KR102253278B1 - Concrete Carbonation Hole Depth Measuring Device for Structural Safety Diagnosis - Google Patents

Abstract

The present invention relates to a concrete carbonation hole depth measuring device for a structural safety diagnosis, comprising: a gauge fixing plate (30) in which a digital depth gauge (20) is installed; an opening unit (31) vertically formed on the gauge fixing plate (30); side plates (32) parallelly folded from both edges of the gauge fixing plate (30) toward a rear side; support legs (33) formed on a lower end unit of the side plates (32); vertical long holes (34) formed on the side plates; a coupler (40) installed on a lower end of a slide measuring bar (21) moving along the digital depth gauge (20); a measuring rod (50) installed on a lower end of the coupler (40) to enter through a punching hole (12) formed on a concrete structure (10) and come in contact with a hole floor unit (13); a lowering lever (60) installed on a rear side of the coupler (40); an elevation rod (70) installed on the lowering lever (60) in a cross shape, having both ends moving along the vertical long holes (34); male screw units (71) formed on both ends of the elevation rod (70); handle nuts (72) engaged with the male screw units (71); spring hanging rods (80) placed at a higher place than the elevation rod (70) to cross the gap between the side plates (32) and have both ends supported by the side plates (32); and return springs (81) installed by hanging on the spring hanging rods (80) and the elevation rod(70). The present invention aims to provide a concrete carbonation hole depth measuring device for a structural safety diagnosis, which is able to precisely measure the depth of a punching hole formed on a concrete structure.

Description

Concrete Carbonation Hole Depth Measuring Device for Structural Safety Diagnosis}

The present invention relates to a concrete carbonation hole depth measuring device for structural safety diagnosis, and more particularly, to a concrete carbonation hole depth measuring device for structural safety diagnosis used to measure the depth of a hole drilled in a concrete structure to diagnose carbonation of concrete. About.

Concrete absorbs carbon dioxide gas in the air from the surface and loses alkalinity when calcium hydroxide in the concrete changes to calcium carbonate. This phenomenon is called carbonation or neutralization. The corrosion of the concrete starts and the life of the concrete is shortened.

The carbonation mechanism of concrete proceeds in the order of carbonic acid gas penetration into concrete → carbonation (neutralization) → passive film destruction of reinforcing bars → corrosion of reinforcing bars → volume expansion of reinforcing bars → concrete cracking. + CO2 = CaCO3 (calcium carbonate) + H2O.

Before carbonation proceeds, calcium hydroxide is initially strongly alkaline with a hydrogen ion concentration of about 12 to 13, but the portion that has been changed to calcium carbonate due to carbonation is lowered to about 8.5 to 10 and is neutralized.

If the pH of the concrete is higher than 11, it will not rust even if oxygen is present, but if the pH is lower than 11, rust will occur in the reinforcing bar and cracks will occur in the concrete as the reinforcing bar expands to about 2.5 times the original volume.

As a method of testing for carbonation of concrete, when a 1% solution of phenolphthalein, a test reagent, meets and reacts with an alkaline substance, it changes to red color, and a phenolphthalein solution is sprayed onto the concrete to determine whether or not there is a change in color with the naked eye. .

When a 1% solution of phenolphthalein is sprayed on concrete, it is colorless at pH 9 or lower, and red at higher pH values, so it can be easily identified. Holes are drilled in concrete structures and inspected directly on site.

In the case of inspecting carbonation by drilling a hole in a concrete structure in this way, conventionally, the depth of the hole drilled in the concrete structure was measured using a vernier caliper.

However, if the surface of the vernier caliper and the concrete structure cannot maintain the right angle, the measurement becomes inaccurate.In the past, since the operator holds the vernier caliper with the naked eye and determines the right angle, the measurement becomes inaccurate. there was.

Korean Registered Patent Publication No. 10-1721975 (announcement date 2017.03.31.) Korean Registered Patent Publication No. 10-2016530 (announcement date 2019.08.30.) Korean Registered Patent Publication No. 10-1984502 (announced on May 31, 2019) Korean Registered Patent Publication No. 10-2019720 (announced on November 14, 2019)

The present invention has been made to solve the above problems, and an object thereof is to provide a concrete carbonation hole depth measuring device for structural safety diagnosis capable of accurately measuring the depth of a perforated hole drilled in a concrete structure.

Concrete carbonation hole depth measuring apparatus for structural safety diagnosis for achieving the object of the present invention, a gauge fixing plate on which a digital depth gauge is installed; An opening opening toward the lower end of the gauge fixing plate and formed perpendicular to the gauge fixing plate; A pair of side plates bent side by side toward the rear at both edges of the gauge fixing plate; Support legs each formed in an inverted T-shape at the lower end of the side plate and supported on the surface of the concrete structure; A vertical long hole formed on the side plate; A coupler installed at the bottom of the slide measuring bar moving along the digital depth gauge; A measuring rod installed at the lower end of the coupler, entering the perforated hole formed in the concrete structure, and contacting the bottom of the hole; A lowering lever installed at the rear of the coupler and elevating along the opening; An elevating rod that is installed in a cross shape on the descending lever across the side plates and has both ends moving in the vertical direction along the vertical long hole; Male screw portions formed at both ends of the lifting rod and protruding to the outside of the side plate through vertical long holes, respectively; A handle nut coupled to each of the male threads and stopping the lowering position of the slide measuring bar; A spring locking rod positioned at a higher place than the lifting rod and having both ends supported by the side plate across the side plates; It is installed by hanging on the spring locking rod and the lifting rod, and has a characteristic including a return spring that applies an elastic force to the descending lever in the upward direction through the lifting rod.

The present invention is installed at the bottom of the digital depth gauge, a buffer ring for mitigating the impact generated between the digital depth gauge and the coupler; A square hole formed in the buffer ring and passing through the slide measuring bar; A hemispherical tip formed at the tip of the measuring rod and in contact with the bottom of the hole; It is characterized by including a crossbar installed on the support legs at both ends across the gap between the support legs.

In the present invention as described above, in the state where the digital depth gauge 20 is vertically maintained from the surface of the concrete structure 10 by the gauge fixing plate 30, the side plate 32, and the support leg 33, the hole ( Since it is configured to measure the hole depth (T) of 12), there is an effect that a uniform and precise hole depth can be measured at all times.

Since the lifting rod 70 moves along the vertical long hole 34 when the slide measuring bar 21 is lowered by the descending lever 60, the slide is measured in the front and rear direction, which is the thickness direction of the slide measuring bar 21. Since bending of the bar 21 can be minimized, there is an effect of measuring the hole depth T of the perforated hole 12 more precisely.

Since the elastic restoring force is always applied to the lifting rod 70 in the upward direction, which is the direction in which the return spring 81 contracts, the slide measuring bar 21 and the coupler 40, the measuring rod 50, and the lifting rod ( 70), there is an effect of preventing the slide measuring bar 21 from being naturally lowered by its own weight by the handle nut 72, the lowering lever 60 and its surrounding components.

It is configured to automatically return to the raised position by the elastic restoring force of the return spring 81 by measuring the hole depth (T) of the drilling hole 12 by the lowering lever (60) and then removing your hand from the lowering lever (60). Therefore, it has the effect of being convenient to use.

When the measurement rod 50 is lowered, the lowering position can be maintained by tightly tightening the handle nut 72, making it convenient not only to perform the measurement, but also to the gauge output value (L) output through the liquid crystal display (24). It has the effect of being able to read conveniently.

When the microcontroller 100 and the display unit 102 are provided, and the tip of the measuring rod 50 is composed of a hemispherical tip 51, the microcontroller 100 is used to quickly and conveniently use the triangular ratio of a right triangle. After calculating the hole depth (T) of the perforated hole 12, there is an effect that can be displayed through the display unit 102.

By the opening 31 formed in the gauge fixing plate 30, there is an effect of preventing the lowering lever 60, the coupler 40, and surrounding components from interfering with the gauge fixing plate 30.

Furthermore, the present invention can prevent the spreading of the support leg 33 by the crossbar 90 crossing the support leg 33, and the spread of the side plate 32 and the opening 31 can also be prevented. Effects can also be expected.

1 is a perspective view according to the present invention
Figure 2 is a rear perspective view of Figure 1
Figure 3 is a side cross-sectional view according to the present invention
Figure 4 is a rear view according to the present invention
Figure 5 is a rear perspective view showing that the measuring rod has entered the perforation hole by the lowering lever from the state of Figure 2
FIG. 6 is a perspective view showing that the measuring rod has entered the perforation hole by the lowering lever from the state of FIG. 1
7 is a side cross-sectional view showing that the measurement rod enters the perforation hole by the lowering lever from the state of FIG. 3
8 is a front view showing that the measuring rod according to the present invention has entered the perforated hole
9 is an exploded perspective view according to the present invention
10 is an exploded perspective view of FIG. 9 viewed from the opposite side
11 is an exploded perspective view showing a lowering lever, a coupler, a lifting rod, and components around it according to the present invention
12 is a top cross-sectional view showing a descending lever and a lifting rod according to the present invention
13 is a view for explaining the concept of measuring the depth of the perforated hole by the measurement rod according to the present invention
14 is a block diagram according to the present invention

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 14 of the accompanying drawings, the present invention provides a gauge fixing plate 30 on which a digital depth gauge 20 is installed; It opens toward the lower end of the gauge fixing plate 30 and includes an opening 31 formed perpendicular to the gauge fixing plate 30.

The gauge fixing plate 30 may be constructed using a metal plate having a certain thickness, and the opening 31 may be formed in an inverted U-shape from the center of the gauge fixing plate 30 in a vertical direction.

The opening 31 is for avoiding interference with the lowering lever 60, the coupler 40, and surrounding components thereof to the gauge fixing plate 30 below.

In the gauge fixing plate 30, as shown in FIGS. 9 and 10, a screw hole 35 in which the center of the screw hole 29 formed on the rear surface of the digital depth gauge 20 and the hole center coincide is formed, thereby forming a flat head screw. The digital depth gauge 20 is installed on the gauge fixing plate 30 by coupling 36 to the screw hole 29 through the screw hole 35.

The digital depth gauge 20 includes a liquid crystal display 24 for displaying the detected value as shown in FIGS. 1, 6 and 8, a power switch 25 for turning on/off the power, and a measuring rod 50. A zero point switch 26 for setting the zero point by contacting the hemispherical tip portion 51 of) to the surface of the concrete structure 10, and a unit conversion switch 27 for converting the display unit into millimeters or inches may be provided.

The present invention is a pair of side plates 32 bent side by side toward the rear at both edges of the gauge fixing plate 30; Each formed in an inverted T-shape at the lower end of the side plate 32 and includes support legs 33 supported on the surface of the concrete structure 10.

The gauge fixing plate 30, the side plate 32, and the support leg 33 may all be integrally constructed from a single metal plate having a certain thickness, and in particular, the support leg 33 is prevented from being lifted from the surface of the concrete structure 10. In order to prevent it, the lower part is formed in the same plane while maintaining the parallelism of the support leg 33.

The present invention is a vertical long hole 34 formed in the side plate 32; A coupler 40 installed at the bottom of the slide measuring bar 21 moving along the digital depth gauge 20; A measuring rod 50 installed at the lower end of the coupler 40 and entering the perforated hole 12 formed in the concrete structure 10 to contact the hole bottom 13; It is installed at the rear of the coupler 40, and includes a lowering lever 60 that is raised and lowered along the opening 31.

The vertical long holes 34 may be formed in a straight line on both side plates 32 as shown in FIGS. 2, 5, 9 and 10, and both vertical long holes 34 are formed to be parallel to each other.

11, in order to couple the coupler 40 to the lower rear side of the slide measuring bar 21, a flat cutting part 41 is formed on the upper front surface of the coupler 40, and the slide measuring bar 21 and Fastening holes 28 and 42 are formed in the coupler 40 in the front and rear direction, and are coupled with the lowering lever 60 through the fastening bolt 43.

At this time, a tap hole 61 is formed in the center of the end of the lowering lever 60 to be combined with the fastening bolt 43, and the fastening bolt 43 located at the lower side is combined with the fastening nut 44 and the coupler 40 It helps to fasten the slide measuring bar (21).

The measuring rod 50 is inserted into the pin hole 45 vertically formed at the lower end of the center of the coupler 40, as shown in Figs. 3 and 7, and from the surface of the coupler 40 toward the pin hole 45 The set screw 47 is coupled to the formed screw hole 46 to press the measuring rod 50 inserted into the pin hole 45.

The present invention is installed in a cross shape on the lowering lever 60 across the side plate 32, both ends of the lifting rod 70 moving in the vertical direction along the vertical long hole 34; Male screw portions 71 formed at both ends of the lifting rod 70 and protruding outward of the side plate 32 through the vertical long hole 34, respectively; It is coupled to each of the male screw portion 71, and includes a handle nut 72 for stopping the lowering position of the slide measuring bar 21.

As shown in FIGS. 3, 7 and 11, a cross hole 62 for inserting the lifting rod 70 is formed to penetrate from the outer peripheral surface of the descending lever 60 toward the center in a perpendicular direction of the axis, and the descending lever A pressing bolt 64 is installed in the tap hole 63 formed from the surface of the cross hole 62 toward the cross hole 62, and the lifting rod 70 inserted into the cross hole 62 is pressed and fixed.

As shown in Fig. 12, a stop ring 73 for inserting the snap ring 74 is formed on the outer circumferential surface of the lifting rod 70, and when a tensile force is applied to the lifting rod 70 by the handle nut 72, the snap ring ( 74) is in close contact with the inner surface of the side plate 32, and the handle nut 72 is configured to be in close contact with the outer surface of the side plate 32 so as to stop the lifting rod 70 at a desired position.

The present invention is located at a higher place than the lifting bar (70), crossing between the side plate (32), both ends of the spring locking rod (80) supported by the side plate (32); It is installed by walking on the spring locking rod 80 and the lifting rod 70, and includes a return spring 81 that applies an elastic force to the descending lever 60 in the upward direction through the lifting rod 70.

As shown in Figs. 9 and 10, the spring locking rod 80 forms male threaded portions 87 at both ends of the spring locking rod 80, and has an annular stop groove 83 for installing the snap ring 84. Is formed on the outer circumferential surface of the spring locking rod 80, and through holes 37 for inserting the male screw portions 87 formed at both ends of the spring locking rod 80 are aligned with the center of each other on the side plates 32 on both sides. To form.

Insert the spring locking rod (80) into the through hole (37) formed in the side plate (32), and then insert the snap ring (84) into the stop groove (83), and the male screw portion (87) protruding outward of the side plate (32) The fixing nut (82) is coupled to and the spring locking rod (80) is installed on the side plate (32).

The return spring 81 may be composed of, for example, a tension coil spring made by spirally winding a spring steel wire, and a C-shaped ring may be formed at both ends of the return spring 81, and the same two It is possible to configure the return spring 81 to achieve.

An annular spring locking groove 75, 85 is formed on the outer circumferential surface of the lifting rod 70 and the spring locking rod 80 to be configured to hang rings (signs omitted) formed at both ends of the return spring 81. have.

The present invention is installed at the bottom of the digital depth gauge 20, the buffer ring 22 for mitigating the impact generated between the digital depth gauge 20 and the coupler 40; It is formed in the buffer ring 22, and includes a square hole 23 to pass through the slide measuring bar (21).

The buffer ring 22 may be formed in the form of a square ring having a certain thickness using synthetic rubber or natural rubber, as shown in FIGS. 9 and 10, and may be adhered to the bottom of the digital depth gauge 20. have.

The present invention is formed at the front end of the measuring rod 50, a hemispherical tip 51 in contact with the hole bottom 13; It includes a crossbar (90) that is installed on both ends of the support legs (33) across the space between the support legs (33).

The crossbar 90 may be installed in parallel to the supporting legs 33, for example, and the crossbar 90 serves to prevent the gap between the supporting legs 33.

The crossbar 90 may be composed of the same as the spring locking rod 80, and a snap ring 94 is installed on the outer circumferential surface of the crossbar 90, and fixing nuts 92 are provided on male threads formed at both ends of the crossbar 90. By combining the crossbar (90) is installed on the support leg (33).

That is, in the crossbar 90, the snap ring 94 is in close contact with the inner surface of the support leg 33, as in the spring locking rod 80, and the fixing nut 92 is in close contact with the outer surface of the support leg 33. (90) is fixed to the support leg (33).

As shown in Fig. 14, a microcontroller 100 that calculates the hole depth T through calculation processing using the gauge output value L output from the digital depth gauge 20, and the calculated hole depth T A display unit 102 may be provided to output a message.

Such a microcontroller 100 is an on-chip or on-board with a built-in volatile memory (RAM) data memory, a nonvolatile memory (EEPROM) program memory, an operation processing unit, a built-in clock generation unit, a timer circuit unit, an input/output interface circuit unit, etc. It can be configured in a form.

The display unit 102 for outputting the hole depth (T) is connected to the output port of the microcontroller 100, and the input port of the microcontroller 100 initializes the screen output output to the display unit 102. A zero switch (SW1) for and a hold switch (SW2) for holding the screen output being output through the display unit 102 may be installed.

A process of measuring the depth of the perforated hole 12 by the measuring rod 50 having the hemispherical tip 51 as shown in FIG. 13 will be described.

First, the diameter (D) of the measuring rod 50 is oriented to the radius R of the hemispherical tip portion 51, and the tip angle (A) of the drill bit (not shown) used to drill the perforated hole 12 is It is the same angle as the angle of the bottom of the hole 13, and data corresponding to the diameter (D) of the measuring rod 50 and the tip angle of the bit (A) for the calculation processing of the microcontroller 100 is the microcontroller 100 It is entered in advance into the program memory built into the device.

At this time, the value detected by the digital depth gauge 20 when the hemispherical tip 51 of the measurement rod 50 comes into contact with the hole bottom 13 is the gauge output value (L), and based on this, the hemispherical tip 51 The gap G, which is the distance from the end of the hole bottom 13 to the vertex of the hole bottom 13, is calculated by the microcontroller 100 to obtain the hole depth T.

The calculation of the gap G can be calculated and obtained by a trigonometric ratio using a right triangle indicated by a broken line in FIG. 13, and through this, the length of the hypotenuse C of the right triangle is first obtained.

Since the sum of the inner angles of a right triangle is 180 degrees, the remaining angles excluding the right angle part can be found by subtracting the value obtained by dividing the bit tip angle (A) in half from 90 degrees, and the radius (R Multiplying by) gives the length of the hypotenuse (C).

The gap (G) can be obtained by subtracting the radius (R) from the calculated length of the hypotenuse (C), and by adding the gap (G) to the gauge output value (L) detected by the digital depth gauge (20), the hole depth ( T) is finally calculated.

Here, the gauge output value L detected by the digital depth gauge 20 is output through the liquid crystal display unit 24 and the hole depth T is output through the display unit 102.

Hereinafter, the operation according to the present invention will be described in detail with reference to the accompanying drawings.

As shown in the accompanying drawings FIGS. 1 to 14, by pressing the power switch 25 installed on the digital depth gauge 20, the power of the digital depth gauge 20 is switched to the'ON' state, and then the digital depth gauge 20 To set the zero point of, loosen the handle nut (72) and lower the lowering lever (60), the slide measuring bar (21) connected to the lowering lever (60), the coupler (40) and the measuring rod (50) will descend. It descends together with the lever 60.

At this time, since the lifting rod 70 moves in a linear direction along the vertical long hole 34, the slide measuring bar 21 is prevented from bending in the front and rear thickness direction, thereby enabling a more precise measurement.

Thereafter, when the hemispherical tip 51 formed at the lower end of the measurement rod 50 is in contact with the surface of the concrete structure 10, by rotating and tightening the handle nut 72, the measurement rod 50 maintains the lowered position. When the zero switch 26 provided in the digital depth gauge 20 is pressed, the number displayed on the liquid crystal display 24 of the digital depth gauge 20 is initialized to '0', and the zero point of the digital depth gauge 20 is a concrete structure. It is set based on the surface of (10).

In this way, when the lowering lever 60 and the lifting rod 70 are lowered, the return spring 81 is elongated and has an elastic restoring force in the contraction direction. At this time, if the handle nut 72 is tightly tightened, it is prevented from automatically rising. can do.

On the other hand, while the measuring rod 50 is raised, the center of the measuring rod 50 is matched with the center of the perforated hole 12 formed in the concrete structure 10, and the lowering lever 60 is lowered so that the measuring rod 50 When entering into the perforated hole 12, the lifting rod 70 moves along the vertical long hole 34, and as the return spring 81 is elongated, it has an elastic restoring force in the contraction direction.

At this time, when the hemispherical tip 51 of the measuring rod 50 comes into contact with the hole bottom 13 of the perforated hole 12 and stops, tightening the handle nut 72 tightly restores the lowered state of the measuring rod 50. It is maintained, and by reading the gauge output value L displayed on the liquid crystal display unit 24 provided in the digital depth gauge 20, the depth of the perforated hole 12 can be known.

The microcontroller 100 as shown in FIGS. 13 and 14 is based on the radius (R) calculated from the diameter (D) of the measuring rod 50 and the tip angle of the bit (A). The gap (G) is calculated by subtracting the radius (R) from the obtained hypotenuse (C) length, and the final hole depth (T) by adding the gap (G) to the gauge output value (L) transmitted from the digital depth gauge (20). Will yield.

At this time, the hole depth T calculated from the microcontroller 100 is output through the display unit 102.

When the measurement rod 50 is lowered, if the hold switch (SW2) is pressed while the lowering lever (60) is pressed without tightening the handle nut (72) in a loose state, the depth of the hole output through the display unit (102) ( Since T) can be held, even if the measurement rod 50 is raised by the return spring 81, the output hole depth T is displayed on the display 102 as it is, enabling quick and convenient measurement. .

On the other hand, when the hole depth (T) measurement work of the perforated hole 12 is completed and the handle nut 72 is loosened, the slide measuring bar 21, the coupler 40, and the measuring rod ( 50), the lifting rod 70, the descending lever 60 and the components around the sphere simultaneously rise and return to their original position.

At this time, impact energy and noise generated between the coupler 40 and the digital depth gauge 20 are reduced by the buffer ring 22 positioned between the coupler 40 and the digital depth gauge 20.

10: concrete structure 12: drilling hole
13: hole bottom 20: digital depth gauge
21: slide measuring bar 22: buffer ring
23: square hole 24: liquid crystal display
25: power switch 26: zero switch
27: unit conversion switch 28, 42: fastening hole
29: screw hole 30: gauge fixing plate
31: opening 32: side plate
33: support leg 34: vertical long hole
35: screw hole 36: flat head screw
37: through hole 40: coupler
41: flat cutting part 43: fastening bolt
44: tightening nut 45: pin hole
46: screw hole 47: set screw
50: measuring rod 51: hemispherical tip
60: lowering lever 61: tapped hole
62: cross hole 63: tap hole
64: pressure bolt 70: lifting rod
71,87: male thread 72: handle nut
73,83: Stopping groove 74,84,94: Snap ring
75,85: spring locking groove 80: spring locking rod
81: return spring 82,92: fixing nut
90: crossbar 100: microcontroller
102: display unit SW1: zero switch
SW2: Hold switch D: Diameter
R: Radius A: Bit tip angle
C: hypotenuse G: gap
L: Gauge output value T: Hole depth

Claims (2)

Gauge fixing plate 30 on which the digital depth gauge 20 is installed;
An opening 31 opened toward the lower end of the gauge fixing plate 30 and formed perpendicular to the gauge fixing plate 30;
A pair of side plates 32 bent side by side toward the rear at both edges of the gauge fixing plate 30;
Support legs 33 each formed in an inverted T shape at the lower end of the side plate 32 and supported on the surface of the concrete structure 10;
A vertical long hole 34 formed in the side plate 32;
A coupler 40 installed at the bottom of the slide measuring bar 21 moving along the digital depth gauge 20;
A measuring rod 50 installed at the lower end of the coupler 40 and entering the perforated hole 12 formed in the concrete structure 10 to contact the hole bottom 13;
A lowering lever (60) installed at the rear of the coupler (40) and elevating along the opening (31);
A lifting rod 70 that is installed in a cross shape on the descending lever 60 across the side plates 32 and has both ends moving in the vertical direction along the vertical hole 34;
Male screw portions 71 formed at both ends of the lifting rod 70 and protruding outward of the side plate 32 through the vertical long hole 34, respectively;
A handle nut 72 coupled to the male screw portion 71 and stopping the lowering position of the slide measuring bar 21;
A spring locking rod 80 positioned higher than the lifting rod 70 and having both ends supported by the side plate 32 across the side plates 32;
A return spring 81 which is installed by walking on the spring locking rod 80 and the lifting rod 70 and applies an elastic force to the descending lever 60 in an upward direction through the lifting rod 70;
Concrete carbonation hole depth measuring device for structural safety diagnosis comprising a. The method according to claim 1,
A buffer ring (22) installed at the lower end of the digital depth gauge (20) and mitigating an impact generated between the digital depth gauge (20) and the coupler (40);
A square hole (23) formed in the buffer ring (22) and passing through the slide measuring bar (21);
A hemispherical tip 51 formed at the tip of the measuring rod 50 and in contact with the hole bottom 13;
A crossbar (90) having both ends installed on the support legs (33) across between the support legs (33);
Concrete carbonation hole depth measuring device for structural safety diagnosis comprising a.

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