Simple device for testing friction coefficient between newly poured concrete and formwork

Abstract

The application discloses a simple device for testing the friction coefficient between newly-poured concrete and a formwork, which comprises an experimental assembly, a pressurizing mechanism and a testing mechanism.The experimental assembly is used for containing the concrete to be detected, and comprises a barrel and a barrel bottom.The barrel is of a tubular structure, and the bottom surface of the barrel is fixedly and sealingly connected with the top surface of the barrel bottom.The pressurizing mechanism comprises a self-balancing assembly and a pressurizing unit.The bottom end of the pressurizing unit penetrates through the self-balancing assembly and is sealingly and slidingly connected with the top end of the side wall of the inner cavity of the barrel.The two ends of the self-balancing assembly are fixedly connected with the top end of the outer side of the barrel.The testing mechanism comprises a torque wrench and a testing assembly.The torque wrench is used for measuring the torque, and is detachably connected with the top end of the testing assembly.The testing assembly penetrates through the pressurizing unit and abuts against the top surface of the barrel bottom.The application can measure the friction coefficient between the newly-poured concrete and the formwork and the change rule of the friction coefficient with time at any time and anywhere according to the requirement on the construction site or in the laboratory.

Description

TECHNICAL FIELD

[0001] The present application relates to the development and application of foundation test devices in the field of civil engineering construction, in particular to a simple device for testing the friction coefficient between newly poured concrete and formwork. BACKGROUND

[0002] At present, concrete is still the most commonly used building material in the field of civil engineering, and whether the design of the formwork for pouring concrete is reasonable not only relates to the construction cost and cost of the project, but also affects the project quality and construction safety. The formwork side pressure calculation is the premise of the concrete formwork design. At present, the formwork side pressure calculation formula given in the specification is a semi-empirical and semi-theoretical formula fitted from test data. With the change of concrete performance indicators and on-site pouring methods, the formula based on test data fitted more than half a century ago cannot meet the current engineering needs. Therefore, it is urgent to propose a new calculation theory and corresponding calculation model of the concrete formwork side pressure based on the classical mechanics model, and the friction coefficient between the newly poured concrete and the formwork is a key basic parameter of the calculation model, but there is no related test technology and supporting device at present. SUMMARY

[0003] The purpose of the present application is to provide a simple device for testing the friction coefficient between newly poured concrete and formwork, to solve the problems existing in the prior art, and to realize the measurement of the friction coefficient between newly poured concrete and formwork and its change rule with time at any time and anywhere according to the needs in the construction site or laboratory.

[0004] To achieve the above-mentioned purpose, the present application provides the following scheme:

[0005] A simple device for testing the friction coefficient between newly poured concrete and formwork, comprising:

[0006] An experimental assembly for containing the concrete to be detected, the experimental assembly comprising a barrel and a barrel bottom, the barrel being a tubular structure, and the bottom surface of the barrel being sealingly and fixedly connected to the top surface of the barrel bottom;

[0007] A pressurizing mechanism for applying a pre-pressure to the concrete to be detected, the pressurizing mechanism comprising a self-balancing assembly and a pressurizing unit, the bottom end of the pressurizing unit penetrating through the self-balancing assembly and being sealingly and slidingly connected to the top end of the side wall of the inner cavity of the barrel, and the two ends of the self-balancing assembly being fixedly connected to the top end of the outer side of the barrel;

[0008] A testing mechanism for testing the friction coefficient between the concrete to be detected and the formwork, the testing mechanism comprising a torque wrench and a testing assembly, the torque wrench being used for measuring the torque, the torque wrench being detachably connected to the top end of the testing assembly, and the testing assembly penetrating through the pressurizing unit and abutting against the top surface of the barrel bottom.

[0009] Preferably, the self-balancing assembly comprises a pressurized beam and two pressurized pull rods, two ends of the pressurized beam are detachably connected with top ends of the pressurized pull rods respectively, bottom ends of the pressurized pull rods are fixedly connected with the outer side of the barrel, and the bottom end of the pressurizing unit penetrates through the pressurized beam and is sealingly and slidably connected with the top end of the side wall of the inner cavity of the barrel.

[0010] Preferably, the pressurizing unit comprises a PTFE sliding sheet, a pressurizing screw and a pressurizing plate, the pressurizing screw penetrates through the pressurized beam and is screwed with the pressurized beam, the bottom end of the pressurizing screw is fixedly connected with the top surface of the pressurizing plate through the PTFE sliding sheet, the side surface of the pressurizing plate is embedded with a sealing rubber ring, and the pressurizing plate is sealingly and slidably connected with the side wall of the inner cavity of the barrel through the sealing rubber ring; the test assembly penetrates through the pressurizing screw, the PTFE sliding sheet and the pressurizing plate in sequence and is sealingly and slidably connected with the center of the pressurizing plate.

[0011] Preferably, the test assembly comprises a torsion rod and a four-rib sleeve, the four-rib sleeve is sleeved and fixedly connected with the middle part of the torsion rod, the four-rib sleeve penetrates through a friction plate, and the friction plate is slidably connected with the four-rib sleeve; the torsion rod penetrates through the pressurizing screw, the PTFE sliding sheet and the pressurizing plate in sequence and is sealingly and slidably connected with the center of the pressurizing plate, and the bottom end of the torsion rod is abuttingly and rotationally connected with the top surface of the barrel bottom.

[0012] Preferably, the friction plate is made of the same material as the formwork actually used on site.

[0013] Preferably, a groove is formed in the center of the top surface of the barrel bottom, and the bottom end of the torsion rod is slidably connected with the groove.

[0014] Preferably, a clamping joint for facilitating clamping of the torsion device is fixedly connected with the top end of the torsion rod.

[0015] The present application has the following technical effects:

[0016] The present application places the friction plate to be tested in the concrete in the barrel, and pressurizes the concrete through the sealing pressurizing unit, so that the friction plate is subjected to a certain pre-pressure through the concrete, and the test of the friction coefficient of the friction plate in different concrete environments is realized. The device can simulate different concrete pouring heights, dynamic and static friction coefficients between newly-poured concrete and the formwork at different times, and test the change rule of the friction coefficient between the newly-poured concrete and the formwork with time. BRIEF DESCRIPTION OF DRAWINGS

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the main structure of the present invention;

[0019] Figure 2 for Figure 1 Enlarged structural diagram at point A in the middle;

[0020] Figure 3 This is a schematic diagram of the main structure of the cylindrical container after it has been filled with concrete according to the present invention.

[0021] Among them, 1. cylindrical barrel; 2. barrel bottom; 3. pressure beam; 4. pressure tie rod; 5. PTFE sliding plate; 6. pressure screw; 7. pressure plate; 8. sealing ring; 9. torsion bar; 10. four-sided sleeve; 11. friction plate; 12. snap-fit ​​connector; 13. torque device. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Depend on Figures 1-3 The device shown is a simple apparatus for testing the friction coefficient between newly poured concrete and formwork, comprising:

[0025] The experimental assembly is used to hold the concrete to be tested. The experimental assembly includes a cylindrical barrel 1 and a barrel bottom 2. The cylindrical barrel 1 is a tubular structure, and the bottom surface of the cylindrical barrel 1 is sealed and fixedly connected to the top surface of the barrel bottom 2.

[0026] The pressurizing mechanism is used to apply pre-pressure to the concrete to be tested. The pressurizing mechanism includes a self-balancing component and a pressurizing unit. The bottom end of the pressurizing unit passes through the self-balancing component and is slidably and sealed to the top of the inner cavity side wall of the cylinder 1. The two ends of the self-balancing component are fixedly connected to the top of the outer side of the cylinder 1.

[0027] The testing mechanism is used for data testing of the friction coefficient of the concrete and the formwork to be tested, and comprises a torque wrench 13 used for measuring the torque and a testing assembly detachably connected with the top end of the torque wrench 13, the testing assembly penetrating the pressurizing unit and abutting against the top surface of the barrel bottom 2.

[0028] Further, the torque wrench 13 can adjust the opening size to adapt to the requirements of twisting different components, and has the function of measuring the torque, which is the prior art and will not be described here.

[0029] The application places the friction plate 11 to be tested in the concrete in the barrel 1, and pressurizes the concrete through the sealed pressurizing unit, so that the friction plate 11 is subjected to a certain pre-pressure by the concrete, and the testing of the friction coefficient of the friction plate 11 in different concrete environments is realized.

[0030] Further optimization scheme, the self-balancing assembly includes a pressurizing beam 3 and two pressurizing pull rods 4, the two ends of the pressurizing beam 3 are respectively detachably connected with the top ends of the pressurizing pull rods 4, the bottom ends of the pressurizing pull rods 4 are fixedly connected with the outer side of the barrel 1, the bottom end of the pressurizing unit penetrates the pressurizing beam 3 and is sealingly and slidably connected with the top end of the inner cavity side wall of the barrel 1, and the pressurizing beam 3 is used to provide support for the counterforce of the pressurizing unit. The pressurizing unit includes a PTFE sliding sheet 5, a pressurizing screw 6 and a pressurizing plate 7, the pressurizing screw 6 penetrates the pressurizing beam 3 and is screwed with the pressurizing beam 3, the bottom end of the pressurizing screw 6 is fixedly connected with the top surface of the pressurizing plate 7 through the PTFE sliding sheet 5, the side surface of the pressurizing plate 7 is embedded with a sealing rubber ring 8, the center of the pressurizing plate 7 is provided with a through hole, and the through hole is also embedded with a sealing rubber ring 8, and the pressurizing plate 7 is sealingly and slidably connected with the inner cavity side wall of the barrel 1 through the sealing rubber ring 8; the testing assembly penetrates the pressurizing screw 6, the PTFE sliding sheet 5 and the pressurizing plate 7 in sequence and is sealingly and slidably connected with the center of the pressurizing plate 7, the pressurizing plate 7 can be sealingly and slidably connected with the inner wall of the barrel 1, and the pressurizing screw 6 is used to apply a certain pre-pressure to the concrete arranged below the pressurizing plate 7.

[0031] Further optimization scheme, the testing assembly includes a torque rod 9 and a four-rib sleeve 10, the four-rib sleeve 10 is sleeved and fixedly connected with the middle part of the torque rod 9, the four-rib sleeve 10 penetrates the friction plate 11, and the friction plate 11 is slidably connected with the four-rib sleeve 10; the torque rod 9 penetrates the pressurizing screw 6, the PTFE sliding sheet 5 and the pressurizing plate 7 in sequence, penetrates the through hole in the middle part of the pressurizing plate 7 and is sealingly and slidably connected with the center of the pressurizing plate 7 through the sealing rubber ring 8; the top surface center of the barrel bottom 2 is provided with a groove, the bottom end of the torque rod 9 is adapted to and slidably connected with the groove, the groove plays a limiting role in the rotation of the torque rod 9, and the horizontal stable rotation of the friction plate 11 is realized. The friction plate 11 is made of the same material as the formwork actually used on site, so that the testing of the application is completely consistent with the actual application, and the testing result has more important reference value for the guidance on site. The top end of the torque rod 9 is fixedly connected with a clamping head 12 convenient for clamping the torque wrench 13.

[0032] The working process of the embodiment is as follows:

[0033] (1) Test preparation: clean and wet the barrel 1 and the barrel bottom 2, install the torsion rod 9, then pour the lower layer of concrete to the middle height position of the four-rib sleeve 10 of the torsion rod 9, vibrate and grind to be flat, then install the friction plate 11. Pour the upper layer of concrete, vibrate and grind to be flat, install the pressing plate 7 and the two sealing rubber rings 8; then install the four-fluorine sliding sheet 5, the pressing screw 6 and the pressing beam 3 in sequence, and connect the pressing beam 3 and the pressing rod 4 through bolts. Thus, the equipment installation and concrete pouring work are completed.

[0034] (2) Concrete pressing: use the torque wrench 13 to twist the pressing screw 6 to apply the torque T y to the concrete in the barrel 1 in the way that the pressing screw presses the pressing plate 7 downward.

[0035] (3) Friction coefficient test: when the pressure in the concrete reaches the test design pressure, use the torque wrench 13 to twist the clamping joint 12 at the top end of the torsion rod 9 to drive the friction plate 11 to rotate in the concrete. Read the torque T j when the friction plate 11 starts to rotate, and the static friction coefficient between the newly poured concrete and the friction plate can be calculated through theoretical calculation. Read the torque T d when the friction plate 11 rotates at a constant speed, and the dynamic friction coefficient between the newly poured concrete and the friction plate can be calculated through theoretical calculation.

[0036] (4) The test mechanism is as follows:

[0037] (a) Apply pressure to the pressing plate 7 through the torque wrench 13 to twist the pressing screw 6 to simulate the vertical pressure stress of the concrete at the position of the friction plate 11 caused by the pouring height of the concrete. The vertical pressure stress acting on the upper and lower surfaces of the friction plate 11 is calculated as follows:

[0038]

[0039]

[0040] In the formula, P is the vertical pre-stress at the position of the friction plate, kPa;

[0041] γ c is the unit weight of the concrete, kN / m 3 ;

[0042] N y is the pressure applied to the concrete through the pressing plate 7, kN;

[0043] A y is the area through the pressing plate 7, m 2 ;

[0044] T y Torque applied when the pressure screw 6 is screwed by the torque wrench 13 for pressure, kN.m;

[0045] k y Torque coefficient of the pressure screw 6;

[0046] d y Diameter of the pressure screw 6, m.

[0047] (b) The horizontal pressure stress acting on the side of the friction plate 11 is calculated as follows:

[0048] P' = K(t) P (3)

[0049] Wherein, K(t) is the reduction coefficient of the concrete side pressure, K(t) = K0 e -0.002t K0 = 0.85 for ordinary concrete and K0 = 0.95 for self-compacting concrete.

[0050] (c) The static friction coefficient between the concrete and the friction plate is calculated as follows:

[0051]

[0052] The dynamic friction coefficient between the concrete and the friction plate is calculated as follows:

[0053]

[0054] Therefore, according to the present application, the dynamic and static friction coefficients between the newly poured concrete and the formwork at any time and under any vertical pressure (concrete pouring height) can be obtained by applying torque to the top end of the torque rod 9 by the torque wrench 13 to slowly transport and rotate the friction plate 11.

[0055] In the description of the present application, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0056] The above-described embodiments are only preferred modes of the present application and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope of the present application as defined by the claims.

Claims

1. A simple device for testing the coefficient of friction between fresh concrete and formwork, characterized in that, The utility model relates to a kind of experimental device for testing the friction coefficient of concrete, including: Experimental assembly for containing concrete to be detected, the experimental assembly includes barrel (1) and barrel bottom (2), the barrel (1) is tubular structure, the bottom surface of the barrel (1) and the top surface of the barrel bottom (2) are sealingly and fixedly connected; Pressure mechanism for applying pre-pressure to the concrete to be detected, the pressure mechanism includes self-balancing assembly and pressure unit, the bottom end of the pressure unit penetrates the self-balancing assembly and is sealingly and slidably connected with the inner cavity side wall top end of the barrel (1), and the two ends of the self-balancing assembly are fixedly connected with the outer side top end of the barrel (1); Test mechanism for testing the friction coefficient of the concrete to be detected and the template, the test mechanism includes torque wrench (13) and test assembly, the torque wrench (13) is used to measure the torque received, the torque wrench (13) is detachably connected with the top end of the test assembly, and the test assembly penetrates the pressure unit and abuts against the top surface of the barrel bottom (2); The self-balancing assembly includes pressure beam (3) and two pressure pull rods (4), the two ends of the pressure beam (3) are respectively detachably connected with the top end of the pressure pull rod (4), the bottom end of the pressure pull rod (4) is fixedly connected with the outer side of the barrel (1), and the bottom end of the pressure unit penetrates the pressure beam (3) and is sealingly and slidably connected with the inner cavity side wall top end of the barrel (1); The pressure unit includes four fluorine sliding sheet (5), pressure screw (6) and pressure plate (7), the pressure screw (6) penetrates the pressure beam (3) and is screwed with the pressure beam (3), the bottom end of the pressure screw (6) is fixedly connected with the top surface of the pressure plate (7) through the four fluorine sliding sheet (5), and the side surface of the pressure plate (7) is embedded with sealing rubber ring (8), the pressure plate (7) is sealingly and slidably connected with the inner cavity side wall of the barrel (1) through the sealing rubber ring (8); the test assembly penetrates the pressure screw (6), the four fluorine sliding sheet (5) and the pressure plate (7) in sequence and is sealingly and slidably connected with the center of the pressure plate (7).

2. The simple device for testing the friction coefficient between the newly poured concrete and the formwork according to claim 1, characterized in that: The test assembly includes torsion bar (9) and four-rib sleeve (10), the four-rib sleeve (10) is sleeved and fixedly connected in the middle of the torsion bar (9), the four-rib sleeve (10) penetrates friction plate (11), and the friction plate (11) is slidably connected with the four-rib sleeve (10); the torsion bar (9) penetrates the pressure screw (6), the four fluorine sliding sheet (5) and the pressure plate (7) in sequence and is sealingly and slidably connected with the center of the pressure plate (7), and the bottom end of the torsion bar (9) abuts against and is rotationally connected with the top surface of the barrel bottom (2).

3. The simple device for testing the friction coefficient between the newly poured concrete and the formwork according to claim 2, characterized in that: The friction plate (11) is the same as the template material actually used on site.

4. The simple device for testing the friction coefficient between the newly poured concrete and the formwork according to claim 2, characterized in that: The top surface of the barrel bottom (2) is provided with a groove, and the bottom end of the torsion bar (9) is slidably connected with the groove.

5. The simple device for testing the friction coefficient between the newly poured concrete and the formwork according to claim 2, characterized in that: The top end of the torsion bar (9) is fixedly connected with a clamping head (12) for facilitating the clamping of the torque wrench (13).

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