JP5950283B2 - Reinforcing bar expansion simulated loading test apparatus and loading test method - Google Patents

Description

  The present invention is intended to easily and accurately experimentally grasp the phenomenon of delamination and delamination caused by the reinforcement corrosion expansion of a reinforced concrete structure affecting the interior and surface of the concrete, by simulating the reinforcement corrosion expansion. The present invention relates to a reinforcing bar expansion simulated loading test apparatus and a loading test method.

  Reinforced concrete that has been properly designed, constructed, and maintained maintains its shape and retains its function over a long period of time.

  However, if cracks occur in the concrete due to improper design / construction or use exceeding the design load, earthquakes, concrete expansion due to alkali silica reaction, etc., chloride ions, oxygen, water, and other concrete will enter the concrete. Undesirable substances enter.

  And the passive film of a reinforcing bar is destroyed inside the reinforced concrete which should be stabilized by being kept alkaline. Reinforcing bars expand due to corrosion and fall into a vicious circle in which cracks further progress, causing the concrete surface to peel off and flake off.

  Therefore, elucidation of the mechanism of concrete peeling and flaking and research on measures to prevent flaking and flaking are urgent issues.

  In order to conduct such research, methods for obtaining physical property values by expanding an apparatus inside concrete and methods for simulating reinforcing bar expansion inside concrete have been proposed (Patent Documents 1 and 2, Non-Patent Document 1). ).

  Patent Document 1 discloses an apparatus and method for measuring a displacement of concrete in a hole diameter direction by drilling a reinforced concrete and inserting a loading test apparatus capable of being pressurized by hydraulic pressure into the hole.

  Patent Document 2 discloses an apparatus and a method for simulating rebar expansion by a structure in which a reinforcing bar in a reinforced concrete is pushed out in a direction perpendicular to the axis of the reinforcing bar and from a direction opposite to the peeling surface.

  In Non-Patent Document 1, a cylindrical elastic rubber is inserted into reinforced concrete provided with a cylindrical cavity, and the elastic rubber is deformed in the insertion direction, thereby displacing in the hole diameter direction and simulating the reinforcement of the reinforcing bar. An apparatus and method is disclosed.

Japanese Patent No. 4358728 JP 2012-172975 A

Takatani et al .: “Empirical verification of rebar corrosion expansion pressure modeling using elastic bodies”, Proceedings of the 59th Annual Conference of the Japan Society of Civil Engineers, pp547, 2004

  In Patent Document 1, in order to measure the hole diameter by applying pressure by hydraulic pressure, a hole diameter of a certain size is required for incorporating the device. In addition, because of the hydraulic device, there is a problem that the entire facility becomes large.

  In Patent Document 2, since the expansion direction is one direction, the actual corrosion expansion cannot always be reproduced. In addition, since the equipment is specially assembled, there is a problem that the whole equipment becomes large and versatility is not high.

  In Non-Patent Document 1, since it is necessary to calculate the amount of expansion in the hole diameter direction and the force for spreading in the hole diameter direction by considering the elastic rubber in the expanded portion as a complete elastic body, the accuracy of the data There is a problem of lacking.

  Therefore, the present invention solves the above-mentioned problems, elucidates the mechanism of peeling and peeling of reinforced concrete, and makes it possible to accurately and easily perform research on measures to prevent peeling and peeling. An object of the present invention is to provide a loading test apparatus and a loading test method.

  In order to achieve the above-mentioned object, the rebar expansion simulation loading test apparatus of the present invention is a loading test apparatus that enables simulation of rebar corrosion expansion by transmitting the effect of rebar expansion of reinforced concrete to the interior and surface of the concrete. The tip has a pyramid-shaped pushing portion, a wedge-shaped inflating portion having the same angle as the angle of the pyramid portion at the tip of the pushing portion, and a hole to the extent that the tip of the pushing portion can be inserted. A guide part, a loading means for pushing the pushing part, a displacement measuring means for measuring a displacement amount of the pushing part while pushing the pushing part, and a pushing part for pushing the pushing part A load measuring means for measuring the load to be pushed in is provided.

  The tip of the push-in part may be conical.

  Moreover, it can be set as the structure further equipped with the groove | channel, rail, or threading for making the operation | movement of an expansion | swelling part into one direction in the said pushing part and an expansion | swelling part.

  Moreover, it can be set as the structure further equipped with the spacer for position adjustment for adjusting the said expansion | swelling part so that it may become the position which is going to simulate rebar corrosion expansion | swelling.

  Further, the loading test method of the present invention is such that the pushing portion, the expanding portion, and the guide portion can be inserted, and a concrete having a cylindrical hole that is in contact with the outer periphery thereof is placed or placed. The step of making a cylindrical hole later, the step of manufacturing a specimen, the step of adjusting the expansion part to be a position to simulate rebar corrosion expansion, and the pushing part, It is provided with a step of pushing the end that is not in contact with the loading device described above, a load measuring means for measuring the load to be pushed in while the push portion is being pushed, and a step for measuring the push amount. And

  Moreover, the above-mentioned load test method can perform the test of the construction method by constructing the construction method which prevents peeling and peeling in the concrete inside or surface.

  In the load test method described above, concrete can be produced in a cylindrical shape, adjusted so that the inflated portion is positioned at the center of the cylindrical shape, and inflated, and the tensile stress of the concrete can be tested.

  Since the present invention can easily produce inflatable portions having different lengths and diameters, various test methods are possible.

  Moreover, since any laboratory can test as long as there is an apparatus that can push in the push-in part, it is very versatile.

  Furthermore, compared with the prior art, there is an excellent point that the amount of change in radius of the expanded portion and the expansion force of the reinforcing bar converted from the pushing force can be calculated easily and accurately.

  Therefore, it is possible to simulate the corrosion expansion of reinforcing bars by transmitting the effect of reinforcing bar expansion of the reinforced concrete to the inside and the surface of the concrete. It becomes easy.

  In addition, since a method for preventing peeling or flaking can be applied to the inside or the surface of the concrete and the method can be easily tested, it can be a test method for a technique for preventing flaking and flaking.

  As other effects, concrete is produced in a cylindrical shape, and a specimen whose thickness is sufficiently small compared to the diameter of the cylinder, and the appropriate pushing-in part and expanding part that are in contact with the inside of the cylinder. When the guide portion is used, it is possible to ignore other than the tensile stress, and it can be considered that only the tensile stress acts on the cylindrical concrete, so that the tensile stress test of the concrete can be performed.

It is the front view which showed the structure of the concrete delamination simulation test of this invention Example. It is the side view which showed the structure of the concrete delamination simulation test of this invention Example. It is the figure which showed the expansion | swelling part typically. It is the front view which added the surface protection construction method which resists peeling to the concrete surface of FIG. It is the side view which added the surface protection construction method which resists peeling to the concrete surface of FIG. It is sectional drawing which showed the concrete tensile test of this invention Example typically.

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

  FIG. 1 is a front view of the embodiment 1 and FIG. 2 is a side view thereof.

  Example 1 is a simulation test that can cause delamination on the surface of reinforced concrete.

  A concrete in which a pushing-in part 1, an inflating part 2 and a guide part 3 can be inserted and a columnar hole is formed so that the outer periphery of the pushing part 1, the concrete part in which the reinforcing bar 6 is arranged at a proper position, and reinforced concrete. The specimen 5 is manufactured and installed on the bottom surface 10.

  A spacer 4, a guide portion 3, an expansion portion 2, and a push-in portion 1, which are adjusted so that the expansion portion 2 is positioned to simulate rebar corrosion expansion, are inserted into a specimen 5 of reinforced concrete.

  If necessary, the load meter 8 and the vertical displacement meter 9 are set and loaded by the loading device 7.

  FIG. 3 is a diagram schematically showing the inflating portion 2.

  In Example 1, the gradient portion of the push-in portion 1 was a regular quadrangular pyramid, and the gradient angle was 3 degrees.

  When loading very slowly, the frictional force of the pushing part 1 and the inflating part 2, and the inflating part 2 and the guide part 3 can be ignored, and the inflating part 2 is about 20 times stronger than the pushing force. Can be inflated.

  In order to make the operation of the expansion part in one direction, the pushing part 1 and the expansion part 2 can be provided with grooves, rails or threading.

  Moreover, the front-end | tip of the pushing part 1 can be made into a cone shape.

  When the pushing portion 1 is loaded, the expanding portion 2 changes the direction of the force at the upper end of the guide portion 3, spreads at right angles to the pushing direction, and spreads the surrounding concrete.

  After a certain stage when the surrounding concrete can no longer withstand the reinforcement of the reinforcing bars, the concrete begins to crack from the inside, and eventually the crack appears on the concrete surface, resulting in peeling.

  In this way, it is possible to accurately grasp the relationship between the expansion force of the reinforcing bar converted from the indentation force and the amount of expansion of the reinforcing bar, and also to grasp the relationship between the time when cracking starts in concrete and the time when separation occurs. it can.

  Therefore, if the corrosion amount and corrosion rate of the reinforcing bar can be predicted, it is possible to accurately predict the time when cracks begin to enter the concrete surface and debond.

  Further, if the corrosion amount of the reinforcing bar can be predicted from the cracked state of the concrete surface, and further the corrosion rate can be predicted, the time to release can be accurately predicted.

  In addition, if the process of crack growth in the concrete can be grasped at each stage of rebar expansion, research for elucidating the mechanism of concrete peeling and flaking can be expected to greatly advance.

  FIG. 4 is a front view of the embodiment 2 and FIG. 5 is a side view thereof.

  Example 2 is a test method capable of inspecting the properties and performance of the surface protection method by applying a surface protection method for preventing peeling and flaking to the concrete surface in addition to the form of Example 1.

  A surface protection work 11 that resists peeling is applied to the surface of the reinforced concrete specimen 5 that is peeled off.

  By comparing the data with and without applying surface protection work, or comparing data with other surface protection work, the properties and effects of surface protection work can be evaluated. It becomes possible.

  6 is a cross-sectional view schematically showing the concrete tensile test of Example 3. FIG.

  Example 3 is a test in which a concrete specimen 5 is produced in a cylindrical shape, placed so that the inflatable portion 2 is at the center of the cylinder, loaded, and tensile stress of the concrete is applied.

  A concrete cylindrical specimen 5 having a sufficiently small cylinder thickness compared to the diameter of the cylinder is prepared, and a push-in part 1, an expansion part 2 and a guide part 3 are prepared and installed in accordance with the inner diameter. And loading.

  If the thickness of the cylinder is sufficiently small compared to the diameter of the cylinder, it can be regarded as a thin cylinder, and it can be considered that only the tensile stress in the circumferential direction acts on the concrete. Can be tested.

  As described above, the examples have been described. However, in view of the development of new materials to replace concrete in the field of civil engineering and construction in the present and future, the test materials targeted by the present invention are not limited to reinforced concrete, but widely applied to civil engineering and building materials in general. In addition, since a loading test simulating rebar expansion can be performed, this is also included in the present invention.

  However, in that case, it is possible in the case where the material of the push-in part, the expansion part and the guide part is sufficiently harder than the material of the specimen to be tested.

  Further, the present invention is not limited to the embodiments described above, and modifications of the embodiments that can be made by those having ordinary knowledge in the art within the scope of the present invention are within the scope of the present invention. included.

DESCRIPTION OF SYMBOLS 1 Pushing part 2 Expansion part 3 Guide part 4 Spacer 5 Specimen 6 Reinforcing bar 7 Loading device 8 Load meter 9 Vertical displacement meter 10 Bottom surface 11 Surface protection work resisting peeling

Claims (7)

It is a loading test device that reproduces the corrosion expansion of reinforcing bars by transmitting the effects of reinforcing bars of reinforced concrete to the interior and surface of the concrete.
The tip has a pyramidal push-in part;
Some wedge-shaped inflatable portions having the same angle as the angle of the pyramid portion at the tip of the push-in portion;
A guide part with a hole to the extent that the tip of the pushing part can be inserted;
Loading means for pushing in the pushing portion;
Load measuring means for measuring the pushing load as the expansion force of the reinforcing bar while pushing the pushing portion;
Displacement measuring means for measuring the pushing amount while pushing the pushing portion,
Reinforcing bar expansion simulation loading test apparatus characterized by comprising: It is a loading test device that reproduces the corrosion expansion of reinforcing bars by transmitting the effects of reinforcing bars of reinforced concrete to the interior and surface of the concrete.
A push-in part having a conical tip , and
Several wedge-shaped inflatable portions having the same angle as the angle of the conical portion at the tip of the push-in portion;
A guide part with a hole to the extent that the tip of the pushing part can be inserted;
Loading means for pushing in the pushing portion;
Load measuring means for measuring the pushing load as the expansion force of the reinforcing bar while pushing the pushing portion;
Displacement measuring means for measuring the pushing amount while pushing the pushing portion,
Reinforcing bar expansion simulation loading test apparatus characterized by comprising: The pushing portion and the inflating portion further include a groove, a rail, or threading for unidirectional movement of the inflating portion,
The reinforcing bar expansion simulation loading test apparatus according to claim 1 or 2. The expansion portion further includes a position adjusting spacer for adjusting the expansion portion so as to be a position to simulate rebar corrosion expansion;
The reinforcing bar expansion simulated loading test apparatus according to any one of claims 1 to 3. A loading test method using the reinforcing bar expansion simulated loading test apparatus according to any one of claims 1 to 4,
The step of producing a specimen by placing the indented portion, the inflatable portion and the guide portion, placing concrete with a cylindrical hole to the extent that the outer periphery thereof is in contact, and
Adjusting the expansion portion to be a position where it is intended to simulate rebar corrosion expansion;
A step of pushing the end of the pushing portion that does not contact the expanding portion with the loading device described above;
A step of measuring the pushing load as an expansion force of the reinforcing bar while pushing the pushing portion; and
Measuring the amount of pushing while pushing the pushing portion; and
A loading test method characterized by comprising: Applying a construction method to prevent peeling and flaking inside and on the concrete, and testing the construction method to prevent the peeling and flaking,
The loading test method according to claim 5. Producing a concrete specimen in a cylindrical shape, adjusting the expanded portion so as to be the central position of the cylindrical shape and expanding it, and testing the tensile stress of the concrete,
The loading test method according to claim 5.