Device and method for testing breaking strength and compressive strength of structural solid concrete

Abstract

The invention discloses a device and method for testing flexural strength and compressive strength of structural solid concrete.The testing device comprises a thrust rod, thrust teeth, a counter-force ring, a hollow jack and a cylindrical force sensor, one end of the thrust rod horizontally penetrates through the side wall of the counter-force ring, and the other end of the thrust rod penetrates through the hollow jack; the thrust teeth are fixed to the thrust rod and located in the counter-force ring. The device further comprises a barrel type force sensor which is arranged on the thrust rod in a sleeving mode and abuts against the outer side of the hollow jack so as to assist in measuring the strength of the concrete entity. According to the device and the method for testing the breaking strength and the compressive strength of the structural solid concrete, the structure is reasonable, the breaking strength and the compressive strength can be tested at one time, and the device and the method have the advantage of high testing efficiency; meanwhile, the test belongs to a micro-damage test, the damage to the concrete is very small in the test process, and the safe use of the solid structure is not influenced after the test surface is repaired.

Description

Technical Field

[0001] The present invention belongs to the technical field of construction engineering, and relates to a test device and method for the flexural strength and compressive strength of structural entity concrete. Background Art

[0002] Due to the direct and repeated action of vehicle loads and the influence of environmental factors (such as temperature and humidity), concrete pavements are required to have high flexural strength, durability, wear resistance and skid resistance in design. Among them, the flexural strength is an important quality control index for concrete pavements. Whether its value meets the design requirements will directly affect the overall quality and service life of the pavement.

[0003] The "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT50081-2019) specifically stipulates the test methods for the flexural strength and compressive strength of concrete. The flexural strength of concrete specified in the standard is the result obtained when a beam-shaped specimen with dimensions of 150mm×150mm×550mm reaches 28 days of the specified age under standard curing conditions and undergoes pure bending failure under a two-point load with a net span of 450mm; the compressive strength of concrete specified in the standard is the result obtained when a cube specimen with dimensions of 150mm×150mm×150mm reaches 28 days of the specified age under standard curing conditions and is loaded to failure on a press. However, this method is only limited to testing specially made beam-shaped specimens or cube specimens under standard curing conditions, that is, the test results can only show whether the concrete mixture meets the design requirements in terms of proportion. In the actual construction process of structural concrete pavements, etc., the hardening process of concrete does not undergo standard curing, which is quite different from the forming conditions of the above standard specimens. That is to say, it is unknown whether the flexural strength and compressive strength of the actual structural concrete meet the design requirements.

[0004] Therefore, people very much want to know whether the flexural strength and compressive strength of the structural concrete after construction meet the design requirements. At present, there is no test method and test device for directly confirming the flexural strength on the concrete entity in the construction of roads, bridges, buildings, airport runways, etc.

[0005] Therefore, it is urgent to design a test device and method for the flexural strength and compressive strength of structural entity concrete to solve the technical problems existing in the prior art. Summary of the Invention

[0006] The object of the present invention is to solve at least to a certain extent some technical problems existing in the prior art, and to provide a test device and method for the flexural strength and compressive strength of structural entity concrete. Its structure is reasonable, and the flexural strength and compressive strength of structural concrete can be tested in one test, which has the advantage of high test efficiency. At the same time, this test belongs to micro-damage test, and the damage to concrete during the test is very small. After the test surface is repaired, it will not affect the safe use of the entity structure.

[0007] To solve the above technical problems, a test device for the flexural strength and compressive strength of structural entity concrete provided by the present invention includes a thrust rod, thrust teeth, a reaction ring and a hollow jack. One end of the thrust rod passes through the side wall of the reaction ring, and the other end of the thrust rod passes through the hollow jack. The thrust teeth are fixed to the thrust rod and located inside the reaction ring. It also includes a cylindrical force sensor, which is sleeved on the thrust rod and abuts against the outside of the hollow jack to measure the lateral thrust value at the moment when the concrete breaks. The reaction ring is sleeved in the outer ring groove of the double-ring groove on the surface of the concrete entity, and the thrust teeth are clamped in the inner ring groove of the double-ring groove. By pushing the reaction ring through the hollow jack, the thrust teeth push the concrete column formed by the inner ring groove in the opposite direction, and the cylindrical force sensor records the load when the concrete column breaks.

[0008] In some embodiments, the reaction ring is a circular ring structure, and its size matches the size of the outer ring groove.

[0009] In some embodiments, the thrust teeth are circular ring structures, which are 1 / 8 - 1 / 4 of the whole ring; the shape of the thrust teeth matches the size of the inner ring groove.

[0010] In some embodiments, a boss is provided at the lower end of the thrust teeth, and the boss extends horizontally towards the outside.

[0011] In some embodiments, the test device for the flexural strength and compressive strength of structural entity concrete further includes a limiting component, which includes a support rod and a limiting wheel. The limiting wheel is installed on the support rod and fixed in the reaction ring; and the support rod is perpendicular to the thrust rod.

[0012] In some embodiments, the support rod and the thrust rod are vertically staggered; the outer peripheral wall of the configured limiting wheel is provided with an arc surface, and the arc surface is matched with the outer diameter of the thrust rod.

[0013] In some embodiments, the end of the thrust rod is configured with a limiting nut and a locking nut. The limiting nut is arranged adjacent to the reaction ring, and the locking nut is arranged adjacent to the cylindrical force sensor. Both are threadedly connected to the thrust rod to fix the reaction ring and the cylindrical force sensor to the thrust rod respectively.

[0014] In addition, the present invention also provides a test method for the flexural strength and compressive strength of structural solid concrete, which uses the test device for the flexural strength and compressive strength of structural solid concrete described above, and includes:

[0015] Step 1: Select a plane to be measured on the concrete structural entity to be measured, and use a coaxial double drill bit to cut a double-ring groove to form an outer ring groove and an inner ring groove, and the cutting depth of the inner ring groove is greater than or equal to 2 times the diameter of the inner ring groove;

[0016] Step 2: Embed the reaction ring into the outer ring groove, adjust the position of the thrust rod in the reverse ring, insert the thrust teeth at the front end of the thrust rod into the inner ring groove, lock the limit nut on the outside of the reaction ring, and successively sleeved the hollow jack and the cylindrical force sensor on the thrust rod and fixed them by the locking nut;

[0017] Step 3: Zero the load meter connected to the cylindrical force sensor, start the hollow jack when the concrete column is not stressed, form a reverse support by the inner and outer walls of the reaction ring abutting against the inner and outer walls of the outer ring groove, apply a lateral force to the concrete column through the thrust teeth, until the concrete column is damaged under the combined action of bending and shear external forces;

[0018] Step 4: Record the thrust value N at the moment when the concrete column is damaged, the distance L between the damaged section and the lateral thrust action point, and the diameter d of the concrete column, and substitute the above data into the previously established concrete flexural strength calculation formula and compressive strength calculation formula, and then deduce the flexural strength and compressive strength of the measured concrete entity.

[0019] In some embodiments, the diameter of the outer ring groove is 1.6 times the diameter of the inner ring groove, and the diameter of the inner ring groove is greater than 2 times the value of the maximum size of the concrete coarse aggregate.

[0020] In some embodiments, the flexural strength of the concrete entity The compressive strength of the concrete entity

[0021] Where: N is the lateral thrust between the test pieces, and the unit is (Newton);

[0022] L is the length from the thrust action point of the test piece to the fracture position, that is, the length of the force arm (mm);

[0023] d is the diameter of the test piece (mm).

[0024] Advantageous effects of the present invention:

[0025] The test device and method for the flexural strength and compressive strength of structural solid concrete provided by the present invention have a reasonable structure and have the following technical effects:

[0026] a. It can complete the tests of flexural strength and compressive strength at one time, with the advantages of low test cost and high test efficiency;

[0027] b. This test belongs to micro-damage test, and the damage to the concrete structure during the test process is very small. After repairing the test surface, it will not affect the safe use of the entity structure;

[0028] c. This test method has high detection accuracy, the test device is easy to carry, and has the advantage of fast operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Through the following detailed description in conjunction with the attached drawings, the above advantages of the present invention will become clearer and easier to understand. These drawings are only schematic and do not limit the present invention, where:

[0030] Figure 1 is a schematic diagram of a test device for the flexural strength and compressive strength of structural entity concrete provided by an embodiment of the present invention;

[0031] Figure 2 is Figure 1 the force diagram of the corresponding test structural entity concrete;

[0032] Figure 3 is a schematic diagram of the thrust tooth of the present invention;

[0033] Figure 4 is an assembly schematic diagram of the limit component, thrust rod and reaction ring provided by an embodiment of the present invention;

[0034] Figure 5 is a cross-sectional view of the reaction ring of the present invention;

[0035] Figure 6 is a schematic diagram of the limit wheel of the present invention;

[0036] Figure 7 is a schematic diagram of a test device for the flexural strength and compressive strength of structural entity concrete provided by another embodiment of the present invention;

[0037] Figure 8 is Figure 6 the flowchart of the test method for the flexural strength and compressive strength of the corresponding structural entity concrete

[0038] Figure 9 is a schematic diagram of a double drill bit provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] Figures 1 to 9 are the related schematic diagrams of the test device and method for the flexural strength and compressive strength of structural entity concrete described in this application. Below, the present invention will be described in detail in conjunction with specific embodiments and drawings.

[0040] The embodiments described herein are specific and particular embodiments of the present invention, which are used to illustrate the concept of the present invention. They are all explanatory and exemplary, and should not be construed as limiting the embodiments of the present invention and the scope of the present invention. Except for the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that make any obvious substitutions and modifications to the embodiments described herein.

[0041] The drawings in this specification are schematic diagrams, which assist in illustrating the concept of the present invention and schematically represent the shapes of various parts and their mutual relationships. Please note that in order to clearly show the structures of the components in the embodiments of the present invention, the drawings are not drawn in the same proportion. The same reference numerals are used to represent the same parts.

[0042] A schematic diagram of a test device for the flexural strength and compressive strength of a structural entity concrete is as Figure 1 shown. A test device for the flexural strength and compressive strength of a structural entity concrete includes a thrust rod 10, a thrust tooth 20, a reaction ring 30, and a hollow jack 40. One end of the thrust rod 10 passes through the side wall of the reaction ring 30, and the other end of the thrust rod 10 passes through the hollow jack 40. The thrust tooth 20 is fixed to the thrust rod 10 and is located inside the reaction ring 30.

[0043] Furthermore, the test device for the flexural strength and compressive strength of a structural entity concrete further includes a cylindrical force sensor 50, which is sleeved on the thrust rod 10 and abuts against the outside of the hollow jack 40 to measure the lateral thrust value at the moment when the concrete column 70 breaks.

[0044] The reaction ring 30 is sleeved in the outer ring groove 61 of a double-ring groove 60 previously cut in the concrete entity ( Figure 2 shown), the thrust tooth 20 is placed in the inner ring groove 62 of the double-ring groove 60. By pushing the reaction ring 30 through the hollow jack 40, the thrust tooth 20 reversely pushes the concrete column 70 formed by the inner ring groove 62, and the cylindrical force sensor 50 records the lateral thrust value at the moment when the concrete column 70 breaks.

[0045] As an embodiment of the present invention, the reaction ring 30 is a circular ring structure, and its size matches the size of the outer ring groove 61.

[0046] Furthermore, the thrust tooth 20 is a circular ring structure, which is 1 / 8 - 1 / 4 of the entire ring; the shape of the thrust tooth 20 matches the size of the inner ring groove 62.

[0047] A boss 21 is provided at the lower end of the thrust tooth 20, as Figure 3 shown. The boss 21 extends horizontally towards the outside. It can be understood that the thrust tooth 20 is of an annular structure, and correspondingly, the boss 21 is also of an annular structure so as to abut against the outer side wall of the concrete column 70. Figure 3 In Figure 3 , the vertical height of the boss 21 is 1 mm, so that the thrust tooth 20 can act on the outer side wall of the concrete column 70 through the narrow strip-shaped boss 21, and then the concrete column 70 is damaged by the lateral thrust.

[0048] Figure 1 In the embodiment shown, a limit nut 91 and a locking nut 92 are arranged at the end of the thrust rod 10. The limit nut 91 is arranged adjacent to the reaction ring 30, and the locking nut 92 is arranged adjacent to the cylindrical force sensor 50. Both are threadedly connected to the thrust rod 10. The locking nut 92 restricts the reaction ring 30, the cylindrical force sensor 50 and the hollow jack 40 on the thrust rod 10 and can axially move freely relative to the thrust rod 10.

[0049] As an embodiment of the present invention, the test device for the flexural strength and compressive strength of structural entity concrete further includes a limit assembly 80, as Figure 4 shown. The limit assembly 80 includes a support rod 81 and a limit wheel 82 that can rotate freely on the support rod 81. The limit wheel 82 is installed on the support rod 81 and fixed in the reaction ring 30; and the support rod 81 is perpendicular to the thrust rod 10.

[0050] Figure 8 In the embodiment shown, the support rod 81 and the thrust rod 10 are vertically staggered to avoid interference between the thrust rod 10 and the limit wheel 82. Figure 5 is Figure 4 a cross-sectional view of the reaction ring 30 in the embodiment. It can be seen that the through hole through which the thrust rod 10 passes and the through hole for fixing the thrust rod 10 are vertically staggered along the side wall of the reaction ring 30, so that the thrust rod 10 can be clamped inside the groove of the limit wheel 82. Further, during the test, the thrust rod 10 always moves along its axial direction without yaw. That is, it prevents the thrust rod 10 from having a small displacement in the direction perpendicular to its axis during the test and affecting the detection accuracy.

[0051] Figure 5 In Figure 5 , a depth limit ring 31 is arranged at the lower end of the reaction ring 30, so that the wall thickness at the lower end of the reaction ring 30 is smaller, facilitating the smooth clamping of the reaction ring 30 inside the outer ring groove 61; at the same time, the setting of the depth limit ring 31 makes the depth of the lower end of the reaction ring 30 inserted into the inner ring groove 62 the same for each test.

[0052] Furthermore, the outer peripheral wall of the limit wheel 82 is provided with an arc surface 82a, asFigure 6 As shown, the arc surface 82a is arranged to match the outer diameter of the thrust rod 10.

[0053] Meanwhile, the present invention also provides a method for testing the flexural strength and compressive strength of structural entity concrete, which uses the testing device for the flexural strength and compressive strength of structural entity concrete described above, and its flowchart is as Figure 8 shown, including:

[0054] Step 1: Select a measured plane on the concrete structural entity to be measured, and use a coaxial double drill bit 100 ( Figure 9 shown) to cut a double annular groove 60 to form an outer annular groove 61 and an inner annular groove 62, and the cutting depth of the inner annular groove 62 is greater than or equal to 2 times the diameter of the inner annular groove; further, the diameter of the outer annular groove 61 is 1.6 times the diameter of the inner annular groove 62, and the diameter of the inner annular groove 62 is greater than 2 times the particle size value of the coarse aggregate of the concrete.

[0055] When processing the double annular groove 60, the inner drill 110 of the coaxial double drill bit 100 is used in cooperation with a general drill to separate the test concrete from the structural concrete, and only the cylindrical concrete root (concrete column 70) is retained and connected to the structural concrete. At the same time, through the outer drill 120 of the coaxial double drill bit 100, a groove (inner annular groove 62) for applying a reaction force during subsequent tests is cut on the structural concrete, and the residual cooling water in the groove is removed.

[0056] Step 2: Embed the reaction ring 30 into the outer annular groove 61, adjust the position of the thrust rod 10 in the reverse ring 30 until the thrust teeth 20 at the front end of the thrust rod 10 are inserted into the inner annular groove 62, and then sleeved the hollow jack 40 and the cylindrical force sensor 50 on the thrust rod 10 in sequence and screw on the locking nut 92;

[0057] Step 3: Zero the load meter 51 connected to the cylindrical force sensor 50, start the hollow jack 40 when the concrete column 70 is not stressed, form a reverse support by the inner and outer walls of the reaction ring 30 abutting against the inner and outer walls of the outer annular groove 61, and then gradually apply a lateral thrust to the concrete column 70 through the thrust teeth 20 until the concrete column 70 is damaged under the combined action of bending and shear external forces;

[0058] Step 4: According to the Figure 2 schematic diagram, record the thrust value N at the moment when the concrete column 70 is damaged, the distance L between the damaged section and the action point of the lateral thrust, and the diameter d of the concrete column 70, substitute the above data into the previously established concrete flexural strength calculation formula and compressive strength calculation formula, and then deduce the flexural strength and compressive strength of the measured concrete entity.

[0059] Among them, N is the thrust force of the testing device on the concrete column 70 (specimen), and N1 and N2 are the reaction forces of the structural concrete entity on the testing device. There is a relationship of N = N1 + N2 between them numerically.

[0060] The flexural strength of the said concrete entity The compressive strength of the said concrete entity

[0061] Among them, N is the lateral thrust force between specimens, with the unit of Newton; L is the length from the acting point of the specimen thrust force to the breaking position, that is, the lever arm length in mm; d is the diameter of the specimen in mm.

[0062] The determination of the flexural (compressive) strength value is carried out according to the following basic principles:

[0063] ① Take the arithmetic mean of the strength values deduced from 3 measuring points as the flexural (compressive) strength value of the concrete poured in this batch, and it should be accurate to 0.1 MPa;

[0064] ② Among the maximum or minimum values of the strength values deduced from 3 measuring points, when the difference between one of them and the intermediate value exceeds 15% of the intermediate value, the maximum and minimum values should be discarded together, and take the intermediate value as the flexural strength value of this group of specimens;

[0065] ③ When the differences between the maximum and minimum values of the strength values deduced from 3 measuring points and the intermediate value both exceed 15% of the intermediate value, the test results of this group of measuring points are invalid.

[0066] When establishing the formula for testing strength in advance, the N, L, d of each group of tests should be recorded in time, and the flexural strength and compressive strength of the concrete obtained through the failure tests of standard specimens should also be recorded. Then, statistical analysis is carried out on the corresponding flexural strength and compressive strength respectively to obtain the flexural strength and compressive strength test formulas that can be actually applied.

[0067] It should be noted that the formulas for the flexural strength and compressive strength of the above-mentioned concrete entity are obtained by using the commonly used sand, gravel aggregate and cement in the Beijing area, preparing specimens of concrete with eight strength grades of C15, C20, C25, C30, C35, C40, C50, and C60 for testing, and statistically regressing and analyzing the test data to obtain the flexural strength and compressive strength calculation formulas.

[0068] The correlation coefficient r of the above flexural strength calculation formula is 0.97, which belongs to a highly correlated. Due to the differences in the concrete using sand, gravel aggregate and cement and other raw materials in different regions, the coefficients of the established flexural strength calculation formulas will also be different. At the same time, the correlation coefficient r of the above compressive strength calculation formula is 0.96, which also belongs to a highly correlated. Due to the differences in the concrete using sand, gravel aggregate and cement and other raw materials in different regions, the coefficients of the established compressive strength calculation formulas will also be different.

[0069] The testing device and testing method for the flexural strength and compressive strength of structural entity concrete provided by the present invention randomly arrange measuring points on the hardened concrete through a double drill bit, making the test results representative. The obtained strength is the compressive strength and flexural strength of the concrete entity, which is applicable to the detection of concrete roads, bridges, buildings and airport runways of various strength grades, and has the advantage of a wide range of applications.

[0070] The present invention is not limited to the above embodiments. Any person can obtain other various forms of products under the inspiration of the present invention. However, no matter what changes are made in its shape or structure, as long as it has the same or similar technical solutions as the present application, it falls within the protection scope of the present invention.

Claims

1. A testing device for the flexural strength and compressive strength of structural concrete, characterized in that: The invention comprises a thrust rod (10), a thrust tooth (20), a reaction ring (30), a hollow jack (40) and a cylindrical force sensor (50), wherein one end of the thrust rod (10) passes horizontally through the side wall of the reaction ring (30), and the other end of the thrust rod (10) passes through the hollow jack (40), and the thrust tooth (20) is fixed to the thrust rod (10) and is located inside the reaction ring (30); and further comprises a cylindrical force sensor (50) which is sleeved on the thrust rod (10) and abuts against the outer side of the hollow jack (40). The method measures the lateral thrust value at the moment when the concrete column 70 breaks; the reaction ring (30) is sleeved in the outer ring groove (61) of the double ring groove (60) on the surface of the concrete entity, the thrust tooth (20) is clamped in the inner ring groove (62) of the double ring groove (60), the reaction ring (30) is pushed horizontally by the hollow jack (40), the thrust tooth (20) pushes the concrete column (70) formed by the inner ring groove (62) in the opposite direction, and the cylindrical force sensor (50) records the load value when the concrete column (70) breaks.

2. The testing device according to claim 1, characterized in that: The reaction ring (30) is a circular ring structure, and its size matches the size of the outer ring groove (61).

3. The testing device according to claim 1, characterized in that: The thrust tooth (20) is a circular ring structure, which is 1 / 8-1 / 4 of the entire circular ring; the shape of the thrust tooth (20) matches the size of the inner ring groove (62).

4. The testing device according to claim 3, characterized in that: A boss (21) is provided at the lower end of the thrust tooth (20), and the boss (21) is formed to extend horizontally toward the outside.

5. The testing device according to claim 1, characterized in that: It also includes a limiting assembly (80), which includes a support rod (81) and a limiting wheel (82), wherein the limiting wheel (82) is installed on the support rod (81) and fixed in the reaction ring (30); and the support rod (81) is perpendicular to the thrust rod (10).

6. The testing device according to claim 5, characterized in that: The support rod (81) and the thrust rod (10) are arranged in a vertically staggered manner; the outer peripheral wall of the limiting wheel (82) is provided with an arc surface (82a), and the arc surface (82a) is matched with the outer diameter of the thrust rod (10).

7. The testing device according to claim 1, characterized in that: The end of the thrust rod (10) is provided with a limit nut (91) and a locking nut (92); the limit nut (91) is arranged adjacent to the reaction ring (30), and the locking nut (92) is arranged adjacent to the cylindrical force sensor (50); both are threadedly connected to the thrust rod (10) to respectively fix the reaction ring (30) and the cylindrical force sensor (50) to the thrust rod (10).

8. A method for testing the flexural strength and compressive strength of structural concrete, characterized in that: Use of the testing device according to any one of claims 1 to 7, comprising: Step 1, selecting a plane to be measured on the concrete structure entity to be measured, using a coaxial double drill bit to cut a double annular groove (60) to form an outer annular groove (61) and an inner annular groove (62), wherein the cutting depth of the inner annular groove 62 is greater than or equal to 2 times the diameter of the inner annular groove (62); Step 2: insert the reaction ring (30) into the outer ring groove (61), adjust the position of the thrust rod (10) in the reaction ring (30), insert the thrust tooth (20) at the front end of the thrust rod (10) into the inner ring groove (62), lock the limit nut (91) on the outside of the reaction ring (30), and sequentially sleeve the hollow jack (40) and the cylindrical force sensor (50) on the thrust rod (10) and fix them with the locking nut (92); Step 3: clear the load table connected to the cylindrical force sensor (50), start the hollow jack (40) when the concrete column (70) is not subjected to force, abut the inner and outer walls of the reaction ring (30) against the inner and outer walls of the outer ring groove (61) to form a reverse support, and apply a lateral force to the concrete column (70) through the thrust teeth (20) until the concrete column (70) is destroyed by the combined external force of bending and shearing; Step 4, record the thrust value N at the moment of concrete column (70) failure, the distance L between the failure section and the lateral thrust application point, and the diameter d of the concrete column (70), substitute the above data into the previously established concrete flexural strength calculation formula and compressive strength calculation formula, and then estimate the flexural strength and compressive strength of the measured concrete entity.

9. The testing method according to claim 8, characterized in that: The diameter of the outer annular groove (61) is 1.6 times the diameter of the inner annular groove (62), and the diameter of the inner annular groove (62) is greater than 2 times the particle size of concrete coarse aggregate.

10. The testing method according to claim 8, characterized in that: The flexural strength of the concrete entity The compressive strength of the concrete entity Where: N is the lateral thrust between the specimens, in Newtons; L is the length from the thrust point of the specimen to the fracture position, that is, the length of the lever arm (mm); d is the specimen diameter (mm).

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