Test method for permeability coefficient of permeable concrete

Abstract

The invention relates to the technical field of permeable concrete, and discloses a test method for the permeability coefficient of permeable concrete, wherein the method comprises the following steps: immersing a test piece in water for 24 hours; sealing four peripheral sides of the test piece by a membrane layer; placing the test piece in the middle of a cylinder cavity; inserting the lower part of a square cylinder into a water tank; and obtaining the permeability coefficient of the permeable concrete by a formula. By using the above method, water can be prevented from penetrating from the contact surface between the test piece and the square cylinder during the test, resulting in errors in the test data, thereby improving the efficiency and further improving the accuracy of the test results.

Description

Technical Field

[0001] The invention relates to the technical field of permeable concrete, and more specifically, to a test method for the permeability coefficient of permeable concrete. Background Art

[0002] The permeability coefficient is a direct indicator of the drainage performance of permeable concrete, and is also an important indicator of permeable concrete material and structural design. At present, there is no unified test standard for the determination of the permeability coefficient of permeable concrete, and common permeability devices are mainly used to determine the permeability coefficient of soil samples.

[0003] Theoretical experimental research on permeable cement concrete started late in China, and the test method for permeability coefficient has not been completely unified. At present, there is no unified test standard for the determination of permeability coefficient of permeable concrete. Common permeability devices are mainly used for the determination of permeability coefficient of soil samples. According to the water head condition, the permeability coefficient test method can be divided into constant water head method and variable water head method. Fine-grained soil and clay soil with poor permeability often use the variable water head method, while sandy soil with good permeability often uses the constant water head method. The Japanese standard (JISA1218T-1979) proposes a standard test method for the permeability coefficient of saturated soil. AASHTOT215-70 / ASTMD2434-74 specifies the test method for the permeability coefficient of granular soil. The commonly used constant water head permeameter in my country is the 70-type permeameter that has formed a standard. The variable water head permeameter device is complex and there are many types, mainly soil sample tube permeameter and Nan 55 type permeameter.

[0004] In the prior art, during the test of the water permeability coefficient of permeable cement concrete, a cylinder is mostly used, and the contact surface between the specimen and the inner wall of the cylinder is prone to water seepage, which has a certain impact on the test results. Therefore, a test method for the water permeability coefficient of permeable concrete is needed. Summary of the invention

[0005] The purpose of the present invention is to provide a test method for permeable concrete permeability coefficient, aiming to solve the problem of water seepage at the contact surface between a permeable concrete permeability coefficient test specimen and a cylinder wall in the prior art.

[0006] The present invention is achieved by: a test method for permeability coefficient of permeable concrete, comprising the following test steps:

[0007] 1) placing a test piece made of permeable concrete in water and soaking it for a set time, wherein the test piece is in a cubic shape, the outer periphery of the test piece has four outer peripheral side surfaces, the top of the test piece has a top end surface, and the bottom of the test piece has a bottom end surface;

[0008] 2) Take the test piece out of the water and seal the four outer sides of the test piece with a membrane layer;

[0009] 3) Provide a square tube, wherein the square tube has a tube cavity that passes through from top to bottom, and place the test piece in the middle of the tube cavity. The membrane layer on the outer periphery of the test piece abuts against the inner side wall of the tube cavity, forming a closed arrangement. The test piece divides the tube cavity into an upper cavity and a lower cavity, wherein the upper cavity is located above the test piece and the lower cavity is located below the test piece; an upper overflow port is provided on the square tube, and the upper overflow port is communicated with the upper cavity;

[0010] 4) Insert the lower part of the square tube into a water tank, the upper part of the water tank has a lower overflow port, the height of the lower overflow port is higher than the top surface of the test piece; inject water into the upper cavity through the water injection pipe, the water passes through the test piece into the lower cavity and the water tank, until water overflows from the lower overflow port of the water tank, adjust the water injection speed of the water injection pipe, keep the water level of the upper cavity of the square tube to reach the set water level, and when the overflow water volume of the upper overflow port and the lower overflow port stabilizes to the set flow rate, use a container to collect water at the lower overflow port, and record the volume Q of water collected by the container within the set time t;

[0011] 5) Measure the water level difference H between the water level in the upper cavity and the water level in the water tank, and measure the water temperature T in the water tank; obtain the permeability coefficient of the permeable concrete by the following formula:

[0012]

[0013] Among them, k T is the water permeability coefficient of the specimen (mm / s);

[0014] Q is the amount of water that penetrates the specimen within time t (mm 3 );

[0015] L is the thickness of the specimen (mm);

[0016] A is the area of ​​the top surface of the specimen (mm 2 );

[0017] H is the water level difference between the water level in the upper chamber and the water level in the water tank (mm);

[0018] T is the setting time (s).

[0019] Preferably, in the test step 2), the membrane layer extends to the periphery of the top end surface of the specimen to form an upper ring membrane arranged in a ring shape, and the upper ring membrane seals the periphery of the top end surface of the specimen.

[0020] Preferably, in the test step 3), adhesive tape is used to connect the upper ring membrane and the inner wall of the barrel cavity respectively.

[0021] Preferably, the rubber ring is arranged around the circumference of the top end surface of the test piece to seal the outer periphery of the top end surface of the test piece and the inner side wall of the barrel cavity.

[0022] Preferably, the height of the upper cavity portion is greater than the height of the lower cavity portion.

[0023] Preferably, the upper overflow port is connected to an upper overflow pipe, and the upper overflow pipe is arranged to be inclined downward and deviate to the outside of the water tank.

[0024] Preferably, the lower overflow port is connected to a lower overflow pipe, and the lower overflow pipe is arranged to be inclined downward.

[0025] Preferably, in the test step 4), when the square tube is inserted into the water tank, a flow gap exists between the bottom of the square tube and the bottom of the water tank.

[0026] Preferably, the top surface of the specimen has an upper ring surface covered by an upper ring membrane, and the upper ring surface is arranged in an arc shape; the upper ring surface is covered with a plurality of bonding ring layers, and the plurality of bonding ring layers are nested in sequence, and there are spacing ring grooves between adjacent bonding ring layers; the upper ring membrane is attached to the plurality of bonding ring layers and embedded in the spacing ring grooves from top to bottom, a water-absorbing filling layer is provided at the bottom of the spacing ring groove, the upper ring membrane is located above the water-absorbing filling layer, and there is an adsorption gap between the upper ring membrane and the water-absorbing filling layer.

[0027] Preferably, in the test step 2), the membrane layer extends to the periphery of the bottom end surface of the test piece to form a lower ring membrane arranged in a ring shape, and the lower ring membrane seals the periphery of the bottom end surface of the test piece;

[0028] The lower annular membrane has an inner annular surface arranged inwardly, and a plurality of inner membrane flow channels are arranged in the lower annular membrane, and the plurality of inner membrane flow channels are arranged at intervals along the circumference of the lower annular membrane, and the inner end of the inner membrane flow channel passes through the inner annular surface, and the outer end of the inner membrane flow channel passes downwardly through the bottom of the lower annular membrane; when the water level in the water tank is rising, the water in the lower cavity flows through the inner membrane flow channel, thereby reducing the pressure impact on the joint between the lower annular membrane and the bottom end surface.

[0029] Compared with the prior art, the permeability coefficient test method of permeable concrete provided by the present invention can avoid water from penetrating from the contact surface between the test piece and the square tube during the test, which causes errors in the test data, thereby improving efficiency and further improving the accuracy of the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of a permeability coefficient test device for a permeability coefficient test method of permeable concrete provided by the present invention;

[0031] Figure 2It is a schematic diagram of the cross-sectional structure of a test piece of a permeable concrete permeability coefficient test method provided by the present invention;

[0032] Figure 3 The present invention provides a method for testing the permeability coefficient of permeable concrete. Figure 2 A schematic diagram of the structure enlargement in the middle;

[0033] Figure 4 It is a schematic diagram of the structure of a test piece in the test method for permeability coefficient of permeable concrete provided by the present invention when viewed from above. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] The implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0036] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0037] Reference Figure 1-4 The figure shows a preferred embodiment of the present invention.

[0038] The test method for permeability coefficient of permeable concrete includes the following test steps:

[0039] 1) Place a test piece 6 made of permeable concrete in water and soak it for a set time. The test piece 6 is in a cubic shape. The outer periphery of the test piece 6 has four outer peripheral sides. The top of the test piece 6 has a top end surface. The bottom of the test piece 6 has a bottom end surface.

[0040] 2) Take the test piece 6 out of the water and seal the four outer peripheral sides of the test piece 6 with the membrane layer 7;

[0041] 3) Provide a square tube 2, wherein the square tube 2 has a tube cavity 3 which is connected from top to bottom, and place a test piece 6 in the middle of the tube cavity 3, wherein the membrane layer 7 on the outer periphery of the test piece 6 abuts against the inner side wall of the tube cavity 3, forming a closed arrangement, and the test piece 6 divides the tube cavity 3 into an upper cavity 4 and a lower cavity 5, wherein the upper cavity 4 is located above the test piece 6, and the lower cavity 5 is located below the test piece 6; an upper overflow port 8 is provided on the square tube 2, and the upper overflow port 8 is connected to the upper cavity 4;

[0042] 4) Insert the lower part of the square tube 2 into the water tank 1. The upper part of the water tank 1 has a lower overflow port 10. The height of the lower overflow port 10 is higher than the top surface of the test piece 6. Inject water into the upper cavity 4 through the water injection pipe 20. The water enters the lower cavity 5 and the water tank 1 through the test piece 6 until water overflows from the lower overflow port 10 of the water tank 1. Adjust the water injection speed of the water injection pipe 20 to keep the water level of the upper cavity 4 of the square tube 2 at the set water level. When the overflow water volume of the upper overflow port 8 and the lower overflow port 10 is stabilized to the set flow rate, use the container 12 to collect water at the lower overflow port 10, and record the volume Q of the water collected by the container 12 within the set time t.

[0043] 5) Measure the water level difference H between the water level of the upper cavity 4 and the water level of the water tank 1, and measure the temperature T of the water in the water tank; obtain the permeability coefficient of the permeable concrete by the following formula:

[0044]

[0045] Among them, k T is the water permeability coefficient of specimen 6 (mm / s);

[0046] Q is the amount of water that penetrates into the specimen 6 within time t (mm 3 );

[0047] L is the thickness of specimen 6 (mm);

[0048] A is the area of ​​the top surface of the specimen 6 (mm 2 );

[0049] H is the water level difference between the water level of the upper chamber 4 and the water level of the water tank 1 (mm);

[0050] T is the setting time (s).

[0051] By using the above method, water can be prevented from penetrating from the contact surface between the test piece 6 and the square tube 2 during the test, which would cause errors in the test data. This improves efficiency and further improves the accuracy of the test results.

[0052] Specifically, in the present invention, in the test step 2), the membrane layer 7 extends to the periphery of the top end surface of the test piece 6 to form an upper ring membrane 13 arranged in a ring shape, and the upper ring membrane 13 seals the periphery of the top end surface of the test piece 6 .

[0053] The upper annular membrane 13 is provided to seal the outer periphery of the top surface of the test piece 6, thereby preventing water from penetrating through the gap between the test piece 6 and the cylinder cavity 3 and the outer periphery of the top surface of the test piece 6, thereby making the test result more accurate.

[0054] Specifically, in the present invention, in the test step 3), the upper annular membrane 13 is connected to the inner wall of the barrel cavity 3 by using adhesive tape.

[0055] The position of the test piece 6 can be restricted by connecting the upper ring membrane 13 and the inner wall of the barrel cavity 3 with adhesive tape, thereby preventing the test piece from sliding down in the barrel cavity 3 due to gravity.

[0056] Specifically, in the present invention, the rubber ring is arranged around the circumference of the top end surface of the test piece 6 to seal the outer circumference of the top end surface of the test piece 6 and the inner side wall of the barrel cavity 3 .

[0057] By sealing the outer periphery of the top surface of the test piece 6 and the inner wall of the barrel cavity 3 with a rubber ring, it is possible to prevent water from penetrating into the lower cavity 5 through the gap between the test piece 6 and the barrel cavity 3, thereby causing errors in the test results.

[0058] Specifically, in the present invention, the height of the upper cavity portion 4 is greater than the height of the lower cavity portion 5 .

[0059] Since the height of the upper cavity 4 is greater than that of the lower cavity 5 , the water pressure in the upper cavity 4 can better penetrate the test piece 6 , thereby improving the test efficiency.

[0060] Specifically, in the present invention, the upper overflow port 8 is connected to an upper overflow pipe 9 , and the upper overflow pipe 9 is arranged to be tilted downward and deviate to the outside of the water tank 1 .

[0061] Since the upper overflow pipe 9 is arranged to be tilted downward, the water in the cylinder cavity 3 can be discharged as quickly as possible when it is higher than the upper overflow port 8, and since the discharge port position of the upper overflow pipe 9 deviates to the outside of the water tank 1, the water flowing out of the upper overflow pipe 9 will not fall into the water tank 1, thereby avoiding the water flowing into the water tank 1 to cause errors in the test results, further improving the accuracy of the test.

[0062] Specifically, in the present invention, the lower overflow port 10 is connected to a lower overflow pipe 11, and the lower overflow pipe 11 is arranged to be inclined downward.

[0063] The lower overflow pipe 11 is arranged to be tilted downward, so that the water in the water tank 1 can be discharged as quickly as possible when the water is higher than the lower overflow port 10 .

[0064] Specifically, in the present invention, in the test step 4), after the square tube 2 is inserted into the water tank 1, a flow gap exists between the bottom of the square tube 2 and the bottom of the water tank 1.

[0065] Through the provided flow gap, water can penetrate the test piece from the upper cavity 4 and flow to the lower cavity 5, and then enter the water tank 1 through the flow gap, so that the water permeability coefficient of the test piece 6 can be calculated according to the water level difference H between the water level of the upper cavity 4 and the water level of the water tank 1.

[0066] Specifically, in the present invention, the top surface of the specimen 6 has an upper ring surface covered by an upper ring membrane 13, and the upper ring surface is arranged in an arc shape; the upper ring surface is covered with a plurality of bonding ring layers 17, and the plurality of bonding ring layers 17 are nested in sequence, and there are spacing ring grooves 18 between adjacent bonding ring layers 17, the upper ring membrane 13 is attached to the plurality of bonding ring layers 17, and is embedded in the spacing ring grooves 18 from top to bottom, and a water-absorbing filling layer 19 is provided at the bottom of the spacing ring groove 18, the upper ring membrane 13 is located above the water-absorbing filling layer 19, and there is an adsorption gap 16 between the upper ring membrane 13 and the water-absorbing filling layer 19.

[0067] Through the structures such as the bonding ring layer 17, the upper ring membrane 13 and the water-absorbing filling layer 19, the water body can be blocked by the multiple spaced ring grooves 18 formed by the bonding ring layers 17, and the setting of the water-absorbing filling layer 19 can further prevent the water body from penetrating into the gap between the upper ring membrane 13 and the test piece 6, thereby ensuring the sealing between the upper ring membrane 13 and the test piece 6, and further preventing the water body from flowing into the lower cavity 5 through the gap between the side of the test piece 6 and the cylindrical cavity 3, thereby further ensuring the accuracy of the test results and avoiding errors.

[0068] Specifically, in the present invention, in the test step 2), the membrane layer 7 extends to the periphery of the bottom end surface of the test piece 6 to form a lower ring membrane 14 arranged in a ring shape, and the lower ring membrane 14 seals the periphery of the bottom end surface of the test piece 6;

[0069] The lower annular membrane 14 has an inner annular surface arranged inwardly, and a plurality of inner membrane flow channels 15 are arranged in the lower annular membrane 14. The plurality of inner membrane flow channels 15 are arranged at intervals along the circumference of the lower annular membrane 14, and the inner membrane flow channels 15 are curved. The inner ends of the inner membrane flow channels 15 penetrate the inner annular surface, and the outer ends of the inner membrane flow channels 15 penetrate downwardly through the bottom of the lower annular membrane 14. When the water level in the water tank 1 is rising, the water in the lower cavity 5 flows through the inner membrane flow channels 15, thereby reducing the pressure impact on the joint between the lower annular membrane 14 and the bottom end surface.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. Test method for permeability coefficient of permeable concrete, It is characterized in that The test steps include: 1) Place a test piece made of permeable concrete in water and soak it for a set time. The test piece is in a cubic shape. The outer periphery of the test piece has four outer peripheral sides. The top of the test piece has a top end surface, and the bottom of the test piece has a bottom end surface. 2) Take the specimen out of the water and seal the four outer sides of the specimen with a membrane layer; 3) Provide a square tube, wherein the square tube has a tube cavity that passes through from top to bottom, and place the test piece in the middle of the tube cavity. The membrane layer on the outer periphery of the test piece abuts against the inner side wall of the tube cavity, forming a closed arrangement. The test piece divides the tube cavity into an upper cavity and a lower cavity, wherein the upper cavity is located above the test piece and the lower cavity is located below the test piece; an upper overflow port is provided on the square tube, and the upper overflow port is communicated with the upper cavity; 4) Insert the lower part of the square tube into a water tank, wherein the upper part of the water tank has a lower overflow port, and the height of the lower overflow port is higher than the top surface of the test piece; Water is injected into the upper cavity through the water injection pipe, and the water passes through the test piece into the lower cavity and the water tank until water overflows from the lower overflow port of the water tank, and the water injection speed of the water injection pipe is adjusted to keep the water level of the upper cavity of the square cylinder to reach the set water level. When the overflow water volume of the upper overflow port and the lower overflow port is stabilized to the set flow rate, a container is used to collect water at the lower overflow port, and the volume Q of water collected by the container within the set time t is recorded; 5) Measure the water level difference H between the water level in the upper cavity and the water level in the water tank, and measure the water temperature T in the water tank; The permeability coefficient of permeable concrete is obtained by the following formula: ； in, is the water permeability coefficient of the specimen, in units of mm / s; Q is the amount of water that penetrates the specimen within time t, unit: mm 3 ; L is the thickness of the specimen, in mm; A is the area of ​​the top surface of the specimen, unit: mm 2 ; H is the water level difference between the water level in the upper chamber and the water level in the water tank, in mm; t is the setting time, unit: s.

2. The permeability coefficient test method of permeable concrete according to claim 1, It is characterized in that In the test step 2), the membrane layer extends to the periphery of the top end surface of the test piece to form an upper ring membrane arranged in a ring shape, and the upper ring membrane seals the periphery of the top end surface of the test piece.

3. The permeability coefficient test method of permeable concrete according to claim 2, It is characterized in that In the test step 3), the upper ring membrane is connected to the inner wall of the barrel cavity by using adhesive tape.

4. The permeability coefficient test method of permeable concrete according to claim 3, It is characterized in that A rubber ring is arranged around the circumference of the top end surface of the test piece to seal the outer circumference of the top end surface of the test piece and the inner side wall of the barrel cavity.

5. The permeability coefficient test method of permeable concrete according to claim 2, It is characterized in that The height of the upper cavity portion is greater than the height of the lower cavity portion.

6. The permeability coefficient test method of permeable concrete according to claim 2, It is characterized in that The upper overflow port is connected with an upper overflow pipe, and the upper overflow pipe is arranged to be inclined downward and deviate to the outside of the water tank.

7. The permeability coefficient test method of permeable concrete according to claim 2, It is characterized in that The lower overflow port is connected with a lower overflow pipe, and the lower overflow pipe is arranged to be inclined downward.

8. The permeability coefficient test method of permeable concrete according to claim 2, It is characterized in that In the test step 4), when the square tube is inserted into the water tank, a flow gap exists between the bottom of the square tube and the bottom of the water tank.

9. The permeability coefficient test method of permeable concrete according to any one of claims 2 to 8, It is characterized in that The top surface of the specimen has an upper ring surface covered by an upper ring membrane, and the upper ring surface is arranged in an arc shape; the upper ring surface is covered with multiple bonding ring layers, and the multiple bonding ring layers are nested in sequence, and there are spacing ring grooves between adjacent bonding ring layers; the upper ring membrane is attached to the multiple bonding ring layers and embedded in the spacing ring grooves from top to bottom, and a water-absorbing filling layer is provided at the bottom of the spacing ring groove, and the upper ring membrane is located above the water-absorbing filling layer and has an adsorption gap between the upper ring membrane and the water-absorbing filling layer.

10. The permeability coefficient test method of permeable concrete according to any one of claims 2 to 8, It is characterized in that In the test step 2), the membrane layer extends to the periphery of the bottom end surface of the test piece to form a lower ring membrane arranged in a ring shape, and the lower ring membrane seals the periphery of the bottom end surface of the test piece; The lower annular membrane has an inner annular surface arranged inwardly, and a plurality of inner membrane flow channels are arranged in the lower annular membrane, and the plurality of inner membrane flow channels are arranged at intervals along the circumference of the lower annular membrane, and the inner end of the inner membrane flow channel passes through the inner annular surface, and the outer end of the inner membrane flow channel passes downwardly through the bottom of the lower annular membrane; when the water level in the water tank is rising, the water in the lower cavity flows through the inner membrane flow channel, thereby reducing the pressure impact on the joint between the lower annular membrane and the bottom end surface.

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