JP2015081907A - Workability evaluation method of fresh concrete - Google Patents

Workability evaluation method of fresh concrete Download PDF

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JP2015081907A
JP2015081907A JP2013221571A JP2013221571A JP2015081907A JP 2015081907 A JP2015081907 A JP 2015081907A JP 2013221571 A JP2013221571 A JP 2013221571A JP 2013221571 A JP2013221571 A JP 2013221571A JP 2015081907 A JP2015081907 A JP 2015081907A
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workability
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concrete
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JP6315435B2 (en
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彦次 兵頭
Hikotsugu Hyodo
彦次 兵頭
祐輔 石井
Yusuke Ishii
祐輔 石井
裕二 三谷
Yuji Mitani
裕二 三谷
充 谷村
Mitsuru Tanimura
充 谷村
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Taiheiyo Cement Corp
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PROBLEM TO BE SOLVED: To provide a method of easily and accurately evaluating workability of fresh concrete.SOLUTION: The present invention provides a workability evaluation method of fresh concrete for evaluating the workability of the concrete on the basis of a ratio of a dark part determined by binarizing a digital image of the fresh concrete into the dark part and a bright part. Preferably, the present invention provides the workability evaluation method of fresh concrete that uses, as an index for evaluating the workability of the fresh concrete, the dark part area ratio calculated by an image picking up process (A), a binarization processing process (B), and a dark part area ratio calculation process (C).

Description

本発明は、フレッシュコンクリートのデジタル画像を二値化することによって、該コンクリートの施工性を評価する方法に関する。   The present invention relates to a method for evaluating the workability of concrete by binarizing a digital image of fresh concrete.

フレッシュコンクリートの施工性は、ワーカビリティー、コンシステンシー、および材料分離抵抗性等のフレッシュ性状の各種特性を包含する概念で、通常、スランプ試験により評価されている。該試験は、スランプコーンにフレッシュコンクリートを詰め、突棒で突いて均質化したあと、スランプコーンを引き上げ、コンクリート頂部が沈下した高さを測定するという極めて簡便な方法であり、フレッシュコンクリートの品質管理手法として、長年、多用されてきた。しかし、近年の混和剤技術の進歩や、天然骨材の枯渇による砕砂・砕石の使用等により、同一のスランプを有するコンクリートであっても、施工性が大きく異なる場合があることが知られてきた。また、最近の耐震設計の変更にともなう構造物の過密配筋によりコンクリートの施工の難易度が高くなり、施工性のより適切な評価が求められている。   The workability of fresh concrete is a concept that includes various properties of fresh properties such as workability, consistency, and material separation resistance, and is usually evaluated by a slump test. The test is an extremely simple method in which fresh concrete is packed into slump cones, struck with a stick and homogenized, the slump cones are pulled up, and the height at which the top of the concrete sinks is measured. Quality control of fresh concrete As a technique, it has been used extensively for many years. However, it has been known that the workability may vary greatly even with concrete having the same slump due to the recent progress in admixture technology and the use of crushed sand and crushed stone due to the depletion of natural aggregates. . In addition, due to overcrowding of structures due to recent changes in seismic design, the difficulty of concrete construction increases, and more appropriate evaluation of workability is required.

そこで、フレッシュコンクリートの施工性を評価する方法がいくつか提案されている。
たとえば、JSCE341委員会が提案した「フレッシュコンクリートの加振ボックス充てん試験方法(案)」は、スランプが8〜21cm程度のコンクリートを評価対象として、図1に示すように、ボックス形容器等の充てん装置とバイブレータを用いて、該装置内のA室とB室の間に設置した障害鉄筋の間にコンクリートを通過させて、コンクリートの施工性(充てん性)を評価する方法である。
また、特許文献1では、下記第一および第二の試験方法による判定結果が所定の基準を満たすか否かで、高流動コンクリートの材料分離抵抗性を評価する方法が提案されている。そして、前記第一の試験方法とは、スランプフロー試験後の平坦に拡がったコンクリート供試体に対し、モルタル分の外縁部と、放射方向の端部に位置する所定の粒径以上の粗骨材の重心との距離を計測してその計測値を平均し、かかる平均値が所定の設定値内に収まるか否かを判定する方法である。また、前記第二の試験方法とは、平坦に拡がったコンクリート供試体を環状の外側部分とこれの内側部分とに分割するとともに、所定の粒径以上の粗骨材に対する、コンクリート供試体全体の粗骨材密度と、前記外側部分の粗骨材密度と前記内側部分の粗骨材密度とを求め、これらの粗骨材密度が略等しいか否かを判定する方法である。
Therefore, several methods for evaluating the workability of fresh concrete have been proposed.
For example, the “Fresh Concrete Vibrating Box Filling Test Method (draft)” proposed by the JSCE 341 Committee is intended for filling concrete boxes with slumps of about 8 to 21 cm as shown in FIG. This is a method for evaluating the workability (fillability) of concrete by passing concrete between obstacle rebars installed between room A and room B in the apparatus using the apparatus and vibrator.
Patent Document 1 proposes a method for evaluating the material separation resistance of high-fluidity concrete based on whether or not the determination results by the following first and second test methods satisfy a predetermined standard. And said 1st test method is the coarse aggregate more than the predetermined particle diameter located in the outer edge part for a mortar, and the edge part of a radial direction with respect to the concrete test piece expanded flatly after the slump flow test. This is a method of measuring the distance from the center of gravity and averaging the measured values and determining whether or not the average value falls within a predetermined set value. In addition, the second test method is to divide a flat concrete specimen into an annular outer part and an inner part thereof, and to measure the whole concrete specimen against coarse aggregate having a predetermined particle size or more. In this method, the coarse aggregate density, the coarse aggregate density of the outer portion, and the coarse aggregate density of the inner portion are obtained, and it is determined whether or not these coarse aggregate densities are substantially equal.

また、特許文献2では、同一材料を用いた分離していないフレッシュな普通コンクリートと、フレッシュな高流動コンクリートとの表面を色差測定することにより、高流動コンクリートの分離状態を評価する方法が提案されている。
さらに、特許文献3では、筒状のタンク部と、仕切板によって前記タンク部の下部と区画された所定の傾きの傾斜フロー部とを備えた傾斜フロー試験器の前記タンク部に、未硬化のフレッシュコンクリートの試料を所定の高さまで詰め込み、前記仕切板を開放して前記傾斜フロー部に前記試料を流下させ、その際の前記試料の流下速度を測定して該試料のワーカビリティーを評価する方法が提案されている。
しかし、前記の方法はいずれも、特別な試験装置が必要であることに加え、一般に行われるスランプ試験と比べ格段に手間がかかる。
Further, Patent Document 2 proposes a method for evaluating the separation state of high-fluidity concrete by measuring the color difference between the surface of fresh plain concrete that is not separated using the same material and fresh high-fluidity concrete. ing.
Further, in Patent Document 3, an uncured tank portion of an inclined flow tester including a cylindrical tank portion and an inclined flow portion having a predetermined inclination partitioned from a lower portion of the tank portion by a partition plate is uncured. A method for evaluating the workability of the sample by filling a sample of fresh concrete to a predetermined height, opening the partition plate, causing the sample to flow down to the inclined flow part, and measuring the flow rate of the sample at that time Proposed.
However, all of the above methods require a special test apparatus, and require much more labor than a generally performed slump test.

特開平10−267921号公報Japanese Patent Laid-Open No. 10-267921 特開平11−264794号公報Japanese Patent Laid-Open No. 11-264794 特開2004−069363号公報JP 2004-0669363 A

そのため、本発明は、特別な試験装置を使用することなく、フレッシュコンクリートの施工性を簡便かつ精度よく評価できる方法を提供することを目的とする。     Therefore, an object of this invention is to provide the method which can evaluate the workability of fresh concrete simply and accurately, without using a special test apparatus.

本発明者らは、前記目的にかなう評価方法について試行錯誤を重ねた結果、スランプ試験後のフレッシュコンクリートの明部および暗部の割合と施工性に一定の関係があること、具体的には、暗部が多いほど施工性が低下することを見い出した。
しかし、明暗を施工性の評価指標に用いる場合、明暗の目視観察では、観察する人の主観に大きく左右されるため評価は定性的にならざるを得ず、評価の信頼性は低いと云える。
そこで、本発明者らは、フレッシュコンクリートのデジタル画像を用いて二値化処理を行いフレッシュコンクリートの明部と暗部を分離し、明部と暗部の割合を定量化すると評価精度が向上することを見い出し、本発明を完成させた。
As a result of repeated trial and error on the evaluation method for the purpose, the present inventors have a certain relationship between the ratio of bright and dark parts of the fresh concrete after the slump test and workability, specifically, the dark part. We found that the greater the amount, the lower the workability.
However, when using light and dark as an evaluation index for workability, the visual evaluation of light and dark depends greatly on the subjectivity of the person being observed, so the evaluation must be qualitative and the reliability of the evaluation can be said to be low. .
Therefore, the present inventors have performed a binarization process using a digital image of fresh concrete to separate the bright and dark portions of the fresh concrete and quantify the ratio of the bright and dark portions to improve the evaluation accuracy. Discovered and completed the present invention.

すなわち、本発明は下記の構成を有するフレッシュコンクリートの施工性評価方法である。
[1]フレッシュコンクリートのデジタル画像を暗部と明部に二値化して求めた暗部の割合に基づき、該コンクリートの施工性を評価することを特徴とするフレッシュコンクリートの施工性評価方法。
[2]下記(A)〜(C)工程を経て算出した暗部面積率を、フレッシュコンクリートの施工性を評価するための指標として用いる、前記[1]に記載のフレッシュコンクリートの施工性評価方法。
(A)スランプ試験においてスランプコーンを引き上げた後のフレッシュコンクリートを、デジタルカメラを用いて撮影して画像を得る、画像撮影工程
(B)前記画像をグレースケールに変換してデジタル化して得た輝度に基づき閾値を定め、該閾値に基づき該画像を暗部と明部に二値化する、二値化処理工程
(C)前記暗部の面積と明部の面積に基づき、下記(1)式を用いてコンクリートの暗部面積率を算出する、暗部面積率算出工程
暗部面積率=100×暗部の面積/(暗部の面積+明部の面積) ・・・(1)
[3]前記二値化処理工程において、下記(2)式のクラス間分散/クラス内分散の比が最大になるt値を前記閾値と定める、前記[1]または[2]に記載のフレッシュコンクリートの施工性評価方法。
That is, the present invention is a method for evaluating the workability of fresh concrete having the following configuration.
[1] A method for evaluating the workability of fresh concrete, wherein the workability of the concrete is evaluated based on the ratio of the dark part obtained by binarizing a digital image of the fresh concrete into a dark part and a bright part.
[2] The method for evaluating the workability of fresh concrete according to [1], wherein the dark area ratio calculated through the following steps (A) to (C) is used as an index for evaluating the workability of fresh concrete.
(A) A fresh concrete after lifting the slump cone in the slump test is photographed using a digital camera to obtain an image. (B) Luminance obtained by digitizing the image by converting it to a gray scale. A threshold value is determined based on the threshold value, and the image is binarized into a dark part and a bright part based on the threshold value. (C) Based on the area of the dark part and the area of the bright part, the following equation (1) is used. The dark area ratio calculation step for calculating the dark area ratio of the concrete. Dark area ratio = 100 × area of dark area / (area of dark area + area of bright area) (1)
[3] The fresh according to [1] or [2], wherein, in the binarization processing step, a t value that maximizes a ratio of interclass variance / intraclass variance in the following equation (2) is defined as the threshold value. Concrete workability evaluation method.

Figure 2015081907
Figure 2015081907

本発明のフレッシュコンクリートの施工性評価方法を用いれば、フレッシュコンクリートの施工性を特別な試験装置を用いることなく、簡便かつ精度よく評価できる。   If the method for evaluating the workability of fresh concrete according to the present invention is used, the workability of fresh concrete can be easily and accurately evaluated without using a special test apparatus.

上図はスランプコーンを引き上げた後のコンクリート頂部の画像をグレースケールに変換した画像であり、下図は該画像をデジタル化して得た輝度の一部を示す画像である。The upper figure is an image obtained by converting the image of the concrete top after the slump cone is raised to gray scale, and the lower figure is an image showing a part of the luminance obtained by digitizing the image. 輝度とその頻度を示すグラフであって、自動二値化処理により暗部と明部に分けたグラフである。It is a graph which shows a brightness | luminance and its frequency, Comprising: It is a graph divided into the dark part and the bright part by the automatic binarization process. JSCE321委員会が提案した「フレッシュコンクリートの加振ボックス充てん試験方法(案)」における、ボックス形容器の使用態様を示す図である。It is a figure which shows the usage condition of a box-shaped container in the "exciting box filling test method (plan) of fresh concrete" proposed by the JSCE321 committee. 本発明により求めた暗部面積率と、前記「フレッシュコンクリートの加振ボックス充てん試験方法(案)」により求めた、A室とB室の粗骨材量変化率の平均値(以下「平均粗骨材量変化率」という。)との間の相関性を示す図である。The dark area ratio determined according to the present invention and the average value of the change rate of coarse aggregate amount in room A and room B (hereinafter referred to as “average coarse bone” determined by the above-mentioned “examination box filling test method for fresh concrete (draft)”). It is a figure which shows correlation with "material amount change rate".).

本発明は、フレッシュコンクリートのデジタル画像を暗部と明部に二値化して求めた暗部の割合に基づき、該コンクリートの施工性を評価するフレッシュコンクリートの施工性評価方法である。
また、本発明が対象とする前記フレッシュコンクリートは、好ましくは、スランプ試験においてスランプコーンを引き上げた後のフレッシュコンクリートであり、該コンクリートのスランプは、好ましくは4〜18cm、より好ましくは5〜16cmである。スランプコーンを引き上げた後のフレッシュコンクリートのスランプが4〜18cmであれば、評価の精度がより高くなる。
また、本発明は、好ましくは、(A)画像撮影工程、(B)二値化処理工程、および(C)暗部面積率算出工程を経て算出した暗部面積率を、フレッシュコンクリートの施工性を評価するための指標として用いる方法である。
以下、(A)画像撮影工程、(B)二値化処理工程、および(C)暗部面積率算出工程に分けて詳細に説明する。
The present invention is a workability evaluation method for fresh concrete in which the workability of the concrete is evaluated based on the ratio of dark parts obtained by binarizing a digital image of fresh concrete into dark parts and bright parts.
The fresh concrete targeted by the present invention is preferably fresh concrete after the slump cone is pulled up in the slump test, and the slump of the concrete is preferably 4 to 18 cm, more preferably 5 to 16 cm. is there. If the slump of fresh concrete after pulling up the slump cone is 4 to 18 cm, the accuracy of evaluation becomes higher.
In the present invention, preferably, the dark area ratio calculated through (A) the image photographing process, (B) the binarization processing process, and (C) the dark area ratio calculation process is used to evaluate the workability of the fresh concrete. It is a method used as an index for
Hereinafter, it will be described in detail by dividing into (A) an image photographing step, (B) a binarization processing step, and (C) a dark area ratio calculation step.

(A)画像撮影工程
該工程は、スランプ試験においてスランプコーンを引き上げた後のフレッシュコンクリートを、デジタルカメラを用いて撮影して画像を得る工程である。
前記スランプ試験は、例えば、JIS A 1101 「コンクリートのスランプ試験方法」に準拠して行うとよい。また、前記スランプコーンは、上端の内径が100mm、下端の内径が200mm、高さが300mm、および厚さが5mm以上の金属製のものが好ましい。
スランプコーンを引き上げた後の、コンクリート頂部側からの画像の一例を図1に示す。暗部が多いほど、コンクリートの施工性は低下する傾向にある。
また、前記デジタルカメラは特に制限されず、市販のデジタルカメラで十分である。
(A) Image photographing step This step is a step of obtaining an image by photographing the fresh concrete after lifting the slump cone in the slump test using a digital camera.
The slump test may be performed in accordance with, for example, JIS A 1101 “Concrete slump test method”. The slump cone is preferably made of metal having an inner diameter of 100 mm at the upper end, an inner diameter of 200 mm at the lower end, a height of 300 mm, and a thickness of 5 mm or more.
FIG. 1 shows an example of an image from the concrete top side after the slump cone is pulled up. The more dark parts, the lower the concrete workability.
The digital camera is not particularly limited, and a commercially available digital camera is sufficient.

(B)二値化処理工程
該工程は、前記画像をグレースケールに変換してデジタル化して得た輝度に基づき閾値を定め、該閾値に基づき該画像を暗部と明部に二値化する工程である。
グレースケールへの変換は、例えば。アドビ社のフォトショップ(登録商標)等の市販のソフトウェアを用いて行うことができる。なお、図1に、コンクリート頂部側からの画像をデジタル化して得た輝度の一例を示す。
また、本発明において画像を暗部と明部に二値化する方法は、例えば判別識別法が挙げられる。該方法は、分離度を大きくする観点から、前記(2)式のクラス間分散/クラス内分散の比が最大になるt値を求め、図2に示すように、該t値を前記暗部と明部に二値化するための輝度の閾値(中央の線で示す。)として用いる方法である。なお、前記(2)式中のクラス間分散は前記(3)式に、クラス内分散は前記(4)式に示す。また、前記(4)式中のクラス1の分散は前記(5)式に、クラス2の分散は前記(6)式に示す。
また、本発明において二値化する方法は、前記判別識別法のほかに、モード法、Kittler法、3σ法、およびP−タイル法等を用いてもよい。
(B) Binarization processing step This step is a step of determining a threshold value based on the luminance obtained by converting the image into a gray scale and digitizing, and binarizing the image into a dark part and a bright part based on the threshold value. It is.
For example, conversion to grayscale. This can be done using commercially available software such as Adobe Photoshop (registered trademark). In addition, in FIG. 1, an example of the brightness | luminance obtained by digitizing the image from the concrete top side is shown.
In the present invention, a method for binarizing an image into a dark part and a bright part includes, for example, a discrimination identification method. From the viewpoint of increasing the degree of separation, the method obtains a t value that maximizes the ratio of inter-class variance / intra-class variance in the equation (2), and, as shown in FIG. This is a method used as a luminance threshold value (indicated by the center line) for binarizing the bright part. The interclass variance in the equation (2) is shown in the equation (3), and the intraclass variance is shown in the equation (4). The class 1 variance in the formula (4) is shown in the formula (5), and the class 2 variance is shown in the formula (6).
Further, in the present invention, the binarization method may use a mode method, a Kittler method, a 3σ method, a P-tile method, or the like in addition to the discrimination / identification method.

(C)暗部面積率算出工程
該工程は、前記暗部の面積と明部の面積に基づき、前記(1)式を用いてコンクリートの暗部面積率を算出する工程である。この暗部面積率が高いほど、図4に示すように、フレッシュコンクリートの施工性は低下する。
(C) Dark part area ratio calculation process This process is a process of calculating the dark part area ratio of the concrete using the formula (1) based on the area of the dark part and the area of the bright part. The higher the dark area ratio, the lower the workability of fresh concrete as shown in FIG.

以下、本発明を実施例により説明するが、本発明は該実施例に限定されない。
〔コンクリートの施工性評価試験〕
表1に記載の材料を用いて表2に記載の配合に従い、JIS A 1138「試験室におけるコンクリートの作り方」に準拠してフレッシュコンクリートを調製した。そして、該コンクリートを用いてJIS A 1101「コンクリートのスランプ試験方法」に準拠してスランプ試験を行い、コンクリート頂部側からデジタルカメラを用いて撮影して図1の画像を得た。
次に、エクセルソフト「Image Processing」を用いて、前記画像をグレースケールに変換してデジタル化し輝度を得た(図1下)。そして、該輝度を用いて前記判別識別法により輝度の閾値(90)を求めた後、該閾値に基づき暗部と明部に分け、各面積を求めて前記(1)式により暗部面積率を算出した。また、比較のため、「フレッシュコンクリートの加振ボックス充てん試験方法(案)」に従い、ボックス形容器(図3)を用いて、A室とB室の平均粗骨材量変化率を求めた。前記暗部面積率と平均粗骨材量変化率を表2に、また、前記暗部面積率と平均粗骨材量変化率の相関性を図4に示す。
図4から分かるように、前記暗部面積率と平均粗骨材量変化率は、スランプが8cmと15cmのいずれのフレッシュコンクリートにおいても高い相関を示している。したがって、本発明のフレッシュコンクリートの施工性評価方法を用いれば、フレッシュコンクリートの施工性を簡便かつ精度よく評価することができる。
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to this Example.
[Concrete workability evaluation test]
Using the materials listed in Table 1, fresh concrete was prepared according to JIS A 1138 “How to make concrete in a laboratory” in accordance with the formulation described in Table 2. Then, a slump test was performed using the concrete in accordance with JIS A 1101 “Concrete slump test method”, and a digital camera was used to capture the image shown in FIG.
Next, using Excel software “Image Processing”, the image was converted to gray scale and digitized to obtain luminance (lower part of FIG. 1). Then, after obtaining the luminance threshold (90) by the discrimination / identification method using the luminance, it is divided into a dark part and a bright part based on the threshold, and each area is obtained and the dark part area ratio is calculated by the equation (1). did. For comparison, the average coarse aggregate amount change rate of the A room and the B room was determined using a box-shaped container (FIG. 3) according to the “fresh concrete vibration box filling test method (draft)”. The dark area ratio and the average coarse aggregate amount change rate are shown in Table 2, and the correlation between the dark area ratio and the average coarse aggregate amount change rate is shown in FIG.
As can be seen from FIG. 4, the dark area ratio and the average coarse aggregate amount change rate show a high correlation in the fresh concrete having slumps of 8 cm and 15 cm. Therefore, if the method for evaluating the workability of fresh concrete according to the present invention is used, the workability of fresh concrete can be easily and accurately evaluated.

Figure 2015081907
Figure 2015081907

Figure 2015081907
Figure 2015081907

Claims (3)

フレッシュコンクリートのデジタル画像を暗部と明部に二値化して求めた暗部の割合に基づき、該コンクリートの施工性を評価することを特徴とするフレッシュコンクリートの施工性評価方法。   A method for evaluating the workability of fresh concrete, wherein the workability of the concrete is evaluated based on the ratio of the dark part obtained by binarizing a digital image of the fresh concrete into a dark part and a bright part. 下記(A)〜(C)工程を経て算出した暗部面積率を、フレッシュコンクリートの施工性を評価するための指標として用いる、請求項1に記載のフレッシュコンクリートの施工性評価方法。
(A)スランプ試験においてスランプコーンを引き上げた後のフレッシュコンクリートを、デジタルカメラを用いて撮影して画像を得る、画像撮影工程
(B)前記画像をグレースケールに変換してデジタル化して得た輝度に基づき閾値を定め、該閾値に基づき該画像を暗部と明部に二値化する、二値化処理工程
(C)前記暗部の面積と明部の面積に基づき、下記(1)式を用いてコンクリートの暗部面積率を算出する、暗部面積率算出工程
暗部面積率=100×暗部の面積/(暗部の面積+明部の面積) ・・・(1)
The method for evaluating the workability of fresh concrete according to claim 1, wherein the dark area ratio calculated through the following steps (A) to (C) is used as an index for evaluating the workability of fresh concrete.
(A) A fresh concrete after lifting the slump cone in the slump test is photographed using a digital camera to obtain an image. (B) Luminance obtained by digitizing the image by converting it to a gray scale. A threshold value is determined based on the threshold value, and the image is binarized into a dark part and a bright part based on the threshold value. (C) Based on the area of the dark part and the area of the bright part, the following equation (1) is used. The dark area ratio calculation step for calculating the dark area ratio of the concrete. Dark area ratio = 100 × area of dark area / (area of dark area + area of bright area) (1)
前記二値化処理工程において、下記(2)式のクラス間分散/クラス内分散の比が最大になるt値を前記閾値と定める、請求項1または2に記載のフレッシュコンクリートの施工性評価方法。
Figure 2015081907
The method for evaluating the workability of fresh concrete according to claim 1 or 2, wherein in the binarization processing step, a t value that maximizes the ratio of inter-class variance / intra-class variance in the following equation (2) is defined as the threshold value. .
Figure 2015081907
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