Polymer cement waterproof coating self-closing property tester and test method

Abstract

The invention discloses a polymer cement waterproof coating self-closing property tester and a test method, and belongs to the technical field of constructional engineering, the polymer cement waterproof coating self-closing property tester comprises a lower water tank used for providing a water source; the upper water tank is arranged on the upper side of the lower water tank and is communicated with the lower water tank through an upper water pipe; the automatic water feeding device is used for ensuring the water pressure intensity in the water feeding tank; testing the test piece; the clamping assembly is arranged on one side of the upper water tank and communicated with the water outlet of the upper water tank, and the clamping assembly is used for clamping and positioning the test piece and guiding water seeping from a crack of the test piece; the probe is arranged on the lower side of the clamping assembly and used for detecting water seepage. By means of the design of the water guide groove, it can be ensured that water seeping out of a crack flows down through the water guide rod and drips onto the probe, the flow of the water is accurately detected, the self-healing speed is accurately measured through the arc-shaped inverted groove formed between the second through hole of the front pressing plate and the water guide groove, and the self-healing effect of the polymer cement waterproof coating is determined in a standard mode.

Description

Technical Field

[0001] The invention belongs to the technical field of construction engineering, and in particular relates to a self-sealing tester and a test method for a polymer cement waterproof coating. Background Art

[0002] In the field of construction engineering, structural micro cracks (usually 0.2-0.4 mm) caused by shrinkage during the hardening of concrete or mortar are the main cause of structural leakage. The most advanced treatment method is to paste or apply waterproof coatings with automatic healing and repair functions on the water-facing or water-retaining surfaces, and use the self-healing function of waterproof materials to isolate water from passing through structural cracks, thereby achieving the purpose of waterproofing. However, there is still a lack of performance testing equipment for such waterproof coatings that can automatically heal and repair structural cracks. Summary of the invention

[0003] In order to solve the above problems, the present invention adopts the following technical solutions:

[0004] A polymer cement waterproof coating self-closing tester, comprising:

[0005] A lower water tank for providing water source;

[0006] An upper water tank, which is arranged on the upper side of the lower water tank and is connected with the lower water tank through an upper water pipe;

[0007] Automatic water supply device, used to ensure the water pressure strength in the water supply tank;

[0008] Test specimens;

[0009] A clamping assembly, which is arranged at one side of the upper water tank and communicated with the water outlet of the upper water tank, and is used to clamp and position the test piece and seal and guide water seeping from the cracks of the test piece;

[0010] A probe is arranged at the lower side of the clamping assembly and is used to detect water seepage.

[0011] Furthermore, the clamping assembly comprises:

[0012] A rear pressure plate, the rear pressure plate is arranged on one side of the upper water tank, a first through hole is arranged at the center of the rear pressure plate, the first through hole is connected with the water outlet of the upper water tank through a connecting pipe, a probe fixing groove is obliquely arranged at the lower end of the rear pressure plate, and the probe is insulated from the machine body;

[0013] A front pressing plate, the front pressing plate is arranged on a side of the rear pressing plate away from the upper water tank and is detachably connected to the rear pressing plate, a second through hole is arranged at the center of the front pressing plate, a water guide groove is arranged on a side of the front pressing plate close to the rear pressing plate, and the water guide groove is arranged corresponding to the probe fixing groove;

[0014] A water guide rod is installed in the water guide groove, a first end of the probe is installed in the probe fixing groove, and a second end extends to the lower end of the water guide rod.

[0015] Furthermore, an arc-shaped inverted groove is provided between the second through hole and the water guiding groove.

[0016] Furthermore, the water guiding rod is made of wood or bamboo.

[0017] Furthermore, sealing gaskets are provided between the rear pressure plate, the front pressure plate and the test piece, and the sealing gaskets are rubber gaskets.

[0018] Furthermore, it also includes a controller and a control panel, wherein the controller is electrically connected to the probe, and the controller is electrically connected to the control panel.

[0019] Furthermore, the test piece is prepared by a mold, and the mold comprises:

[0020] Base plate;

[0021] A first limiting rod, wherein the first limiting rod is fixed to one side of the bottom plate;

[0022] A second limiting rod, the second limiting rod is fixed to the other side of the bottom plate, and a plurality of fixing members are arranged on the second limiting rod;

[0023] A spacer bar, which is arranged on the bottom plate, and has one end abutting against the first limiting rod, and the other end abutting against the second limiting rod;

[0024] An upper frame is installed on the bottom plate.

[0025] Furthermore, one side of the partition bar is in a dovetail shape.

[0026] Furthermore, the preparation steps of the test piece are:

[0027] S1. Take two cement mortar boards, evenly apply silicone structural sealant on both sides of the chamfered side 10mm away from the center, and then make the glued surfaces butt joint;

[0028] S2. Insert a stainless metal gasket with a height of 20 mm, a width of 10 mm, and a thickness of 0.5 mm into the reserved center position before the two mortar boards come into contact, and butt the two mortar boards together in the clamping clamp and press and fix them;

[0029] S3. Use a scraper to trim the sealant to be flush with the mortar board, and trim a water guide groove on the sealant near the center hole;

[0030] S4. After the sealant is cured, carefully remove the reserved metal gasket and get a 10mm×0.5mm gap in the center of the butt mortar board;

[0031] S5. Insert a polyethylene plastic sheet with a height of 20 mm, a width of 10 mm, and a thickness of 0.4 mm into the gap, with the top flush with the flat surface of the butt mortar board;

[0032] S6. Apply the polymer cement waterproof coating sample mixed in the specified ratio on one side of the flat surface of the butted mortar board, and the wet film thickness of the coating is 1.0 mm;

[0033] S7. Gently push the polyethylene plastic sheet out of the coating layer by 5mm and stop. The two sides of the plastic sheet are still in close contact with the wet coating. Place it under standard test conditions for 24±1h. After the first coating is completely dry, gently shake the plastic sheet without damaging the coating, and pull it out from the bottom of the mortar board until its top is flush with the upper surface of the coating.

[0034] S8, repeat S6-S7 to perform a second coating and ejection of the plastic sheet, and finally make the coating thickness 1.5-2.0 mm, and a crack with a length of 10 mm and a width of 0.5 mm can be obtained at the center of the coating film of the two butted cement mortar boards;

[0035] S9. After curing for 7 days under standard test conditions, use an optical microscope to measure the actual width of the cracks in the specimen and record it.

[0036] A method for using a polymer cement waterproof coating self-sealing tester, using any of the polymer cement waterproof coating self-sealing testers described above, the method comprising the following steps:

[0037] S10. Place the cured test piece between the front platen and the rear platen, with the coating facing the water;

[0038] S20, there are sealing gaskets between the test piece and the front and rear pressure plates, and finally the front pressure plate is pressed tightly and fastened with bolts to the rear pressure plate;

[0039] S30. Fill the lower water tank with sufficient clean water at 23℃±2℃, turn on the power of the equipment, and pump water into the upper water tank so that the height from the liquid level to the center of the test piece is 200mm. Keep the liquid level unchanged during the test;

[0040] S40. Observe the water seepage at the cracks of the specimen. There should be no water leakage from the sealing gaskets between the specimen and the front and rear pressure plates. The water in the upper water tank will flow out from the cracks of the mortar specimen along the horizontal connecting pipe, and flow along the water guide groove and the guide wooden stick to the water probe fixed at the center of the lower part of the front pressure plate. When the dripping amount is less than 1 drop / 2 minutes, the equipment will stop timing and alarm.

[0041] S50. Record the time from water injection to the time when no water seeps through the cracks of the specimen. If the test time exceeds 120h, the test fails.

[0042] S60, placing the test piece after the test in step S40 under standard test conditions for 24 hours, and observing with an optical microscope whether the cracks of the test piece are closed;

[0043] S70. If the crack is closed, test again according to S10 and observe for 24 hours. If the crack is still closed and the time h without water seepage at the crack is significantly shortened, the test is passed.

[0044] Beneficial effects:

[0045] The design of the water guide groove of the present invention can ensure that water seeping from the cracks flows down through the water guide rod and drips onto the probe, thereby accurately detecting the water flow rate. The arc-shaped inverted groove arranged between the second through hole of the front pressure plate and the water guide groove can accurately measure the self-healing speed and standardize the self-healing effect of the polymer waterproof coating.

[0046] The invention realizes the inverted groove design of the base mortar cement board through the design of the middle spacer, and solves the problem of base slag removal for polymer cement coating.

[0047] The present invention realizes controllable prefabricated cracks through the design of a 0.5m wide*5mm long plastic sheet, and solves the problem of inconsistent prefabricated cracks when a wallpaper knife is used to cut the prefabricated cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0049] Figure 2 This is a schematic diagram of the front pressing plate structure of the present invention;

[0050] Figure 3 This is a schematic diagram of the mold bottom plate of the present invention;

[0051] Figure 4 This is a schematic diagram of the upper frame structure of the mold of the present invention;

[0052] Figure 5 It is a schematic diagram of the structure of the spacer bar of the present invention;

[0053] Figure 6 It is a schematic diagram of the test piece structure of the present invention;

[0054] Figure 7 It is a physical schematic diagram of the overall structure of the present invention;

[0055] Figure 8 It is a schematic diagram of the front view of the test piece of the present invention;

[0056] Fig. 9 It is a schematic diagram of a top view of a test piece of the present invention.

[0057] Among them, 1. front pressure plate; 2. sealing gasket; 3. test piece; 4. rear pressure plate; 5. observation window; 6. upper water tank; 7. upper water pipe; 8. probe; 9. first through hole; 10. second through hole; 11. water guide groove; 12. water guide rod; 13. upper frame; 14. bottom plate; 15. control panel; 16. partition bar; 17. water level probe. DETAILED DESCRIPTION

[0058] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0059] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0060] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0061] Example 1

[0062] refer to Figure 1-Figure 2 and Figure 7 , a polymer cement waterproof coating self-closing tester, comprising:

[0063] A lower water tank for providing water source;

[0064] An upper water tank 6, which is arranged on the upper side of the lower water tank and is connected to the lower water tank through an upper water pipe 7;

[0065] Automatic water supply device, used to ensure the water pressure strength in the water supply tank 6;

[0066] Test specimens;

[0067] A clamping assembly, which is arranged at one side of the upper water tank 6 and is connected to the water outlet of the upper water tank 6. The clamping assembly is used to clamp and position the test piece 3 and to seal and guide the water seeping out of the cracks of the test piece 3;

[0068] Probe 8, which is arranged at the lower side of the clamping assembly, is used to detect water seepage.

[0069] The self-closing tester of the present invention is used for testing the performance of waterproof coatings under the action of water, in which cracks in the coatings heal and close themselves through physical and chemical reactions. It is suitable for testing the self-closing properties of polymer cement waterproof coatings, so that the cracks of the test piece are subjected to water pressure, and the time from the occurrence of water seepage at the cracks of the test piece to the cessation of water seepage is reported.

[0070] In specific implementation, an upper water pipe 7 is provided between the upper water tank and the lower water tank, and an observation window 5 is provided on one side of the upper end.

[0071] During specific implementation, the upper water pipe 7 extends to the bottom end of the lower water tank, and the upper end extends to more than 300 mm above the bottom surface of the upper water tank.

[0072] A water level probe 17 is provided on the upper side of the upper water tank 6 , and the water level probe 17 is electrically connected to the controller and is used to detect the water level in the upper water tank 6 and maintain the water level ≥ 200 mm.

[0073] In this embodiment, the clamping assembly includes:

[0074] The rear pressure plate 4 is arranged on one side of the upper water tank 6. A first through hole 9 is arranged at the center of the rear pressure plate 4. The first through hole 9 is connected with the water outlet of the upper water tank 6 through a connecting pipe. A probe fixing groove is obliquely arranged at the lower end of the rear pressure plate 4. The probe 8 is insulated from the machine body.

[0075] The front pressure plate 1 is arranged on the side of the rear pressure plate 4 away from the upper water tank 6 and is detachably connected to the rear pressure plate 4. A second through hole 10 is arranged at the center of the front pressure plate 1. A water guide groove 11 is arranged on the side of the front pressure plate 1 close to the rear pressure plate 4. The water guide groove 11 is arranged corresponding to the probe fixing groove.

[0076] The water guide rod 12 is installed in the water guide groove 11 . The first end of the probe 8 is installed in the probe fixing groove, and the second end extends to the lower end of the water guide rod 12 .

[0077] The design of the water guide groove of the present invention can ensure that the water seeping from the crack flows down through the water guide rod 12 and drips onto the probe, thereby accurately controlling the flow rate and velocity of the water.

[0078] In this embodiment, an arc-shaped inverted groove is provided between the second through hole 10 and the water guiding groove 11 .

[0079] The invention accurately measures the speed of self-healing by arranging an arc-shaped inverted groove between the second through hole of the front pressure plate and the water guide groove.

[0080] In this embodiment, the water guide rod 12 is made of wood or bamboo.

[0081] In this embodiment, sealing gaskets 2 are provided between the rear pressing plate 4 , the front pressing plate 1 and the test piece 3 .

[0082] In this embodiment, the sealing pad 2 is a rubber pad.

[0083] In this embodiment, a controller and a control panel 15 are further included. The controller is electrically connected to the probe 8 , and the controller is electrically connected to the control panel 15 .

[0084] Example 2

[0085] refer to Figure 3 - Figure 6 , Figure 8-Figure 9 , this embodiment provides a mold for preparing the test piece in Example 1.

[0086] In this embodiment, the test piece 3 is prepared by a mold, and the mold includes:

[0087] Bottom plate 14;

[0088] A first limiting rod, the first limiting rod is fixed to one side of the bottom plate 14;

[0089] A second limiting rod, the second limiting rod is fixed to the other side of the bottom plate 14, and a plurality of fixing members are arranged on the second limiting rod;

[0090] A spacer bar 16 is disposed on the bottom plate 14, and one end of the spacer bar 16 abuts against the first limiting rod, and the other end of the spacer bar 16 abuts against the second limiting rod;

[0091] The upper frame 13 is mounted on the bottom plate 14 .

[0092] In this embodiment, one side of the partition bar 16 is in a dovetail shape.

[0093] The invention realizes the inverted groove design of the base mortar cement board through the design of the middle spacer, and solves the problem of base slag removal for polymer cement coating.

[0094] In specific implementation, the preparation steps of the test piece are as follows:

[0095] S1. Take two cement mortar boards, evenly apply silicone structural sealant on both sides of the chamfered side about 10mm from the center, and then make the glued surfaces butt together;

[0096] S2. Insert a stainless metal gasket with a height of 20 mm, a width of 10 mm, and a thickness of 0.5 mm into the reserved center position before the two mortar boards come into contact, and butt the two mortar boards together in the clamping clamp and press and fix them;

[0097] S3. Use a scraper to trim the sealant to be flush with the mortar board, and trim a water guide groove on the sealant near the center hole;

[0098] S4. After the sealant is cured, carefully remove the reserved metal gasket and get a 10mm×0.5mm gap in the center of the butt mortar board;

[0099] S5. Insert a polyethylene plastic sheet with a height of 20 mm, a width of 10 mm, and a thickness of 0.4 mm into the gap, with the top flush with the flat surface of the butt mortar board;

[0100] S6. Apply the polymer cement waterproof coating sample mixed in the specified ratio on one side of the flat surface of the butted mortar board, and the wet film thickness of the coating is about 1.0 mm;

[0101] S7. Gently push the polyethylene plastic sheet out of the coating layer by about 5mm and stop. The two sides of the plastic sheet are still in close contact with the wet coating. Leave it under standard test conditions for about 24±1h. After the first coating is completely dry, gently shake the plastic sheet without damaging the coating, and pull it out from the bottom of the mortar board until its top is flush with the upper surface of the coating.

[0102] S8, repeating steps S6 and S7 to perform a second coating and ejection of the plastic sheet, finally making the coating thickness 1.5-2.0 mm, and obtaining a crack of 10 mm in length and 0.5 mm in width at the center of the coating film of the two butted cement mortar boards;

[0103] S9. After curing for 7 days under standard test conditions, use an optical microscope to measure the actual width of the cracks in the specimen and record it.

[0104] Example 3

[0105] refer to Figure 1 - Fig. 9 This embodiment is a method for using a polymer cement waterproof coating self-sealing tester, using the polymer cement waterproof coating self-sealing tester of embodiment 1 and a test block made by the mold in embodiment 2, and the method includes the following steps:

[0106] S10. Place the cured test piece between the front pressure plate (with observation hole and overflow hole) and the rear pressure plate, with the coating facing the water direction;

[0107] S20, there are sealing gaskets between the test piece and the front and rear pressure plates, and finally the front pressure plate is pressed tightly and fastened with bolts to the rear pressure plate;

[0108] S30. Fill the lower water tank with sufficient clean water at 23℃±2℃, turn on the power of the equipment, and pump water into the upper water tank so that the height from the liquid level to the center of the test piece is 200mm. Keep the liquid level unchanged during the test;

[0109] S40. Observe the water seepage at the cracks of the specimen. There should be no water leakage from the sealing gaskets between the specimen and the front and rear pressure plates. The water in the upper water tank will flow out from the cracks of the mortar specimen along the horizontal connecting pipe, and flow along the water guide groove and the guide wooden stick to the water probe fixed at the center of the lower part of the front pressure plate. When the dripping amount is less than 1 drop / 2 minutes, the equipment will stop timing and alarm.

[0110] S50, record the time from water injection to no water seepage at the crack of the specimen. If the test time exceeds 120h, the test fails;

[0111] S60, placing the test piece after the test in step S40 under standard test conditions for 24 hours, and observing with an optical microscope whether the cracks of the test piece are closed;

[0112] S70. If the crack is closed, perform the test again according to step S10 and observe for 24 hours. If the crack is still closed and the time h without water seepage at the crack is significantly shortened, the test is passed.

[0113] The self-closing tester of the present invention is used for testing the performance of waterproof coatings under the action of water, in which cracks in the coatings heal and close themselves through physical and chemical reactions. It is suitable for testing the self-closing properties of polymer cement waterproof coatings, so that the cracks of the test piece are subjected to water pressure, and the time from the occurrence of water seepage at the cracks of the test piece to the cessation of water seepage is reported.

[0114] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A polymer cement waterproof coating self-closing tester, characterized in that: include: A lower water tank for providing water source; An upper water tank, which is arranged on the upper side of the lower water tank and is connected with the lower water tank through an upper water pipe; Automatic water supply device, used to ensure the water pressure strength in the water supply tank; Test specimens; A clamping assembly, which is arranged at one side of the upper water tank and communicated with the water outlet of the upper water tank, and is used to clamp and position the test piece and seal and guide water seeping from the cracks of the test piece; A probe is arranged at the lower side of the clamping assembly and is used to detect water seepage.

2. The polymer cement waterproof coating self-sealing tester according to claim 1 is characterized in that: The clamping assembly comprises: A rear pressure plate, the rear pressure plate is arranged on one side of the upper water tank, a first through hole is arranged at the center of the rear pressure plate, the first through hole is connected with the water outlet of the upper water tank through a connecting pipe, a probe fixing groove is obliquely arranged at the lower end of the rear pressure plate, and the probe is insulated from the machine body; A front pressing plate, the front pressing plate is arranged on a side of the rear pressing plate away from the upper water tank and is detachably connected to the rear pressing plate, a second through hole is arranged at the center of the front pressing plate, a water guide groove is arranged on a side of the front pressing plate close to the rear pressing plate, and the water guide groove is arranged corresponding to the probe fixing groove; A water guide rod is installed in the water guide groove, a first end of the probe is installed in the probe fixing groove, and a second end extends to the lower end of the water guide rod.

3. The polymer cement waterproof coating self-sealing tester according to claim 2 is characterized in that: An arc-shaped inverted groove is arranged between the second through hole and the water guiding groove.

4. The polymer cement waterproof coating self-sealing tester according to claim 2, characterized in that: The water guide rod is made of wood or bamboo.

5. The polymer cement waterproof coating self-sealing tester according to claim 2, characterized in that: Sealing pads are arranged between the rear pressing plate, the front pressing plate and the test piece, and the sealing pads are rubber pads.

6. The polymer cement waterproof coating self-sealing tester according to claim 1, characterized in that: The device also includes a controller and a control panel. The controller is electrically connected to the probe, and the controller is electrically connected to the control panel.

7. The polymer cement waterproof coating self-sealing tester according to claim 1, characterized in that: The test piece is prepared by a mold, and the mold comprises: Base plate; A first limiting rod, wherein the first limiting rod is fixed to one side of the bottom plate; A second limiting rod, the second limiting rod is fixed to the other side of the bottom plate, and a plurality of fixing members are arranged on the second limiting rod; A spacer bar, which is arranged on the bottom plate, and has one end abutting against the first limiting rod, and the other end abutting against the second limiting rod; An upper frame is installed on the bottom plate.

8. The polymer cement waterproof coating self-sealing tester according to claim 7, characterized in that: One side of the partition bar is in a dovetail shape.

9. The polymer cement waterproof coating self-sealing tester according to claim 8, characterized in that: The preparation steps of the test piece are: S1. Take two cement mortar boards, evenly apply silicone structural sealant on both sides of the chamfered side 10mm away from the center, and then make the glued surfaces butt joint; S2. Insert a stainless metal gasket with a height of 20 mm, a width of 10 mm, and a thickness of 0.5 mm into the reserved center position before the two mortar boards come into contact, and butt the two mortar boards together in the clamping clamp and press and fix them; S3. Use a scraper to trim the sealant to be flush with the mortar board, and trim a water guide groove on the sealant near the center hole; S4. After the sealant is cured, carefully remove the reserved metal gasket and get a 10mm×0.5mm gap in the center of the butt mortar board; S5. Insert a polyethylene plastic sheet with a height of 20 mm, a width of 10 mm, and a thickness of 0.4 mm into the gap, with the top flush with the flat surface of the butt mortar board; S6. Apply the polymer cement waterproof coating sample mixed in the specified ratio on one side of the flat surface of the butted mortar board, and the wet film thickness of the coating is 1.0 mm; S7. Gently push the polyethylene plastic sheet out of the coating layer by 5mm and stop. The two sides of the plastic sheet are still in close contact with the wet coating. Place it under standard test conditions for 24±1h. After the first coating is completely dry, gently shake the plastic sheet without damaging the coating, and pull it out from the bottom of the mortar board until its top is flush with the upper surface of the coating. S8, repeat S6-S7 to perform a second coating and ejection of the plastic sheet, and finally make the coating thickness 1.5-2.0 mm, and a crack with a length of 10 mm and a width of 0.5 mm can be obtained at the center of the coating film of the two butted cement mortar boards; S9. After curing for 7 days under standard test conditions, use an optical microscope to measure the actual width of the cracks in the specimen and record it.

10. A testing method for a polymer cement waterproof coating self-closing tester, characterized in that: Using the polymer cement waterproof coating self-sealing tester according to any one of claims 1 to 9, the method comprises the following steps: S10. Place the cured test piece between the front platen and the rear platen, with the coating facing the water; S20, there are sealing gaskets between the test piece and the front and rear pressure plates, and finally the front pressure plate is pressed tightly and fastened with bolts to the rear pressure plate; S30. Fill the lower water tank with sufficient clean water at 23℃±2℃, turn on the power of the equipment, and pump water into the upper water tank so that the height from the liquid level to the center of the test piece is 200mm. Keep the liquid level unchanged during the test; S40. Observe the water seepage at the cracks of the specimen. There should be no water leakage from the sealing gaskets between the specimen and the front and rear pressure plates. The water in the upper water tank will flow out from the cracks of the mortar specimen along the horizontal connecting pipe, and flow along the water guide groove and the guide wooden stick to the water probe fixed at the center of the lower part of the front pressure plate. When the dripping amount is less than 1 drop / 2 minutes, the equipment will stop timing and alarm. S50. Record the time from water injection to the time when no water seeps through the cracks of the specimen. If the test time exceeds 120h, the test fails. S60, placing the test piece after the test in step S40 under standard test conditions for 24 hours, and observing with an optical microscope whether the cracks of the test piece are closed; S70. If the crack is closed, test again according to S10 and observe for 24 hours. If the crack is still closed and the time h without water seepage at the crack is significantly shortened, the test is passed.

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