A device for testing the compressive strength of solid concrete by circular ring pulling and cutting method

Abstract

A device for testing the compressive strength of solid concrete using the ring tensile shear method includes a T-shaped cylindrical specimen located in solid concrete, on which a cylindrical indenter and a miniature screw hydraulic jack are sequentially arranged. The cylindrical indenter is connected to the head of the miniature screw hydraulic jack via a spherical support. A circular plate base is installed at the tail of the miniature screw hydraulic jack. A force-applying structure for applying tensile shear force is installed on the circular plate base. A digital pressure gauge is also installed on the circular plate base. An L-shaped reaction ring that can surround and clamp the T-shaped cylindrical specimen is connected around the circular plate base. The longitudinal axes of the T-shaped cylindrical specimen, cylindrical indenter, miniature screw hydraulic jack, circular plate base, and L-shaped reaction ring are coaxial. This invention uses an L-shaped reaction ring to encircle a T-shaped cylindrical sample in solid concrete. Then, a cylindrical indenter, a micro-screw hydraulic jack, and the L-shaped reaction ring are used to apply a tensile shear force to the T-shaped cylindrical sample until it fails. The maximum tensile shear force value is then read, and the concrete compressive strength is estimated based on the conversion formula established between the concrete compressive strength and the tensile shear force value. This invention has a wide range of applications, is highly practical, and provides accurate testing.

Description

Technical Field

[0001] The invention relates to a device for detecting the compressive strength of solid concrete by a circular ring pulling and cutting method. Background Art

[0002] Compressive strength is one of the important performance parameters of concrete, which is directly related to the quality, safety and normal use of concrete components and even the entire project. Therefore, testing the compressive strength of solid concrete is a very important task.

[0003] In the prior art, there are many common methods for testing the compressive strength of solid concrete, which are as follows:

[0004] (1) Shear compression method. Using a concrete shear compression instrument, a pressure perpendicular to the pressure-bearing surface is applied to the right-angled surface of the concrete component, causing local shear compression failure on the right-angled side of the concrete component, and the compressive strength of the concrete component is estimated based on the shear pressure at this time. The shortcomings of this method are: it is not suitable for concrete with a thickness of less than 80 mm, such as the ground surface layer, which is generally 40 mm to 60 mm thick and cannot be tested, affecting the practicality of the test. (2) Core drilling method. Drill concrete specimens on the concrete component and process them into standard core samples, and then test their compressive strength on a pressure testing machine. The shortcomings of this test method are: since the size of the standard core sample is ø100×100 mm, it is impossible to test thin layers of concrete, such as the ground surface layer, which is generally 40 mm to 60 mm thick, which affects the practicality of the test. (3) Rebound method. The compressive strength of the concrete component is estimated based on the relationship between the surface hardness and strength of the concrete component. The shortcomings of this test method: the compressive strength derived from the relationship between surface hardness and strength is of low accuracy, which affects the accuracy of the test; it is not applicable to concrete with an age of more than 1,000 days, which affects the practicality of the test. (4) Ultrasonic rebound comprehensive method. The compressive strength of concrete is estimated based on the hardness of the concrete component surface and the ultrasonic wave velocity in the concrete component. The shortcomings of this test method: the test operation process is relatively cumbersome, and there are relatively many factors affecting the test, which is prone to produce multiple test deviations, affecting the accuracy of the test; it is not applicable to concrete with an age of more than 2,000 days, which affects the practicality of the test. (5) Pull-out method. The compressive strength of concrete is estimated based on the pull-out force when the concrete component is destroyed within the range of 30 mm on the surface of the concrete component. The shortcomings of this test method: the test process requires complex drilling and grooving processes, and it is not applicable to concrete with a thickness of less than 80 mm, such as the ground surface layer, which is generally 40 mm to 60 mm thick and cannot be tested, which affects the practicality of the test. (6) Pull-off method. On the hardened concrete component, a core specimen with a diameter of 44 mm and a depth of 44 mm is drilled, and a pull-off test is performed using a device with an automatic clamping test specimen. The concrete compressive strength is estimated based on the pull-off strength value of the core specimen. The shortcomings of this detection method are: when calculating the stress of the pull-off specimen, the diameter size of the mutually perpendicular position near the fracture of the specimen needs to be measured. Due to the small diameter of the specimen, accurate measurement is difficult, which affects the detection accuracy.

[0005] In summary, the above detection methods are unable to accurately and effectively detect the compressive strength of concrete with a thickness of less than 80 mm and an age of more than 2000 days, so design improvements are needed. Summary of the invention

[0006] The present invention proposes a solid concrete compressive strength circular pull-cut method detection device with strong practicality, accurate detection and reasonable design. The device can solve the problem that various existing solid concrete compressive strength detection methods cannot accurately and effectively detect the compressive strength of concrete with a thickness of less than 80 mm and an age of more than 2000 days.

[0007] The technical solution adopted by the present invention is: a circular ring shearing method detection device for the compressive strength of solid concrete, including a T-shaped cylindrical specimen located in the solid concrete, on which a cylindrical pressure head and a micro screw hydraulic jack are arranged in sequence; the cylindrical pressure head is connected to the head of the micro screw hydraulic jack through a spherical support; a circular plate base is installed at the tail of the micro screw hydraulic jack; a force applying structure for applying shearing force is installed on the circular plate base; a digital pressure gauge is also installed on the circular plate base; an L-shaped reaction force pull ring is connected to the periphery of the circular plate base and can encircle the T-shaped cylindrical specimen; the longitudinal axes of the T-shaped cylindrical specimen, the cylindrical pressure head, the micro screw hydraulic jack, the circular plate base and the L-shaped reaction force pull ring are coaxial. The present invention uses an L-shaped reaction force pull ring to clamp a T-shaped cylindrical specimen in solid concrete, and then applies a shearing force to the T-shaped cylindrical specimen through a cylindrical pressure head, a micro screw hydraulic jack and an L-shaped reaction force pull ring until the T-shaped cylindrical specimen is sheared and destroyed, reads the maximum shearing force value, and infers the compressive strength of the concrete based on a conversion formula established between the compressive strength of the concrete and the shearing force value.

[0008] Furthermore, the T-shaped cylindrical specimen comprises an upper cylinder and a lower cylinder with the same longitudinal axis. The upper cylinder has a diameter of 100 mm and a height of 30 mm; the lower cylinder has a diameter of 80 mm and a height of 10 mm. The lower surface of the upper cylinder is connected to the upper surface of the lower cylinder, and the lower surface of the lower cylinder is connected to the solid concrete.

[0009] Furthermore, the cylindrical pressure head is made of steel and has a diameter of 20 mm.

[0010] Furthermore, the circular plate base is made of steel, and 8 connecting circular holes are evenly drilled around the periphery.

[0011] Furthermore, the force-applying structure includes a screw sleeve connected to the micro screw hydraulic jack, the screw sleeve is parallel to the longitudinal axis of the micro screw hydraulic jack, a screw is arranged in the screw sleeve, and a T-shaped socket wrench for applying shear force is installed at the end of the screw.

[0012] Furthermore, the digital pressure gauge is connected to the micro screw hydraulic jack.

[0013] Furthermore, the L-shaped reaction pull ring is made of steel, and includes an upper annular body and a lower annular body with the same longitudinal axis. The lower surface of the upper annular body is connected to the upper surface of the lower annular body. The outer diameter of the upper annular body is equal to the outer diameter of the lower annular body. It is divided into four pieces along the longitudinal axis and assembled as it is. The inner diameter of the upper annular body is (100-102) mm, and the inner diameter of the lower annular body is (80-82) mm. The top surface of the upper annular body is drilled with 8 connecting screw holes corresponding to the positions of the connecting circular holes on the circular plate base, and the connecting screw holes are screwed with connecting bolts connected and fixed to the circular plate base.

[0014] The beneficial effects of the present invention are as follows: (1) During the detection process, a detection device is used to apply shear force to concrete, and the maximum shear force value is measured. The compressive strength of concrete is estimated based on the conversion formula established between the compressive strength of concrete and the shear force value. The present invention has a wide range of applications, strong practicality, and accurate detection. (2) The present invention solves the problem that the existing solid concrete compressive strength shear method, coring method, rebound method, ultrasonic-rebound method, pull-out method, and pull-off method cannot accurately and effectively detect the compressive strength of concrete with a thickness of less than 80 mm and an age of more than 2000 days. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a front view schematic diagram of the use of the present invention.

[0016] Figure 2 It is a top view schematic diagram of the use of the present invention.

[0017] Figure 3 It is a top view schematic diagram of the L-shaped reaction force pull ring structure of the present invention. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all possible alternatives, improvements and equivalents within the scope of the claims.

[0019] Reference Figure 1-3A device for detecting the compressive strength of solid concrete by a circular shearing method comprises a T-shaped cylindrical specimen 16 located in a solid concrete 14, on which a cylindrical pressure head 13 and a micro screw hydraulic jack 2 are arranged in sequence; the cylindrical pressure head 13 is connected to the head of the micro screw hydraulic jack 2 through a spherical support 12; a circular plate base 6 is installed at the tail of the micro screw hydraulic jack 2; a force applying structure 1 for applying shearing force is installed on the circular plate base 6; a digital pressure gauge 4 is also installed on the circular plate base 6; an L-shaped reaction force pull ring 11 that can encircle the T-shaped cylindrical specimen 16 is connected to the periphery of the circular plate base 6; the longitudinal axes of the T-shaped cylindrical specimen 16, the cylindrical pressure head 13, the micro screw hydraulic jack 2, the circular plate base 6, and the L-shaped reaction force pull ring 11 are coaxial. The present invention uses an L-shaped reaction force pull ring 11 to enclose a T-shaped cylindrical specimen 16 in a solid concrete 14, and then applies a shearing force to the T-shaped cylindrical specimen 16 through a cylindrical pressure head 13, a micro screw hydraulic jack 2 and an L-shaped reaction force pull ring 11 until the T-shaped cylindrical specimen 16 is sheared and destroyed, reads the maximum shearing force value, and infers the compressive strength of the concrete based on a conversion formula established between the compressive strength of the concrete and the shearing force value.

[0020] The T-shaped cylindrical specimen 16 described in this embodiment includes an upper cylinder and a lower cylinder with the same longitudinal axis. The upper cylinder has a diameter of 100 mm and a height of 30 mm; the lower cylinder has a diameter of 80 mm and a height of 10 mm. The lower surface of the upper cylinder is connected to the upper surface of the lower cylinder, and the lower surface of the lower cylinder is connected to the solid concrete.

[0021] The cylindrical pressure head 13 described in this embodiment is made of steel, with a diameter of 20 mm and a height of 20 mm.

[0022] The circular plate base 6 described in this embodiment is made of steel, with a diameter of 130 mm and a thickness of 20 mm; 8 connecting circular holes 9 with a hole diameter of 7 mm are evenly drilled around the periphery.

[0023] The force-applying structure 1 described in this embodiment includes a screw sleeve 7 connected to the micro screw hydraulic jack 2. The screw sleeve 7 is parallel to the longitudinal axis of the micro screw hydraulic jack 2. A screw 5 is arranged in the screw sleeve 7. The end of the screw 5 is installed with a T-shaped socket wrench 3 for applying a shearing force.

[0024] The digital pressure gauge 4 described in this embodiment is connected to the micro screw hydraulic jack 2.

[0025] The L-shaped reaction pull ring 11 described in this embodiment is made of steel, and includes an upper annular body and a lower annular body with the same longitudinal axis. The lower surface of the upper annular body is connected to the upper surface of the lower annular body. The outer diameter of the upper annular body and the outer diameter of the lower annular body are equal, both of which are 130㎜. They are divided into four pieces along the longitudinal axis and assembled as they are. The inner diameter of the upper annular body is 101㎜, and the height is slightly greater than (the height of the micro screw hydraulic jack 2 + the height of the spherical support 12 + 50㎜); the inner diameter of the lower annular body is 81㎜, and the height is 9㎜. The top surface of the upper annular body is drilled with 8 connecting screw holes 10 corresponding to the position of the connecting circular holes 9 on the circular plate base 6, with a hole diameter of 6㎜; the connecting screw holes 10 are screwed with connecting bolts 8 with a specification of M6 that are connected and fixed to the circular plate base 6.

[0026] The detection steps of this embodiment are as follows: (1) Finishing: The surface of the solid concrete 14 is polished and leveled with a portable concrete polishing machine. (2) Sample preparation: Use one diamond thin-wall hollow drill bit with an inner diameter of 100 mm and one diamond thin-wall hollow drill bit with an inner diameter of 150 mm. First, install the hollow drill bit with an inner diameter of 100 mm on a drilling machine that has been fixed in position, and drill a concrete annular groove with a depth of about 45 mm in the solid concrete 14 to form a concrete cylinder with a diameter of 100 mm; then replace it with a hollow drill bit with an inner diameter of 150 mm, drill a concrete annular groove with a depth of about 45 mm, remove the concrete between the two annular grooves, and level the bottom of the groove. A cylindrical sintered diamond grinding head is used with a hand-held concrete groove grinding machine with an extension rod and a positioning device. The grinding head is 10 mm thick, the distance from the edge of the grinding head to the edge of the extension rod is 10 mm, and the distance between the top surface of the grinding head and the surface of the solid concrete 14 is 30 mm. The extension rod is rotated and ground against the side of the concrete cylinder to form a concrete grinding groove 15 and a T-shaped cylindrical specimen 16. (3) Positioning and fixing: The lower circular ring bodies of the four L-shaped reaction pull rings 11 are inserted into the concrete grinding groove 15, assembled as they are, and encircled the T-shaped cylindrical specimen 16; the eight M6 connecting bolts 8 are passed through the connecting circular holes 9 on the circular plate base 6, screwed into the connecting screw holes 10 on the top surface of the L-shaped reaction pull ring 11, and tightened. (4) Measurement: Put the T-shaped socket wrench 3 on the end of the screw 5, rotate the screw 5 continuously and evenly to apply force, so that the cylindrical pressure head 13 presses against the surface of the T-shaped cylindrical specimen 16, and at the same time drive the L-shaped reaction force pull ring 11 to move upward relative to the T-shaped cylindrical specimen 16 through the circular plate base 6 until the T-shaped cylindrical specimen 16 is sheared and damaged. Read the maximum shear force value, and estimate the concrete compressive strength based on the conversion formula established between the concrete compressive strength and the shear force value.

[0027] In this embodiment, the conversion formula is as follows:

[0028] Yi=AXi+B

[0029] Wherein: Yi is the converted value (MPa) of the compressive strength of the i-th concrete entity 14 when tested by the circular ring shearing detection device; Xi is the maximum shearing force value (N) applied to the i-th concrete entity 14 when tested by the circular ring shearing detection device; A and B are the regression coefficients of the regression equation.

[0030] Of course, in addition to the above formula, the conversion formula between concrete compressive strength and shear force value may also be other formulas, and is not limited to the above formula.

Claims

1. A device for testing the compressive strength of solid concrete by a circular ring pulling method, characterized in that: It includes a T-shaped cylindrical specimen located in solid concrete, on which a cylindrical pressure head and a micro screw hydraulic jack are arranged in sequence; the T-shaped cylindrical specimen includes an upper cylinder and a lower cylinder with coaxial longitudinal axes; the upper cylinder has a diameter of 100 mm and a height of 30 mm; the lower cylinder has a diameter of 80 mm and a height of 10 mm; the lower surface of the upper cylinder is connected to the upper surface of the lower cylinder; the lower surface of the lower cylinder is connected to the solid concrete; the cylindrical pressure head is made of steel and has a diameter of 20mm; the cylindrical pressure head is connected to the head of the micro screw hydraulic jack through a spherical support; a circular plate base is installed at the tail of the micro screw hydraulic jack; a force-applying structure for applying shear force is installed on the circular plate base; a digital pressure gauge is also installed on the circular plate base; an L-shaped reaction force pull ring that can encircle the T-shaped cylindrical specimen is connected to the periphery of the circular plate base; the longitudinal axes of the T-shaped cylindrical specimen, cylindrical pressure head, micro screw hydraulic jack, circular plate base and L-shaped reaction force pull ring are coaxial.

2. A solid concrete compressive strength detection device using a circular ring pulling and cutting method according to claim 1, characterized in that: The circular plate base is made of steel, and 8 connecting circular holes are evenly drilled around the periphery.

3. The device for detecting the compressive strength of solid concrete by a circular ring pulling method according to claim 1, characterized in that: The force-applying structure comprises a screw sleeve connected with the micro screw hydraulic jack, the screw sleeve is parallel to the longitudinal axis of the micro screw hydraulic jack, a screw is arranged in the screw sleeve, and a T-shaped socket wrench for applying shear force is installed at the end of the screw.

4. The device for detecting the compressive strength of solid concrete by a circular ring pulling method according to claim 1, characterized in that: The digital pressure gauge is communicated with the micro screw oil pressure jack.

5. The device for detecting the compressive strength of solid concrete by a circular ring pulling method according to claim 1, characterized in that: The L-shaped reaction pull ring is made of steel, and comprises an upper annular body and a lower annular body coaxial with the longitudinal axis. The lower surface of the upper annular body is connected to the upper surface of the lower annular body. The outer diameter of the upper annular body is equal to the outer diameter of the lower annular body. It is divided into four pieces along the longitudinal axis and assembled as is; the outer diameter of the upper annular body is 100㎜-102㎜; the inner diameter of the lower annular body is 80㎜-82㎜; 8 connecting screw holes corresponding to the positions of the connecting circular holes on the circular plate base are drilled on the top surface of the upper annular body, and connecting bolts connected and fixed to the circular plate base are screwed into the connecting screw holes.

6. A detection method for a solid concrete compressive strength detection device using a circular pull-cut method, using the detection device as claimed in claim 1, comprising the following detection steps: (1) finishing: grinding the solid concrete surface flat with a portable concrete grinder; (2) sample preparation: using a diamond thin-walled hollow drill bit with an inner diameter of 100 mm and one with an inner diameter of 150 mm; firstly installing the hollow drill bit with an inner diameter of 100 mm on a drilling machine whose position has been fixed, drilling a concrete annular groove with a depth of about 45 mm in the solid concrete to form a concrete cylinder with a diameter of 100 mm; then replacing it with a hollow drill bit with an inner diameter of 150 mm, drilling a concrete annular groove with a depth of about 45 mm, clearing the concrete between the two annular grooves, and leveling the groove bottom; using a portable concrete groove grinding machine with an extended rod having a positioning device and a matching cylindrical sintered diamond grinding head, the grinding head thickness is 10mm, the distance from the edge of the grinding head to the edge of the extension rod is 10mm, the distance between the top surface of the grinding head and the solid concrete surface is 30mm, the extension rod is rotated and ground closely to the side of the concrete cylinder to form a concrete grinding groove and make a T-shaped cylindrical specimen; (3) Positioning and fixing: insert the lower circular ring body of the four L-shaped reaction pull rings into the concrete grinding groove, assemble them as they are, and surround the T-shaped cylindrical specimen; pass the eight M6 connecting bolts through the connecting circular holes on the circular plate base, screw them into the connecting screw holes on the top surface of the L-shaped reaction pull ring, and tighten them; (4) Measurement: put a T-shaped socket wrench on the end of the screw, rotate the screw continuously and evenly to apply force, so that the cylindrical pressure head presses against the surface of the T-shaped cylindrical specimen, and at the same time drives the L-shaped reaction pull ring to move upward relative to the T-shaped cylindrical specimen through the circular plate base until the T-shaped cylindrical specimen is sheared and damaged, read the maximum shear force value, and infer the compressive strength of the concrete.

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