32 are correspondingly provided with a plurality of screw holes 25, the screw rod 27 passes through the screw holes 25 and is fixed through the nut 26;

[0079] The gasket adjusting part includes a gasket 19 and a gasket adjusting area 18, the gasket 19 is placed inside the gasket adjusting area 18, and the gasket 19 is arranged between the lower part of the gasket adjusting baffle 17 and the upper part of the test block 21;

[0080] The diameter of the test block 21 is slightly smaller than the diameter of the test block placing cavity 20, the side surface of the test block 21 is coated with a mixture of paraffin and rosin, the gasket adjusting baffle 17, the gasket 19 and the fixing plate 32 are provided with holes in the middle, and the upper and lower contact surfaces of the gasket 19 are coated with a mixture of paraffin and rosin.

[0081] The liquid level detection device includes a liquid level gauge 15 and a liquid level gauge automatic reader 16, the liquid level gauge 15 is arranged on the outside of the upper cavity 14 and is communicated with the inside of the upper cavity 14, the liquid level gauge 15 is provided with the liquid level gauge automatic reader 16, and the liquid level gauge automatic reader 16 is in communication connection with the computer 28;

[0082] The temperature control device includes a heating band 30 and a temperature control box 31, the heating band 30 is arranged on the outside of the lower half of the upper machine body 13, and the temperature control box 31 is electrically connected to the heating band 30.

[0083] A concrete water and gas permeability coefficient detection and minimum contact area measurement method, including the following contents:

[0084] Content 1: measuring the minimum permeation contact area of concrete;

[0085] Content 2: measuring the gas permeability of concrete;

[0086] Content 3: measuring the water permeability of concrete.

[0087] Measuring the minimum permeation contact area of concrete, specifically:

[0088] Step 101: Pretreat the test block 21 before the test;

[0089] Step 102: Invert the upper machine body 13 on the rack 29, place the gasket 19 on the gasket adjusting baffle 17, coat a layer of paraffin and rosin mixture on the surface of the gasket 19, invert the test block 21 into the test block placement cavity 20, and press the gasket 19;

[0090] Turn on the power of the temperature control box 31, raise the temperature of the heating band 30, and inject the rosin and paraffin solution along the inner wall of the upper machine body 13 until the paraffin and rosin mixture is flush with the bottom of the upper machine body 13;

[0091] Use multiple bolts to connect the upper and lower machine bodies 22 through the screw holes 25 and nuts 26, tighten them, and then place the machine after 30 minutes;

[0092] Step 103: Open the water sealing valve 6, the water pressure gauge protection valve 4, the gas sealing valve 1, and the gas pressure gauge protection valve 3, open the water pressure pump 12, make the water fill 2 / 3 of the volume of the upper cavity 14, and connect the air pressure pump 10;

[0093] Step 104: Close the water sealing valve 6, use the air pressure pump 10 to increase the pressure, the initial pressure is 0.8Mpa, observe the water leakage amount of the gas-water outlet 24, if the water leakage amount is less than 1.7*10 -3 ml / min, increase the water pressure by 0.1Mpa step by step, until the water leakage amount is stable and greater than or equal to 1.7*10 -3 ml / min, the maximum pressure should not exceed 1.5Mpa, and the pressure should be kept stable;

[0094] Step 105: According to the change of the water pressure gauge 5 with time, calculate the water permeability of the concrete;

[0095] Step 106: According to the above test method, place gaskets 19 with different inner diameters in the gasket adjusting area 18, repeat steps 104 and 105 to test and measure;

[0096] Step 107: According to the different contact areas and permeability coefficients, draw a graph, when the permeability coefficient does not change with the increase of the contact area, the contact area at this time is the minimum permeation contact area;

[0097] Measuring the water permeability of concrete, specifically:

[0098] Step 201: Pretreat the test block 21 before the test;

[0099] Step 202: According to the minimum penetration contact area test, determine the appropriate gasket 19, place the upper body 13 upside down on the bench 29, place the gasket 19 on the gasket adjusting baffle 17, coat a layer of paraffin and rosin mixture on the surface of the gasket 19, and place the test block 21 upside down in the test block placing cavity 20, and press the gasket 19;

[0100] Turn on the power of the temperature control box 31, and make the temperature of the heating band 30 rise. Use a thermal transfer pipette to inject the paraffin and rosin solution along the inner wall of the upper body 13 until the paraffin and rosin mixture is flush with the bottom edge of the upper body 13;

[0101] Use multiple bolts 27 to connect the upper and lower bodies 22 through the screw holes 25, and tighten the nuts 26. After standing for 30 minutes, place the body upright, connect the air pressure pump 10, and connect the air pressure pump 10;

[0102] Step 203: Open the water seal valve 6, the water pressure gauge protection valve 4, the gas seal valve 1 and the gas pressure gauge protection valve 3, and open the water pressure pump 12 to make the water fill 2 / 3 of the volume of the upper cavity 14. Close the water pressure pump 12;

[0103] Step 204: Close the water seal valve 6, use the air pressure pump 10 to increase the pressure, the initial pressure is 0.8Mpa, observe the water leakage amount of the gas-water outlet 24, if the water leakage amount is less than 1.7*10 -3 ml / min, the water pressure needs to be increased by 0.1Mpa step by step until the water leakage amount is stable and greater than or equal to 1.7*10 -3 ml / min, the maximum pressure cannot exceed 1.5Mpa, and the pressure is kept stable;

[0104] Step 205: Observe the water pressure gauge 5 reading, when the water pressure gauge 5 reading is stable and the gas-water outlet 24 leakage amount is stable, it is the start time of the experiment, click the start button on the computer 28 software, record the gas-liquid outlet 24 leakage amount at fixed time intervals, after 16h, the experiment is finished, click the end button on the computer 28;

[0105] Step 206: According to the change of the water pressure gauge 5 reading with time, the water permeability of concrete is calculated:

[0106]

[0107] ΔP=P i -P a

[0108]

[0109] In the formula: Q is the average flow per period, V w is the liquid penetration amount of the test block 21, V1 is the volume of water at the beginning of the test, Vn V is the volume of water at a certain time in the experiment, Δt is the time interval between each two records, ΔP is the pressure difference value, P i is the initial air pressure, P a is the atmospheric pressure, K w is the water permeability coefficient, μ2 is the water viscosity coefficient, is 0.8949 × 10 -6 (kPa·S), L is the height of the concrete test block, and A represents the cross-sectional area of the test block.

[0110] The concrete gas permeability is measured, specifically:

[0111] Step 301: Pretreat the test block 21 before the experiment;

[0112] Step 302: Determine the appropriate gasket 19 according to the minimum contact area, place the upper machine body 13 upside down on the rack 29, place the gasket 19 on the gasket adjusting baffle 17, coat a layer of paraffin and rosin mixture on the surface of the gasket 19, and place the test block 21 upside down in the test block placement cavity 20, and press the gasket 19;

[0113] Turn on the power of the temperature control box 31, and make the heating band 30 temperature rise, use the heat transfer pipette to inject the paraffin and rosin solution along the inner wall of the upper machine body 13, until the paraffin and rosin mixture is flush with the bottom edge of the upper machine body 13;

[0114] Use multiple bolts 27 to connect the upper and lower machine bodies 22 through the screw holes 25, and tighten the nuts 26, and after standing for 30 min, place the machine body, and connect the air booster pump 10;

[0115] Step 303: Close the water seal valve 6 and the water pressure gauge protection valve 4, open the gas seal valve 1 and the gas pressure gauge protection valve 3, and open the air booster pump 10; when the gas pressure gauge 2 shows a number greater than 770 kPa, close the gas seal valve 1, and close the air booster pump 10;

[0116] Step 304: Observe the gas pressure gauge 2, when the gas pressure gauge 2 shows a number of 750 kPa, it is the start time of the experiment, click the start button on the computer 28 software, and when the gas pressure gauge 2 shows a number of 650 kPa, the experiment is ended, click the end button on the computer 28;

[0117] Step 205: According to the change of the gas pressure gauge 2 with time, the gas permeability of the concrete is calculated:

[0118] ΔP = P i -P f

[0119]

[0120] ΔP m = Pm -P a

[0121]

[0122]

[0123]

[0124] P = P0 + ΔP i P0 is the initial pressure in the test, P f P is the pressure when it drops to a certain value, ΔP is the pressure difference, P m P is the average pressure in the upper cavity 14 within a certain time, ΔP m P is the pressure difference on the test block 21, P n P is the average pressure in the test block 21, P a P is the atmospheric pressure, Q m V is the average flow rate in the test block 21, V t V is the volume of the upper cavity 14, Δt is the test time, μ1 is the gas viscosity coefficient, which is 2.2×10 -5 (Pa·S), L is the height of the concrete test block, A is the cross-sectional area of the test block, K g is the gas permeability coefficient.

[0125] An embodiment of the present application is:

[0126] Minimum contact area test method:

[0127] Step 101: Prepare the concrete material, prepare the test block 21 with a diameter of 150mm and a height of 150mm according to the test ratio, and the number of each test block 21 is 2;

[0128] Step 102: The test block is cured for 28 days or 56 days according to the “Standard Test Method for Physical and Mechanical Properties of Concrete” (GB / T50081-2019) standard;

[0129] Step 103: After reaching the test age, take out the test block 21, wipe it clean, and require the upper and lower bottoms of the test block 21 to be smooth surfaces. If they are not smooth, polish them smooth, and use a steel wire brush to brush the center part of the upper top surface with a diameter of 60mm;

[0130] After weighing the test block 21, vacuum saturate it for more than 8h, and after saturation, weigh it to make the water retention of the test block 21 reach more than 40%.

[0131] Step 104: Perform paraffin and rosin sealing treatment on part of the surface of the column, and dry it at room temperature for 30min;

[0132] Step 105: Invert the upper body 13 on the rack 29, first place the gasket 19 with outer diameter 150mm and inner diameter 50mm on the gasket adjusting baffle 17, coat a layer of paraffin and rosin mixture on the surface of the gasket 19, then invert the test block 21 in the test block placing cavity 20 and press the gasket 19;

[0133] Turn on the power of the temperature control box 31, raise the temperature of the heating band 30 to the melting point of the paraffin and rosin, use a hot pipette to inject the paraffin and rosin solution along the inner wall of the upper body 13 until the paraffin and rosin mixture is flush with the bottom of the upper body 13, turn off the power of the temperature control box 31, and after solidification, the paraffin and rosin mixture completely seals and joins the test block 21 and the inner wall of the upper body 13;

[0134] Use multiple bolts 27 to connect the upper body 13 and the lower body 22 through the screw holes 25 and the nuts 26, tighten them, and after 30 minutes of standing, place the device, and connect the water inlet pipe 8 to the water pressure pump 12;

[0135] Step 106: Open the water seal valve 6, the water pressure gauge protection valve 4, the gas seal valve 1 and the gas pressure gauge protection valve 3, turn on the water pressure pump 12, fill the upper cavity 14 with 2 / 3 of water, and connect the air pressure pump 10;

[0136] Step 107: Close the water seal valve 6, use the air pressure pump 10 to increase the pressure, the initial pressure is 0.8Mpa, observe the water leakage amount of the gas-water outlet 24, if the water leakage amount is less than 1.7*10 -3 ml / min, increase the water pressure by 0.1Mpa step by step, until the water leakage amount is stable and greater than or equal to 1.7*10 -3 ml / min, the maximum pressure should not exceed 1.5Mpa, and the pressure should be kept stable;

[0137] Step 108: According to the time and pressure change law obtained by the test, use the Darcy formula:

[0138] Calculate the water permeability of the test block 21:

[0139]

[0140] ΔP=P i -P a

[0141]

[0142] Q=K w V n is the volume of water at a certain time during the test, and Δt is the time interval between each two records, ΔP is the pressure difference value, Pi P is the initial air pressure a K is the atmospheric pressure w μ is the water permeability coefficient, and μ2 is the water viscosity coefficient, which is 0.8949*10 -6 (kPa·S), L is the height of the concrete test block, and A represents the cross-sectional area of the test block.

[0143] Step 109: According to the above test method, the gaskets 19 with inner diameters of 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, and 120 mm are respectively placed in the gasket adjusting area 18, and steps 105-108 are repeated;

[0144] Step 110: According to the different contact areas and permeability coefficients, a graph is drawn, and when the permeability coefficient no longer changes with the increase of the contact area, the contact area at this time is the minimum contact area A1;

[0145] Water permeability test:

[0146] Step 201: Prepare the concrete material, and prepare test blocks 21 with a diameter of 150 mm and a height of 150 mm according to the test ratio. The number of each test block 21 is 2.

[0147] Step 202: The test blocks are cured for 28 days or 56 days according to the standard of “Standard Test Methods for Physical and Mechanical Properties of Concrete” (GB / T50081-2019);

[0148] Step 203: After reaching the test age, the test block 21 is taken out, cleaned, and the upper and lower surfaces of the test block 21 are required to be smooth. If they are not smooth, they need to be polished to be smooth. The center of the upper top surface with a diameter of 60 mm is brushed with a steel wire brush;

[0149] Step 204: Determine the minimum permeation contact area A1 according to the minimum contact area permeation test, and replace the inner hole area A2 of the gasket 19 (A2>A1);

[0150] Step 205: After weighing the test block 21, vacuum water saturation for more than 8 hours, and after saturation, weighing, the water retention of the test block 21 reaches more than 40%, and the surface of the column is sealed with paraffin and rosin, and dried at room temperature for 30 minutes;

[0151] Step 206: Calculate the volume of the upper cavity 14, open the gas sealing valve 1, the gas pressure gauge protection valve 3, the water sealing valve 6, and the water pressure gauge protection valve 4, open the water pressure pump 12, so that the water fills 2 / 3 of the volume of the upper cavity 14, close the water sealing valve 6, open the air pressure pump 10 for pressurization, the initial pressure is 0.8Mpa, and observe the water seepage amount of the gas-water outlet 24. If the water seepage amount is less than 1.7*10 -3ml / min, the water pressure should be increased step by step by 0.1Mpa until the amount of seepage water is stable and greater than or equal to 1.7*10 -3 ml / min, the maximum pressure should not exceed 1.5Mpa, and the pressure should be kept stable;

[0152] Step 207: Observe the reading of the water pressure gauge 6. When the reading of the water pressure gauge and the seepage volume of the gas-water outlet are stable, start the experiment. Record the seepage volume of the gas-water outlet 24 every 15-30 minutes. End the experiment after 16 hours and click the end button on the computer.

[0153] Step 208: Calculate the water permeability of the test block 21 based on the time and pressure variation patterns obtained from the test:

[0154]

[0155] ΔP=P i -P a

[0156]

[0157] Where: Q is the average flow rate in each period, V w is the amount of liquid infiltration into the test block 21, V1 is the volume of water at the beginning of the test, V n is the volume of water at a certain moment in the test, Δt is the time between two records, ΔP is the pressure difference, P i is the starting pressure, P a is atmospheric pressure, K w is the water permeability coefficient, μ2 is the water viscosity coefficient, which is 0.8949×10 -6 (kPa·S), L is the height of the concrete specimen, and A represents the cross-sectional area of ​​the specimen.

[0158] Gas permeability test method:

[0159] Step 301: Determine the minimum contact area A2 according to the minimum penetration test, and replace the gasket 19 corresponding to the minimum contact area A3 (A3>A2);

[0160] Step 302: Prepare concrete materials, and prepare test blocks 21 with a diameter of 150 mm and a height of 150 mm according to the test ratio, with two test blocks 21 for each test;

[0161] Step 303: Curing the test blocks for 28 days or 56 days according to the Standard for Test Methods of Physical and Mechanical Properties of Concrete (GB / T50081-2019);

[0162] Step 304: After reaching the test age, the test block 21 is taken out, cleaned, and the upper and lower bases are required to be smooth surfaces. If they are not smooth, they are polished smooth. The center of the upper top surface is brushed with a steel wire brush to a diameter of 60 mm;

[0163] After the test block 21 is weighed, it is placed in an oven for drying for 7 days at a drying temperature of 60°C. The dried test block 21 is weighed to calculate the initial moisture content;

[0164] Step 305: The column surface is sealed with paraffin and rosin, and is air-dried at room temperature for 30 min;

[0165] Step 306: The water sealing valve 6 and the water pressure gauge protection valve 4 are closed, and the gas sealing valve 1, the gas pressure gauge protection valve 3, and the air booster pump 10 are opened. When the gas pressure gauge 2 shows a value of 770 kPa or more, the gas sealing valve 1 and the air booster pump 10 are closed;

[0166] Step 307: The gas pressure gauge 2 is observed. When the gas pressure gauge 2 shows a value of 750 kPa, the start button on the computer 28 software is clicked. When the gas pressure gauge 2 shows a value of 650 kPa, the test is ended, and the end button on the computer is clicked;

[0167] Step 309: The gas permeability of the test block 21 is calculated using Darcy's formula based on the time and pressure change law obtained by the test:

[0168] ΔP = P i -P f

[0169]

[0170] ΔP m = P m -P a

[0171]

[0172]

[0173]

[0174] In the formula, P i is the initial pressure in the test, P f is the pressure when it drops to a certain value, ΔP is the pressure difference, P m is the average pressure in the upper cavity within a certain time, ΔP m is the pressure difference between the upper and lower test blocks, P n is the average pressure in the test block, P a is the atmospheric pressure, and Q m is the average flow rate in the test block, and Vt V is the volume of the upper cavity, Δt is the test time, μ1 is the gas viscosity coefficient, is 2.2*10 -5 (Pa*S), L is the height of the concrete block, A is the cross-sectional area of the block, K g is the gas permeability coefficient.

[0175] The concrete water and gas permeability coefficient detection and minimum contact area determination device and method provided by the application can change the contact area by replacing the gasket size to study the minimum contact area experiment; the water inlet is closed during the gas permeability experiment, and the gas inlet is closed during the water permeability experiment; the upper cavity can store gas and water respectively; the equipment can simultaneously realize the detection test of three kinds of concrete performance, i.e., gas permeability, water permeability and minimum contact area, and has high concentration; the concrete permeability experiment is carried out in the way of pressure increase, the experimental pressure range is wide, and the actual situation is met; the computer is used to record the pressure gauge data, which is real-time, accurate, fast and intuitive to express the permeability of the concrete.

[0176] The principles and implementation modes of the application are described by applying specific examples in the present application; the above examples are only used to help understand the method of the application and its core idea; meanwhile, according to the idea of the application, the specific implementation mode and application range will be changed by the general technical personnel in the field; in conclusion, the content of the present application should not be understood as the limitation of the application.

Claims

1. A method for measuring the water vapor permeability coefficient of concrete and the minimum contact area measuring device, characterized in that: The concrete water vapor permeability coefficient detection and minimum contact area measurement device includes: an upper body, a test block placement portion, a lower body, a stand, and a computer, wherein the lower body is sleeved on the outside of the upper body, the test block placement portion is located inside the lower body and the upper body, the lower body is placed on the stand, and the upper body is electrically connected to the computer; The upper body portion includes an air and water intake portion, an upper body, and a liquid level detection device. The air and water intake portion is provided on the top of the upper body. An upper cavity is provided inside the upper body. A liquid level detection device is provided on the side of the upper body, and the liquid level detection device is communicated with the upper cavity. The liquid level detection device is electrically connected to the computer. A lower cavity is provided inside the lower body, and an air and water outlet is provided at the bottom of the lower body, and the air and water outlet is communicated with the lower cavity; The test block placement part includes a test block placement cavity, a test block fixing part, a gasket adjustment part and a temperature control device. The test block fixing part is provided at the bottom of the upper cavity and the upper part of the gasket adjustment part, and the upper cavity is communicated with the gasket adjustment part. The test block placement cavity is provided at the bottom of the gasket adjustment part, the lower cavity is provided at the bottom of the test block placement cavity, the test block fixing part is provided at the junction of the test block placement cavity and the lower cavity, the upper body and the lower body are connected by the test block fixing part, the test block is provided inside the placement cavity, and the temperature control device is provided on the outer side of the lower part of the upper body; The measuring method comprises the following contents: Content 1: Measure the minimum penetration contact area of ​​concrete; Content 2: Measuring gas permeability of concrete; Content 3: Measuring concrete water permeability; Measure the minimum penetration contact area of ​​concrete, specifically: Step 101: Pre-treating the test block before testing; Step 102: Place the upper body upside down on the stand, place a gasket on the gasket adjustment baffle, apply a layer of paraffin and rosin mixture on the surface of the gasket, place the test block upside down in the test block placement cavity, and press the gasket tightly; Turn on the power of the temperature control box to increase the temperature of the heating tape, and inject the rosin and paraffin solution along the inner wall of the upper body until the paraffin and rosin mixture is flush with the bottom of the upper body; Use multiple bolts to connect the nuts of the upper and lower bodies through the screw holes, tighten them, let them stand for 30 minutes, and then put the body upright; Step 103: Open the water sealing valve, water pressure gauge protection valve, gas sealing valve and gas pressure gauge protection valve, turn on the water pressure pump to fill 2 / 3 of the upper cavity volume with water, turn off the water pressure pump, and connect the air booster pump; Step 104: Close the water sealing valve and use the air booster pump to increase the pressure. The initial pressure is 0.8 MPa. Observe the amount of water seepage from the air and water outlet. If the amount of water seepage is less than 1.7*10 -3 ml / min, the water pressure should be increased step by step by 0.1Mpa until the amount of seepage water is stable and greater than or equal to 1.7*10 -3 ml / min, the maximum pressure should not exceed 1.5Mpa, and the pressure should be kept stable; Step 105: Calculate the concrete water permeability based on the change of the water pressure gauge reading over time; Step 106: According to the above test method, place gaskets with different inner diameters in the gasket adjustment area respectively, and repeat steps 104 and 105 to perform tests and measurements; Step 107: Plotting different contact areas and permeability coefficients. When the permeability coefficient no longer changes with the increase of the contact area, the contact area is the minimum permeability contact area.

2. A method for measuring the water vapor permeability coefficient of concrete and the minimum contact area according to claim 1, characterized in that: The air and water intake part includes an air intake part and a water intake part; The water inlet part includes a water tank, a water pressure pump and a water inlet pipe. The water pressure pump is installed on the water tank, and the water pressure pump is connected to the water inlet pipe. The water inlet pipe is connected to the upper cavity. The water sealing valve, water pressure gauge, water pressure gauge protection valve, and water pressure transmitter are installed on the water inlet pipe. The water pressure transmitter is electrically connected to the computer. The air intake part includes an air booster pump and an air intake pipe. The air booster pump is connected to the air intake pipe. The air intake pipe is communicated with the upper cavity. The gas sealing valve, gas pressure gauge, gas pressure gauge protection valve and gas pressure transmitter are arranged on the air intake pipe. The gas pressure transmitter is electrically connected to the computer.

3. The method for measuring the water vapor permeability coefficient of concrete and the minimum contact area according to claim 1, wherein: The test block fixing member includes a gasket adjustment baffle, a fixing plate, a nut and a screw. The gasket adjustment baffle is provided at the junction of the gasket adjustment portion and the upper cavity, and the fixing plate is provided at the junction of the test block placement cavity and the lower cavity. The gasket adjustment baffle and the fixing plate are correspondingly provided with a plurality of screw holes, and the screw passes through the screw holes and is fixed by the nut. The gasket adjustment portion includes a gasket and a gasket adjustment area, the gasket is placed inside the gasket adjustment area, and the gasket is arranged between the lower part of the gasket adjustment baffle and the upper part of the test block; The diameter of the test block is smaller than the diameter of the test block placement cavity, the side of the test block is roll-coated with a mixture of paraffin and rosin, the interiors of the gasket adjustment baffle, gasket and fixed plate are hollow, and the upper and lower contact surfaces of the gasket are coated with a mixture of paraffin and rosin.

4. The method for measuring the water vapor permeability coefficient of concrete and the minimum contact area according to claim 1, wherein: The liquid level detection device includes a liquid level gauge and a liquid level gauge automatic reader. The liquid level gauge is arranged on the outer side of the upper cavity and communicates with the interior of the upper cavity. The liquid level gauge is provided with a liquid level gauge automatic reader, and the liquid level gauge automatic reader is connected to the computer for communication; The temperature control device includes a heating tape and a temperature control box. The heating tape is wound around the outside of the lower half of the upper body, and the temperature control box is electrically connected to the heating tape.

5. The method for measuring the water vapor permeability coefficient of concrete and the minimum contact area according to claim 1, wherein: Measures concrete water permeability, specifically: Step 201: pre-treating the test block before testing; Step 202: Determine a suitable gasket based on the minimum permeation contact area test, invert the upper body onto the stand, place the gasket on the gasket adjustment baffle, apply a layer of paraffin wax and rosin mixture on the gasket surface, invert the test block into the test block placement cavity, and tighten the gasket; Use multiple bolts to connect the nuts of the upper and lower bodies through the screw holes and tighten them. After standing for 30 minutes, turn the body upright and connect the air booster pump. Step 203: Open the water sealing valve, water pressure gauge protection valve, gas sealing valve and gas pressure gauge protection valve, turn on the water pressure pump to fill 2 / 3 of the upper cavity volume with water, turn off the water pressure pump, and connect the air booster pump; Step 204: Close the water sealing valve and use the air booster pump to increase the pressure. The initial pressure is 0.8 MPa. Observe the amount of water seepage from the air and water outlet. If the amount of water seepage is less than 1.7*10 -3 ml / min, the water pressure should be increased step by step by 0.1Mpa until the amount of seepage water is stable and greater than or equal to 1.7*10 -3 ml / min, the maximum pressure should not exceed 1.5Mpa, and the pressure should be kept stable; Step 205: Observe the water pressure gauge reading. The experiment starts when the water pressure gauge reading and the gas-water outlet seepage volume are stable. Click the Start button on the computer software. Record the gas-water outlet seepage volume at regular intervals. The experiment ends after 16 hours. Click the End button on the computer. Step 206: Calculate the concrete water permeability based on the change in the water pressure gauge reading over time: ； Where: Q is the average flow, V w is the liquid seepage of the test block, Δt is the test time, ΔP is the pressure difference value, P i The stable air pressure in the cavity is the water pressure gauge reading, Pa is the atmospheric pressure, K w is the water permeability coefficient, μ2 is the water viscosity coefficient, which is 0.8949×10 -6 (kPa·S), L is the height of the concrete specimen, and A represents the cross-sectional area of ​​the specimen.

6. The method for measuring the water vapor permeability coefficient of concrete and the minimum contact area according to claim 1, wherein: Measures concrete gas permeability, specifically: Step 301: pre-treating the test block before testing; Step 302: Determine a suitable gasket based on the minimum permeation contact area, invert the upper body onto the stand, place the gasket on the gasket adjustment baffle, apply a layer of paraffin wax and rosin mixture on the gasket surface, invert the test block into the test block placement cavity, and press the gasket tightly; Step 303: Close the water sealing valve and the water pressure gauge protection valve, open the gas sealing valve and the gas pressure gauge protection valve, and start the air booster pump. When the gas pressure gauge reading is greater than 770 kPa, close the gas sealing valve and turn off the air booster pump. Step 304: Observe the gas pressure gauge reading. When the gas pressure gauge reading drops to 750 kPa, the experiment begins. Click the Start button on the computer software. When the gas pressure gauge reading decreases to 650 kPa, the experiment ends. Click the End button on the computer software. Step 305: Calculate the concrete gas permeability based on the change in the gas pressure gauge reading over time: ； Where: P i is the starting pressure in the test, P f is the pressure when it drops to a certain value, ΔP is the pressure difference, P m is the average pressure of the upper cavity within a certain period of time, ΔP m P is the pressure difference between the upper and lower parts of the test block, n is the average pressure in the test block, P a is atmospheric pressure, Q m is the average gas flow rate in the test block, V t is the volume of the upper cavity, Δt is the test time, μ1 is the gas viscosity coefficient, and the viscosity of air is 2.2×10 -5 (Pa·S), L is the height of the concrete specimen, A is the cross-sectional area of ​​the specimen, and K g is the gas permeability coefficient.

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