JP6564230B2 - Synthetic floor slab manufacturing method, synthetic floor slab management method, concrete structure manufacturing method, and concrete structure management method - Google Patents

Description

  The present invention relates to a technique for imparting crack resistance by adding an expansion material to a concrete and applying chemical prestress in the construction of a concrete structure having a complicated steel structure such as a synthetic floor slab. The present invention relates to a technique for estimating the amount of chemical prestress imparted to concrete with respect to the amount of expansion material to be added.

  When constructing a structure using concrete, it is known that when the material concrete is cast, cracks occur on the surface as the cast concrete dries. This occurs because the concrete that has been casted generates heat due to a hydration reaction and the inside expands, and the concrete surface contracts due to the removal of moisture from the concrete surface. If there are many cracks on the surface of the concrete, there may be a problem that the strength of the concrete structure is lowered and the life is shortened.

  When manufacturing bridges for cars and railroads to pass through, steel plates such as composite floor slabs or steel and concrete such as shaped steel and concrete are constructed in one piece, and floor slabs configured to resist loads are used. There are cases to use. Synthetic floor slabs have many advantages, such as high durability and long life, saving labor for maintenance, and reducing life cycle costs. On the other hand, stress is generated between steel and concrete, and in some cases it may cause cracks, so in order to offset the tensile stress received from steel, an expansion material is added to the concrete to apply chemical prestress. A method of generating may be used.

  Patent Document 1 discloses a technique regarding a method for determining a unit expansion material amount of a concrete structure. In the surface members constituting structures such as slabs and walls where cracks due to drying shrinkage become prominent, the amount of unit expansion material of the concrete structure that can suppress or prevent cracks due to drying shrinkage that becomes initial drying, It calculates | requires using the relational expression of the ratio of the water determined for every predetermined | prescribed temperature range, and the unit amount of an expandable material. By doing so, it is possible to determine an appropriate unit expansion material amount to be added to the concrete structure in order to suppress or prevent cracking due to drying shrinkage that becomes an initial defect.

JP 2012-16459 A

  However, Patent Document 1 is a technique for determining the amount of expansion material to be added based on the proportion of water for each temperature inside the concrete, and calculating the relational expression using a test specimen to determine the unit expansion material amount. ing. On the other hand, it is necessary to consider the influence of steel materials such as reinforcing bars in addition to temperature and water, especially in concrete structures where steel and concrete are compounded, such as synthetic floor slabs, where strain distribution and changes are observed. It becomes complicated and it is considered difficult to easily estimate the amount of chemical prestress introduced into the composite slab. For this reason, the technique which can estimate the chemical prestress amount of a synthetic floor slab was calculated | required.

  Accordingly, the present invention provides a method for producing a synthetic slab that can estimate the amount of chemical prestress generated in the synthetic slab and determine the amount of the necessary expansion material, a method for managing the synthetic slab, and a concrete structure. It aims at providing the manufacturing method and the management method of a concrete structure.

  In order to achieve the above object, a method for producing a synthetic slab according to an aspect of the present invention has the following characteristics.

(1) In a method for producing a synthetic slab formed by placing concrete added with an expansion material, an expansion test is performed, and a constant work amount law is applied to the result of the expansion test. From the analysis value, the expansion coefficient in the composite floor slab is estimated, and it is confirmed that the expansion coefficient is within the range of shrinkage compensation applied to the composite floor slab. The amount of chemical prestress in the synthetic slab is estimated from the expansion rate, and the amount of the expansion material added is determined from the amount of chemical prestress to an amount that can cancel or reduce the tensile stress generated in the synthetic slab. It is characterized by doing.

  According to the aspect described in the above (1), the amount of chemical prestress can be estimated by an expansibility test based on JIS A 6202B or the lightweight formwork method, etc., so that the optimum amount for the concrete for forming the composite slab It is possible to add the expansion material. As a result, it is possible to apply appropriate chemical prestress to the synthetic floor slab. Here, “the amount that can cancel or reduce the tensile stress generated in the composite floor slab” is the range in which the amount of expansion material added is the amount of expansion compensation caused by adding the expansion material to the concrete within the shrinkage compensation range. It is intended to be an amount that can be offset within the range of the shrinkage compensation if it cannot be offset.

  A relational expression between the expansibility test and the amount of chemical prestress is obtained in advance. By using this relational expression, it is possible to determine the addition amount of the expansive material from the result of the expansibility test of JIS A 6202B. It is because it becomes. That is, an appropriate chemical prestress can be applied to the composite floor slab by simple means, and the crack resistance of the composite floor slab can be appropriately increased.

  Moreover, in order to achieve the said objective, the manufacturing method of the synthetic floor slab by the other aspect of this invention has the following characteristics.

(2) In a method for producing a composite slab formed by placing concrete added with an expandable material, an expandability test is performed, and the law of constant work is applied to the result of the expandability test. From the analyzed value, the expansion rate in the synthetic slab is estimated, the compressive strength in the synthetic slab is obtained, and it is confirmed that the compressive strength is not significantly lower than the standard composition of the concrete, and the expansion It is confirmed whether the rate satisfies the required amount, the amount of chemical prestress in the synthetic slab is estimated from the expansion rate with respect to the result of the expansibility test, and the amount of expansion is calculated from the amount of chemical prestress. The addition amount of the material is determined to be an amount capable of canceling the tensile stress generated in the composite slab.

  According to the aspect described in the above (2), even when the range of shrinkage compensation is not set for the concrete used for the composite floor slab, the expansion rate generated in the composite floor slab is determined based on the result of the expansibility test. Determine the amount of chemical prestress after determining whether the compressive strength in the control specimen is not significantly lower than the standard composition of concrete, and whether the expansion rate satisfies the required amount, etc. The amount of material added can be determined. For this reason, similarly to (1), an appropriate chemical prestress can be given to a synthetic floor slab with a simple means, and the crack tolerance of a synthetic floor slab can be improved appropriately.

(3) In the method for producing a synthetic slab described in (1) or (2), the expansibility test is preferably a test using a JIS A 6202B method.

(4) In the method for producing a synthetic slab according to (1) or (2), the expansibility test is preferably a test using a lightweight formwork method.

  According to the aspect described in the above (3) or (4), an expansibility test is performed using a measurement result of a strain value obtained by a conventionally known JIS A 6202B method or a constrained expansion test using a lightweight formwork. Since the expansion coefficient of the management specimen used for the property test can be obtained, an appropriate chemical prestress can be applied to the synthetic floor slab, and the crack resistance of the synthetic floor slab can be appropriately increased.

  Moreover, in order to achieve the said objective, the management method of the synthetic floor slab by other aspect of this invention has the following characteristics.

(5) In the management method of the composite floor slab formed by placing concrete added with an expansion material, as the quality control of the concrete, the residual chemical prestress of the material age is obtained from the strain value obtained from the lightweight formwork method. It is characterized by calculating the amount and predicting cracks from the future prediction of the strain value. According to this aspect, it becomes possible to increase the crack resistance of the placed composite floor slab and to predict the future strain value. Based on this prediction, preventive measures against the occurrence of future strain are taken, and the composite floor slab is used. It is possible to manage so as to extend the lifetime.

  Moreover, in order to achieve the said objective, the manufacturing method of the concrete structure by the other aspect of this invention has the following characteristics.

(6) In a method for producing a concrete structure in which a steel sheet is used as a structural material and concrete added with an expansion material is cast and formed, an expansibility test is performed, and the work amount is constant with respect to the result of the expansibility test. From the analytical value obtained by applying the law, the expansion rate in the concrete structure is estimated, and it is confirmed that the expansion rate is within the range of shrinkage compensation applied to the concrete structure. The amount of chemical prestress in the concrete structure is estimated from the expansion rate with respect to the result of the test, and the tensile stress generated in the concrete structure is calculated from the amount of chemical prestress by adding the amount of the expansion material. Determining an amount that can be offset or reduced.

  According to the aspect described in (6) above, as in the method for producing a synthetic slab described in (1), the chemical pre-treatment in the concrete structure is performed by an expansibility test based on JIS A 6202B or the lightweight formwork method. Since the amount of stress can be estimated, it is possible to add an optimal amount of expansion material to the concrete for forming the concrete structure. As a result, it is possible to apply an appropriate chemical prestress to a concrete structure such as a synthetic floor slab.

(7) In a method for producing a concrete structure in which steel sheet is used as a structural material and concrete added with an expansion material is cast, an expansion test is performed, and the work amount is constant with respect to the result of the expansion test. From the analytical value obtained by applying the law, the expansion rate in the concrete structure is estimated, the compressive strength in the concrete structure is obtained, and the compressive strength is not significantly lower than the standard composition of the concrete Confirming that the expansion rate satisfies the required amount, estimating the amount of chemical prestress in the concrete structure from the expansion rate with respect to the result of the expansion test, and The amount of the expansion material added is determined from the amount of prestress to an amount capable of offsetting the tensile stress generated in the concrete structure.

  According to the aspect described in the above (7), even when the range of shrinkage compensation is not set for the concrete used for the concrete structure, the expansion rate generated in the concrete structure is determined based on the result of the expansibility test. Determine the amount of chemical prestress after determining whether the compressive strength in the control specimen is not significantly lower than the standard composition of concrete, and whether the expansion rate satisfies the required amount, etc. The amount of material added can be determined. For this reason, similarly to (2), an appropriate chemical prestress can be given to a concrete structure with a simple means, and the crack resistance of a concrete structure can be appropriately increased.

  Moreover, in order to achieve the said objective, the management method of the concrete structure by the other aspect of this invention has the following characteristics.

(8) In a method for managing a concrete structure in which a steel sheet is used as a structural material and concrete formed by adding an expansion material is cast, as a quality control of the concrete, the strain value obtained from the lightweight formwork method It is characterized by calculating the amount of residual chemical pre-stress of the age and predicting cracks from the future prediction of the strain value.

  According to the aspect described in (8) above, in the management of concrete structures including composite floor slabs, it becomes possible to predict the future strain value in a concrete structure in which concrete has been placed in the field. Based on this, it is possible to take preventive measures against future distortions. For example, if the strain increases due to external stress, measures to relieve the stress can be considered. As a result, it is possible to appropriately manage the concrete structure including the synthetic floor slab and to prolong the service life.

It is a perspective view of a bridge of a 1st embodiment. It is a graph which shows the relationship between the amount of chemical prestress of a floor slab upper edge, and the length change of the specimen for management of 1st Embodiment. The flowchart regarding the work procedure of 1st Embodiment is shown. It is front sectional drawing of the mini model of the composite floor slab of 1st Embodiment. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is CC sectional drawing of FIG. It is a graph which shows the relationship between the distortion of a mini model of 1st Embodiment, and the result of an expansibility test. It is a related figure of a matter relevant when estimating the quantity of expansion material of a 1st embodiment. It is a flowchart regarding the work procedure of 2nd Embodiment. It is a graph which shows the correlation with the cross-sectional analysis result using the expansion coefficient obtained from the lightweight mold method of 3rd Embodiment, and the distortion value of a large sized test body. It is a graph which shows the relationship between the distortion by the lightweight formwork method of 3rd Embodiment, and the result of a JIS method expansibility test. It is a graph which shows the relationship between the amount of chemical prestress of a floor slab upper edge, and the change rate of the length of the lightweight formwork method of 3rd Embodiment. The flowchart regarding the work procedure of 4th Embodiment is shown.

  First, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a bridge according to the first embodiment. The bridge 100 includes a composite floor slab 150 disposed on the main girder 110 and a wall height column 160 fixed to the composite floor slab 150. Among them, the composite floor slab 150 is a floor plate portion for transmitting the weight of a vehicle or the like passing over the bridge to the main girder 110 or the pier of the bridge 100, and a steel plate (lateral rib 115, bottom steel plate 120) and a reinforcing bar 130 are installed. After that, the concrete is casted and the steel plate and the concrete are integrated to resist the external force. That is, the composite floor slab 150 can be said to be an aspect of a concrete structure. There are various types of structures called composite floor slabs, but the first embodiment adopts a shape called Robinson type. This is because the applicant has confirmed that this type is highly consistent with the actual product. However, application of the present invention to other shapes is not prevented.

  As shown in FIG. 1, the composite floor slab 150 includes a lateral rib 115 passed over the main girder 110, a bottom steel plate 120 fixed to the lateral rib 115, and a stud gibber 125 disposed on the bottom steel plate 120. It is formed by placing a rebar 130 and placing concrete 135 therein. A waterproof layer 136 is provided on the concrete 135 and a pavement 137 is applied. Concrete 135 to which a predetermined amount of expansion material D is added as an admixture is used.

  Next, a process related to the determination of the addition amount of the expansion material D will be described. FIG. 2 is a graph showing the relationship between the amount of chemical prestress on the upper edge of the floor slab and the rate of change in length due to the control specimen. The vertical axis indicates “chemical prestress at the upper edge of the floor slab”, and indicates the amount of chemical prestress (hereinafter referred to as CP amount) generated at the upper edge of the synthetic floor slab 150. The horizontal axis shows the “length change rate”. The rate of change in length indicates the rate of change in length obtained by an expansibility test of a management specimen using the JIS A 6202B method (hereinafter simply referred to as JIS method expansibility test). This relationship diagram is obtained from a certain work law considering the rigidity of the composite floor slab 150.

  In FIG. 2, the amount of CP for the upper edge portion of the composite floor slab 150 is shown as a graph. This is because the crack of the synthetic floor slab 150 occurs on the upper surface, that is, the upper edge portion of the synthetic floor slab 150, and the chemical prestress of the synthetic floor slab 150 is also weakest at the upper edge portion. The amount of CP at the upper edge portion of the composite floor slab 150 is correlated with the rate of change in length obtained from the JIS method expansibility test. Using the relationship as shown in FIG. 2, the optimum amount of the expansion material D to be added to the concrete of the composite slab 150 can be determined.

This is because it is known that when the expansion material D is added to the concrete 135 and condensed, distortion corresponding to the amount of the expansion material D to be added is generated, and therefore, for example, the expansion material D shown in FIG. Compared with the case where “20 kg / m ³ ” is added and the case where “30 kg / m ³ ” is added to the expansion material D, and confirms that the amount is within the “specification range”. To decide. Thus, the amount of the expansion material D to be added to the concrete 135 used for the composite floor slab 150 is determined and construction is performed.

Next, a specific work procedure will be described. FIG. 3 shows a flowchart. First,
In S10, the quantity of the expansion material D mix | blended with the concrete 135 is determined. In the first embodiment, it is within the specification limits set forth in the specifications or the like "20 kg / ^{m 3"} are performed in 3 loading of "25 kg / ^{m 3,"} "30kg / ^{m 3."} Then, the process proceeds to S11. At S11, concrete test mixing is performed. Then, the process proceeds to S12. At S12, the fresh properties of the concrete are confirmed. Measure concrete kneading temperature, air volume, slump, etc., and confirm that the planned performance is achieved. Then, the process proceeds to S13. At S13, a management specimen for the JIS method expansibility test is prepared. Then, the process proceeds to S14.

In S14, σ7 that is the compressive strength of the concrete of the management specimen is 7 days old is measured. Then, the process proceeds to S15. In S15, it is determined whether the expansion rate of the material age of 7 is within a predetermined range. When the expansion rate at the age of 7 days is within the shrinkage compensation range, 150 × 10 ⁻⁶ to 250 × 10 ⁻⁶ , the process proceeds to S16. If the expansion rate of the age of 7 days is out of the shrinkage compensation range, it is determined that the usage amount is not applicable and the process proceeds to S10.

  In S16, [sigma] 28 which is the compressive strength of concrete having a material age of 28 is measured. Then, the process proceeds to S17. In S17, it is determined whether σ28 is greater than the call strength. The nominal strength is set higher than the design standard strength. If σ28 maintains the nominal strength or more, the process proceeds to S18. When σ28 decreases and is less than the nominal strength, it is determined that the usage amount is not applicable, and the process proceeds to S10. In S18, it is determined that the usage amount is applicable, and the process proceeds to S19. In this case, it is desirable to preliminarily measure σ91, which is the compressive strength of concrete of age 91, and determine whether σ91 is equal to or higher than the nominal strength. In S19, the CP amount is estimated from the CP calculation graph. Then, the process ends.

  Since the manufacturing method of the composite floor slab 150 of the present invention has the above-described configuration, the following operations and effects are achieved.

  First, by using the method for manufacturing the composite floor slab 150 of the first embodiment, it is possible to estimate the amount of CP generated in the composite floor slab 150 and determine the necessary amount of expansion material D to be added. That is, the effect is that the amount of CP in the composite floor slab 150 can be quantitatively evaluated. This is a method for producing a composite slab 150 formed by casting concrete added with an expansion material D, and obtaining a relational expression between the result of the JIS method expansibility test and the CP amount of the upper edge of the slab. This is because the amount of the expansion material D added to the concrete 135 forming the composite floor slab 150 is determined from the equation.

  FIG. 9 shows a relationship diagram of matters related to estimating the amount of the expansion material D. According to the applicant's confirmation, the strain distribution of the composite floor slab 150, which is an actual structure, has a relationship that approximates the strain distribution of the mini model 200 described later. This is because, in the mini model 200 simulating the composite floor slab 150, the strain distribution by analysis obtained from the rule of constant work and the actually measured strain distribution are approximated. It depends. The relevance between the mini model 200 and the JIS method expansibility test is as shown in FIG.

  Then, the CP amount at the upper edge of the mini model 200 can be assumed by using the “concept of constant work amount” indicating that the chemical energy amount specific to the expanded concrete is constant. Then, a relationship diagram between the CP amount and the rate of change in length as shown in FIG. 2 is obtained. As a result, the CP amount obtained by adding the expansion material D added to the concrete used when forming the mini model 200 is found. This is as shown in FIG. That is, by using the correlation (relational expression) shown in FIG. 2, the amount of CP generated in the concrete 135 used for the composite floor slab 150 can be assumed using the result of the JIS method expansibility test, and the expansion material D can be assumed therefrom. It is possible to derive an appropriate amount of addition.

  Next, the reason why the correlation shown in FIG. 2 is established will be described in a little more detail. First, the correlation between the mini model 200 and the JIS method expansibility test will be described. In FIG. 4, front sectional drawing of the mini model 200 of the composite floor slab 150 is shown. FIG. 5 is a cross-sectional view taken along AA in FIG. FIG. 6 shows a BB cross-sectional view of FIG. FIG. 7 shows a CC cross-sectional view of FIG. FIG. 8 is a graph showing the correlation between the distortion of the mini model 200 and the result of the expansibility test. The mini model 200 is a model obtained by simplifying a part of the structure of the composite floor slab 150, and the partition walls 201 are respectively welded to both ends of the floor plate 220 corresponding to the bottom steel plate 120. Two steel bars 131 each having a screw portion corresponding to the above are fixed. A nut 202 is welded and fixed to one partition wall 201 to screw the steel rod 131 provided. A steel rod 131 is passed through the other partition wall 201 and both ends are locked with nuts 202.

  On the floor plate 220, M6 dimension bolts 225 corresponding to the stud gibber 125 are welded at four locations, and lateral ribs 215 corresponding to the lateral ribs 115 are welded at two locations. Further, as shown in FIGS. 5 to 7, a horizontal plate 204 is provided. That is, the mini model 200 is formed in a box shape with the upper surface opened, and a steel bar 131 corresponding to the reinforcing bar 130 is disposed. Each partition wall 201 is provided with a gauge plug 205 at the center. The material used for the mini model 200 conforms to the material used for the composite floor slab 150. Concrete is placed on the mini model 200 having such a structure. And the distortion which arises in the center of the mini model 200 is measured using the gauge plug 205 provided in each partition wall 201. FIG.

In FIG. 8, the vertical axis represents “mini model distortion” and the horizontal axis represents “length change rate according to JIS A 6202B”. In each of the straight lines indicated by the broken line or the alternate long and short dash line in FIG. 8, UL indicates the theoretical value of the upper edge of the mini model 200, CL indicates the theoretical value of the central portion of the mini model 200, and DL indicates the mini model 200. The theoretical value of the lower edge is shown. The concrete used for the mini model 200 described above is examined for distortion by changing the amount of the expansion material D added. The result of the mini model to which the expansion material D is not added is “0 kg / m ³ ”. In addition, the expansion material D is added “20 kg / m ³ ”, “25 kg / m ³ ”, and “30 kg / m ³ ”. Results are shown. Here, the unit amount (kg / m ³ ) indicates the weight of the expansion material contained in 1 m ³ .

In the mini model 200, four types of concrete 135 with different amounts of the expansion material D were placed, and strain was measured using a gauge plug 205. As a result, a result as shown in FIG. 8 is obtained, and the strain shown with the passage of time of “0 kg / m ³ ”, “20 kg / m ³ ”, “25 kg / m ³ ”, and “30 kg / m ³ ” It was found that both closely approximated the CL indicated by the calculated value at the center. In addition, the length change rate varies depending on the amount of the expansion material D added to the concrete 135 of “0 kg / m ³ ”, “20 kg / m ³ ”, “25 kg / m ³ ”, and “30 kg / m ³ ”. Differences can also be confirmed from FIG. Therefore, the correlation between the mini model 200 shown in FIG. 9 and the result of the JIS method expansibility test can be confirmed.

  Note that the distortion obtained from the mini model 200 is detected by the gauge plug 205 at the central portion of the mini model 200 as shown in FIG. 4 and the like, and therefore has a correlation if approximated to CL. It can be said. That is, any of the experimental data obtained by changing the addition amount of the expansion material D is consistent with the calculated value, and the correlation between the mini model 200 and the JIS method expansion test can be confirmed. As a result, the correlation between the strain data at the center of the mini model 200 and the calculated value in the expansibility test can be confirmed, and it is assumed that the upper edge has the same correlation as UL and the lower edge has the same correlation as DL.

Thus, using the correlation between the amount of CP at the upper edge of the composite floor slab 150 as shown in FIG. 2 and the rate of change in length obtained as a result of the JIS method expansibility test, the expansive material D added to the concrete 135 Can be determined. Specifically, compared with the case where the expansion material D of “20 kg / m ³ ” shown in FIG. 8 is added to the concrete 135, the case where the expansion material D of “30 kg / m ³ ” is added to the concrete 135 is better. It can be seen that the amount of CP introduced into the concrete 135 is increased, and that it is within the range of shrinkage compensation. Thus, the optimal addition amount of the expansion material D can be determined, and it can contribute to the improvement of the crack tolerance of the synthetic floor slab 150. In addition, about the addition amount of the expansion | swelling material D exceeding the range of shrinkage compensation, if it is a range which does not generate | occur | produce a compressive strength fall, it can be used.

Conventionally, it is common to add an expansion material D of “20 kg / m ³ ” to concrete 135, and chemical pre-stress occurs within the range of “specification range” shown in FIG. 2 as a range of shrinkage compensation. It was assumed that the expansion material D was added. However, since the addition amount of the expansion material D was set to “20 kg / m ³ ”, there was a problem that the actual expansion rate of the concrete 135 varied with the width of the specification range for each construction. Moreover, it was difficult to measure and estimate the chemical prestress introduced by the expansion material D. The chemical prestress is a method of giving resistance to the long-term drying shrinkage of concrete by the action of the expansion material D added in advance during the concrete placement, and improving the cracking resistance of the composite slab 150. it can.

However, since the amount of the expansion material D added to the concrete 135 is “20 kg / m ³ ”, depending on the site, there are cases where the crack resistance is low despite the addition of the expansion material D. Conceivable. This is largely due to the fact that local materials are used as the material for the concrete 135 and that the environment is affected by changes in the local environment. The JIS method expansibility test is a method for obtaining the rate of change in the length of concrete when the reinforcing bar 130 is not used. However, as the mini model 200 shows, the composite floor slab 150 has a configuration in which the lateral ribs 115, the stud gibber 125, the reinforcing bars 130, and the like are arranged in a complicated manner. Therefore, it was thought that it was difficult to assume the chemical prestress which arises in an actual structure from the calculation result which used the expansibility test simply.

  However, as confirmed in the test using the mini model 200 shown in FIG. 8, the correlation was also confirmed in the result of the strain measurement of the mini model 200 correlated with the concrete 135 and the result of the JIS method expansibility test. Yes. Therefore, when constructing the composite floor slab 150, the CP amount of the concrete 135 can be assumed by using the correlation of FIG. 2 using the result of the JIS method expansibility test. The amount can be determined.

  Further, if the structure of the composite slab 150 is substantially the same and the structure has the same rigidity, the optimal expansion material D to be added to the concrete can be obtained by performing the JIS method expansion test without remaking the mini model 200. The amount added can be determined. For this reason, it becomes possible to determine the optimum addition amount in placing the concrete 135 of the composite floor slab 150 only by the JIS method expansibility test, and it is possible to form the composite floor slab 150 having high cracking durability. Note that the method of the first embodiment can be widely applied not only to the composite floor slab 150 but also to concrete structures including the composite floor slab 150.

  Next, a second embodiment of the present invention will be described with reference to the drawings. The second embodiment has substantially the same configuration as the first embodiment, but the work procedure is different. This will be described below.

FIG. 10 is a flowchart regarding the work procedure of the second embodiment. For convenience of explanation, the procedure is simplified. The greatest difference from the flowchart of the first embodiment shown in FIG. 3 is whether or not the test kneading is performed within the range of shrinkage compensation. In the first embodiment, test kneading is performed with the above-described three blends, but in the second embodiment, test kneading is performed with the reference blend (20 kg / m ³ ). This is because a case where the range of shrinkage compensation is not set in advance is assumed. Then, the amount of the expansion material D to be added to the concrete 135 used for the test kneading is determined by looking at a value such as σ7 of the reference blend.

In S20, test mixing is performed. A test kneading of a blend using 20 kg / m ³ of the expansion material D is performed on concrete. Here, the management specimen for measuring the compressive strength later is also created. Then, the process proceeds to S21. In S21, a crack index is set. Set the target crack index for the structure. For example, when it is desired to prevent cracking, the cracking index is set to 1.85 or more, and when it is desired to suppress cracking as much as possible, the cracking index is set to 1.40 or more. Then, the process proceeds to S22. In S22, the reduction amount of the tensile stress degree is examined. A reduction amount of the degree of tensile stress that satisfies the crack index set in S21 is calculated. This is realized by calculating the necessary CP amount, and the factors due to the structure type and the placement order are examined. Then, the process proceeds to S23.

  In S23, the required amount of expansion material is calculated. Then, the process proceeds to S24. In S24, a test is conducted. The amount of the expansion material D calculated in S23 is mixed with concrete and subjected to test kneading. And the compressive strength is investigated using the test sample for management on the age of 7 days, and a JIS expansibility test is done. Then, the process proceeds to S25. In S25, it is determined whether or not there is a significant decrease in strength relative to σ7 of the reference blend. As a result of the test kneading performed in S24, if a significant decrease in strength is recognized due to the value of σ7, the crack index is reviewed again in S21. If there is no problem with the value of σ7, the process proceeds to S26.

  In S26, it is determined whether the expansion rate at the age of 7 days satisfies the required amount. If the required amount is not satisfied, the crack index is again reviewed in S21. If the required amount is satisfied, the process proceeds to S27. In S27, it is determined whether σ28 is equal to or greater than the call strength. Here, a compressive strength test is performed using a management specimen of 28 days of age, and a numerical value of σ28 is obtained. In addition, when the compressive strength of σ28 is lower than the nominal strength, the crack index is again reviewed in S21. If the compressive strength of σ28 is higher than the nominal strength, the process proceeds to S28. In S28, the amount of use is determined. Then, the process ends.

  Since 2nd Embodiment is the said structure, there exists an effect | action and effect similar to 1st Embodiment. Further, unlike the first embodiment, the second embodiment assumes a case where the range of shrinkage compensation is not set or the expansion material D is added exceeding the range of shrinkage compensation. Therefore, when making a concrete structure that has not been used so far, it is possible to effectively improve the crack resistance performance by using this method. The concrete structure here refers to all the structures that combine steel and concrete. For example, a reinforced concrete structure including the bridge 100 is applicable.

  Next, a third embodiment of the present invention will be described with reference to the drawings. Although the third embodiment has substantially the same configuration as the first embodiment, it is not the result of the JIS method expansibility test, but a simple restraint test method using a lightweight steel mold (hereinafter referred to as a lightweight mold method). It differs in that it uses the rate of change in length required by This will be described below.

  The lightweight mold method is a method in which a strain gauge is attached to the central portion of a tin-made lightweight steel mold (summit can) to measure the distortion of the mold. In addition, an SG mold can and a summit can can be similarly used as a specimen for management. FIG. 11 is a graph showing the correlation between the cross-sectional analysis result using the expansion coefficient obtained from the lightweight formwork method and the strain value of the large specimen (partial model of the composite floor slab 150) according to the third embodiment. . As shown in FIG. 11, it can be seen that the cross-sectional analysis result shown as “analysis value” and the strain of the large specimen shown as “actual measurement value” show a high correlation. From this fact, it can be seen that the strain distribution in the structure can be estimated by performing a cross-sectional analysis based on the expansion coefficient obtained from the lightweight mold method without installing a strain gauge directly in the composite floor slab 150. Further, the CP amount and the shrinkage compensation strain on the surface of the structure can be quantified from the strain distribution.

  FIG. 12 is a graph showing the relationship between the distortion by the lightweight mold method and the result of the JIS method expansibility test. FIG. 13 is a graph showing the relationship between the amount of CP at the upper edge of the composite floor slab 150 and the rate of change in the length of the management specimen in the lightweight form method. As shown in FIG. 12, it is confirmed that the test result of the material age of 7 days is in a relationship that approximates the strain value of the JIS method expansibility test and the strain value of the lightweight mold method. Then, similarly to FIG. 2 of the first embodiment, as shown in FIG. 13, a correlation is confirmed between the CP amount and the distortion value by the lightweight mold method.

  That is, the addition amount of the expansion material D added to the concrete 135 can be determined by using a lightweight formwork method instead of the JIS method expansion test of the first embodiment. As a result of the experiment, the lightweight mold method tended to show a slightly smaller value than the JIS method expansibility test, but showed the same tendency. Since the lightweight formwork method is closer to the behavior of the actual composite floor slab 150, more accurate results can be expected. This is because, while the JIS method expansibility test is underwater curing, the restraint expansion test using a lightweight formwork employs curing in a sealed state, so that the behavior of the actual composite floor slab 150 is close. It is thought that. It should be noted that if conditions such as the structure of the bridge 100 change, the result of the JIS method expansibility test will be closer to the actual behavior, and both the lightweight form method and the JIS method expansibility test are the first embodiment or Application to the second embodiment is possible.

  The lightweight mold method can be performed by a simpler method than the JIS method expansibility test. This is because the light-weight formwork method is performed by a method in which concrete with an expansion material D added is enclosed in a metal can having a diameter of about 100 mm, and the cost of the experiment is also lower than that of the JIS method expansibility test. Just do it. Therefore, a big advantage including the point which can be easily implemented on site is obtained. That is, since the expansive material D can be determined using the lightweight formwork method for each site, a more appropriate CP amount can be given to the concrete 135, and the crack resistance characteristics of the composite floor slab 150 can be improved. It becomes possible.

  Next, a fourth embodiment of the present invention will be described with reference to the drawings. In the fourth embodiment, the method for manufacturing the composite floor slab 150 of the first to third embodiments or the method for applying the method to other concrete structures is also applied to the on-site placement of the composite floor slab 150. This is an example.

  FIG. 14 shows a flowchart regarding the work procedure of the fourth embodiment. In S30, on-site placement is performed. At this time, a necessary number of SG molds or summit cans are prepared. A simple strain measuring instrument is also prepared. Then, concrete is packed in an SG mold or a summit can, and a management specimen for use in a simple restraint test method (hereinafter referred to as a lightweight mold method) using a lightweight steel mold is created. Then, the process proceeds to S31. In S31, the strain / compression strength of each material age is measured. The distortion of each material age, such as material age 3 days, material age 7 days, material age 14 days, material age 28 days, is measured. Then, the process proceeds to S32.

  In S32, the measurement distortion of each age is analyzed as an input value. Then, the process proceeds to S33. In S33, the distortion distribution is output. The result obtained by the analysis performed in S32 is output as a strain distribution. Then, the CP amount is calculated from this strain distribution, and the remaining CP amount is confirmed. Then, the process proceeds to S34. In S34, a crack is predicted. After predicting the future strain value, the remaining CP amount with respect to the future strain value is calculated to predict whether cracks will occur. Take measures if cracks are expected. Then, the process ends.

  Thus, having the configuration of the fourth embodiment provides the following operations and effects. By using the management method related to the composite floor slab 150 of the fourth embodiment, it is possible to predict cracks occurring on the surface of the concrete 135 of the composite floor slab 150 in the future and take appropriate measures. It is possible to contribute to extending the lifetime of 150. For specific measures to extend the life of the composite floor slab 150, for example, by extending the wet curing period or applying a coating film curing agent or shrinkage reducing agent to the concrete surface at the stage where cracks are predicted, It is conceivable to prevent an increase in drying shrinkage. Further, if it is estimated that the increase in strain generated in the composite floor slab 150 is caused by external stress, it is assumed that a structural member that resists the external stress is added. .

  Conventionally, when managing the expansion rate of concrete on-site, a specimen for management conforming to JIS A 6202B is collected on-site and cured on site until the age of one day, and then the expansion rate, compressive strength, etc. Was brought into a test institute capable of measuring, cured under water in an environment of 20 ° C., and the expansion rate and compressive strength at each age were measured. In this method, the curing temperature is constant according to the JIS standard, but since it is different from the curing environment in the field, measures are taken to extend the life of the composite floor slab 150 using the result as it is. It was difficult. In that respect, in the management method of the composite floor slab 150 of the fourth embodiment, a simple restraint test method using a lightweight steel formwork can be used, and a result close to the on-site curing environment can be realized. It is possible to take high measures.

  As mentioned above, although embodiment of the manufacturing method of the composite floor slab 150 concerning this invention was described, this invention is not necessarily limited to this, A various change is possible in the range which does not deviate from the meaning. For example, the structure of the composite floor slab 150 and the structure of the mini model 200 are not prevented from being changed as appropriate. The configuration of the composite floor slab 150 is as shown in FIG. 1, but the present invention can also be applied to a composite floor slab that adopts other configurations. Further, as mentioned in the second embodiment, the present invention can be applied to a concrete structure other than the composite floor slab 150. Moreover, although demonstrated in 3rd Embodiment, you may use the lightweight formwork method for 1st Embodiment or 2nd Embodiment instead of a JIS method expansibility test. Moreover, although the test result by the JIS A 6202B method is shown, you may use the JIS A 6202A method for a test method.

100 Bridge 110 Main girder 115 Horizontal rib 120 Bottom steel plate 125 Stud gibber 130 Reinforcing bar 131 Steel bar 135 Concrete 136 Waterproof layer 137 Pavement 150 Composite floor slab 160 Wall railing 200 Mini model 201 Partition wall 202 Nut 204 Horizontal plate 205 Gauge plug D Expansion material

Claims (6)

In a method for producing a synthetic slab formed by placing concrete added with an expansion material,
Perform an expansibility test using the JIS A 6202B method or the lightweight formwork method ,
From the analytical value obtained by applying the law of constant work to the result of the expansibility test, estimate the expansion rate in the composite floor slab,
Confirm that the expansion coefficient is within the range of shrinkage compensation applied to the composite slab,
Estimating the amount of chemical prestress in the synthetic floor slab from the expansion rate for the result of the expansibility test,
From the chemical prestress amount, determining the amount of the expansion material added to an amount capable of offsetting or reducing the tensile stress generated in the synthetic slab,
A method for producing a synthetic floor slab characterized by the following. In a method for producing a synthetic slab formed by placing concrete added with an expansion material,
Based on the analysis value obtained by conducting the expansibility test using the JIS A 6202B method or the lightweight formwork method and applying the law of constant work to the expansibility test result, the expansion in the composite floor slab Estimate the rate, determine the compressive strength in the composite slab,
Confirm that the compressive strength is not significantly lower than the standard composition of the concrete,
Check if the expansion coefficient satisfies the required amount,
The amount of chemical prestress in the synthetic slab is estimated from the expansion rate for the result of the expansibility test,
From the amount of the chemical prestress, determining the amount of the expansion material added to an amount capable of offsetting the tensile stress generated in the synthetic slab,
A method for producing a synthetic floor slab characterized by the following. In the management method of the composite slab that is formed by placing concrete with an expansion material added,
As a quality control of the concrete, from the strain value obtained from the lightweight form method, calculate the amount of residual chemical prestress of the material age, and predict cracks from the future prediction of the strain value,
A management method for composite floor slabs. In the manufacturing method of a concrete structure using a steel plate as a structural material and placing and forming concrete with an expansion material added,
An expansion test using the JIS A 6202B method or a lightweight formwork method is performed, and an expansion in the concrete structure is obtained from an analysis value obtained by applying a law with a constant work amount to the result of the expansion test. Estimate the rate,
Confirm that the expansion coefficient is within the range of shrinkage compensation applied to the concrete structure,
The amount of chemical pre-stress in the concrete structure is estimated from the expansion rate for the result of the expansibility test,
From the amount of the chemical prestress, determining the amount of the expansion material added to an amount capable of offsetting or reducing the tensile stress generated in the concrete structure;
A method for producing a concrete structure characterized by the above. In the manufacturing method of a concrete structure using a steel plate as a structural material and placing and forming concrete with an expansion material added,
An expansion test using the JIS A 6202B method or a lightweight formwork method is performed, and an expansion in the concrete structure is obtained from an analysis value obtained by applying a law with a constant work amount to the result of the expansion test. Estimate the rate,
Determine the compressive strength in the concrete structure, confirm that the compressive strength is not significantly lower than the standard blend of concrete,
Confirming that the expansion rate satisfies the required amount, estimating the amount of chemical prestress in the concrete structure from the expansion rate with respect to the result of the expansion test,
From the amount of the chemical prestress, determining the amount of the expansion material added to an amount capable of offsetting the tensile stress generated in the concrete structure;
A method for producing a concrete structure characterized by the above. In a method for managing a concrete structure, in which a steel plate is used as a structural material, and concrete added with an expansion material is cast and formed,
As a quality control of the concrete, from the strain value obtained from the lightweight form method, calculate the amount of residual chemical prestress of the material age, and predict cracks from the future prediction of the strain value,
A method for managing a concrete structure characterized by the above.

Images