Air permeability testing device and permeability testing method

Abstract

To assess the permeability performance in a depth direction of concrete or the like.SOLUTION: An air permeability testing device 1 is composed of: a test device body 4 that is inserted into a perforation 3 provided in a test object 2, has a chamber 5 having an opening 6 directed outward formed therein, and is arranged such that a surface where the opening 6 is formed is in close contact with an inner surface of the perforation 3; a reaction force member 8 that presses the surface where the opening 6 of the test device body 4 is formed against the inner surface of the perforation 3 using the inner surface of the perforation 3 as a reaction force, the member being located on the opposite side of the surface where the opening 6 is formed; a vacuum pump 9 for depressurizing the inside of the chamber 5; a valve 10 that shuts off an airflow between the chamber 5 and the vacuum pump 9 when a pressure inside the chamber 5 is reduced to a predetermined pressure or lower by the vacuum pump 9; and a pressure gauge 11 for measuring the pressure inside the chamber 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an air permeability testing device and an air permeability testing method that are capable of measuring the air permeability, which is the mass transfer resistance of concrete or the like, in the depth direction of concrete or the like. [Background technology]

[0002] Conventionally, the quality of concrete structures has been evaluated and controlled based on the compressive strength obtained in compressive strength tests and the mix of materials used in concrete production, such as the water-cement ratio.

[0003] Furthermore, when a fire breaks out in a reinforced concrete building or a steel-framed building, fire damage investigations, diagnosis, repairs, and reinforcement of the damaged building are carried out based on the guidelines disclosed in Non-Patent Document 1 below. In the fire damage investigation disclosed in this document, a primary investigation is conducted to determine the surface heat receiving temperature and the extent of fire damage through visual observation of the state of soot adhesion, discoloration and deformation of surrounding components, discoloration, cracks, lifting, and spalling of concrete, exposed rebar, and deflection and deformation of beams and floor components. Subsequently, based on the results of the primary investigation, a secondary investigation is conducted as necessary to grasp the extent of fire damage in detail through mechanical tests focusing on concrete strength, etc., and material analysis to estimate heat receiving temperatures in the depth direction. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Architectural Institute of Japan, Guidelines and Commentary on Fire Damage Diagnosis and Repair / Reinforcement Methods for Buildings, 2015 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with conventional methods for evaluating the quality of concrete structures, even if there are no problems with compressive strength or mix proportions in concrete structures that have actually been constructed, there is a risk that deterioration factors such as moisture, oxygen, carbon dioxide, and airborne salt will penetrate into the concrete more than expected due to insufficient density and compactness within the concrete, causing early deterioration and reducing the durability of the concrete.Since such problems are related to the density (air permeability) of concrete, it is particularly important to check the quality of not only the surface layer of the concrete but also the depth direction throughout the interior when considering durability.

[0006] Furthermore, in the fire damage investigation described in Non-Patent Document 1, a primary investigation is conducted in which the surface condition of concrete, mortar, etc. is visually observed, and based on the results of this primary investigation, a secondary investigation is conducted, where necessary, in which material analysis is performed to estimate the heat-receiving temperature in the depth direction. However, there is insufficient consideration given to methods for accurately evaluating the distribution of fire damage in the depth direction.

[0007] Therefore, a main object of the present invention is to provide an air permeability testing device and an air permeability testing method that can grasp the air permeability performance of concrete or the like in the depth direction. [Means for solving the problem]

[0008] In order to solve the above problem, the present invention according to claim 1 comprises a test device body that is inserted into a borehole provided in a test object, a chamber having an opening facing outward is formed, and the surface on which the opening is formed is placed in close contact with the inner surface of the borehole; a reaction force member that presses the surface of the testing apparatus body opposite to the surface on which the opening is formed against the inner surface of the perforation, using the inner surface of the perforation as a reaction force; a vacuum pump for reducing the pressure inside the chamber; a valve that blocks the flow of air between the chamber and the vacuum pump when the pressure in the chamber is kept below a certain pressure by the vacuum pump; and a pressure gauge for measuring the pressure inside the chamber.

[0009] In the invention described in claim 1 above, a hole is formed in a test specimen such as concrete from the surface in the depth direction, and the test device body of the air permeability tester is inserted into the hole to conduct an air permeability test, thereby investigating the air permeability performance of the test specimen in the depth direction.

[0010] The air permeability testing device is provided with a chamber having an opening facing outward, and a testing device main body that is positioned with the surface on which the opening is formed in intimate contact with the inner surface of the perforation, and a reaction member on the side of the testing device main body opposite the surface on which the opening is formed that presses the surface on which the opening is formed against the inner surface of the perforation, using the inner surface of the perforation as a reaction force.

[0011] Then, with the surface of the testing device body on which the opening is formed pressed against the inner surface of the perforation by the reaction force member, the vacuum pump is used to reduce the pressure inside the chamber, and when the pressure inside the chamber falls below a certain pressure, the valve is closed to block the flow of air between the chamber and the vacuum pump, and the change in pressure over time is measured until the pressure returns to the specified pressure.

[0012] This allows the measurement of the air permeability, which is the mass transfer resistance of the test specimen. By measuring the air permeability at multiple locations in the depth direction of the perforations in the test specimen, the air permeability performance in the depth direction can be accurately determined.

[0013] The present invention according to claim 2 provides an air permeability testing apparatus according to claim 1, wherein the reaction member is constituted by a reaction force generating means arranged on the side of the testing apparatus body opposite to the side on which the opening is formed, and which presses the side on which the opening is formed against the inner surface of the perforation.

[0014] In the invention described in claim 2, the reaction force member for pressing the surface of the testing apparatus body on which the openings are formed against the inner surface of the perforation is configured by a reaction force generating means disposed on the side of the testing apparatus body opposite to the surface on which the openings are formed, which presses the surface on which the openings are formed against the inner surface of the perforation. The reaction force generating means makes it possible to press the opposite surface on which the openings are formed against the inner surface of the perforation. Therefore, when the chamber is depressurized by a vacuum pump, air leakage from the gap between the surface on which the openings are formed and the inner surface of the perforation can be reliably prevented, and the air permeability, which is the mass transfer resistance of the test specimen, can be more accurately determined.

[0015] The present invention according to claim 3 provides an air permeability testing device according to claim 1, wherein the surface of the testing device body on which the opening is formed is formed as an arcuate surface that fits the diameter of the perforation.

[0016] In the invention described in claim 3, the surface of the testing device body on which the opening is formed is formed with a curved surface having an arc-shaped cross section that matches the diameter of the perforation, which makes it easier for the surface on which the opening is formed to adhere to the inner surface of the perforation.

[0017] The present invention according to claim 4 provides the air permeability testing device according to claim 1, wherein a sealant is attached to the surface of the testing device body on which the opening is formed.

[0018] In the invention described in claim 4 above, a sealing material is attached to the surface of the test device body on which the opening is formed, thereby sealing the gap between the surface on which the opening of the test device body is formed and the inner surface of the perforation.

[0019] As a fifth aspect of the present invention, there is provided an air permeability testing method using the air permeability testing device according to any one of claims 1 to 4, a drilling forming step of forming a drilling hole in the test piece; a test device body installation step of inserting the test device body into the borehole and pressing the surface on which the opening is formed against the inner surface of the borehole by the reaction force member; a chamber decompression step of operating the vacuum pump to reduce the pressure inside the chamber, and closing the valve to stop the decompression when the pressure inside the chamber reaches a certain pressure or less; and a measuring step of measuring the change in pressure over time until the pressure in the chamber recovers to a predetermined pressure.

[0020] The invention described in claim 5 above is a method for conducting an air permeability test by first drilling a borehole in the depth direction from the surface of a test specimen such as concrete, and then inserting the test apparatus into the borehole. During the test, the surface of the test apparatus with the opening formed therein is pressed against the inner surface of the borehole by the reaction member, and a vacuum pump is operated to reduce the pressure inside the chamber. When the pressure inside the chamber drops below a certain pressure, the valve is closed to stop the reduction in pressure, and the change in pressure over time until the pressure inside the chamber recovers to the predetermined pressure is measured. The air permeability of the concrete or the like is then evaluated from the time it takes for the pressure inside the chamber to recover to the predetermined pressure.

[0021] The present invention according to claim 6 provides the air permeability testing method according to claim 5, in which measurements are made at a plurality of positions in the depth direction of the perforation.

[0022] In the invention of claim 6, in order to accurately evaluate the air permeability performance in the depth direction of the test specimen, the measurements are similarly carried out at a plurality of positions in the depth direction of the perforation.

[0023] The present invention according to claim 7 provides an air permeability testing method according to claim 5, wherein the vacuum pump is used to reduce the pressure until the pressure measured by the pressure gauge reaches a pressure reduction end pressure, the valve is closed, and the measurement start time is determined to be the time when the pressure measured by the pressure gauge recovers to a measurement start pressure that is higher than the pressure reduction end pressure, and the change in pressure over time is measured until the pressure measured by the pressure gauge recovers to a measurement end pressure that is higher than the measurement start pressure.

[0024] The invention described in claim 7 above shows the change in pressure when the test is performed. [Effects of the Invention]

[0025] As described above in detail, the present invention can provide an air permeability testing device and an air permeability testing method for determining the air permeability performance of concrete and the like in the depth direction. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic diagram showing an air permeability testing device 1 according to the present invention. [Figure 2] FIG. 2 is a perspective view showing a test device main body 4. [Figure 3] 1A shows a test device main body 4, in which (A) is a plan view, (B) is a side view, and (C) is a view taken along the CC line in (A). [Figure 4] FIG. 2 is a perspective view showing the assembled state of the test device main body 4 and the ventilation pipe. [Figure 5] 1 shows the assembled state of the test device main body 4 and the ventilation pipe, where (A) is a side view, (B) is an end view, (C) is a plan view, and (D) is a view taken along the line DD in (C). [Figure 6] FIG. 2 is an exploded side view showing the reaction member 8. [Figure 7] 1 is a flow chart of an air permeability test method. [Figure 8] 1 shows a test specimen 2 made of a steel pipe, (A) being a front view and (B) being a side view. [Figure 9] 1 shows a test specimen 2 made of mortar and concrete, (A) is a front view, and (B) is a side view. [Figure 10] 10 is a graph showing the experimental results of a test piece 2 made of a steel pipe. [Figure 11] 10 is a graph showing the experimental results of a test piece 2 made of mortar. [Figure 12] 10 is a graph showing the experimental results of a test specimen 2 made of concrete. DETAILED DESCRIPTION OF THE INVENTION

[0027] DETAILED DESCRIPTION OF THE INVENTION The present invention provides a novel air permeability testing device and method that are particularly suitable for investigating the air permeability performance of a test piece 2 such as concrete in the depth direction from the surface.

[0028] [Air permeability test device 1] As shown in FIG. 1, the air permeability testing apparatus 1 according to the present invention is equipped with a testing apparatus main body 4 that is inserted into a borehole 3 formed in a test specimen 2 such as concrete or mortar to form a chamber 5 having an outward-facing opening 6, and that is placed with the surface on which the opening 6 is formed in intimate contact with the inner surface of the borehole 3, and a reaction member 8 that is located on the side of the testing apparatus main body 4 opposite to the surface on which the opening 6 is formed, and that presses the surface on which the opening 6 is formed against the inner surface of the borehole 3, using the inner surface of the borehole 3 as a reaction force.

[0029] Furthermore, in addition to the above-mentioned test apparatus main body 4 and reaction member 8, as shown in FIG. 1 , the air permeability test apparatus 1 further includes a vacuum pump 9 for reducing the pressure inside the chamber 5, a valve 10 for cutting off the flow of air between the chamber 5 and the vacuum pump 9 when the pressure inside the chamber 5 is kept below a certain pressure by the vacuum pump 9, and a pressure gauge 11 for measuring the pressure inside the chamber 5.

[0030] The specimen 2 is made of concrete, mortar, or the like, and is a member having a predetermined thickness from the surface, such as a wall, floor, or pillar of a building. A borehole 3 is formed in the specimen 2 from the surface to a predetermined depth, preferably penetrating the member. The borehole 3 is a space extending from the surface of the specimen 2 in the depth direction, and is formed as a cylindrical space having a predetermined diameter, for example, by a drilling tool such as a core drill.

[0031] The diameter of the perforation 3 is strictly determined because the test device body 4 must be tightly attached to the inner surface of the perforation 3, and the shape of the test device body 4 is formed to match the diameter of the perforation 3. A preferred range for the diameter of the perforation 3 is 20 to 100 mm, particularly 40 to 70 mm, and in the example described later, the diameter is 53 mm.

[0032] 2 and 3, the test apparatus main body 4 is a block-shaped member formed in a substantially rectangular parallelepiped shape and made of an air-impermeable material such as resin or metal, and has an opening 6 in the center of its underside, from which a chamber 5 is formed, recessed in a concave shape. The chamber 5 is a space for reducing the pressure inside the perforation 3 to the size of the opening 6. There are no particular restrictions on its shape, and in the illustrated example, it is formed in a cylindrical shape with a circular cross section for the most part. In this embodiment, the chamber 5 is formed with an opening 6 having an area equal to or larger than the cylindrical cross section, and in the illustrated example, an area larger than the circular cross section of the circular cross section.

[0033] In the test apparatus main body 4, when the test apparatus main body 4 is inserted into the inside of the perforation 3 and the surface on which the opening 6 is formed is brought into close contact with the inner surface of the perforation 3 to reduce the pressure inside the chamber 5, the surface on which the opening 6 of the test apparatus main body 4 is formed is formed as an arc surface that fits the diameter of the perforation 3 when the perforation 3 is formed as a cylinder with a predetermined diameter, so that air does not enter through the gap between the surface of the test apparatus main body 4 and the inner surface of the perforation 3. In other words, the surface of the test apparatus main body 4 on which the opening 6 is formed is formed as an arc shape that has the same diameter as the diameter of the perforation 3 along the axial direction of the perforation 3 in a cross section perpendicular to the axial direction of the perforation 3. This allows the surface around the opening 6 of the test apparatus main body 4 to be in close contact with the inner surface of the perforation 3, making it less likely for air to leak.

[0034] The shape of the surfaces of the test device main body 4 other than the surface on which the opening 6 that is in close contact with the inner surface of the perforation 3 is formed can be arbitrary, but in the illustrated example, they are formed as flat planes.

[0035] Furthermore, as shown in FIG. 1 , a sealant 7 is attached to the surface of the test apparatus main body 4 where the opening 6 is formed, thereby ensuring more reliable airtightness. The presence of the sealant 7 between the outer surface of the test apparatus main body 4 and the inner surface of the perforation 3 enhances the airtightness between them, allowing air to flow into the chamber 5 only through the opening 6. The sealant 7 can be made of any material commonly used to improve airtightness, such as polyurethane, silicone, acrylic, rubber, or fluorine, and can also be made of thermoplastic polyurethane-polyether polyol. The sealant 7 can be used as is unless it deteriorates. However, the sealant 7 can be made detachable from the test apparatus main body 4 and replaced with a new one after each test, or after multiple tests.

[0036] A through hole 12 is formed on the side of the testing apparatus main body 4, leading from the outside to the chamber 5. A pipe leading to the vacuum pump 9 is connected to this through hole 12, and in the embodiment shown in Figures 4 and 5, a vent pipe 13 communicating with the chamber 5 is inserted into this through hole 12, and an outer pipe 14 protecting the outside of the vent pipe 13 is also inserted into this through hole 12. The tip of the outer pipe 14 is held by a lid 15.

[0037] The ventilation pipe 13 is a hard thin tube made of resin or metal, and one tip end is formed with a male thread portion that screws into a female thread portion 12a (see Figure 3(C)) formed in the through hole 12 of the testing device main body 4.

[0038] The outer tube 14 is a hard thin tube made of resin or metal, and both ends are formed with male threads that screw into the female threads 12b (see Figure 3(C)) formed in the through hole 12 of the testing device main body 4, and also with male threads that screw into the female threads formed in the cover body 15.

[0039] 1, a connection hose 16 is connected to the other end of the vent pipe 13, branching midway and being connected to a vacuum pump 9 and a pressure gauge 11, respectively. The valve 10 is provided between the branching point of this connection hose 16 and the vacuum pump 9, so that when the pressure inside the chamber 5 drops below a certain level due to pressure reduction by the vacuum pump 9, the flow of air between the chamber 5 and the vacuum pump 9 can be cut off. Any known hose made of resin, metal, or the like can be used as the connection hose 16 without any restrictions, but it is particularly preferable to use a soft hose made of silicone.

[0040] There are no particular limitations on the pressure gauge 11 as long as it is capable of measuring air pressure, but it is preferable to use a digital manometer so that measurement work can be easily performed.

[0041] As shown in Figure 1, the test device main body 4 is inserted into the perforation 3 after a sealing material 7 has been attached to the part of the surface on which the opening 6 is formed other than the opening 6, and with the sealing material 7 in close contact with the lower inner surface of the perforation 3, a reaction member 8 is attached to the upper surface on the opposite side, which presses the lower surface on which the opening 6 is formed against the lower inner surface of the perforation 3, using the upper inner surface of the perforation 3 as a reaction force.

[0042] The reaction force member 8 is configured as a reaction force generating means disposed on the side of the testing apparatus main body 4 opposite to the side on which the opening 6 is formed, and which presses the side on which the opening 6 is formed against the inner surface of the borehole 3. The reaction force generating means may be configured to press the testing apparatus main body 4 with a constant pressure, or may be configured to apply a variable pressing pressure. The reaction force generating means may be a hydraulic jack or a screw jack, as long as it can press the testing apparatus main body 4 from above. Alternatively, as shown in FIGS. 1 and 6, the reaction force generating means may be a screw member 17 that protrudes in the direction opposite to the side on which the opening 6 is formed of the testing apparatus main body 4, with the tip of the protrusion abutting against the inner surface of the borehole 3. In this way, by tightening the screw member 17 toward the inner surface of the borehole 3 with a constant torque, the side on which the opening 6 is formed of the testing apparatus main body 4 can be pressed against the inner surface of the borehole 3 with a constant pressure. Because the test device main body 4 is pressed against the inner surface of the perforation 3 with a constant pressure in this way, there is no need to construct multiple chambers, such as an outer chamber around the outer periphery of an inner chamber for measurement, as in the conventional Trent method air permeability test, and the test device can be constructed with only one chamber, which makes it possible to reduce the size of the test device main body 4 and also makes it possible to reduce the diameter of the perforation 3 to be made in the test piece 2.

[0043] 6, the screw member 17 is threaded onto a nut 19 that can be inserted into one insertion hole 18a of an extension ratchet 18, and a torque wrench 20 is inserted into the other insertion hole 18b of the extension ratchet 18 and rotated in a direction that loosens the nut 19 with a certain torque. This causes the screw member 17 threaded onto the nut 19 to thread outward (upward) and its tip to abut against the upper inner surface of the drilling hole 3, thereby generating a reaction force that presses the testing device body 4 downward via the extension ratchet 18. Note that when the nut 19 is rotated by the torque wrench 20, it is preferable to hold the screw member 17 so that it does not rotate with a tool such as a box wrench, in order to prevent the nut 19 and the screw member 17 from rotating together. In addition, in order to ensure that the entire testing device body 4 is pressed with uniform force, a steel plate 21 that covers the entire upper surface of the testing device body 4 is interposed between the testing device body 4 and the extension ratchet 18.

[0044] The means for generating a reaction force by the screw member 17 is not limited to the above-mentioned configuration, and may be any means that allows the screw member 17 to thread upward by rotating the nut onto which the screw member 17 is threaded with a constant torque.An example of such a means is one in which the screw member 17 is threaded onto a nut such as a hose nut that is rotatable with its axial movement restricted relative to a fixed plate on the testing apparatus main body 4, and the screw member 17 threaded onto this nut is allowed to thread upward by rotating the nut with a constant torque.

[0045] [Air permeability test method] Next, an air permeability test method using the air permeability test device 1 will be described.

[0046] As shown in FIG. 7 , the air permeability testing method according to the present invention comprises a perforation forming step of forming perforations 3 in a test specimen 2; a test apparatus main body installation step of inserting a test apparatus main body 4 into the interior of the perforation 3 and pressing the surface on which the opening 6 is formed against the inner surface of the perforation 3 with a reaction force member 8; a chamber depressurization step of operating the vacuum pump 9 to reduce the pressure inside the chamber 5 and, when the pressure inside the chamber 5 reaches a certain pressure or below, closing the valve 10 to stop the depressurization; and a measurement step of measuring the change in pressure over time inside the chamber 5 until the pressure inside the chamber 5 returns to the predetermined pressure.

[0047] In the borehole forming step, after borehole 3 is formed in test piece 2 using a core drill or the like, it is preferable to polish the inside of borehole 3 with a wire brush or the like, and then clean the inner surface with a parts cleaner or the like.

[0048] In the test device main body installation process, before the test device main body 4 is installed inside the borehole 3, the sealing material 7 is attached to the test device main body 4 in advance, and the ventilation pipe 13, connection hose 16, etc. are connected.

[0049] Furthermore, by performing measurements at multiple positions in the depth direction of the borehole 3, the test device main body 4 makes it possible to grasp the damage distribution in the depth direction of the borehole 3. Furthermore, by performing measurements multiple times at the same position, the reliability of the measurement values ​​is improved. When performing multiple measurements in the same borehole 3, after completing one measurement, the test device main body 4 is removed from inside the borehole 3 and the next measurement is performed after an interval of at least 15 minutes.

[0050] In the measurement process, after the vacuum pump 9 reduces the pressure to a certain level (decompression end pressure), the valve 10 is closed. The measurement start time is the point at which the pressure measured by the pressure gauge 11 recovers to a higher measurement start pressure. The time-dependent change in pressure is then measured until the pressure measured by the pressure gauge 11 recovers to a higher measurement end pressure. The longer the time it takes for the pressure to recover from the measurement start pressure to the measurement end pressure, the denser the test specimen 2 is, and the better the concrete quality, with less air permeability. The decompression end pressure, measurement start pressure, and measurement end pressure can be determined as appropriate. For example, the measurement start pressure can be 21.3 kPa and the measurement end pressure can be 25.3 kPa. Alternatively, the pressure data measured by the pressure gauge 11 can be transmitted to a computer or other computing device, which can automatically measure the elapsed time it takes for the pressure measured by the pressure gauge 11 to reach the measurement end pressure.

[0051] The above air permeability test makes it possible to measure the air permeability, which is the mass transfer resistance of the test specimen 2. By measuring the air permeability in this way at multiple locations in the depth direction of the perforations 3 provided in the test specimen 2, it is possible to accurately grasp the air permeability performance in the depth direction and also to grasp the distribution of damage caused by fire. [Example]

[0052] Using steel pipes, mortar, and concrete as test specimens 2, air permeability tests were carried out using the air permeability test device 1. The outline and results are shown below.

[0053] The outline of the test specimen 2 made of steel pipe is shown in FIG. 8 and Table 1, and the outline of the test specimen 2 made of mortar and concrete is shown in FIG. 9 and Table 2, respectively.

[0054] [Table 1]

[0055] [Table 2]

[0056] The symbols and materials used in Table 2 are as follows: Gmax: maximum coarse aggregate size (mm), W / C: water-cement ratio (%), s / a: fine aggregate ratio (%), W: tap water, C: ordinary Portland cement (density: 3.16 g / cm) manufactured by Sumitomo Osaka Cement Co., Ltd. 3 ), S: Crushed sand from Ieshima (Nishijima), Himeji City, Hyogo Prefecture (bone-dry density: approx. 2.55 g / cm 3 Water absorption rate: about 1.7%) and crushed sand from Takatsuki, Osaka Prefecture (bone dry density: about 2.60 g / cm 3 Water absorption rate: about 1.7%), G: Crushed stone from Iejima (Nishijima) in Himeji City, Hyogo Prefecture (bone-dry density: about 2.60 g / cm 3 Water absorption rate: about 0.8% and crushed stone from Takatsuki, Osaka Prefecture (bone dry density: about 2.65 g / cm 3 Water absorption rate: about 0.7%, Ad: AE water reducer standard type I.

[0057] The test specimen 2, consisting of mortar and concrete, was sealed and cured indoors, then removed from its form when it was 7 days old, and then left to stand indoors.When it was 48 days old, a borehole 3 with a diameter of 53 mm (inner diameter) was drilled using a dry core drill.

[0058] The testing apparatus main body 4 is provided with a chamber 5 having an opening 6 measuring approximately 25 mm square, which reduces the pressure inside the borehole 3. A sealant 7 made of thermoplastic polyurethane-polyether polyol is attached to the surface of the testing apparatus main body 4 around the chamber 5. The steel plate 21 is placed on the top surface of the testing apparatus main body 4, and an extension ratchet 18 is also placed thereon, with the nut 19 and screw member 17 inserted into one insertion hole 18a. A torque wrench 20 is inserted into the other insertion hole 18b of this extension ratchet 18 and fixed with a torque of 9 N m.

[0059] In the air permeability test, the pressure was reduced by the vacuum pump 9 with the valve 10 open, and after confirming with the pressure gauge 11 that the pressure was less than 5.0 kPa, the valve 10 was closed to stop the reduction in pressure, and the measurement started when the pressure was restored to 10.0 kPa. Thereafter, the pressure was continuously measured until the pressure was restored to 80.0 kPa. Specifically, for the test specimen 2 made of steel pipe, the pressure was measured at 10-second intervals until 420 seconds had elapsed since the measurement, and then at 60-second intervals thereafter. On the other hand, for the test specimen 2 made of mortar and concrete, measurements were taken at 10-second intervals.

[0060] The measurement positions and number of times for each test specimen 2 were as follows: for test specimen 2 made of steel pipe, measurements were taken three times at a depth of 20 mm from the end; for test specimen 2 made of mortar, measurements were taken three times at a position 20 mm from the formwork surface and once at a position 40 mm; and for test specimen 2 made of concrete, measurements were taken three times at a depth of 20 mm from the formwork surface and once each at depths of 40, 60, 80, 100, and 120 mm. For all test specimens 2, after one measurement was completed, the test device main body 4 was removed from inside drilling hole 3, and the next measurement was started after an interval of at least 15 minutes.

[0061] The graphs were arranged with the horizontal axis representing elapsed time (seconds) and the vertical axis representing pressure (kPa). The measurement results for test specimen 2 made of steel pipe are shown in Figure 10, those for test specimen 2 made of mortar in Figure 11, and those for test specimen 2 made of concrete in Figure 12.

[0062] For the test piece 2 made of steel pipe, the relationship between the elapsed time and the pressure showed roughly the same trend for all the measured values, demonstrating extremely high reproducibility.

[0063] Furthermore, in the test specimen 2 made of mortar, the pressure fluctuation tendency was similar to that of the steel pipe, and regardless of the number of measurements and the depth, the tendency to change was generally the same, and the reproducibility was high.

[0064] In contrast, for the concrete specimen 2, the tendency varied depending on the depth. For example, the time required for the pressure to recover to 80.0 kPa was 1510 to 1950 seconds at a depth of 20 mm, 2510 seconds at 40 mm, 1330 seconds at 60 mm, 2520 seconds at 80 mm, 2010 seconds at 100 mm, and 1030 seconds at 120 mm.

[0065] When comparing the time it took for the pressure to recover to 80.0 kPa for each test specimen 2, the test specimen 2 made of steel pipe took the longest, followed by concrete, and the shortest for mortar.

[0066] From the above, it was found that the results of the air permeability test on specimen 2, which consisted of steel pipe, mortar, and concrete, showed that the reproducibility of the measured values ​​was extremely high, and that the differences in materials could be roughly grasped, and it was also made clear that the distribution of air permeability in the depth direction could be measured. Therefore, it is inferred that by conducting this air permeability test on specimen 2, which has deteriorated due to fire, it will be possible to grasp the distribution of damage in the depth direction caused by fire damage.

[0067] [Other examples] In the above embodiment, the surface of the test device main body 4 on which the opening 6 is formed is in close contact with the lower inner surface of the perforation 3, but the surface of the test device main body 4 on which the opening 6 is formed can be positioned in any direction relative to the inner surface of the perforation 3. [Explanation of symbols]

[0068] 1...Air permeability test device, 2...Test object, 3...Drilling, 4...Test device body, 5...Chamber, 6...Opening, 7...Sealing material, 8...Reaction member, 9...Vacuum pump, 10...Valve, 11...Pressure gauge, 12...Through hole, 13...Ventilation pipe, 14...Outer pipe, 15...Cover body, 16...Connecting hose, 17...Threaded member, 18...Extension ratchet, 19...Nut, 20...Torque wrench, 21...Steel plate

Claims

1. a test device body that is inserted into a borehole provided in a test object, forming a chamber having an opening facing outward, and that is placed with the surface on which the opening is formed in intimate contact with the inner surface of the borehole; a reaction force member that presses the surface of the testing apparatus body opposite to the surface on which the opening is formed against the inner surface of the perforation, using the inner surface of the perforation as a reaction force; a vacuum pump for reducing the pressure inside the chamber; a valve that blocks the flow of air between the chamber and the vacuum pump when the pressure in the chamber is kept below a certain pressure by the vacuum pump; and a pressure gauge for measuring the pressure inside the chamber.

2. 2. The air permeability testing apparatus according to claim 1, wherein the reaction member is constituted by a reaction force generating means arranged on the side of the testing apparatus body opposite to the side on which the opening is formed, and which presses the side on which the opening is formed against the inner surface of the perforation.

3. 2. The air permeability testing device according to claim 1, wherein the surface of the testing device body on which the opening is formed is formed as an arcuate surface that matches the diameter of the perforation.

4. 2. The air permeability testing device according to claim 1, wherein a sealing material is attached to the surface of the testing device body on which the opening is formed.

5. An air permeability test method using the air permeability test apparatus according to any one of claims 1 to 4, a drilling forming step of forming a drilling hole in the test piece; a test device body installation step of inserting the test device body into the borehole and pressing the surface on which the opening is formed against the inner surface of the borehole by the reaction force member; a chamber decompression step of operating the vacuum pump to reduce the pressure inside the chamber, and closing the valve to stop the decompression when the pressure inside the chamber reaches a certain pressure or less; and a measuring step of measuring a change in pressure over time until the pressure in the chamber recovers to a predetermined pressure.

6. 6. The air permeability testing method according to claim 5, wherein measurements are made at a plurality of positions in the depth direction of the perforation.

7. 6. The air permeability testing method according to claim 5, wherein the pressure is reduced by the vacuum pump until the pressure measured by the pressure gauge reaches a pressure reduction end pressure, the valve is closed, and the measurement start time is determined to be the time when the pressure measured by the pressure gauge recovers to a measurement start pressure that is higher than the pressure reduction end pressure, and the change in pressure over time is measured until the pressure measured by the pressure gauge recovers to a measurement end pressure that is higher than the measurement start pressure.

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