JP4060292B2 - Concrete filling property evaluation method, concrete separation test apparatus, and vibration flow test apparatus - Google Patents

Description

  The present invention relates to a concrete fillability evaluation method, a concrete separation test apparatus, and a vibration flow test apparatus, and more particularly to a fillability evaluation method, a concrete separation test apparatus, and a vibration flow test apparatus used for concrete mixing design.

  A concrete structure is constructed by placing a rebar after placing a formwork, dropping concrete into the formwork, applying vibration and compacting. At this time, the coarse aggregate having large particles among the constituent materials of the dropped concrete is easily separated from other constituent components. As a result, if the coarse aggregate is unevenly distributed in the mold, it causes the generation of jumpers and cavities. In order to avoid this and build a homogeneous and solid frame, it is necessary to set the free fall height to 1 m or less and to perform sufficient compaction after driving. However, in a thin part such as a wall or a vertical part where reinforcing bars are densely arranged, a tremy tube cannot be inserted, and it may be difficult to suppress the free fall to 1 m or less. The compaction is performed by a vibrator (insertion type or external vibration type vibrator), and the Japan Society of Civil Engineers defines the insertion pitch of the vibrator as 50 cm or less (Non-Patent Document 1). It does not consider the compaction characteristics due to the characteristics of the materials and the formulation.

  In order to judge the finish when the concrete is placed under the concrete placement conditions from the fresh state of the concrete, that is, whether the filling rate is good or not, it is difficult to produce initial defects, and it is difficult to separate the material when impact is dropped. It is necessary to evaluate the ease of repairing defects caused by vibration.

  The difficulty of initial defects is related to the slump value representing the hardness of concrete and can be evaluated by a so-called slump experiment.

  The difficulty of separating materials can be evaluated by the reciprocal of the separation coefficient representing the degree of separation. Various types of separation factors have been proposed in the past. For example, as shown in FIG. 16, the concrete dropped from the hopper 100 collides with a cone 103 installed at the center of two large and small concentric discs 101 and 102 and is scattered. The weight of the concrete dropped onto the upper surface portion A of the large-diameter disk excluding the small-diameter disk, Ma, the weight ratio of coarse aggregate in this concrete to Ga, and the concrete dropped to the upper surface portion B of the small-diameter disk Where Mb is the weight of the coarse aggregate in the concrete, Gb is the weight of the concrete adhering to the surface of the cone C, Mc is the weight of the coarse aggregate in all the dropped concrete, It can be expressed by a formula (Non-Patent Document 2).

[Formula 1] S = Ga / Gb
[Formula 2] S = Ma / Mb
[Formula 3] S = (Ga−Go) × Ma / [Ma + Mb + Mc]
In addition, a concentric barrier is surrounded around a slump cone containing fresh concrete placed on the upper surface of the flat plate, and when the slump cone is lifted up, the rough bones that cross over each barrier and are dispersed in the area between each barrier. Representing the difficulty of separating materials by the amount of the material is also performed (Patent Document 1).

The ease of repairing defects due to vibration can be evaluated by the vibration flow speed. This vibration flow speed is, for example, by pulling up the slump cone containing concrete placed on a vibration table 105 with a vibrator 106 as shown in FIG. From the time of arrival, the vibration flow speed is measured as the concrete spreading speed (Non-patent Document 3). Further, as a concept representing a concrete fluidity limit (consistency Te solvency), and slump flow is used that is represented by the spatial spread of the concrete when the concrete containing the slump cone was pulled up from the flat plate, the slump flow There has been proposed a method for indirectly estimating the frequency (Patent Document 2).

In addition, although the index showing the filling property is various, for example, Non-Patent Document 4 describes the volume of the space (for example, inside the mold) to be filled with concrete as V ₁ , and the void volume generated on the surface of this filling space. when the V _2, with _{e = (V 2 / V 1} ) × 100 is proposed to represent the surface porosity being defined, and compaction effect experiments concrete using this index, slump 18cm and A comparison between the case of compacting two types of concrete samples of 8 cm and the case of not compacting them shows a surface porosity of 5 to 6.5% at a slump of 18 cm and 14 at a slump of 8 cm. It is reported that it was 1% or less in slumps 18cm and 8cm when it was compacted with a stick, whereas it was ~ 17.5%.
Patent No. 3139363 JP 2000-162109 A paragraph 0010 Japan Society of Civil Engineers Concrete Standard Specification [Construction] 2002 Akira Yoshimoto, “Separation of concrete by falling”, Cement / Concrete No282, Cement Association, August 1970, p22 Shinji Urano, “Examination of Consistency Evaluation Index of Fresh Concrete by Exciting Slump Flow Test”, Annual Report of Concrete Engineering, Japan Concrete Engineering Association, 2000, Vol. 22, No. 2 p397 Hiromichi Yamada, “Performance Test of Concrete Vibrator”, Takenaka Corporation Takenaka Technical Research Institute, Takenaka Technical Research Institute Report No. 20, October 1978

  According to the applicant's research, the filling rate of uncured concrete is an increasing function with respect to vibration acceleration or action time, but converges when the applied energy exceeds a certain value as described in FIG. It has been found. Therefore, it is necessary to exclude the influence of vibration time etc. on the filling rate by evaluating the filling rate that finally converges after adding sufficient vibration time for compaction to fresh concrete. It is expected that fillability can be evaluated with minimum parameters.

  However, among the slump that indicates the difficulty of the initial defect, the reciprocal of the separation coefficient that indicates the difficulty of separating the material, and the vibration flow rate that indicates the ease of repairing the defect by vibration, there is a certain degree of relationship with the filling property. Only the slump is grasped (see, for example, the above-mentioned Non-Patent Document 4), and the state of the concrete is merely confirmed visually with respect to the remaining two indicators. Visual evaluation is skillful and sensuous and may lack objectivity.

  In addition, evaluation indexes such as separation factor and vibration flow speed are quantities that depend on the structure of the measuring device, so that it is close to the condition of concrete being dropped or compacted into the formwork at the actual concrete placement site. Although it is necessary to measure, since the separation device of Non-Patent Document 2 uses a single cone-shaped flow obstacle, the state where the concrete collides with the reinforcing bars arranged in the mold and separates them. The vibration flow test apparatus as shown in FIG. 17 is not sufficiently reproduced, and if the excitation force is too strong, a vibration table and a concrete loading plate (not shown) fixed on the table are provided. The accuracy is worsened due to the occurrence of misalignment, the difference in the excitation force transmitted due to slight differences in the fixing degree and the support conditions, or the irregular excitation force.

  The present invention objectively and easily predicts the filling rate (referred to as the final filling rate) when sufficient vibration time is given to the concrete from indices indicating the softness, separation resistance, and deformability of the concrete. These indicators are comprehensively evaluated so that the suitability of fillability can be judged on the basis of a certain threshold value regardless of the material and composition, and the concrete separation test apparatus and vibration flow test suitable for this fillability evaluation experiment The object is to provide a device.

The first means is to measure the separation resistance evaluation index indicating the difficulty of separating the aggregate by colliding the flowing fresh concrete with the flow obstacle (30), and applying vibration to the fresh concrete having the same composition. Measure the slump flow or flow speed and other deformability evaluation indexes representing the ease of deformation during vibration, and determine the suitability of the fillability by synergistically evaluating these deformability evaluation indexes and separation resistance evaluation indexes. The content is to do.

  The means for solving the invention of the present specification and the “filling rate” in the claims are mainly the above-mentioned final filling rate, that is, the filling rate finally converged by compaction, or a bundle thereof. It means the filling rate when the vibration time is sufficiently long to be regarded as a value.

  A device for measuring the separation resistance evaluation index is preferably a separation test device according to a tenth means described later, but is not limited to this, and a conventionally known separation test device, for example, shown in FIG. The device described in Non-Patent Document 2 can also be used.

  The apparatus for measuring the deformability evaluation index is preferably a vibration flow apparatus according to a twelfth means described later, but is not limited to this, and a conventionally known vibration flow test apparatus such as the apparatus shown in FIG. Can also be used.

  In addition, when evaluating the filling property of concrete from a deformability evaluation index | exponent, it is desirable to determine a reference value using the concrete sample whose kind of fine aggregate is the same as the fresh concrete which is an evaluation object.

  Assessing both indices synergistically refers to comparing both indices with each other, as described later, with a predetermined reference value, but in addition to this, the deformability evaluation index and the separation resistance evaluation When any of the indexes falls below the respective reference value, it may be determined that the filling property is poor.

  When determining each reference value, as described in the first means or the second means, each evaluation index is determined in advance for a plurality of concrete samples, and the filling rate of each sample is determined. To do.

The second means includes the first means, and the overall evaluation index obtained by multiplying the deformability evaluation index and the separation resistance evaluation index is based on a reference value determined in advance from a plurality of concrete samples. When the ratio is too large, it is determined that the filling rate is good.

Third means, in the second means, instead of the comprehensive evaluation index according to the means of the second, obtained by multiplying the deformation evaluation index and separation resistance evaluation index and slump value of the fresh concrete The content is to use a comprehensive evaluation index.

The fourth means includes the second means, and the determination of the reference value is performed using the same measurement conditions as the measurement apparatus used for measuring the evaluation index of the fresh concrete to be evaluated. Measure the separation resistance evaluation index or deformability evaluation index of a plurality of concrete samples with different materials and compositions, and measure the filling rate of each of the concrete samples measured by placing them in a mold and compacting them. It is performed by determining an evaluation index necessary to achieve a required filling rate from the results as a numerical value unique to the measuring device.

The fifth means includes the first means, and the separation resistance evaluation index is proportional to the weight or composition ratio of each of the two concrete parts separated by the collision with the flow obstacle (30). It is defined as the reciprocal of the separation factor.

  The separation factor may be a ratio of increase / decrease in the specific gravity of the coarse aggregate in the two concrete parts separated by the collision with the flow obstruction 30. More specifically, the separation factor has been proposed by the aforementioned Non-Patent Document 2. Equations 1 to 3 may be used.

Sixth means includes the fifth means, and a concrete dropping port (8) and first and second concrete receivers (40) and (46) arranged on the lower side of the dropping port. Among the concrete that collided with the flow obstacle, a concrete part with a low degree of scattering is placed in the first concrete receiver (40), and a concrete part with a high degree of scattering is received in the second concrete part. It comprises so that it may each enter into a container (46), and it is content to obtain | require the said separation factor from the mass ratio of the coarse aggregate of the concrete part in each concrete receptacle and / or the mass ratio of concrete.

The seventh means includes the fifth means, and uses the product of the ratio of the slump flow to the slump and the bulk volume of the coarse aggregate as an estimated value of the separation coefficient instead of the separation coefficient. Yes.

The eighth means is a concrete separation test apparatus used for measuring the separation resistance evaluation index in the concrete filling property evaluation method according to claim 3, and is laterally outward with respect to the perpendicular D passing through the concrete dropping port (8). On the virtual inclined surface V that slopes downward, a flow obstruction (30) is formed by arranging a plurality of horizontal obstruction bars (34) in parallel with each other at a fixed interval. A first concrete receiver (40) for receiving a portion of the fresh concrete dropped from the mouth (8) that has passed through the horizontal obstacle bar (34) , is adjacent to the first concrete receiver. A second concrete receiver (46) for receiving a concrete portion scattered outward from the horizontal obstacle bar (34) is disposed.

  The virtual inclined surface V is preferably a pair of inverted V-shaped inclined planes that are symmetrical with respect to the perpendicular D, as will be described later. In this case, a plurality of parallel inclined planes V are formed along these inclined planes. A straight bar-shaped horizontal obstacle bar 34 may be arranged. However, the horizontal obstacle bars 34 may be arranged on only one of the pair of inclined slopes. Further, the virtual inclined surface V may be a conical surface, and concentric ring-shaped horizontal obstacle bars 34... Which gradually increase in diameter from the upper side to the lower side may be arranged in this conical surface shape.

  It should be noted that the distance (effective gap) seen from above the horizontal obstacle bars is preferably at least larger than the maximum particle diameter of the coarse aggregate, and is preferably equal.

The ninth means includes the eighth means, and the movable bottom wall (16) closing the lower surface of the base cylinder portion (14) of the upper and lower double-sided openings can be pulled out to the outside. 8) is provided with a dropping port member (6) provided so as to open, and the inner surface of the dropping port member has a straight cylindrical shape that does not prevent free fall of concrete or a tapered cylindrical shape that expands downward.

A tenth means is a vibration flow test apparatus used for measuring a deformability evaluation index in the concrete fillability evaluation method according to claim 3 , wherein the vibration table (50) with a vibrator (54), the vibration A concrete loading plate (60) placed on the table; and a fixing means (70) for fixing the concrete loading plate (60) to the vibration table (50). The concrete loading plate (60) is configured to be fixed by directly or indirectly tightening and pressing, and the concrete loading plate can be loosely fixed on the vibration table (50) by adjusting the tightening force. ing.

The eleventh means has tenth means, and the concrete loading plate (60) is wider than the vibration table (50) in at least one of the front, rear, left and right sides thereof, and on the surface of the vibration table. The fixing means includes the fixed arm (72) that can be protruded to both sides in the one direction, and the fastening tool (78) that can be tightened in a state where the protruded fixed arm and the concrete loading plate (60) are stacked. (70).

  The fixed arm 72 may be configured to protrude outward from the state of being attached at an appropriate position on the surface of the vibration table 50 by rotating or sliding.

  According to the first aspect of the invention, since the filling property of the concrete is evaluated using the separation resistance evaluation index measured by the collision with the flow obstacle 30, the vertical direction of the columns and the like in which the reinforcing bars are arranged relatively densely. The concrete can be blended so that the concrete can be satisfactorily filled with little separation at the site.

According to the invention according to the first means, by measuring the deformability evaluation index under vibration, it is so arranged to evaluate the filling factor than the indicator initially driving the concrete was dropped into the mold Even if it has a defect such as a jumper, concrete can be blended so that the defect is repaired by compaction and high filling property can be obtained.

According to the invention according to the first aspect, the a modified evaluation index and separation resistance evaluation index because synergistically evaluated, it is possible to improve the accuracy of evaluation of the filling of the concrete.

According to the invention relating to the second means, the filling rate is good when the comprehensive evaluation index obtained by multiplying the deformability evaluation index and the separation resistance evaluation index is larger than the reference value determined in advance from the concrete sample. Therefore, the suitability of the filling property can be determined based on a certain reference value without being influenced by the material and the composition of the concrete.

According to the invention relating to the third means, since the evaluation index obtained by multiplying the slump value, the deformability evaluation index, and the separation resistance evaluation index is employed, more accurate evaluation is possible.

According to the invention relating to the fourth means, the determination of the reference value is carried out by using the same measuring conditions and the same material and composition as the measuring apparatus used for measuring the evaluation index of the concrete to be evaluated. Since the separation resistance evaluation index or the deformability evaluation index of a plurality of changed concrete samples is measured and the final filling rate of the samples is measured, it is based on the reference value determined for each measuring apparatus and measurement condition. Accurate evaluation is possible.

According to the invention relating to the fifth means, the separation resistance evaluation index is the reciprocal of the separation coefficient proportional to the ratio of each weight or composition of the two concrete parts separated by the collision with the flow obstacle 30. The degree of material separation can be expressed more accurately.

According to the sixth aspect of the present invention, the flow hindrance 30 is interposed between the concrete dropping port 8 and the first and second concrete receivers 40 and 46 disposed below the dropping port, and the flow In the concrete that collided with the obstacle, the concrete part with a low degree of scattering enters the first concrete receiver 40 and the concrete part with a high degree of scattering enters the second concrete receiver 46, respectively. Since the above separation factor was determined from the specific gravity of the coarse aggregate of the concrete part of the concrete, it was possible to reproduce the state when the concrete was dropped into the formwork at the placement site and to accurately evaluate its fillability it can.

According to the invention relating to the seventh means, since the product of the ratio of the slump flow to the slump and the bulk volume of the coarse aggregate is used as the estimated value of the separation coefficient, there is no need to experimentally measure the separation coefficient. Easy to operate.

According to the eighth aspect of the invention, the portion of the fresh concrete dropped from the concrete drop opening 8 that has passed through the horizontal obstacle bars 34 is the first concrete receiver 40 and the horizontal obstacle. The concrete part scattered outward from the bar 34 is provided to be received by the second concrete receiver 46, so that the concrete dropped from the concrete outlet collides with the reinforcing bars arranged in the formwork and separated. Can be reproduced more accurately, and the filling property of the concrete can be evaluated more accurately.

According to the ninth aspect of the invention, the movable bottom wall 16 that closes the bottom surface of the base tube portion 14 of the drop port member 6 can be pulled out to the outside, and the concrete drop port 8 is opened by the drawing. Therefore, it is possible to avoid variations in the falling speed of the concrete depending on the type of material as in the case of dropping concrete from a hopper or the like.

According to the tenth means, since the concrete loading plate 60 can be loosely fixed on the vibration table 50, a stable and constant excitation force can be applied to the concrete sample, which is in good condition. Can measure the vibration flow speed.

According to the eleventh aspect of the invention, the vibration table 50 can be made compact without being bulky.

  1 to 6 show a concrete separation test apparatus according to the present invention.

  This concrete separation test apparatus includes a concrete dropping means 2, a pair of front and rear partition walls 24, 24, a flow obstruction 30, a first concrete receiver 40, and a second concrete receiver 46.

  The concrete dropping means 2 includes a dropping port member 6 and a support member 4 that supports the dropping port member. Although this support member may have any configuration, in the illustrated example, a drop port member mounting hole 4b is formed in a top plate 4a that hangs the support posts 4c from a square. In addition, the dropping port member 6 is a funnel-shaped hopper in the illustrated example, and a concrete dropping port 8 opened on the lower surface thereof is provided so as to be opened and closed by a shutter 10. Further, a low frequency vibration motor 12 is attached to the outer surface of the drop opening member 6.

  The partition walls 24, 24 are positioned in front of and below the drop opening member 6 and stand up from the ground to the vicinity of the drop opening 8 with a certain distance from the drop opening 8 into the gap. It is configured to be able to throw in concrete. Both partition walls 24, 24 are preferably installed parallel to each other as shown. In the illustrated example, a barrier rod described later is installed between the partition walls 24 and 24 to integrate both partition walls.

  The flow obstruction 30 is placed between the partition walls 24 and 24 so as to be positioned directly below the drop opening 8. In the illustrated example, the flow obstructions 30 and 30 are provided in two upper and lower stages, but one of them may be omitted, or three or more flow obstructions may be provided. Each flow obstruction is constructed by laying a plurality of horizontal obstruction bars 34 having sufficient rigidity between a pair of front and rear frame plates 32, 32 having an inverted V shape when viewed from the front, at equal intervals. Is firmly fixed to the partition walls 24, 24. Each flow obstacle 30 is provided such that the inverted V-shaped apex angle is located at one point on the perpendicular D passing through the center of the drop opening 8, and the inclined surface V that obliquely slopes downward and outward from the one point. , The horizontal obstacle bars 34 are positioned on V. The angle formed by each inclined surface V with respect to the perpendicular D is preferably about 40 degrees. Further, the interval between the horizontal bars (effective gap interval d) viewed from above is preferably about 1.5 times the maximum particle size of the coarse aggregate in the concrete to be dropped.

  The first concrete receiver 40 is a box-shaped container having an upper surface opening, and is disposed directly below the concrete dropping port 8 with the flow obstacle 30 interposed therebetween. In the illustrated example, the first concrete receiver 40 is formed by small containers 40a, 40b, 40c, 40d having two rectangular openings on the upper and lower sides, as shown in FIG. The containers are brought into close contact with each other so that the concrete dropped in each small container can be taken out as a separate test sample for each small container. However, the first concrete receiver 40 may be a single container or a pair of left and right small containers. The front and rear surfaces of the first concrete receiver 40 (the front surface of the front small container and the rear surface of the rear small container) may be in close contact with the opposing inner surfaces of the partition walls 24, 24. Is preferably substantially the same as the lateral width of the flow obstacle 30. Each of the small containers 40a... Stands upright from the bottom wall, and the outer side walls of the peripheral walls of the left small containers 40a and 40b and the right small containers 40c and 40d It stands up to the vicinity of the extended line of the inclined line V in which the obstacle bars 34 are arranged, and the partition plate 42 is erected along the perpendicular D from between the inner side wall portions of the peripheral walls. . It is desirable that the partition plate extends to near the top of the lower inverted V-shaped flow obstruction.

  The second concrete receivers 46 and 46 are respectively arranged adjacent to the left and right sides of the first concrete receiver 40. The second concrete receiver 46 is a box-shaped container that is lower than the first concrete receiver 40 and has a rectangular opening on the upper surface. The front and rear width of the second concrete receiver 46 is the same as that of the first concrete receiver 40. The outer surfaces of both the front and rear walls of the second concrete receiver 46 are opposed to the inner surfaces of the partition walls 24 and 24, and each second concrete receiver. The inner surface of the inner side wall portion of the peripheral wall of the receiver 46 is brought into close contact with the outer surface of the corresponding side wall portion of the peripheral wall of the first concrete receiver 40.

  In the above configuration, when fresh concrete is dropped from the concrete dropping port 8, coarse aggregate having a large particle size and density among the constituent particles of the concrete may collide with the horizontal obstacle rod 34 and scatter to the left and right sides outward. On the other hand, the fine aggregate or mortar component easily passes through the horizontal obstacle bars 34 and falls down. Therefore, the ratio of the coarse aggregate in the concrete portion entering the second concrete receiver 46 is larger than that in the concrete portion entering the first concrete receiver 40. The separation factor of fresh concrete can be determined by measuring the composition or weight of the concrete components in both receivers.

  It should be noted that the amount of concrete entering the second concrete receiver 46 is a small amount for all the dropped concrete samples, and the ratio of the coarse aggregate of the concrete entering the first concrete receiver 40 is coarse in mixing. Since it is substantially equal to the aggregate ratio, the separation factor may be obtained by using the coarse aggregate ratio of the concrete entering the second concrete receiver 46 and the coarse aggregate ratio in the blend.

  FIG. 4 shows a modification of the main part of the concrete separation test apparatus shown in FIGS. 1 to 3, in which the shape of the flow obstacle 30 is changed. This flow obstruction 30 has a concentric ring-shaped horizontal obstruction bar 34 arranged on a tapered virtual inclined surface V centering on a perpendicular D passing through the concrete outlet 8 and each horizontal obstruction bar is connected to a connecting rod 36. It is connected with. The gap (effective gap interval d) between the horizontal obstacle bars 34 as viewed from above is preferably about 1.5 times the maximum particle size of the coarse aggregate in the dropped concrete. A circular first concrete receiver 40 is provided below the flow obstacle 30 and a second concrete receiver 46 is surrounded by the first concrete receiver 40. In the illustrated example, a concrete receiving plate having a diameter larger than that of the first concrete receiver is attached below the first concrete receiver 40, and the concrete receiving plate portion excluding the first concrete receiver is used as the second concrete receiver. 46.

  The separation factor can be determined by measuring the composition or weight of the concrete part entering the first concrete receiver 40 and the concrete part entering the second concrete receiver 46 of the concrete dropped from the concrete dropping port 8.

  FIGS. 5 and 6 show another modification of the main part of the concrete separation test apparatus shown in FIGS. 1 to 3, and the configuration of the drop opening member 6 is changed.

  That is, the drop port member 6 of this modification is composed of a rectangular cylindrical base tube portion 14 that opens the concrete drop port 8 on the lower surface, and a movable bottom wall 16 that closes the lower surface of the base tube portion. The fresh concrete can be stored in the space defined by the base tube portion 14 and the movable bottom wall 16. The base tube portion 14 is fitted into a mounting hole 4b opened in the top plate 4a of the support member 4, and is fixed to the top plate 4a with a fixture 18 in the fitted state. The movable bottom wall 16 can be drawn outward in the left-right direction, and the concrete dropping port 8 can be opened by the drawing. A grip 16a is formed at one end of the movable bottom wall. In the illustrated example, a guide plate 20 is provided that protrudes inwardly from the lower end of a vertical plate portion 20a that hangs down from the outer surfaces of both front and rear walls of the base tube portion 14, and the front and rear walls of the base tube portion 14 are provided. Between the lower end surface and the upper surface of the engaging convex portion 20b, the front and rear side portions of the movable bottom wall 16 are slidably held. It is desirable that the engaging convex portion 20b is provided so as not to protrude inward from the inner surface of the base tube portion 14.

  In this configuration, when fresh concrete is stored in the base tube portion 14 and the movable bottom wall 16 is pulled out sideward, the fresh concrete falls freely without colliding with the inner surface of the base tube portion 14, Regardless of the composition, it is possible to drop at a constant speed, and the separation factor can be measured more precisely.

  7 and 9 show a vibration flow test apparatus according to the present invention.

  First, a known part of the configuration of the test apparatus will be described. The apparatus includes a vibration table 50 and a concrete loading plate 60.

  The vibration table 50 includes a table plate 52 provided with a vibrator 54 at the center of the back surface, leg portions 56 suspended from the four corners of the back surface of the table plate, and four reinforcements installed between the upper end portions of the leg portions. Horizontal plates 58 for use.

  The concrete loading plate 60 has an area sufficient for measuring the vibration flow of fresh concrete within a predetermined time. In this illustrated example, both the left and right widths and the front and rear widths are wider than the table plate 52. Shall be formed. A line to be a mark having a diameter of 50 mm may be drawn on the upper surface of the concrete loading board 60.

  In the present invention, fixing means 70 for fixing the concrete loading plate 60 to the vibration table 50 is provided. This fixing means can be formed by a fixing arm 72 attached to the horizontal plate 58 so as to be able to be pulled out to the outside, and a fastening tool 78 for tightening the fixed arm in the drawn state to the concrete loading plate 60. . In the illustrated example, the fixed arm 72 is formed in an inverted L-shaped cross section, and one end portion of the vertical plate portion 72a of the fixed arm is pivotally attached 74 to the horizontal plate 58. The bolt 76 is fastened to the horizontal plate 58, the bolt is released when in use, and the other end of the fixed arm 72 protrudes outward by rotating the fixed arm 72 around the pivot 74. The horizontal plate portion 72b at the tip of the arm is provided so as to be overlapped with the concrete loading plate 60 and tightened.

  The fastening tool 78 is adjustable so that the fastening force can be adjusted, and is provided so that the concrete loading plate 60 can be loosely fixed to the fixing arm 72. In addition, the method of attaching the metal fitting which prevents the horizontal shift by vibration with a concrete loading board and a vibration table may be used.

  An elastic plate 62 made of rubber or the like is interposed between the concrete loading plate 60 and the table plate 52. Further, an elastic end 64 is attached to the lower end of each leg 56.

In the above configuration, the fixed arm 72 is compactly incorporated in the side surface of the vibration table 50 in the state shown in FIG. From the state of FIG. 7, the fixed arm 72 is pulled outward, the horizontal plate portion 72 b of the fixed arm and the concrete loading plate 60 are overlapped, and both the plates are fixed slightly loosely by the fasteners 78 and the above. When fresh concrete is placed on the concrete loading plate 60 and the vibrator 54 is operated, the horizontal component of the vibration of the vibrator is caused by the fixed arm 72 and the concrete loading plate 60 being shaken, and the vertical component is Since the elastic plate 62 and the elastic end portion 64 perform a cushioning action, it is possible to prevent a large acceleration from being instantaneously applied to the fresh concrete and an accidental excitation force from being applied to the concrete sample. Moreover, if the acting excitation force is set to a value corresponding to a position of 25 to 30 cm from the inserted vibrator, a vibration state close to that when the fresh concrete in the mold is compacted can be reproduced.
If the time for the concrete flow to reach a certain size is measured while applying vibration, the vibration flow speed can be obtained.

Hereinafter, an example of a preferred embodiment for evaluating the filling property of concrete according to the present invention will be described in accordance with the procedure of an experiment actually performed by the applicant.
(1) Preparation of concrete samples In order to test the filling properties of concrete, prepare multiple concrete samples with different types of fine aggregate, fine aggregate rate (s / a), bulk volume of coarse aggregate, etc. . In this embodiment, regarding the type of fine aggregate, the mixture of sea sand and crushed sand with high viscosity (type I), mountain sand A (type II) with coarse particles and low fluidity, and particle distribution of particles are ideal. Three types of samples of mountain sand B (type III) with high fluidity were prepared.
(2) Measurement of slump, slump flow and vibration flow rate for each sample As a slump test method, generally put a steel slump cone (top inner diameter 10cm, bottom inner diameter 20cm, height 30cm) on a flat plate After stuffing, after finishing stuffing, pull the cone straight up in about 2 to 3 seconds, measure the height of the central part of the concrete remaining on the flat plate, and express the drop from 30 cm in cm as the slump value Yes (JIS A 1101).

  In the slump flow test, a lamp cone filled with a concrete sample is placed on a concrete loading plate with the opening facing down, and the concrete is pulled up vertically, and the time elapses due to the balance between the weight and softness of the concrete. When the flow of the concrete spreading on the base plate is stationary, measure the longest part of the concrete spread and the spread in the direction perpendicular to the longest part. In many cases, the average value is a slump flow.

  Furthermore, when measuring the vibration flow speed, the sample used for the slump flow test is placed on the vibration table together with the concrete loading plate, and the time until it reaches a certain size (usually 50 cm) after vibration is measured. The vibration flow speed may be obtained by dividing the moving distance of the tip by the time required for the deformation.

  Since the vibration transmission efficiency differs depending on the shape before vibration, the vibration flow speed can be evaluated fairly by testing the original shape as the same. For example, it is preferable to test in a shape in which a flat container is filled and deformation due to gravity is suppressed as much as possible before the start of vibration. As another method for evaluating the ease of deformation, it can also be evaluated by the amount of spread (tapping flow) when a concrete loading board on which a specimen after a slump test is placed is hit.

Each of these tests is performed on each of the concrete samples prepared previously. In this embodiment, the excitation force is 0.26N. In the measurement of the slump flow and vibration flow speed, it is desirable to record the measurement conditions so that they can be reproduced later.
(3) Measurement of separation factor for each sample The separation factor is measured experimentally using an experimental device that reproduces the state in which concrete falls and collides with a reinforcing bar or formwork. For the part where the reinforcing bars are arranged in parallel, it is better to experiment using the apparatus shown in FIGS. 1 to 3 of this application, and to the part where the reinforcing bars are arranged in a loop shape using the apparatus of FIG. Although it is possible to reproduce the image more faithfully, it is not always necessary to do so. For example, the conventional separation test apparatus described above may be used. As for the separation factor, in this embodiment, the expression 3 described above (multiplying the weight ratio of the scattered concrete to the input concrete and the increment of the ratio of the coarse aggregate in the concrete before and after the scattering) is used. However, other conventionally known equations for the separation factor may be used.

In any case, the value of the separation factor is an amount that depends on the distance from the concrete outlet to the collision with the flow obstacle, the shape of the flow obstacle, the arrangement of the concrete receiver, etc. as well as the definition equation of the coefficient. It is necessary to accurately record the measurement conditions so that they can be reproduced when measuring the concrete to be evaluated later.
(4) Measurement of final filling rate by compaction of concrete sample After performing a separation test using the separation test apparatus shown in FIGS. 1 to 3, fresh concrete stored in the four small containers 40a, 40b,. Each of the samples was placed on a vibration table and the filling rate (in this embodiment, filling area / formwork area) was measured after compaction hardening at 0 seconds, 10 seconds, 30 seconds, and 90 seconds. The result of FIG. 10 was obtained. According to this, it can be seen that the filling rate of any sample converges exponentially to a certain value, and the compaction time required for the convergence is about 10 to 40 seconds. Therefore, the concrete filling rate when the compaction time is about 10 to 40 seconds can be regarded as the final filling rate.

  Based on the above knowledge, the final filling rate may be measured for the concrete sample of the type described above. The above experimental results are summarized as follows. In the table, 1-1 to 1-9 are type I samples, 2-1 to 2-7 are type II samples, and 3-1 to 3-5 are type III samples. Respectively.

(５)基準値の検討
図１１は、振動フロー速度と最終充填率との関係を示している。同図によれば、タイプIIIの流動性の大きい山砂Ｂに関する各プロット（黒塗りの点）は、他の点と極端に傾向が異なる１点を除いて最終充填率が100％の付近に集中している。上記１点を測定誤差によるものと考えると、タイプIIIの試料は理想的な粒度分布を示しており、下記の基準値を定めるまでもなく充填性は良好であると判断できる。これに対して薄塗りで描いたタイプIIの流動性の低い山砂Ａのプロット、及び白抜きで描いたタイプＩの海砂と砕砂との混合物では、左下から右上への正の相関関係がある。これらのデータをもとに最小二乗法による近似式をグラフに書き込むと、タイプＩでは太い破線のように、又タイプIIでは細い破線のようになる。最終充填率の目標値を95％とすると、この目標値を達成するために振動フロー速度が満たすべき基準値は、タイプＩでは1.0cm/s，タイプIIでは1.4cm/sとなる。

(5) Examination of Reference Value FIG. 11 shows the relationship between the vibration flow speed and the final filling rate. According to the figure, each plot (filled point) for type III sand with a high fluidity of type III has a final filling rate of around 100% except for one point that is extremely different from the other points. focusing. If one point is considered to be due to a measurement error, the type III sample shows an ideal particle size distribution, and it can be determined that the filling property is good without setting the following reference value. On the other hand, in the plot of Type II low-fluidity mountain sand A drawn thinly and the mixture of Type I sea sand and crushed sand drawn white, there is a positive correlation from the lower left to the upper right. is there. When an approximate expression based on the least square method is written in the graph based on these data, it appears as a thick broken line in Type I and as a thin broken line in Type II. If the target value of the final filling rate is 95%, the reference value to be satisfied by the vibration flow speed to achieve this target value is 1.0 cm / s for Type I and 1.4 cm / s for Type II.

  FIG. 12 shows the relationship between the separation factor and the final filling rate. In the same figure, for Type III mountain sand B, the final filling rate is concentrated around 100% except for one point, but Type I and Type II have a negative correlation from upper left to lower right. . As in the case of FIG. 11, when the type I approximation is written with a thick broken line and the type II approximation is written with a thin broken line, and the target value of the final filling rate is 95%, the reference value of the separation factor is 0.007 for type I. For Type II, it is 0.009. This reference value is a dimensionless quantity.

  FIG. 13 shows the relationship between the overall evaluation index obtained by dividing the vibration flow speed by the separation factor and the final filling rate. According to this figure, in the range of the overall evaluation index of 40 (cm / s) or more, the overall evaluation index is 40-60 regardless of the type of fine aggregate, except for one point estimated as a singular point due to measurement error. It can be seen that the final filling rate tends to converge to a constant value in the vicinity of 100% after standing up rapidly in the range (cm / s). If an approximate line is drawn along these points as shown in the figure and the target value of the final filling rate is 90%, the standard value of the overall evaluation index is 60 (cm / s), and the target value of the final filling rate is If it is 95%, 75 (cm / s) is obtained as the reference value of the overall evaluation index.

FIG. 14 shows the relationship between the overall evaluation index obtained by dividing the product of the slump value and the vibration flow speed by the separation factor and the final filling rate. By including the slump value in the evaluation index in this way, the ease of initial defects in fresh concrete can be reflected in the evaluation.
(6) Measurement and evaluation of slump, slump flow, vibration flow speed, and separation factor of fresh concrete to be evaluated As described above, the reference values of vibration flow speed and separation coefficient and other data were measured for a plurality of concrete samples. After that, the vibration flow speed and / or the separation factor are measured for fresh mix, which is the evaluation object under the same measurement conditions using the same measuring device. In order to improve the accuracy of the evaluation, it is desirable to measure two evaluation indices, but it is troublesome to perform both measurement experiments, so only one of the indices can be measured. On the other hand, in order to further improve the accuracy of the evaluation, in addition to the vibration flow speed and the separation factor described above, the three evaluation indices of slump are measured, and these three evaluation indices are multiplied to measure the concrete sample. You may evaluate by comparing with the reference value of the corresponding evaluation index obtained from data.

  The quality of the final filling rate can be predicted by comparing the evaluation index of the concrete related to the evaluation object measured in this way or calculated from the measured value with the reference value obtained from the concrete sample. When evaluating only with vibration flow speed or separation factor, the reference value obtained from the measurement test of the concrete sample (for example, sea sand if sea sand) is the same as the object of the evaluation and the type of fine aggregate It is important to contrast.

  In the above embodiment, the measured value is used as the separation factor of the concrete sample and the fresh concrete to be evaluated. However, when the separation factor experimental device becomes large and it is difficult to obtain experimentally, The separation factor may be estimated by combining other variables correlated with the separation factor.

  As a preferable estimation method, the separation factor can be estimated from the product of the ratio of the slump flow to the slump and the bulk volume of the coarse aggregate. FIG. 15 shows the estimated value of the separation coefficient by this method on the horizontal axis and the measured value of the separation coefficient on the vertical axis. It can be seen that there is a clear correlation between the two. Therefore, if a graph corresponding to FIG. 13 is drawn using the estimated value of the separation coefficient, an approximate expression showing a similar tendency will be established although the numerical values are different.

It is a front view of the concrete separation test apparatus concerning the present invention. It is the principal part top view seen along the II-II line of FIG. 1 is a side view of the device. It is a principal part modification of the apparatus of FIG. It is the other principal part modification of the apparatus of FIG. It is an enlarged view of the modification of FIG. It is a front view of the use condition of the vibration flow test apparatus concerning the present invention. It is the figure which looked up at the said apparatus along the VIII-VIII line of FIG. 7 is a longitudinal cross-sectional view of the device when not in use. It is a graph showing the relationship between the compaction time in this invention evaluation method, and a filling rate. It is a graph showing the relationship between the vibration flow speed and final filling rate in this invention evaluation method. It is a graph showing the relationship between the separation coefficient in this invention evaluation method, and a final filling rate. It is a graph showing the relationship between the vibration flow speed / separation coefficient and the final filling rate in the evaluation method of the present invention. It is a graph showing the relationship between the slump x vibration flow speed / separation coefficient and the final filling rate in the evaluation method of the present invention. It is a graph showing the relationship between the separation factor and coarse aggregate bulk volume in this invention evaluation method. It is a structural example of a conventionally well-known separation test apparatus. It is a structural example of a conventionally well-known vibration flow test apparatus.

Explanation of symbols

2 ... Concrete dropping means 4 ... Support member 4a ... Top plate 4b ... Mounting hole 4c ... Post 6 ... Drop opening member 8 ... Drop opening 10 ... Shutter 12 ... Low frequency vibration motor
14 ... Base tube 16 ... Movable bottom wall 18 ... Fixing tool 20 ... Guide plate 20a ... Vertical plate
20b ... engagement convex part 24 ... partition wall
30 ... Flow obstruction 32 ... Frame plate 34 ... Horizontal obstruction rod 36 ... Connecting rod 38 ... Leg
40 ... 1st concrete receptacle 40a, 40b, 40c, 40d ... Small container 42 ... Partition plate
46 ... Second concrete receiver
50 ... Vibrating table 52 ... Table plate 54 ... Vibrator 56 ... Leg 58 ... Horizontal plate
60… Concrete loading plate 62… Elastic plate 64… Elastic edge
70 ... Fixing means 72 ... Fixing arm 72a ... Vertical plate portion 72b ... Horizontal plate portion
74 ... Pivoting shaft 76 ... Fixing bolt 78 ... Clamp
100 ... hopper 101,102 ... disc 103 ... cone 105 ... vibrating table

Claims (11)

  Measure the separation resistance evaluation index, which indicates the difficulty of separating the aggregate by colliding the flowing fresh concrete with the flow obstruction (30), and apply vibration to fresh concrete of the same composition to increase the slump flow or flow speed, etc. It measures the deformability evaluation index representing the ease of deformation at the time of vibration, and synergistically evaluates the deformability evaluation index and the separation resistance evaluation index to judge the suitability of the filling property Concrete fillability evaluation method.   When the overall evaluation index obtained by multiplying the deformability evaluation index and the separation resistance evaluation index is larger than a reference value determined in advance from a plurality of concrete samples, it is determined that the filling rate is good. The concrete fillability evaluation method according to claim 1.   The overall evaluation index obtained by multiplying the slump value of the fresh concrete, the deformability evaluation index, and the separation resistance evaluation index is used instead of the overall evaluation index of claim 2. The concrete fillability evaluation method described.   The determination of the above reference value is based on the separation resistance of multiple concrete samples with different materials and compositions under the same measurement conditions using the same configuration as the measurement device used for measuring the evaluation index of the fresh concrete to be evaluated. Measure the evaluation index or deformability evaluation index, measure the filling rate of each of the concrete samples that have been placed into a formwork and compact, and evaluate the necessary index to achieve the required filling rate The concrete fillability evaluation method according to claim 2, wherein the method is performed by determining as a numerical value unique to the measuring device.   2. The separation resistance evaluation index is defined as a reciprocal of a separation coefficient proportional to a ratio of each weight or composition of two concrete parts separated by collision with a flow obstacle (30). The concrete fillability evaluation method described. A flow obstacle (30) is interposed between the concrete drop opening (8) and the first and second concrete receivers (40) and (46) arranged below the drop opening to collide with the flow drop. Each of the concrete receivers is configured such that the concrete part with a low degree of scattering enters the first concrete receiver (40) and the concrete part with a high degree of scattering enters the second concrete receiver (46). 6. The method for evaluating the filling property of concrete according to claim 5, wherein the separation factor is obtained from the mass ratio of coarse aggregate and / or the mass ratio of concrete in the concrete portion. 6. The concrete fillability evaluation according to claim 5, wherein the product of the ratio of the slump flow to the slump and the bulk volume of the coarse aggregate is used as an estimated value of the separation factor instead of the separation factor. Method. A concrete separation test apparatus for use in measuring a separation resistance evaluation index of the concrete filling property evaluation method according to claim 1, wherein the virtual inclination is inclined downward and outward with respect to a perpendicular D passing through the concrete drop opening (8). On the surface V, a flow obstruction (30) is formed by arranging a plurality of horizontal obstruction bars (34) in parallel with each other at regular intervals, and dropped from the concrete drop opening (8) below the flow obstruction. A first concrete receiver (40) for receiving a portion of the concrete that has passed through the horizontal obstacle bar (34) of the fresh concrete formed, and a horizontal obstacle bar (34) adjacent to the first concrete receiver. ) A concrete separation test apparatus, characterized in that a second concrete receiver (46) for receiving the concrete portion scattered more outwardly from the side is arranged.   A drop opening member (6) is provided so that the movable bottom wall (16) closing the lower surface of the base cylinder portion (14) of the upper and lower double-sided openings can be pulled out to the outside and the concrete drop opening (8) is opened by the pulling. 9. The concrete separation test apparatus according to claim 8, wherein the inner surface of the dropping port member is a straight cylinder shape that does not prevent free fall of concrete or a tapered cylinder shape that expands downward. It is a vibration flow test apparatus used for the measurement of a deformability evaluation index | exponent among the concrete fillability evaluation methods of Claim 1 , Comprising: It mounts on the vibration table (50) with a vibrator (54), and this vibration table. And a concrete loading plate (60) and a fixing means (70) for fixing the concrete loading plate (60) to the vibration table (50). It is configured to be fixed by directly or indirectly tightening and pressing, and the concrete loading plate can be loosely fixed on the vibration table (50) by adjusting the tightening force. , Vibration flow test equipment. The concrete loading plate (60) is wider than the vibration table (50) in at least one of the front, rear, left and right sides thereof, and is a fixed arm that can be protruded to both sides of the vibration table. The fixing means (70) is constituted by (72) and a fastening tool (78) capable of being tightened in a state where the protruding fixed arm and the concrete loading plate (60) are overlapped. 1 0 vibrating flow test apparatus described.

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