Slump estimation method

Abstract

To easily estimate a change in fluidity caused by the force-feeding of concrete.SOLUTION: The slump estimation method includes: a correlation acquisition step of performing secondary mixing on the test concrete using a mixer to obtain a test correlation indicating a correlation between a secondary mixing parameter related to a shear energy applied to the test concrete by the secondary mixing and a slump loss of the test concrete after the secondary mixing; a correspondence acquisition step of substantially matching a reference correlation indicating a correlation between the secondary mixing parameter and a pumping distance obtained from a result of a concrete pumping test performed in advance with the test correlation by correction, and obtaining a correspondence between the secondary mixing parameter and the pumping distance; and a slump change acquisition step of obtaining the slump loss corresponding to a planned pumping distance at which the concrete is pumped at a construction site from the test correlation and obtaining the secondary mixing parameter corresponding to the obtained pumping distance from the test correlation.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a slump estimation method for estimating a change in the fluidity of concrete. [Background technology]

[0002] Patent Document 1 discloses a method for determining the slump of concrete after a predetermined time has elapsed since the concrete was mixed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-186978 Summary of the Invention [Problem to be solved by the invention]

[0004] Appropriate pouring of concrete at a construction site requires adequate fluidity, and therefore it is necessary to grasp the slump value at pouring, i.e., the degree of slump loss that has occurred since the concrete was mixed. To determine the degree of slump at pouring, for example, it is conceivable to conduct experiments simulating a construction site, but this would require large-scale experimental equipment for each construction site, which may increase construction costs and prolong the construction period. It is also conceivable to grasp the slump using a method such as that described in Patent Document 1, but the fluidity of concrete is affected not only by the elapsed time since the concrete was mixed, but also by the pumping distance, etc., making it difficult to accurately estimate the slump value at pouring.

[0005] The present invention aims to easily estimate changes in fluidity associated with pumping of concrete. [Means for solving the problem]

[0006] The present invention is a slump estimation method for estimating changes in fluidity due to pumping of concrete at a construction site, and includes the following steps: a correlation acquisition step of using a mixer that generates shear deformation in concrete to perform secondary mixing on test concrete of equivalent specifications to the concrete to be pumped at the construction site, and obtaining a test correlation that shows the correlation between secondary mixing parameters related to the shear energy imparted to the test concrete by secondary mixing and the slump loss of the test concrete after secondary mixing; a correspondence relationship acquisition step of correcting the test correlation to a reference correlation that shows the correlation between pumping distance and slump loss obtained from the results of a concrete pumping test conducted in advance, and obtaining a correspondence relationship between the secondary mixing parameters and the pumping distance; and a slump change acquisition step of obtaining, from the correspondence relationship, secondary mixing parameters that correspond to the planned pumping distance over which the concrete will be pumped at the construction site, and obtaining, from the test correlation, the slump loss corresponding to the obtained secondary mixing parameters, as a change in fluidity due to pumping of the concrete at the construction site. [Effects of the Invention]

[0007] According to the present invention, it is possible to easily estimate the change in fluidity of concrete that occurs during pumping. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an example of a construction site where concrete is pumped. [Figure 2] 1 is a flowchart illustrating steps performed in a slump estimation method according to an embodiment of the present invention. [Figure 3] 1 is a diagram showing a schematic configuration of a mixer used in a slump estimation method according to an embodiment of the present invention. [Figure 4] 1 is a graph for explaining data measured in a slump estimation method according to an embodiment of the present invention. [Figure 5] 1 is a graph showing a correlation obtained from data measured in a slump estimation method according to an embodiment of the present invention. [Figure 6] 10 is a graph showing another correlation obtained from data measured in a slump estimation method according to an embodiment of the present invention. [Figure 7] FIG. 1 is a diagram showing a schematic configuration of a test device used in a concrete pumping test carried out in advance. [Figure 8] 10 is a graph for explaining data acquired in a concrete pumping test carried out in advance. [Figure 9] 1 is a graph used in the process of estimating changes in the fluidity of concrete. [Figure 10] 1 is a graph used in the process of estimating changes in the fluidity of concrete. [Figure 11] 1 is a graph used in the process of estimating changes in the fluidity of concrete. [Figure 12] 1 is a graph showing the transition of estimated concrete slump loss. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a slump estimation method according to an embodiment of the present invention will be described with reference to the drawings.

[0010] The slump estimation method according to an embodiment of the present invention is a method for estimating changes in fluidity that occur during pumping of concrete at a construction site. For example, as shown in FIG. 1, the method is used to estimate slump loss that occurs when concrete is filled into a concrete-filled steel tubular column (CFT column) or when concrete is poured on a high-rise floor.

[0011] The fluidity of concrete can be considered to be equivalent to the fluidity of a Bingham plastic fluid, which is evaluated by the rheological constants of yield value and plastic viscosity. It has the characteristic that the strain rate is zero, i.e., it does not flow, until the shear stress exceeds the yield stress (yield value), but once it begins to flow, it flows at a strain rate that corresponds to the change in plastic viscosity.

[0012] It is known that the fluidity of such concrete tends to decrease over time, depending on factors such as temperature, type of admixture, amount of admixture, pumping distance, pumping pressure, and pumping flow rate. In particular, at relatively large construction sites where the concrete must be pumped over long distances, the longer the pumping distance, the more the fluidity of the concrete decreases.

[0013] Since the fluidity of concrete has a significant impact on workability, it is necessary to understand the degree of decrease in the fluidity of the concrete when pouring it at the construction site, that is, when it is pumped, such as the degree of decrease in the slump value and slump flow value.

[0014] To understand the effect of pumping distance on the decrease in concrete fluidity at a construction site such as that shown in Figure 1, it is possible to conduct experiments using a full-scale facility that simulates the construction site. However, this would require large-scale experimental equipment for each construction site, which could increase construction costs and lengthen the construction period.

[0015] Therefore, in the slump estimation method according to the embodiment of the present invention, the change in the fluidity of concrete due to pumping is estimated by a simpler test, without setting up a large-scale experimental facility simulating the construction site at each construction site. Note that the fluidity of concrete is a property of concrete that is determined mainly by the yield value and plastic viscosity, as described above.

[0016] Specifically, when concrete is pumped, the concrete flowing through the pipe continues to undergo shear deformation due to shear stress generated on the wall surface of the pipe, and it is thought that the fluidity of the concrete decreases in proportion to the shear energy imparted to the concrete as it undergoes shear deformation.

[0017] Therefore, shear energy equivalent to the shear energy assumed to be imparted to the concrete when it is pumped is simulated using a mixer 10 described below, and the degree of decrease in the concrete's slump value and slump flow value due to pumping is estimated based on the change in the concrete's fluidity that occurs at that time.

[0018] Next, a slump estimation method according to an embodiment of the present invention will be described with reference to the flow shown in FIG. 2 and FIGS.

[0019] In the slump estimation method, first, in step S11 shown in FIG. 2, a test is carried out to measure slump loss using test concrete C1 having the same specifications as the concrete pumped at the construction site (slump loss determination test).

[0020] Specifically, the slump loss determination test includes a time-varying change obtaining step (step S11A) for obtaining the change in slump loss of test concrete C1 over time, and a correlation obtaining step (step S11B) for applying shear energy to test concrete C1 using a mixer 10 as shown in Fig. 3 and obtaining a test correlation line LT (see Fig. 5) that shows the correlation between the applied shear energy and slump loss as a test correlation. The slump loss measured in this test is, for example, the degree of decrease in the slump value measured by a slump test.

[0021] The slump loss measured in the slump loss assessment test is not limited to the degree of decrease in the slump value measured in the slump test, but also includes the degree of decrease in the slump flow value measured in the slump flow test. Specifically, for example, if the slump value changes from 20 cm to 15 cm due to a decrease in the fluidity of concrete, the slump loss is -5 cm, and if the slump flow value changes from 60 cm to 50 cm, the slump loss is -10 cm. In other words, the change in the fluidity of concrete estimated by the slump estimation method according to the embodiment of the present invention includes not only the change in the slump value but also the change in the slump flow value.

[0022] Furthermore, the test concrete C1 does not need to be exactly the same as the concrete actually used at the construction site, but it is preferable that it is made by mixing the same cement raw materials, aggregate from the same region, and admixtures from the same manufacturer in the same proportions as the concrete actually used at the construction site.

[0023] In the time-dependent change acquisition process, the slump loss of the test concrete C1 that has been left standing is measured at predetermined time intervals (for example, every 10 to 30 minutes) after mixing. The measured slump loss is due to water evaporation and the like, and gradually increases with the elapsed time after mixing, as shown by the solid line (standard slump loss) in Figure 4, for example. In other words, it is estimated that the fluidity of concrete used at a construction site gradually decreases over time after mixing, in accordance with the trend shown in Figure 4, even if the concrete is not pumped. Note that the vertical axis of the graph in Figure 4 represents the slump loss of the test concrete C1, and the horizontal axis represents the elapsed time after mixing the test concrete C1.

[0024] Meanwhile, in the correlation acquisition process, first, a secondary mixing is performed to impart a predetermined shear energy to the test concrete C1 using a mixer 10 as shown in Fig. 3. The secondary mixing is a mixing operation that is performed separately from the mixing (primary mixing) performed when producing the test concrete C1, and is performed to simulate shear deformation equivalent to the shear deformation that occurs when concrete is pumped to the construction site, after the test concrete C1 has been sufficiently mixed and is in a state similar to that when it is shipped from a concrete plant.

[0025] The mixer 10 is a so-called mixer that can also be used indoors, and has a storage section 12 that stores the test concrete C1, and an electric motor 14 that rotates and drives agitating blades 16 that can shear the test concrete C1 in the storage section 12. The mixer 10 is not limited to the above configuration, and may be of any type as long as it is a device that can cause shear deformation in the test concrete C1. For example, the mixer 10 may be a two-shaft drive type forced mixer in which agitating blades are provided on two shafts, or a gravity mixer in which the storage section is shaped like an inclined drum.

[0026] The secondary mixing is initiated when a predetermined reference elapsed time T has elapsed since the test concrete C1 was mixed, by rotating the agitator blades 16 with the electric motor 14. The reference elapsed time T is a time that assumes the expected elapsed time TP from when the concrete to be used at the construction site is mixed at the concrete plant until pumping of the concrete begins at the construction site, and if the expected elapsed time TP has been determined, the reference elapsed time T is set to the same time as the expected elapsed time TP. If the expected elapsed time TP has not been determined, the reference elapsed time T is set to a time that is predicted based on the distance from the concrete plant to the construction site, etc.

[0027] The test concrete C1 to be subjected to the secondary mixing may be produced by mixing (primary mixing) using the mixer 10, or by mixing (primary mixing) using another concrete mixing device, or may be produced at a nearby concrete plant, and the secondary mixing is carried out based on the end time (end time of mixing) of the mixing (primary mixing) of the test concrete C1 produced in this manner.

[0028] The secondary mixing is performed by changing the cumulative rotation speed of the mixing blade 16 or the driving time of the electric motor 14 so that three or more different shear energies are applied to the test concrete C1. Figure 4 shows a case where three different shear energies are applied to the test concrete C1 by changing the cumulative rotation speeds N1, N2, and N3 of the mixing blade 16.

[0029] While it is difficult to quantify the shear energy imparted to the test concrete C1, it is believed that the shear energy imparted to the test concrete C1 is correlated with the total number of rotations (cumulative number of rotations) of the agitator blade 16 driven by the electric motor 14 and the power consumed by the electric motor 14 to drive the agitator blade 16, and therefore the cumulative number of rotations of the agitator blade 16 and the power consumption of the electric motor 14 are used as parameters (secondary mixing parameters) that indirectly indicate the magnitude of the shear energy.

[0030] The secondary mixing parameter is not limited to the cumulative rotation speed or power consumption, but may be any parameter that is related to the shear energy imparted to the test concrete C1. For example, it may be the duration for which the secondary mixing is performed, i.e., the driving time of the electric motor 14, or the integrated value of the pressure acting on the rotating mixing blades 16.

[0031] Next, as shown by the circles in Figure 4, the slump losses of test concrete C1 are measured after the application of three different shear energies, and the difference between each point and the standard slump loss obtained in the time-dependent change acquisition process is calculated as pumping-equivalent slump losses Lo1, Lo2, and Lo3, which correspond to the slump loss caused by pumping. In calculating pumping-equivalent slump losses Lo1, Lo2, and Lo3, the standard slump loss used is the value at the time when the application of shear energy began (reference elapsed time T), i.e., the time when pumping is considered to have begun.

[0032] When the pumping-equivalent slump losses Lo1, Lo2, and Lo3 for the cumulative rotational speeds N1, N2, and N3 (shear energy) are found at multiple points in this manner, a test correlation line LT indicating the correlation between the shear energy imparted to the test concrete C1 and the pumping-equivalent slump loss is obtained by the least squares method, as shown in Figure 5. Note that Figure 5 shows the case where the test correlation line LT is a regression line (approximate line) passing through the origin, but the test correlation line LT may also be represented by a non-linear (non-linear) function passing through the origin.

[0033] On the other hand, the test correlation line LT shown in Figure 5 shows the relationship when the reference elapsed time T, which is the start time of secondary mixing, is the same, and it cannot grasp how the pressure-equivalent slump loss changes when the start time of secondary mixing is changed.

[0034] For this reason, in the correlation acquisition process, in addition to the above-mentioned pumping-equivalent slump losses Lo1, Lo2, and Lo3, the pumping-equivalent slump loss when the secondary mixing start time is shifted by a predetermined time α before or after the reference elapsed time T is also obtained, as shown by the triangle and square marks in Fig. 4. Note that the shear energy imparted to the test concrete C1 at this time is set to be equal to the shear energy imparted to the test concrete C1 when obtaining the test correlation line LT, and in the example shown in Fig. 4, the cumulative rotation speed of the mixing blade 16 is set to be the same cumulative rotation speed N2.

[0035] As a result, as shown in Figure 6, under the condition that the shear energy imparted to the test concrete C1 is the same, it is possible to grasp the rate at which the pumping-equivalent slump loss (absolute value) changes when the secondary mixing start time, i.e., the pumping start time, deviates from the reference elapsed time T. Note that, as described above, if the scheduled elapsed time TP has been determined and the reference elapsed time T is set to the same time as the scheduled elapsed time TP, it is not necessary to obtain the relationship shown in Figure 6.

[0036] When the slump loss detection test using the test concrete C1 is completed in this manner, the process proceeds to step S12.

[0037] In step S12 (correspondence acquisition step), the correspondence between the secondary mixing parameter correlated with shear energy and the pumping distance is finally obtained, but prior to this, a reference correlation (reference correlation line LB described below) showing the correlation between the pumping distance and the pumping slump loss due to pumping is obtained from the results of a concrete pumping test conducted in advance. Then, the correspondence between the secondary mixing parameter and the pumping distance is obtained based on the obtained reference correlation and the test correlation line LT obtained as the test correlation in the correlation acquisition step described above.

[0038] The concrete pumping test is a test conducted in advance to determine the general correlation between pumping distance and pumping slump loss due to pumping, and the results of this test are shared when estimating changes in concrete fluidity due to pumping at each construction site.

[0039] As shown in Figure 7, the concrete pumping test is carried out using a test device 20 that is mainly composed of a storage section 22 in which the standard concrete CS is stored, a pumping pump 24 that pumps the standard concrete CS in the storage section 22, and a test pipe 26 through which the pumped standard concrete CS flows.

[0040] The standard concrete CS used in concrete pumping tests is concrete of standard specifications defined by the Japanese Industrial Standards (JIS) etc., and does not have to be of the same specifications as the above-mentioned test concrete C1 or the concrete to be used at the construction site.

[0041] In the concrete pumping test, to obtain a graph such as that shown in Fig. 8, the pumping slump loss of standard concrete CS pumped by pumping pump 24 and flowing through test pipe 26 is measured at predetermined distance intervals (for example, every 50 to 100 m) up to a maximum of approximately 500 m. Then, based on the measurement results at multiple points, a graph showing the relationship between the pumping distance and the pumping slump loss is obtained as a regression line passing through the origin using the least squares method.

[0042] The graph shown in Figure 8 shows the change in pumping slump loss when the pumping rate Q (discharge rate of the pumping pump 24) is changed, but in the concrete pumping test, in addition to this, the change in pumping slump loss when the inner diameter of the test pipe 26 is changed and the change in pumping slump loss when the temperature of the standard concrete CS is changed are also measured.

[0043] In the correspondence relationship acquisition step, first, a reference correlation line LB is obtained based on the construction conditions at the construction site, as shown in FIG. 9, from the results of the concrete pumping test carried out in advance.

[0044] The construction conditions include the amount of concrete pumped, the length of the pumping pipeline, the inner diameter of the pumping pipeline, the temperature of the concrete during pumping, and the total flow rate of the concrete. For example, if the set amount of concrete pumped is between the two pumping rates Q1 and Q2 shown in Figure 8, the regression line created by regression analysis will be the reference correlation line LB. Also, if the inner diameter of the pumping pipeline and the temperature of the concrete during pumping are set, the regression line obtained by regression analysis taking these into consideration will be the reference correlation line LB. In addition to interpolation and interpolation methods, regression analysis also uses extrapolation.

[0045] Even if the reference correlation line LB obtained in this manner and the test correlation line LT obtained in the correlation acquisition step described above are simply superimposed on a graph with a common vertical axis (slump loss), as shown in Figure 9, the slopes are different and there is no correlation on the horizontal axis, making it impossible to grasp the correspondence between the pumping distance and the cumulative rotation speed (shear energy), which is a secondary mixing parameter. In other words, simply obtaining the reference correlation line LB and the test correlation line LT makes it impossible to evaluate the pumping slump loss caused by pumping using the cumulative rotation speed (secondary mixing parameter), that is, to convert the shear energy expected to be received by concrete when it is pumped the planned pumping distance LP at the construction site into the shear energy received by the mixer 10 when it is operated.

[0046] Here, since the pumping distance is considered to be equivalent to the accumulation of shear deformation, the reference correlation line LB can be said to show the change in slump loss in response to the accumulation of shear deformation imparted to standard concrete CS, and the test correlation line LT can be said to show the change in slump loss in response to the accumulation of shear deformation imparted to test concrete C1 by secondary mixing.

[0047] In this way, the relationship between the secondary mixing parameter, cumulative rotation speed (shear energy), and slump loss, and the relationship between pumping distance and slump loss show the same trend, that is, the change in slump loss according to the accumulation of shear deformation, and therefore it can be said that the slope of the test correlation line LT and the slope of the reference correlation line LB show the same trend.

[0048] In other words, by making the slope of the test correlation line LT and the slope of the reference correlation line LB approximately coincident on the graph, the correspondence between the pumping distance and the cumulative rotation speed (shear energy), which is a secondary kneading parameter, is shown.

[0049] Therefore, in the correspondence relationship acquisition step, as shown in FIG. 10, the horizontal axis of the test correlation line LT is enlarged to correct the slope of the test correlation line LT, and the slope of the test correlation line LT is adjusted so that it approximately matches the slope of the reference correlation line LB.

[0050] This clarifies the correspondence between the pumping distance and the cumulative rotation speed (shear energy), which is a secondary mixing parameter, and makes it possible to evaluate the pumping slump loss caused by pumping using the cumulative rotation speed (shear energy).In other words, it makes it possible to convert the shear energy that the concrete is expected to receive when it is pumped the planned pumping distance LP at the construction site into the shear energy that the concrete receives when the mixer 10 is operated.

[0051] As a correction method for making the slope of the test correlation line LT and the slope of the reference correlation line LB approximately coincident, instead of correcting the slope of the test correlation line LT by expanding or contracting the horizontal axis of the test correlation line LT, the horizontal axis of the reference correlation line LB may be expanded or contracted to correct the slope of the reference correlation line LB, or both the horizontal axes of the test correlation line LT and the reference correlation line LB may be expanded or contracted so that the test correlation line LT and the reference correlation line LB approach each other. Furthermore, as a correction method for making the slope of the test correlation line LT and the slope of the reference correlation line LB approximately coincident, either or both of the horizontal axes of the test correlation line LT and the horizontal axis of the reference correlation line LB may be normalized or standardized.

[0052] Once the correspondence between the cumulative rotation speed, which is a secondary mixing parameter, and the pumping distance has been determined in this way in the correspondence relationship acquisition process, the process proceeds to step S13, where a slump change acquisition process is carried out to determine an estimated slump loss, which indicates the change in fluidity associated with pumping of concrete at the construction site, based on the correspondence between the cumulative rotation speed (shear energy) and the pumping distance determined in the correspondence relationship acquisition process and the test correlation line LT (test correlation) determined in the correlation acquisition process.

[0053] In the slump change acquisition process, first, the cumulative rotation speed (shear energy) equivalent value NT corresponding to the planned pumping distance LP over which concrete is pumped at the construction site is obtained from the correspondence relationship obtained in the correspondence relationship acquisition process (see Figure 10).

[0054] Next, the pumping-equivalent slump loss (estimated slump loss LoE) corresponding to the calculated cumulative rotational speed converted value NT is calculated from the test correlation line LT (see Figure 11) as the change in fluidity associated with pumping of concrete at the construction site.

[0055] The estimated slump loss LoE calculated here is the value when the planned elapsed time TP until the concrete pumping starts at the construction site is the same as the reference elapsed time T, so the estimated slump loss LoE is corrected according to the time difference between the planned elapsed time TP and the reference elapsed time T.

[0056] The slump loss ratio shown in Fig. 6, which is obtained in the correlation acquisition process, is used as the correction coefficient for correcting the estimated slump loss LoE, and the earlier the planned elapsed time TP is compared to the reference elapsed time T, the smaller the estimated slump loss LoE becomes after correction, and the longer the planned elapsed time TP is compared to the reference elapsed time T, the larger the estimated slump loss LoE becomes after correction. Note that only when the planned elapsed time TP is the same as the reference elapsed time T, the estimated slump loss LoE is not corrected and remains the value obtained from the test correlation line LT.

[0057] Once the pumping-equivalent slump loss (estimated slump loss LoE or corrected estimated slump loss LoE) is calculated as the change in fluidity associated with pumping concrete at the construction site in this way, the process proceeds to step S14, where a slump loss estimation process is carried out to estimate the progress of the slump loss of the concrete at the construction site.

[0058] In the slump loss estimation process, the change in slump loss from the time the concrete is mixed until pumping begins at the construction site, i.e., until the scheduled elapsed time TP, is estimated based on the standard slump loss of the test concrete C1 obtained in the time-dependent change acquisition process (see Figure 4).

[0059] Since it is estimated that the same change over time as the standard slump loss of test concrete C1 will occur even when the concrete is moved from the concrete plant to the construction site, as shown in Figure 12, the slump loss up to the scheduled elapsed time TP will have the same change curve as the standard slump loss of test concrete C1.

[0060] Next, in the slump loss estimation step, the transition of the slump loss after the expected elapsed time TP has elapsed is estimated based on the estimated slump loss LoE obtained in the slump change acquisition step.

[0061] Specifically, it is estimated that as the concrete is pumped, the slump loss of the concrete at the construction site will further decrease by the estimated slump loss LoE obtained in the slump change acquisition process. Note that if the estimated slump loss LoE is corrected by the slump loss ratio obtained in the correlation acquisition process, it is estimated that the slump loss of the concrete at the construction site will further decrease by the corrected estimated slump loss LoE.

[0062] In addition, from the start of pumping concrete to the completion of pumping, a predetermined pumping time will elapse depending on the pump pumping rate, the inner diameter of the pumping pipeline, and the total flow rate of the concrete being pumped.

[0063] Therefore, in the slump loss estimation process, the planned pumping period PP from the planned elapsed time TP (the time when pumping starts) until the pumping of the concrete is completed is calculated based on the pumping rate of the pump, the inner diameter of the pumping pipeline, and the total flow rate of the concrete to be pumped, which are preset as construction conditions.As shown in Figure 12, it is estimated that the fluidity of the concrete will further decrease by the estimated slump loss LoE until the planned pumping period PP calculated from the planned elapsed time TP has elapsed.

[0064] Then, since it is estimated that the slump loss of the concrete after pumping is complete will change over time in a manner equivalent to the standard slump loss of test concrete C1 obtained in the time-dependent change acquisition process, the slump loss after the fluidity of the concrete has decreased by the estimated slump loss LoE will have the same change curve as the standard slump loss of test concrete C1, as shown in Figure 12. Specifically, in the standard slump loss graph shown in Figure 4, the change curve for the portion of the time elapsed since mixing is the sum of the planned elapsed time TP and the planned pumping period PP is used as the transition of the slump loss of the concrete at the construction site after pumping is complete.

[0065] Once the transition of the slump loss of the concrete at the construction site has been estimated in this way, the estimation result is output to a display device (not shown) in the following step S15.

[0066] After the above steps are completed, a graph showing the transition of slump loss as shown in FIG. 12 is output, and the control flow then ends.

[0067] The above-described slump estimation method is executed in accordance with the control flow shown in Fig. 2 by starting a slump estimation program stored in advance in a ROM or the like in a system in which a computer having a general calculation function and including a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and I / O interface (Input / Output Interface) is used as a processing device (not shown). In other words, the calculations such as calculation of the regression line and correction performed in each of the above-described steps are performed by the processing device.

[0068] In addition, the system that executes the slump estimation method has an input device (not shown) that is operated by a test manager or the like and is used to input test results into the processing device, and a display device (not shown) that displays the results processed by the processing device, and the test manager can determine whether the fluidity of the concrete is sufficiently maintained at the construction site from the estimated results output on the display device.

[0069] According to the above embodiment, the following effects are achieved.

[0070] According to the above-mentioned slump estimation method, secondary mixing parameters (cumulative rotation speed, power consumption, etc.) corresponding to the planned pumping distance LP over which the concrete to be poured is pumped at the construction site are determined from the correspondence between the results of a pumping test conducted in advance and the results of a laboratory test using the mixer 10, and the slump loss equivalent to pumping corresponding to the determined secondary mixing parameters is determined from the test correlation line LT (test correlation) obtained from the results of the laboratory test as a change in fluidity due to the pumping of the concrete.

[0071] In this way, by linking the results of laboratory tests with the results of pumping tests conducted in advance, it is possible to easily estimate changes in fluidity associated with pumping concrete, such as the progression of slump loss, from the results of the laboratory tests and construction conditions such as the planned pumping distance (LP). This makes it possible to consider in advance whether the fluidity of the concrete will be sufficiently maintained at the construction site and whether there is a risk of clogging in the pipes. Furthermore, by understanding the pumping distance and time until pouring that can be achieved while maintaining fluidity, it is possible to set construction conditions at the construction site and consider countermeasures at the construction site.

[0072] Furthermore, according to the above-described slump estimation method, even if the construction site (construction conditions) is different, the progress of slump loss at the construction site can be easily estimated simply by conducting an indoor test using the mixer 10, without having to conduct experiments simulating the construction site.

[0073] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0074] For example, when obtaining a correspondence between the results of a concrete pumping test conducted in advance and the results of a laboratory test using the mixer 10, the correspondence may be established using multiple test results for each, as shown in the above embodiment, or the correspondence may be established based on a single result for each, assuming that the results of the pumping test and the results of the laboratory test can be approximated by a function passing through the origin. In other words, there may be one or more test results for each of the results of the concrete pumping test conducted in advance and the results of the laboratory test using the mixer 10, and an approximate line (regression line) passing through the origin may be obtained based on the test results. [Explanation of symbols]

[0075] 10. Mixer (a mixer for secondary mixing of test concrete) 20. Test equipment (concrete pumping test equipment)

Claims

1. A slump estimation method for estimating a change in fluidity due to pumping of concrete at a construction site, a correlation acquisition process in which a secondary mixing is performed on a test concrete having the same specifications as the concrete pumped at the construction site using a mixer that generates shear deformation in the concrete, and a test correlation is obtained that indicates the correlation between a secondary mixing parameter related to the shear energy imparted to the test concrete by the secondary mixing and the slump loss of the test concrete after the secondary mixing; a correlation acquisition process for correcting the test correlation to substantially match a reference correlation indicating a correlation between a pumping distance and a slump loss obtained from the results of a concrete pumping test conducted in advance, and determining a correspondence relationship between the secondary mixing parameter and the pumping distance; and a slump change acquisition process for determining, from the correspondence relationship, the secondary mixing parameter corresponding to the planned pumping distance for pumping concrete at the construction site, and determining, from the test correlation, a slump loss corresponding to the determined secondary mixing parameter as a change in fluidity associated with pumping concrete at the construction site. Slump estimation method.

2. The method further includes a time-dependent change acquisition step of determining the time-dependent change in slump loss of the test concrete, The slump loss from the completion of mixing of the concrete to the start of pumping of the concrete at the construction site, and the slump loss of the concrete after pumping are estimated based on the change over time of the slump loss of the test concrete obtained in the change over time acquisition step. The slump estimation method according to claim 1 .

3. The secondary mixing is carried out after a predetermined reference time has elapsed since the test concrete was mixed, In the slump change acquisition step, the slump loss obtained from the test correlation as a change in fluidity associated with pumping of the concrete at the construction site is corrected according to the time difference between the scheduled elapsed time from the completion of mixing of the concrete to the start of pumping of the concrete at the construction site and the reference elapsed time. The slump estimation method according to claim 1 or 2.

4. In the correspondence relationship acquisition step, the pumping distance and the secondary mixing parameter are brought into a corresponding relationship with each other by making the test correlation and the reference correlation approximately coincident with each other through normalization or standardization. The slump estimation method according to claim 1 or 2.

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