JP6647799B2 - Quality control method for fresh concrete and method for manufacturing concrete structure - Google Patents

Description

  The present invention relates to a method for estimating the compressive strength of concrete, and more specifically, to a technique for performing quality control of fresh concrete by measuring the compressive strength of concrete by performing accelerated curing using microwaves.

  Conventionally, in quality control of fresh concrete, when fresh concrete is driven, a test specimen for management is prepared from fresh concrete used for the driving, and the compressive strength is measured. The measurement of the compressive strength is usually performed using a 28-year-old management specimen, and judgment is made based on this. This is a test for preparing a control specimen from fresh concrete used for a concrete structure and confirming the compressive strength at the time of setting and hardening over 28 days. For this reason, there has been a long-felt need for a technique for shortening the time and quickly obtaining the compressive strength.

  Patent Literature 1 discloses a technique related to a method for manufacturing a test specimen. The mold filled with fresh concrete is accommodated in a pressure vessel and irradiated with microwaves to cure the concrete at high temperature and high pressure for a predetermined time. Thereafter, the mold is taken out of the pressure vessel and the mold is removed to prepare a test specimen. As described above, the curing at high temperature and high pressure using microwaves enables early preparation of the control specimen, thereby enabling early confirmation of the compressive strength of fresh concrete. By using this control specimen, quality control of fresh concrete that is actually cast on site can be realized.

JP-A-6-191966

  However, the technology described in Patent Document 1 requires a large and powerful microwave generator, and as a result of actual testing by the applicant, deformation of the mold is recognized depending on experimental conditions, and the compressive strength is reduced. It was found that the measurement accuracy was affected. Also, a powerful microwave generator is not suitable for on-site operation due to power supply problems and size problems. Further, it was found that there was a problem in work efficiency and the like due to the size of the mold.

  Then, in order to solve such a subject, this invention aims at providing the more efficient and highly accurate quality control method of fresh concrete.

  In order to achieve the above object, a quality control method for fresh concrete according to one embodiment of the present invention has the following features.

(1) A mold made of a resin having heat resistance is filled with fresh concrete, and the fresh concrete is dehydrated by applying pressure in the mold, and using microwave irradiation means from outside the mold. Irradiated with microwaves, cured for a predetermined time in a high-temperature, high-pressure state where the temperature in the mold is equal to or lower than a predetermined temperature at which deformation of the mold is suppressed, and hardened the fresh concrete, and the hardened from the mold. It is characterized in that the fresh concrete is removed from the mold to form an accelerated curing specimen, and the compressive strength of the accelerated curing specimen is measured.

  According to the embodiment described in the above (1), fresh concrete is irradiated with microwaves using microwave irradiation means to perform curing under a high temperature and high pressure state, thereby producing an accelerated curing specimen. This makes it possible to shorten the time required for setting and hardening fresh concrete, which is necessary for preparing a control specimen for performing a compressive strength test. In experiments conducted by the applicant, it has been confirmed that the results of the accelerated curing test performed by irradiating microwaves show a correlation with σ28, which is the compressive strength of a 28-year-old specimen for management. . As a result, the management specimen can be manufactured quickly, and the deformation of the mold can be suppressed, so that the accuracy of the compression strength test can be improved. As a result, it is possible to provide a more efficient and accurate method for quality control of fresh concrete.

(2) In the quality control method for fresh concrete according to (1), a temperature of the fresh concrete filled in the formwork is measured using a temperature measuring means, and a change in the temperature is monitored. It is preferable that the microwave irradiation by the microwave irradiation unit is completed before the temperature exceeds the predetermined temperature, and the accelerated curing specimen is prepared.

  According to the aspect described in the above (2), the accelerated curing specimen can be prepared using the temperature measuring means, and therefore, it is possible to cope with a change in the material of the fresh concrete. In order to determine the “predetermined time” described in the above (1), it is necessary to perform an experiment in advance so that appropriate temperature conditions are obtained. Therefore, by preparing the accelerated curing specimen while monitoring the temperature with a temperature measuring means such as a thermocouple, it is expected that the time for the preliminary experiment can be reduced.

(3) In the quality control method for fresh concrete according to (1) or (2), polyphenylene sulfide is used for the resin of the mold, and the temperature in the mold is set to 200 ° C. or less; Is preferred.

  According to the embodiment described in (3), polyphenylene sulfide having high dimensional stability due to high heat resistance and low water absorption is used as the resin, and the temperature in the mold is kept at 200 ° C. or lower. As a result, since the deformation can be restrained while resisting the thermal expansion of the concrete, it is possible to increase the dimensional accuracy of the management specimen manufactured by the mold and improve the accuracy of the compressive strength test.

(4) In the quality control method for fresh concrete according to any one of (1) to (3), the size of the form is set to a size such that the specimen becomes a cube of 75 mm or less. preferable.

  According to the aspect described in the above (4), the required microwave output can be suppressed by setting the size of the mold so that the length of one side of the management specimen is 75 mm or less. It is possible to increase the number of control specimens that can be produced at the same time, and it is possible to reduce the time required for the compressive strength test.

(5) In the quality control method for concrete according to any one of (1) to (4), as a preliminary preparation, a test mix is performed to determine a composition of the fresh concrete, and the promotion is performed based on the composition. The compressive strength obtained from the cured specimen and the compressive strength correlation, which is a correlation between the compressive strength obtained from the control specimen of a predetermined age, are examined. From the strength, it is preferable to estimate the compressive strength of the management specimen of a predetermined age using the compressive strength correlation to confirm that the fresh concrete satisfies the required quality.

  According to the aspect described in the above (5), it is possible to estimate the result obtained in the compressive strength test at the time of unloading at the time of implementation work, that is, before driving the fresh concrete, so that the quality of the fresh concrete Management can be improved. In addition, since the σ28, which is the compressive strength of the 28-year-old material, is checked later, double check is also performed. As a result, concrete of even more reliable quality can be driven.

(6) In the quality control method for concrete according to (5), when preparing the accelerated curing specimen in the test kneading, a time-temperature correlation that is a correlation between a heating time and a temperature is examined. It is preferable that the predetermined time is determined using the time temperature correlation in the preparation of the accelerated curing specimen performed at the time of the above.

  According to the mode described in the above (6), it is possible to determine a predetermined time for preparing the accelerated curing specimen using the time-temperature correlation, so that it is troublesome to prepare the accelerated curing specimen while measuring the temperature at the time of execution. Can be omitted. This can contribute to simplification of equipment used and cost reduction.

  In order to achieve the above object, a method for manufacturing a concrete structure according to another aspect of the present invention has the following features.

(7) Concrete is driven by using the concrete quality control method according to any one of (1) to (6).

  According to the aspect described in the above (7), since concrete of higher quality can be driven, human errors such as mixing mistakes of concrete and variations in compressive strength in the structure can be suppressed, so that a concrete structure that is safe and reliable. It becomes possible to provide goods.

It is a perspective view of the formwork of 1st Embodiment which produces an accelerated curing specimen. It is a flowchart which shows the work procedure of the compression strength test of 1st Embodiment. It is a flowchart which shows the preparation procedure of the accelerated curing specimen of 1st Embodiment. Fig. 3 schematically illustrates a procedure for preparing an accelerated curing specimen of the first embodiment, wherein (a) shows a fresh concrete filling step, (b) shows a pressurized dehydration step, and (c) shows an accelerated curing. The process is shown in (d), the demolding process, (e), the measuring process of the accelerated curing specimen, and (f), the compressive strength test process. It is a mimetic diagram showing an example of conveyance of fresh concrete of a 1st embodiment. 4 is a graph illustrating a relationship between a heating time and a temperature according to the first embodiment. It is a graph which shows the relationship of (sigma) 28 and promotion intensity | strength of 1st Embodiment. It is a graph which shows the relationship of (sigma) 28 and promotion intensity | strength of 1st Embodiment. 6 is a graph showing another relationship between σ28 and acceleration intensity according to the first embodiment. It is a flow chart which shows a work procedure of a compression strength test of a 2nd embodiment. It is a flowchart in 2nd Embodiment which shows the preparation procedure of an accelerated curing specimen.

  First, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a perspective view of a mold 100 for producing an accelerated curing specimen TP according to the first embodiment. The mold 100 is made of polyphenylene sulfide resin (hereinafter, PPS) reinforced with glass fiber. The mold 100 is made up of five plate members, each having a thickness of about several cm. The upper surface of the mold 100 is open, and is closed by the upper lid 101. Bolts 102 are provided at four corners of the mold 100. The bolt 102 may have an embedded structure or a structure in which the bolt 102 penetrates from the lower surface of the mold 100.

  Holes penetrating the bolts 102 are provided at four corners of the upper lid 101. Then, when the upper lid 101 is put on the mold 100, the bolts 102 provided on the mold 100 are passed through the upper lid 101. In this state, as shown in FIG. 4, which will be described later, by tightening with a wing nut 103 or the like, the inside of the upper cover 101 is pressed to press the fresh concrete FC filled therein, so that pressure dehydration can be performed. I have. The inner dimensions of the mold 100 are designed such that a cube of 75 mm on one side of the accelerated curing specimen TP can be formed. The material used for the mold 100 is not limited to PPS, but may be a heat-resistant synthetic resin capable of transmitting microwaves or a material having high heat resistance such as ceramics.

  FIG. 2 is a flowchart showing the operation procedure of the compression strength test. FIG. 3 is a flowchart showing a procedure for preparing the accelerated curing specimen TP. Note that these flowcharts are described with simplified procedures for convenience of explanation. FIG. 4 schematically shows a procedure for preparing the accelerated curing specimen TP. (A) is a fresh concrete FC filling step, (b) is a pressure dehydration step, (c) is an accelerated curing step, (d) is a demolding step, and (e) is an accelerated curing specimen TP. The measuring step, (f), schematically shows the compressive strength test step. First, the operation procedure of the compression strength test will be described with reference to FIG.

In S10, test kneading is performed to create a correlation diagram. The test mixing is based on the water cement ratio (
Three or more types of compounds having different W / C) are used. By this test kneading, the accelerating strength, which is the compressive strength of the accelerated curing specimen TP described below (hereinafter, the “compressing strength of the accelerated curing specimen TP” is referred to as “accelerated strength”) and the age of the control specimen 28 days The correlation with the result of σ28 (hereinafter, “the compressive strength of the management specimen at the age of 28 days” is referred to as “σ28”) is examined, and the correlation indicating the compressive strength correlation between the acceleration strength and σ28 is obtained. Create a diagram. FIG. 8 is a graph showing the relationship between σ28 and the acceleration intensity. FIG. 8 shows the relationship between σ28 produced by changing the W / C by performing test kneading and the accelerating strength, and shows that the correlation shows a correlation coefficient of 0.986. FIG. 8 is used for estimating σ28 of fresh concrete FC poured on site from the compressive strength test result of the accelerated curing specimen TP described later.

  In S11, the concrete is mixed. Aggregate (gravel), water and additives are added to ordinary portland cement and kneaded to produce a fresh concrete FC. In the first embodiment, ordinary portland cement is used. However, it does not prevent using other types of cement such as high strength cement and blast furnace cement. This fresh concrete FC is used for a concrete structure constructed on the site 50 described later. The accelerated curing specimen TP is also made at this time using the same fresh concrete FC. The fresh concrete FC mixed here is generally used for concrete structures.

  In S12, an accelerated curing specimen TP is prepared by a microwave curing method. In the first embodiment, a microwave oven 200 is used as a microwave generator. The fresh concrete FC is placed in the mold 100, and the microwave M is irradiated inside the microwave oven 200 to perform accelerated curing. The details will be described later. In S13, the outer dimensions of the accelerated curing specimen TP produced in S12 are measured. This corresponds to FIG.

  In S14, it is determined whether or not the dimensions of the accelerated curing specimen TP are within a specified range. If the dimensions, flatness, and the like do not fall within the specified ranges, the process is repeated from the process of preparing the accelerated curing specimen TP in S12. If it is within the specified size, the process moves to S15. In S15, a compression strength test is performed. As shown in FIG. 4 (f), a compressive strength test is performed on the accelerated curing specimen TP to check the compressive strength. The tester used for the compressive strength test conforms to one or more of the grades specified in JIS B7721 7 (grade of tester). Here, σ28 of the fresh concrete FC is estimated from the result of the compressive strength test of the accelerated curing specimen TP using the correlation diagram obtained in S10.

  In S16, the test results are evaluated. In S17, it is determined whether or not the result of the compression strength test is within a specified range. If the compressive strength is not within the specified range, the process is repeated from the mixing of the concrete in S11. If it falls within the specified range, the process ends. When starting over from S11, the driving on site is not performed.

  Next, a procedure for preparing the accelerated curing specimen TP will be described with reference to FIG. In S20, fresh concrete FC is driven into the formwork 100. This is a process corresponding to FIG. In S21, the thermocouple 110 is embedded in the fresh concrete FC poured into the mold 100. The thermocouple 110 measures the temperature in the fresh concrete FC. However, in addition to the temperature measurement by the thermocouple 110, the outer surface temperature of the mold 100 is measured using a radiation thermometer (not shown).

  In S22, the mold 100 is tightened with bolts 102 and dewatered under pressure. This is a process corresponding to FIG. 4 (b). As described above, bolts 102 are provided on all sides of the mold frame 100, and the upper lid 101 is disposed therethrough. Then, the fresh concrete FC injected into the inside is pressurized by closing it from above using a wing nut 103 or the like. Thereby, the fresh concrete FC is dehydrated under pressure, and several tens g of water is dehydrated. By appropriately dehydrating, the acceleration strength can be appropriately increased.

  In S23, the mold 100 is put into the microwave oven 200 and heated. Since the mold 100 transmits the microwave M, the microwave M generates heat by vibrating water molecules in the fresh concrete FC. This heat promotes the hydration reaction in the fresh concrete FC.

  In S24, it is determined that the temperature is 200 ° C. or less. The monitored temperatures are the temperature inside the fresh concrete FC measured by the thermocouple 110 disposed inside the mold 100 and the temperature measured by the radiation thermometer that measures the outer surface temperature of the mold 100. Based on these results, monitoring is performed so that the temperature of the fresh concrete FC in the mold 100 does not exceed 200 degrees. If it exceeds 200 degrees, the process proceeds to S25, and heating is continued until that time. It should be noted that this temperature check is performed after the temperature exceeds a shelf temperature section shown in FIG. 6 described later.

  In S25, the heating ends. Irradiation of the microwave M to the mold 100 arranged inside the microwave oven 200 heats the inside of the fresh concrete FC, but by stopping irradiation of the microwave M, heating of the fresh concrete FC ends. . The test time is assumed to be about 8 minutes, but the required heating time varies depending on the blending of the fresh concrete FC and the like, so that control by temperature is desirable.

  In S26, the mold is released and the accelerated curing specimen TP is taken out. In a process corresponding to FIG. 4D, when the temperature of the mold 100 has dropped, the mass of the hardened fresh concrete FC is removed from the mold 100 to obtain an accelerated curing specimen TP. Then, the process ends.

  FIG. 9 is a graph showing the relationship between σ28 and the acceleration intensity. FIG. 9 is a correlation diagram obtained as a result of test mixing performed on fresh concrete FC used in a different site from FIG. The correlation coefficient is 0.899, which indicates that σ28 and the promotion intensity show a high correlation. As described above, since the result varies depending on the composition, it is necessary to conduct a compressive strength test according to the procedure shown in FIG. 2 for each site.

この表１では、「品質確認時期」について、左側に「従来方法」を右側に「第１実施形態の方法」について説明している。「工場」は図５に示されるフレッシュコンクリートを製造する工場でのことであり、「荷卸し時」は図５に示されるミキサー車に積載されたフレッシュコンクリートを現場に供給する際である。 Table 1 shows the quality control items for concrete.

In Table 1, the “conventional method” is described on the left side of the “conventional method” and the “method of the first embodiment” on the right side. “Factory” refers to a factory that manufactures the fresh concrete shown in FIG. 5, and “at the time of unloading” refers to supplying fresh concrete loaded on the mixer truck shown in FIG. 5 to the site.

  The compressive strength is checked by conducting a compressive strength test 28 days after the production of the control specimen. In the concrete quality control method of the first embodiment, the inspection is basically performed at "unloading time" and at the "factory", and a double check is performed. “Chloride content” and “unit water amount” are the same as the conventional ones because it is sufficient to perform an inspection once at “unloading”.

  FIG. 5 shows an example of transporting fresh concrete FC. The fresh concrete FC is manufactured at the ready-mixed concrete plant 20 and transported to a site 50 where a concrete structure is constructed by the mixer truck 25. Then, the fresh concrete FC is driven by the pump truck 30 at the site 50. It is expected that the transportation time in the mixer truck 25 is about 30 minutes, and that the unloading takes about 15 minutes, and it takes about 45 minutes from the ready-mixed concrete plant 20 to the driving at the site 50.

  Since the quality control method of the fresh concrete of the first embodiment has the above-described configuration, the following operations and effects can be obtained.

  First, the quality control method for fresh concrete according to the first embodiment is as follows. A mold 100 made of a resin having heat resistance is filled with fresh concrete FC, and a microwave oven 200 serving as a microwave irradiation unit is filled from outside the mold 100. Irradiate the microwave M using, curing at a high temperature and high pressure state for a predetermined time at a temperature setting at which the temperature in the mold 100 is equal to or lower than a predetermined temperature at which the deformation of the mold 100 is suppressed, and hardens the fresh concrete FC, The cured fresh concrete FC is removed from the mold frame 100 to obtain an accelerated curing specimen TP, and the compressive strength of the accelerated curing specimen TP is measured.

  In addition, it is preferable that PPS is used as the resin used for the material of the mold 100 and the temperature inside the mold 100 is set to 200 ° C. or less. In addition, it is preferable that the size of the mold 100 is such that the length of one side of the accelerated curing specimen TP is 75 mm or less.

  It is similar to Patent Document 1 in that PPS, which is a heat-resistant resin, is used for the formwork 100. However, by performing temperature control, the test accuracy of the accelerated curing specimen TP is improved, and it is used in the field The difference is that the technology is endurable. The heat deformation temperature of PPS is 260 ° C., and the glass fiber reinforced PPS is used in the first embodiment. However, when heated under conditions exceeding 200 ° C., the dimensional tolerance of the accelerated curing specimen TP due to temperature deformation is large. It is expected to be. FIG. 6 is a graph showing the relationship between the heating time and the temperature. In FIG. 6, the vertical axis shows the internal temperature (° C.) of the fresh concrete FC injected into the mold 100. The horizontal axis shows the elapsed time (sec). The heating condition is that one mold 100 is placed inside the microwave oven 200, and the heating is continuously performed at 750W for 10 minutes.

  According to this, after the temperature of the fresh concrete FC rises to around 120 ° C., a shelf temperature section in which the temperature rise stops for a predetermined time continues, and thereafter, a sharp temperature rise has been confirmed. The applicant has confirmed that the temperature of the fresh concrete FC has increased to 250 ° C. after continuous heating for 10 minutes. This temperature tendency of the fresh concrete FC is the same even when the heating conditions are changed, and if the temperature is around 200 ° C., the accelerated curing specimen TP can be produced before the temperature at which the mold 100 is deformed. Make sure that. Also, it has been confirmed that the shelf temperature section tends to be shortened by increasing the output of the microwave oven 200 as a heating condition.

  The miniaturization of the size of the mold 100 so as to be a cube having a side of 75 mm is also effective. Conventionally, one side of the accelerated curing specimen TP was 100 mm, but in the first embodiment, one side is 75 mm. The applicant has confirmed that it is possible to produce a required accelerated curing specimen TP using a mold 100 of this size. By reducing the size of the accelerated curing test sample TP, the number that can be heated at one time by the microwave oven 200 could be increased to two. It has been confirmed that the necessary accelerated curing specimen TP can be formed.

  FIG. 7 is a graph showing the relationship between the promotion intensity and σ28 confirmed by the applicant. The vertical axis indicates the test result of σ28, and the horizontal axis indicates the test result of the acceleration strength. In this graph, the correlation of σ28 under the same condition as the result of heating the mold 100 in the microwave oven 200 and performing accelerated curing is graphed, and data under different temperature conditions is also used as graph data. As a result, the correlation coefficient between the acceleration intensity and σ28 was about 0.8. Then, by setting a confidence interval as shown in FIG. 7 and adopting only data falling within the range, an improvement in accuracy can be expected. It was also confirmed that when the data was narrowed down to only those having the same temperature condition, a correlation coefficient of 0.9 or more was obtained. From this, a strong correlation between the acceleration intensity and σ28 can be confirmed. That is, by using the accelerated curing of the first embodiment, it is possible to perform appropriate quality control of the fresh concrete FC.

  Further, in the first embodiment, by heating with the microwave oven 200 while monitoring the temperature of the fresh concrete FC filled in the inside of the mold 100, accelerated curing is enabled while suppressing deformation of the mold 100. Furthermore, by setting one side to 75 mm, it becomes easy to process a plurality of molds 100 at the same time, and the amount of energy required for each mold 100 can be kept low. Improving efficiency.

  Generally, the performance of fresh concrete is highly dependent on the material, and a certain degree of performance variation is likely to occur. Therefore, the Concrete Standard Specification states that the compressive strength "can be estimated with an appropriate producer risk factor that the probability of falling below the design standard strength is 5% or less". Conventionally, a control specimen was prepared using fresh concrete FC, and σ28 was confirmed. Of the three tests, one test had a nominal strength of 85% or more, and the average value of three tests was the nominal strength. It was determined whether the above conditions were satisfied. If the conditions are not satisfied, measures such as reinforcement and repair are applied to the corresponding concrete structure, and if the conditions are satisfied, it is determined that the poured concrete satisfies the producer risk ratio.

  However, in the first embodiment, more preferable results can be obtained by performing the compressive strength test after the lapse of the specified number of days and also when unloading the fresh concrete FC. Further, when unloading the fresh concrete FC, it is desirable to perform an accelerated curing test in the ready-mixed concrete plant 20 and determine whether or not to drive the fresh concrete FC depending on the test result. While transporting the fresh concrete FC from the ready-mixed concrete plant 20 to the site 50 by the mixer truck 25, an accelerated curing test can be performed. Since accelerated curing is completed in about 7 to 10 minutes per time, it can be completed within 30 minutes including the execution of the compressive strength test.

  In other words, after shipping the fresh concrete FC from the ready-mixed concrete plant 20, accelerated curing is performed, and after performing a compressive strength test, it is determined whether the fresh concrete FC arriving at the site 50 is the fresh concrete FC suitable for driving. Judgment can be made before casting fresh concrete FC on site. In the production of fresh concrete FC, human errors such as mixing errors and variations in compressive strength in the structure were unavoidable, but the quality control method of the first embodiment allowed fresh concrete FC that does not meet the standards in advance to be manufactured. Can be eliminated. That is, the above-described producer risk rate itself can be eliminated, and as a result, it is possible to contribute to quality improvement.

  Further, if a test specimen for management is separately prepared and σ28 is confirmed and double-checked, it is possible to further contribute to quality improvement. Moreover, since the concrete structure cast using the fresh concrete FC manufactured in this way maintains high quality, it can contribute to extending the life of the concrete structure as a result.

  This is because of the nature of the fresh concrete FC, as the time from mixing to unloading becomes longer, the slump and the amount of air of the fresh concrete FC decrease, causing the generation of initial cracks, the generation of cold joints, and the failure of filling. This is because the fear increases. For this reason, JIS also specifies that the time from mixing to unloading is within 90 minutes. However, the properties of such fresh concrete FC are affected not only by temperature dependency but also by aggregates, etc., so that management of only the time from mixing to unloading can guarantee the minimum quality of concrete. It did not lead to quality improvement.

  In the first embodiment, by adopting an operation form as shown in Table 1, it is possible to increase the inspection accuracy regarding the quality of concrete. This also contributes to extending the life of the concrete structure. In addition, according to the quality control method of the fresh concrete FC of the first embodiment, it is possible to check whether or not the quality has changed during the movement by the mixer truck. If such a change in quality can be monitored, there is a possibility that, in the fresh concrete FC manufacturing process in the ready-mixed concrete plant 20, compounding, kneading, and the like corresponding to the change in quality can be performed in advance.

  Further, since the quality of the fresh concrete FC can be checked by a simple inspection, it is possible to contribute to the improvement of the quality of the fresh concrete FC. Various methods for quality control of fresh concrete FC have been proposed so far, but in reality, they are hardly actually performed due to factors such as time consuming and time consuming. However, the inspection time can be reduced by devising such that one side of the accelerated curing specimen TP is 75 mm. In addition, by controlling the temperature of the accelerated curing using the thermocouple 110 or the like, it is possible to contribute to increasing the dimensional accuracy of the accelerated curing specimen TP, and it is possible to increase the reliability of the compressive strength test. This contributed to the improvement of the quality of fresh concrete FC.

  Next, a second embodiment of the present invention will be described. The second embodiment uses almost the same equipment and procedure as the first embodiment, but differs in that a correlation between time and temperature is obtained and used in the preparation of the accelerated curing specimen TP. This will be described below.

  FIG. 10 is a flowchart showing the operation procedure of the compression strength test according to the second embodiment. FIG. 10 is almost the same as the flowchart of FIG. 2 except for the description of S30. At S30, in addition to the correlation diagram showing the correlation of the compressive strength, a time-temperature correlation, which is the correlation between the heating time and the temperature, in preparing the accelerated curing specimen TP is examined to obtain a correlation diagram. The temperature-time correlation in S30 is used when preparing the accelerated curing specimen TP by the microwave curing method in S32.

  FIG. 11 is a flowchart showing a procedure for preparing the accelerated curing specimen TP. FIG. 11 is almost the same as the flowchart of FIG. 3, but the procedure of embedding the thermocouple corresponding to S21 of FIG. 2 is unnecessary, and the procedure of determining based on the temperature in S24 requires a predetermined time as shown in S43. It is determined by the passage of time. The accelerated curing specimen TP produced at the time of the test kneading in S30 of FIG. 10 is produced based on the procedure of FIG. 3, and the time-temperature correlation is examined at this time.

  Since the quality control method for fresh concrete of the second embodiment has the above-described configuration, the following functions and effects can be obtained.

  In the second embodiment, unlike the first embodiment, the time-temperature correlation was examined at the stage of the test kneading in S30, and the temperature of a thermocouple or the like was measured for the preparation of the accelerated curing specimen TP at the time of implementation. Instead of using any means, they are managed by time. As a result, the procedure at the time of preparing the accelerated curing specimen TP is simplified, and the cause of human error can be reduced. Further, simplification of equipment to be used and cost reduction can be achieved.

  Although the embodiment of the quality control method for fresh concrete according to the present invention has been described above, the present invention is not limited to this, and various changes can be made without departing from the gist of the present invention.

20 ready-mixed plant 25 mixer truck 30 pump truck 50 site 100 formwork 101 top lid 102 bolt 103 wing nut 110 thermocouple 200 microwave oven FC fresh concrete TP accelerated curing specimen

Claims (5)

As a preparation,
Perform trial kneading to determine the mix of fresh concrete,
Filling the fresh concrete into a mold made of heat-resistant resin,
Dehydrating the fresh concrete by pressurizing in the formwork,
Irradiate microwaves using microwave irradiation means from outside the formwork,
Curing for a predetermined time in a high temperature and high pressure state in which the temperature in the mold is equal to or lower than a predetermined temperature at which deformation of the mold is suppressed, and hardens the fresh concrete,
Demolding the fresh concrete hardened from the formwork to accelerated curing specimen,
Measure the compressive strength of the accelerated curing specimen,
Based on the composition, the compressive strength obtained from the accelerated curing specimen, and the compressive strength correlation, which is a correlation between the compressive strength obtained from the control specimen of a predetermined age, is examined.
Examine the time-temperature correlation, which is the correlation between heating time and temperature,
During the construction work,
Determine the predetermined time using the time temperature correlation, to prepare an implementation curing accelerated curing specimen in the procedure of the advance preparation ,
From the compressive strength obtained from the accelerated curing test specimen for practical implementation , the compressive strength of the control test specimen of a predetermined age was estimated using the compressive strength correlation, and it was confirmed that the fresh concrete satisfied the required quality. To do,
A quality control method for fresh concrete, characterized by: In the quality control method of fresh concrete according to claim 1,
The temperature of the fresh concrete filled inside the formwork is measured using a temperature measuring means,
Monitoring the temperature change and ending the microwave irradiation by the microwave irradiating means before exceeding the predetermined temperature,
Producing the accelerated curing specimen,
A quality control method for fresh concrete, characterized by: In the fresh concrete quality control method according to claim 1 or 2,
Using polyphenylene sulfide for the resin of the mold, the temperature in the mold is set to 200 ° C. or less,
A quality control method for fresh concrete, characterized by: In the quality control method for fresh concrete according to any one of claims 1 to 3,
The size of the mold, the length of one side of the accelerated curing specimen is a cube of 75 mm or less,
A quality control method for fresh concrete, characterized by: Driving concrete using the quality control method for fresh concrete according to any one of claims 1 to 4,
A method for manufacturing a concrete structure, comprising:

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