JP2011075528A - Composition estimation method of concrete hardened body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition estimation method of a concrete hardened body capable of estimating composition accurately even in the case of the concrete hardened body including a limestone aggregate, fly ash or the like, and estimating the composition by a simple operation. <P>SOLUTION: In this composition estimation method of the concrete hardened body, a multi-valued image of the concrete hardened body is subjected to binarization processing by using a threshold for aggregate amount estimation, and an estimation value of a unit aggregate amount is calculated based on expression (1) from an aggregate area ratio calculated from an acquired binarization-processed image. In the expression (1), V<SB>agg</SB>is the 'aggregate area ratio (%)'. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for estimating the blend of a hardened concrete.

  It is necessary to estimate the mix of the hardened concrete in order to check the quality of the placed concrete and diagnose the durability of the concrete structure. In particular, the unit water amount is one of the factors affecting the quality such as the strength of the concrete placed together with the unit cement amount in the blended hardened concrete.

  Therefore, for example, when cracks or the like occur in a hardened concrete body such as a concrete structure, it is caused by a decrease in compressive strength due to poor blending, or due to a decrease in compressive strength due to deterioration over time. In order to judge whether it is what to do, it is necessary to estimate correctly the mixing | blending of a concrete hardening body.

  Conventionally, as a method of estimating the mixing ratio of a hardened concrete body, after treating a sample obtained by pulverizing a hardened concrete body to a predetermined particle size with hydrochloric acid, insoluble residue and calcium oxide are quantified, and the unit aggregate is used as an index. A method for estimating the amount and unit cement amount (see Non-Patent Document 1), a method in which a sample obtained by pulverizing a hardened concrete to a predetermined particle size is dissolved in sodium gluconate, and the unit cement amount is estimated from the dissolved amount (non- Patent Document 2) has been proposed.

"Concrete Technical Committee Report F-18 Joint Test Report on Estimating Compounding of Hardened Concrete," Cement Association, September 1967 "Method for testing the amount of cement in effect concrete with sodium gluconate", Japan Nondestructive Inspection Association Standard, NDIS-3422, 2002

  However, as described in detail below, the method described in Non-Patent Document 1 has a problem in that the accuracy of the blend estimated value is low and the reliability is lacking.

  That is, in the method described in Non-Patent Document 1, a concrete sample containing a limestone aggregate that can be dissolved in hydrochloric acid is obtained by dissolving a concrete sample in 0.1N hydrochloric acid and using a residue obtained by filtration as an aggregate amount. There exists a problem that it cannot apply to a hardening body.

  In addition, in the above method, the air volume cannot be estimated because it is not possible to distinguish between the void generated due to the hydration reaction and the entrapped air. Therefore, there is concern that the unit water amount may be overestimated or underestimated.

  Furthermore, since the unit water amount is estimated by subtracting the unit amount of the other compounding material from the unit volume mass of the hardened concrete body, the estimated unit water amount includes an error with respect to the unit amount of the other compounding material. There is a problem that the estimation accuracy is low.

  On the other hand, the method described in Non-Patent Document 2 can be applied to a hardened concrete containing limestone aggregate or the like in order to dissolve the pulverized concrete in sodium gluconate. In addition to the necessity, there is a problem that sodium gluconate has a high viscosity and takes time for filtration.

  In view of such problems, the present invention is capable of accurately estimating the blending of a hardened concrete containing limestone aggregate, and capable of estimating the blending by a simple operation. An object of the present invention is to provide a method for estimating the formulation of

  In order to solve the above-mentioned problem, the present invention is a method for estimating the blending of a hardened concrete body, wherein the multi-valued image of the hardened concrete body is binarized using an aggregate amount estimation threshold, A combination estimation method is provided, wherein a unit aggregate amount estimated value is calculated based on the following formula (1) from the aggregate area ratio calculated from the obtained binarized image (claim 1). ).

式（１）中、Ｖ_ａｇｇは「骨材面積率（％）」を表す。

In formula (1), V _agg represents “aggregate area ratio (%)”.

  According to the above invention (Invention 1), it is not necessary to dissolve the hardened concrete in a solvent such as hydrochloric acid or sodium gluconate, and the unit bone is obtained from the binarized image of the multi-valued image obtained by imaging the hardened concrete. Since the amount of material can be calculated, it is possible to accurately and easily estimate the blend of the hardened concrete body regardless of the type of aggregate, admixture, etc. contained in the hardened concrete body. In the present specification, the “multi-valued image” means an image in which the gradation of each pixel in the image is greater than 2, and includes, for example, a 256-gradation color image or a monochrome image.

  Further, the present invention is a method for estimating the blending of a hardened concrete body, wherein the multivalued image of the hardened concrete body is binarized using an air amount estimation threshold, and the obtained binarization process An area ratio of an entrapment air portion extracted from an image based on an entrapment air portion determination parameter is calculated, and the obtained area ratio is estimated as an air amount in the hardened concrete body. (Claim 2).

  According to the above invention (invention 2), the amount of air that could not be estimated by the conventional method can be estimated from the binarized image of the multi-valued image obtained by imaging the hardened concrete body. It is possible to accurately estimate the mixture of the hardened concrete.

  In the above invention (invention 2), the substantially circular portion displayed on the lower luminance side than the unhydrated cement portion, the cement hydrate portion, and the aggregate portion in the multi-valued image is an image of the entrapment air portion. It is preferable to extract as (Claim 3).

  The entrapment air portion in the hardened concrete body is displayed as a substantially circular portion on the lower luminance side than the unhydrated cement portion, cement hydrate portion and aggregate portion on the image. According to 3), since the space | gap part and entrapped air part in a hardened concrete body can be distinguished clearly, the air quantity of a hardened concrete body can be estimated more correctly.

  In the above inventions (inventions 2 and 3), the entrapment air portion determination parameter is a circular power or a circle-equivalent diameter, and based on the circular power or a circle-equivalent diameter, It is preferable to extract an image of the entrapment air portion.

  Some of the nearly circular particles in the binarized image are cracks generated in the hardened concrete and voids caused by cement hydration, etc., and these cracks and voids are extracted as entrapped air parts. If it does, there is a possibility that the estimation accuracy of the air amount and the estimation accuracy of the unit water amount, which will be described later, may be lowered. On the other hand, the air bubbles (entrapped air) contained in the hardened concrete body are substantially circular particles as a circular particle. According to the above invention (Claim 4), since it is represented on the image, it is possible to distinguish a crack, a void portion, and an entrapped air portion from the binarized image based on the circular power or the equivalent circle diameter. Therefore, the air amount can be estimated more accurately.

  Furthermore, the present invention is a method for estimating the blend of a hardened concrete body, wherein the multivalued image of the hardened concrete body is binarized using a threshold value for water cement ratio estimation, and from the binarized image. Provided is a composition estimation method characterized by calculating a water cement ratio estimated value based on the following formula (2) from the calculated unhydrated cement area ratio, void area ratio, and cement hydrate area ratio ( Claim 5).

式（２）中、Ｖ_Ｗは「水体積率（％）」を、Ｖ_Ｃは「初期セメント体積率（％）」を、Ｖ_ＨＰは「セメント水和物面積率（％）」を、δ_Ｖは「セメントの水和膨張係数」を、Ｖ_ＣＰは「空隙面積率（％）」を、Ｖ_ＡＨは「未水和セメント面積率（％）」を、ρ_Ｃは「セメントの密度（ｇ／ｃｍ^３）」を表す。

In Formula (2), V _W is “water volume fraction (%)”, V _C is “initial cement volume fraction (%)”, V _HP is “cement hydrate area ratio (%)”, δ _V is “cement hydration expansion coefficient”, V _CP is “void area ratio (%)”, V _AH is “unhydrated cement area ratio (%)”, and ρ _C is “cement density (g / Cm ³ ) ”.

  According to the above invention (invention 5), it is not necessary to dissolve the hardened concrete in a solvent such as hydrochloric acid or sodium gluconate, and from the image obtained by binarizing the multi-valued image obtained by imaging the hardened concrete, water cement Since the ratio can be calculated, the mixture of the hardened concrete body can be accurately and easily estimated regardless of the types of aggregates and admixtures contained in the hardened concrete body.

  Furthermore, the present invention is a method for estimating the blend of a hardened concrete body, and from the unhydrated cement area ratio calculated by the blend estimation method according to the above invention (invention 5), the following formula (3) The initial cement volume fraction is calculated based on the above, the aggregate area ratio calculated in the blend estimation method according to the invention (Claim 1), and calculated in the blend estimation method according to the invention (Claims 2 to 4). Further, the present invention provides a blending estimation method characterized in that a unit cement amount estimated value is calculated based on the following formula (4) from the area ratio of the entrapment air portion and the initial cement volume ratio (Claim 6).

式（３）中、Ｖ_Ｃは「初期セメント体積率（％）」を、Ｖ_ＡＨは「未水和セメント面積率（％）」を、Ｖ_ＨＰは「セメント水和物面積率（％）」を、δ_Ｖは「水和膨張係数」を表し、式（４）中、Ｖ_ａｇｇは「骨材面積率（％）」を、Ｖ_ａｉｒは「エントラップトエア部分の面積率（％）」を、Ｖ_Ｃは「初期セメント体積率（％）」を、ρ_Ｃは「セメント密度（ｇ／ｃｍ^３）」を表す。

Wherein (3), _{V C} is the "initial cement volume ratio (%)" _{a, V AH} is "Mimizuwa cement area ratio (%)" _{a, V HP} is "cement hydrate area ratio (%)" Δ _V represents “hydration expansion coefficient”, and in formula (4), V _agg represents “aggregate area ratio (%)”, and V _air represents “area ratio of entrapped air part (%)”. , V _C represents “initial cement volume fraction (%)”, and ρ _C represents “cement density (g / cm ³ )”.

  According to the above invention (invention 6), it is not necessary to dissolve the hardened concrete in a solvent such as hydrochloric acid or sodium gluconate, and the unit cement is obtained from the binarized image of the multi-valued image obtained by imaging the hardened concrete. Since the amount can be calculated, the mixture of the hardened concrete can be estimated accurately and easily regardless of the type of aggregate or admixture contained in the hardened concrete.

  In addition, the present invention is a method for estimating the blending of a hardened concrete body, the water cement ratio estimated value calculated by the blending estimation method according to the above invention (invention 5), and the above invention (invention 6). From the unit cement amount estimated value calculated by the blending estimation method, a unit water amount estimated value is calculated based on the following formula (5) (claim 7).

  According to the above invention (invention 7), it is not necessary to dissolve the hardened concrete in a solvent such as hydrochloric acid or sodium gluconate, and the unit water amount is obtained from the binarized image of the multi-valued image obtained by imaging the hardened concrete. Therefore, regardless of the types of aggregates and admixtures contained in the hardened concrete body, it is possible to accurately and easily estimate the mixture of the hardened concrete body.

  In the said invention (inventions 1-7), it is preferable that the said multi-value image is a multi-value image which imaged one surface of the test piece obtained by cut | disconnecting the said concrete hardening body to a predetermined | prescribed magnitude | size. (Claim 8).

  According to the said invention (invention 8), mixing | blending can be estimated using some concrete hardened bodies, such as a concrete structure, as a sample piece.

  In the said invention (invention 8), it is preferable that the said multi-value image is a multi-value image which image | photographed one surface of the polished said test piece (invention 9). According to this invention (invention 9), it is possible to estimate the mixture of the concrete hardened body more accurately by polishing the imaging surface.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a hardened concrete body containing a limestone aggregate, while being able to estimate a mixing | blending correctly, the mixing estimation method of the hardened concrete body which can estimate a mixing | blending by simple operation is provided. be able to.

It is a flowchart which shows the preparation process of the test piece in the mixing | blending estimation method of the hardened concrete body which concerns on one Embodiment of this invention. It is a flowchart which shows the unit aggregate amount estimation process in the embodiment. It is a flowchart which shows the air quantity estimation process in the embodiment. It is a flowchart which shows the water cement ratio in the same embodiment, a unit cement amount, and a unit water amount estimation process.

Hereinafter, the concrete estimation method of a hardened concrete according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a flowchart showing a test piece preparation step in the method for estimating the mixture of hardened concrete according to the present embodiment, and FIG. 2 is a flowchart showing a unit aggregate amount estimating step in the same embodiment. These are the flowcharts which show the air quantity estimation process in the same embodiment, and FIG. 4 is a flowchart which shows the water cement ratio, unit cement quantity, and unit water quantity estimation process in the same embodiment.

(Preparation of test piece)
As a method of preparing a blend estimation test piece used in the blend concrete estimation method according to the present embodiment, as shown in FIG. 1, first, a part of the concrete cured body to be blended is sampled. (S101).

  Examples of the hardened concrete body to be blended and estimated in the present embodiment include, but are not limited to, a foundation part of a reinforced concrete structure, a tunnel lining, a bridge girder, and the like.

  The cement contained in the hardened concrete is not particularly limited. For example, various Portland cements such as ordinary Portland cement, early-strength Portland cement, moderately hot Portland cement, low heat Portland cement; Or the cement (eco-cement) etc. which consist of the pulverized material and gypsum of the baked material manufactured using the sewage sludge incineration ash as a raw material are mentioned.

  The type of aggregate contained in the hardened concrete body is not particularly limited, and may be natural aggregate or artificial aggregate. For example, sand, gravel, crushed sand, crushed stone Silica sand or the like can be used, and it can be applied to a concrete concrete body including limestone aggregate. The particle size of the aggregate is not particularly limited, but considering the size of the test piece used in the composition estimation method according to the present embodiment, the maximum size of the aggregate is about 20 mm. Is preferred.

  Furthermore, the above-mentioned hardened concrete may contain an admixture used in the production of ordinary concrete. For example, water reducing agents such as lignin, naphthalene sulfonic acid, melamine, and polycarboxylic acid. , An AE water reducing agent, a high performance water reducing agent, a high performance AE water reducing agent, an AE agent (air amount adjusting agent), a condensation adjusting agent, a rust preventive agent and the like may be contained.

  When a part of the hardened concrete body is collected, it may be collected from any part of the hardened concrete body, but it is preferably collected from a healthy part of the hardened concrete body. By collecting from the healthy part, it is possible to estimate the blending with higher accuracy.

  When a part of the hardened concrete is collected, the amount to be collected may be very small. Specifically, the length is 2 cm × width 3 cm × thickness 1.5 cm to length 10 cm × width 10 cm × thickness 1. The size may be about 5 cm. If it is a magnitude | size of this grade, mixing | blending estimation with sufficient high precision will be attained.

A portion of the hardened concrete body thus collected is cut into a predetermined size (S102). As the size of the test piece after cutting, for example, the size of the imaging surface of the test piece may be about 6 to 100 cm ² , and preferably about 36 to 100 cm ² .

  Next, the cut specimen is dried (S103). If water is contained in the voids or the like in the test piece collected from the hardened concrete body, there is a possibility that the resin cannot sufficiently flow into the voids or the like in the test piece in the resin impregnation (S104) step described later. However, by drying the test piece, it is possible to remove moisture contained in the voids and the like, and it is possible to estimate the blending with higher accuracy.

  The method for drying the test piece is not particularly limited, and may be performed by a conventional method, for example, by a method such as vacuum drying, heat drying, freeze drying, or the like.

  Subsequently, the dried test piece is impregnated with a predetermined resin (S104). By impregnating the test piece with the resin, the resin enters the void portion or the like in the test piece, so that the void portion can be accurately extracted at the time of image processing (binarization processing) in each estimation process described later. become.

  Examples of the resin impregnated with the test piece include an epoxy resin, an acrylic resin, a polyester resin, a methacrylic resin, and the like, and the stretchability when the resin is cured is preferably low shrinkage, The viscosity of the resin is preferably 200 cP or less. If the viscosity of the resin exceeds 200 cP, it may be difficult to flow the resin into the voids in the test piece.

  The resin impregnating the test piece is preferably colored by kneading an opaque resin pigment or the like. By kneading the pigment, it is possible to accurately determine the aggregate and the void in the unit aggregate amount estimation step described later.

  After drying the test piece impregnated with the predetermined resin to cure the resin, the imaging surface of the test piece is polished (S105). When the resin impregnated with the test piece is cured on the imaging surface of the test piece, the imaging surface becomes uneven, and if the imaging surface is imaged as it is, shadows due to the unevenness appear on the image, thereby Although the mixing | blending estimation precision of a hardened concrete body will fall, the mixing | blending of a hardened concrete body can be estimated with high precision by grind | polishing the said imaging surface.

  The method for polishing the imaging surface of the test piece is not particularly limited, and may be performed using a commonly used polishing apparatus. Examples of the abrasive that can be used in the polishing step include, but are not limited to, silicon carbide abrasive, boron carbide abrasive, diamond paste, and alumina powder. Moreover, the average particle size of these abrasives should just be about 8-60 micrometers.

  As will be described later, when a reflected electron image is to be obtained using an electron microscope as an imaging device for a test piece, the surface of the test piece polished using the above-described abrasive is used as an abrasive. Buffing using an alumina powder having a particle diameter of 0.3 to 3 μm or the like is preferably further performed.

  Finally, a vapor deposition film is formed on the surface of the test piece whose imaging surface is polished, and conductivity is imparted to the test piece (S106). As will be described later, at least in the air amount estimation step (FIG. 3) and the water cement ratio, unit cement amount and unit water amount estimation step (FIG. 4), the reflected electron image of the scanning electron microscope image of the test piece is obtained. Will get. However, since concrete does not have electrical conductivity, when attempting to acquire a reflected electron image without forming a deposited film on the test piece, the surface of the test piece is charged by continuing to irradiate the electron beam, and the reflected electrons The pattern is disturbed, and an accurate reflected electron image cannot be acquired. Therefore, an accurate reflected electron image can be acquired by forming a vapor deposition film having conductivity on the surface of the test piece.

  Although it does not specifically limit as said vapor deposition film as long as electroconductivity can be provided to the surface of a test piece, For example, carbon, platinum palladium, gold | metal | money etc. are mentioned. Moreover, it does not specifically limit as a method of forming a vapor deposition film, It can carry out by a conventionally well-known method.

[Unit aggregate amount estimation process]
In this embodiment, in order to estimate the unit aggregate amount of the hardened concrete body, as shown in FIG. 2, first, a color image (multi-valued image) of the imaging surface of the test piece prepared by the above-described test piece preparation step. ) Is acquired (S201).

  Examples of the method of acquiring the color image include a method of photographing the imaging surface of the test piece with a digital camera or the like, a method of acquiring a color image of the imaging surface of the test piece using a scanner, and the like. It is not limited.

  The resolution of the color image to be acquired is preferably 600 to 2400 dpi, and more preferably 800 to 1200 dpi. If the resolution is less than 600 dpi, it may be difficult to determine the interface between the aggregate portion and the cement paste portion in the image. If the resolution exceeds 2400 dpi, it may take a long time for image processing or a commercially available image processing software. There is a risk that it will not be possible.

  Next, a process of removing noise from the acquired color image is performed (S202). Examples of the process for removing noise include a process for applying a moving average filter, a median filter, and the like to a color image.

  The color image from which noise has been removed as described above is binarized to obtain a first binarized image (S203). The binarization process uses a luminance difference or brightness difference between the aggregate portion and the cement paste portion in the color image from which noise has been removed to set a threshold value that can distinguish the aggregate portion and the cement paste portion. It can be set appropriately. Thereby, the aggregate part and the cement paste part can be clearly distinguished on the first binarized image.

  On the other hand, the color image acquired in S201 is subjected to monochrome conversion by a conventional method to acquire a monochrome image (S204), and then the noise of the monochrome image is removed (S205). The process for removing the noise may be the same as the process for removing the noise of the color image (S202).

  The monochrome image from which noise has been removed in this way is binarized to obtain a second binarized image (S206). Such binarization processing is desirably performed using a dynamic threshold method so that it visually matches the aggregate portion in the color image acquired in S201, but is extracted from the first binarized image. There is no particular limitation as long as it is a method that can extract an aggregate portion that has not been distinguished (an aggregate portion that has almost no difference in brightness and brightness from the cement paste portion and that is not distinguished from the cement paste portion).

  Further, the color image from which noise has been removed in S202 is binarized using the chromaticity difference between the gap and other parts as a threshold, and the gap on the color image acquired in S201 is determined. The extracted third binarized image is acquired (S207). Since the void portion on the color image is displayed with the color of the pigment contained in the resin that has flowed into the void, the chromaticity difference as the threshold may be set as appropriate based on the color of the pigment.

  Subsequently, the third binarized image is subtracted from the first binarized image, and the second binarized image is further added to obtain a fourth binarized image (S208). . The first binarized image obtained as described above is extracted as an aggregate part because it is binarized using the chromaticity difference and brightness difference between the aggregate part and the cement paste part. The void portion is included in the portion. In addition, some aggregate parts having chromaticity and lightness that cannot be distinguished from the chromaticity and lightness of the cement paste part are extracted as cement paste parts. Therefore, by subtracting the third binarized image from the first binarized image and further adding the second binarized image, the aggregate portion in the hardened concrete body is more accurately 2 It can be expressed as a valued image, and the amount of unit aggregate can be estimated with high accuracy.

  Then, the number of gradations of each pixel in the fourth binarized image so that the aggregate portion on the fourth binarized image matches the aggregate portion on the color image acquired in S201. (0 or 1) is corrected (S209). Such correction makes it possible to estimate the unit aggregate amount with higher accuracy.

The area ratio (aggregate area ratio (%), V _agg ) of the aggregate part in the fourth binarized image corrected in this way is calculated (S210). Since the aggregate area ratio calculated in this way can be regarded as an aggregate volume ratio based on stereology theory, an estimated value of the unit aggregate amount is calculated according to the following formula (1) ( S211).

式（１）中、Ｖ_ａｇｇは「骨材面積率（％）」を表す。

In formula (1), V _agg represents “aggregate area ratio (%)”.

  Thus, according to this embodiment, the amount of unit aggregate can be estimated by analyzing the digital color image on the imaging surface of the prepared test piece, so that the concrete includes limestone aggregate as the aggregate. Even if it is a hardened body, the amount of unit aggregate can be estimated with high accuracy and simple operation.

[Air volume estimation process]
In order to estimate the amount of air in the hardened concrete body in the present embodiment, as shown in FIG. 3, first, a reflection obtained by imaging the test piece prepared by the above-described test piece preparation step using a scanning electron microscope. An electronic image is acquired (S301).

  When imaging with a scanning electron microscope, it is preferable to set the acceleration voltage to about 10 to 15 keV and the irradiation current to about 200 to 500 pA. Within this range, a reflected electron image with high resolution can be acquired. Furthermore, by setting the number of fields of view to about 10 to 20, it becomes possible to reduce the influence of the uneven distribution of bubbles due to the imaging location.

  In obtaining a reflected electron image using a scanning electron microscope, the observation magnification with the scanning electron microscope is preferably 50 to 100 times, and more preferably 80 to 100 times. The resolution of the reflected electron image is preferably 0.1 to 2.0 μm / pixel, and particularly preferably 0.5 to 1.0 μm / pixel.

  Subsequently, the obtained reflected electron image is smoothed to remove noise from the reflected electron image (S302). Then, the reflected electron image from which the noise has been removed is binarized to obtain a fifth binarized image (S303).

  Since the entrapped air (air bubbles) part contained in the hardened concrete is represented as a substantially circular particle shape on the reflected electron image, the unhydrated cement part on the reflected electron image in the binarization process. It is preferable to set a threshold at which substantially circular particles recognized on the lower luminance side than the cement hydrate portion and the aggregate portion can be extracted.

  In addition, the substantially circular particles recognized on the low-luminance side on the backscattered electron image include cracks generated in the hardened concrete and voids generated by hydration of the cement. Therefore, they are recognized in the fifth binarized image. If the air amount is calculated based on the area ratio of the substantially circular particles to be produced, there is a possibility that an estimation error of the air amount occurs.

  Therefore, in the present embodiment, a portion corresponding to the entrapment air is extracted from the substantially circular particles on the fifth binarized image obtained as described above using the circular power or the equivalent circle diameter as an index. A sixth binarized image is acquired (S304).

  Specifically, of the substantially circular particles on the fifth binarized image, substantially circular particles having a circular power of 0.95 or more or an equivalent circle diameter of 10 μm or more are extracted as an entrapment air portion.

  Thereafter, the number of gradations (0 or 1) of each pixel in the sixth binarized image is set so that the entrapped air portion on the sixth binarized image matches the entrapped air portion on the backscattered electron image. ) Is corrected (S305), and the area ratio of the entrapped air portion is calculated (S306).

  Since the area ratio of the entrapped air part calculated in this way can be regarded as equivalent to the volume ratio of the entrapped air part from the theory of stereology, the area ratio is calculated based on the amount of air in the hardened concrete body. Can be estimated.

  Thus, according to this embodiment, it is possible to accurately estimate the amount of air in the hardened concrete that cannot be estimated by the conventional method.

[Water cement ratio, unit cement amount, unit water amount estimation process]
In this embodiment, in order to estimate the water cement ratio, unit cement amount and unit water amount in the hardened concrete body, as shown in FIG. 4, first, the test piece prepared by the above-mentioned test piece preparation step is scanned. A reflected electron image captured using an electron microscope is acquired (S401).

  When imaging with a scanning electron microscope, it is preferable to set the acceleration voltage to about 10 to 15 keV and the irradiation current to about 500 pA to 2 nA. Within this range, a reflected electron image with high resolution can be acquired. Furthermore, the number of fields of view may be set as appropriate so that the aggregate portion and the entrapped air portion can be eliminated as much as possible from the reflected electron image. Specifically, the number of fields of view should be set to about 20 to 30. Good.

  In obtaining a reflected electron image using a scanning electron microscope, the observation magnification with the scanning electron microscope is preferably 250 to 1000 times, and more preferably about 500 times. The resolution of the reflected electron image is preferably 0.01 to 0.02 μm / pixel, and particularly preferably 0.01 μm / pixel.

  Next, noise in the obtained reflected electron image is removed (S402). Then, the reflected electron image from which noise has been removed is binarized using the luminance difference between the cement paste portion, the aggregate portion, and the crack portion as a threshold value, and the aggregate portion and the crack portion are extracted. A binarized image is acquired (S403). Then, the number of gradations of each pixel in the seventh binarized image is such that the aggregate portion and crack portion on the seventh binarized image coincide with the aggregate portion and crack portion on the reflected electron image. (0 or 1) is corrected, and the total area ratio of the aggregate portion and the crack portion is calculated from the corrected seventh binarized image.

  Next, the obtained seventh binarized image is added to the reflected electron image, or the seventh binarized image is subtracted from the reflected electron image, thereby performing mask processing on the reflected electron image (S404). Thereby, parts (an aggregate part, a crack part) other than the cement paste part can be excluded from the reflected electron image.

  Subsequently, the masked backscattered electron image is binarized, an eighth binarized image from which the unhydrated cement portion of the cement paste portion can be extracted, and void portions generated by cement hydration A ninth binarized image from which can be extracted is acquired (S405).

  In obtaining the eighth and ninth binarized images, it is preferable to set threshold values for extracting the unhydrated cement portion and the void portion, respectively, and to binarize the masked backscattered electron image. . In particular, in the extraction of the void portion, it is preferable to set the inflection point at which the slope changes from the low luminance side slope to the cement hydrate slope as the threshold value based on the gray level cumulative frequency distribution graph in the reflected electron image.

  Then, from each of the eighth and ninth binarized images, the area ratio of the unhydrated cement portion and the area ratio of the void portion are calculated (S406), and the area ratio of the cement hydrate is calculated by the following formula. (S407).

式（６）中、Ｖ_ＨＰは「セメント水和物面積率（％）」を、Ｖ_{ｃｒａｃｋ}は「骨材部分及びひび割れ部分合計面積率（％）」を、Ｖ_ＡＨは「未水和セメント面積率（％）」を、Ｖ_ＣＰは「空隙面積率（％）」を表す。

Wherein _{(6), V HP} is the "cement hydrate area ratio (%)" _{a, V crack} the "aggregate portion and crack portions total area ratio _{(%)", V AH} is "Mimizuwa cement area “ _CP (%)”, and V _CP represents “Void area ratio (%)”.

  From the cement hydrate area ratio, the unhydrated cement area ratio and the void area ratio calculated in this way, a water cement ratio estimated value is calculated according to the following formula (2) (S408).

式（２）中、Ｖ_Ｗは「水体積率（％）」を、Ｖ_Ｃは「初期セメント体積率（％）」を、Ｖ_ＨＰは「セメント水和物面積率（％）」を、δ_Ｖは「セメントの水和膨張係数」を、Ｖ_ＣＰは「空隙面積率（％）」を、Ｖ_ＡＨは「未水和セメント面積率（％）」を、ρ_Ｃは「セメントの密度（ｇ／ｃｍ^３）」を表す。

In Formula (2), V _W is “water volume fraction (%)”, V _C is “initial cement volume fraction (%)”, V _HP is “cement hydrate area ratio (%)”, δ _V is “cement hydration expansion coefficient”, V _CP is “void area ratio (%)”, V _AH is “unhydrated cement area ratio (%)”, and ρ _C is “cement density (g / Cm ³ ) ”.

  Subsequently, an initial cement volume ratio is calculated from the calculated cement hydrate area ratio according to the following formula (3) (S409).

式（３）中、Ｖ_Ｃは「初期セメント体積率（％）」を、Ｖ_ＡＨは「未水和セメント面積率（％）」を、Ｖ_ＨＰは「セメント水和物面積率（％）」を、δ_Ｖは「水和膨張係数」を表す。

Wherein (3), _{V C} is the "initial cement volume ratio (%)" _{a, V AH} is "Mimizuwa cement area ratio (%)" _{a, V HP} is "cement hydrate area ratio (%)" _ΔV represents “hydration expansion coefficient”.

  Furthermore, from the calculated initial cement volume ratio, the aggregate area ratio calculated by the unit aggregate amount estimation step, and the area ratio of the entrapment air portion calculated by the air amount estimation step, the following formula (4) is used. The unit cement amount estimated value is calculated (S410).

式（４）中、Ｖ_ａｇｇは「骨材面積率（％）」を、Ｖ_ａｉｒは「エントラップトエア部分の面積率（％）」を、Ｖ_Ｃは「初期セメント体積率（％）」を、ρ_Ｃは「セメント密度（ｇ／ｃｍ^３）」を表す。

In the formula _(4), the _{V agg} is "aggregate area ratio _(%)", the _{V air} is "area ratio of the entrapped air portion (%)", _{V C} is the "initial cement volume ratio (%)" , Ρ _C represents “cement density (g / cm ³ )”.

  Furthermore, a unit water amount is calculated according to the following formula (5) from the water cement ratio estimated value and the unit cement amount estimated value calculated as described above (S411).

  As described above, according to the present embodiment, an image of the imaging surface of the test piece of the hardened concrete body is obtained, and only by analyzing the image, the water cement ratio, unit cement amount and The unit water amount can be accurately estimated by a simple operation.

  Regardless of the type of aggregate or admixture compounded in the hardened concrete, the concrete hardened by the above-mentioned unit aggregate amount estimation step, air amount estimation step, water cement ratio, unit cement amount and unit water amount estimation step The composition of the body can be accurately estimated. Therefore, according to the blending estimation method according to the present embodiment, blending can be accurately estimated even with a hardened concrete containing limestone aggregate, and blending can be estimated by a simple operation.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, in the test piece preparation step of the above embodiment, the resin impregnation step (S104) and the imaging surface polishing step (S105) are performed once, but the present invention is not limited to this and is repeated twice or more. You may go. In this case, in the second and subsequent imaging surface polishing steps (S105), it is preferable to polish the imaging surface with a buffing machine using alumina powder or the like as an abrasive.

[Example 1]
A test piece for mixing estimation (samples 1 to 4) was prepared by using a hardened concrete body exposed for two years in a seawater splash zone as the mixing estimation target concrete. Tables 1 and 2 show the materials used and the composition of the hardened concrete. Samples 1 and 3 in Table 2 are those using ordinary Portland cement as cement, and Samples 2 and 4 are those using low heat Portland cement as cement.

  A 2 cm × 4 cm × 2 cm test piece (aggregate amount estimation test piece) and a 2 cm square test piece (air amount and water cement ratio estimation test piece) were cut out from the hardened concrete body and vacuum-dried for one week.

A test piece for estimating the amount of aggregate after drying was impregnated with a low-viscosity epoxy resin kneaded with vermilion paint (product name: Specifix-20, manufactured by Marumoto Struers, viscosity: 185 to 190 cP) under reduced pressure. . After the impregnated resin is cured, SiC abrasives (# 240, 400, 800) and B ₄ C abrasives (# 1000) are used as abrasives, and a power wrap (product name) manufactured by Marto is used as a polishing machine. The imaging surface of the test piece was used for polishing.

Moreover, the test piece for estimating the air amount and water cement ratio after drying is accommodated in a cylindrical mold having an inner diameter of 1 inch, and a low-viscosity epoxy resin fat (product name: Specifix-20, Marumoto) in the cylindrical mold. Struers, viscosity: 185 to 190 cP) was poured, and the resin was impregnated under reduced pressure. After the impregnated resin is cured, SiC abrasives (# 240, 400, 800) and B ₄ C abrasives (# 1000) are used as abrasives, and a power wrap (product name) manufactured by Marto is used as a polishing machine. The imaging surface of the test piece was used for polishing. After that, impregnation with low-viscosity epoxy resin again, using alumina powder (particle size: 3, 1, 0.3 μm) as an abrasive, and buffing with a buffing machine (manufactured by Engis, product name: KENT3) gave. After polishing, carbon deposition was performed to impart conductivity to the test piece.

  About the test piece for unit aggregate amount estimation obtained in this way, and the test piece for air quantity and water cement ratio estimation, image processing was performed as follows, and the mixture estimation of the hardened concrete body was performed. The image processing was performed using commercially available image analysis software (product name: NanoHunter NS2K-Pro, manufactured by Nanosystem).

(1) Unit Aggregate Amount Estimation A color image of an imaging surface of a unit aggregate amount estimation test piece is obtained by using a scanner (manufactured by Canon Inc., product name: CanoScanLiDE500F), and noise included in the obtained color image Is removed by applying a moving average filter to the color image, and then binarization processing is performed using the chromaticity difference and the brightness difference between the aggregate portion and the cement paste portion, and the first binarized image is obtained. I got it. Further, after the color image was converted into monochrome, the noise was removed by applying a moving average filter to the monochrome image, and then binarization processing was performed by a dynamic threshold method to obtain a second binarized image. Furthermore, the binarization process was performed on the image from which noise included in the color image was removed by using the chromaticity difference between the gap portion and the other portions, and a third binarized image was obtained.

  The third binarized image is subtracted from the acquired first binarized image, the second binarized image is further added, and the aggregate portion on the image after the addition and the aggregate on the color image The gradation of the image after the addition was corrected so that the portion visually matched. The area ratio of the aggregate part was calculated from the binarized image thus obtained, and the unit aggregate amount was calculated from the aggregate area ratio based on the following formula (1).

式（１）中、Ｖ_ａｇｇは「骨材面積率（％）」を表す。

In formula (1), V _agg represents “aggregate area ratio (%)”.

(2) Air amount estimation Using a scanning electron microscope (JSM-7001F, manufactured by JEOL Ltd.), the reflected electron image obtained with an observation magnification of 100 was applied with a moving average filter to remove noise. The threshold is set so that substantially circular particles recognized on the lower luminance side than the unhydrated cement part, cement hydrate part and aggregate part on the backscattered electron image after removing noise can be extracted, and binary The treatment was performed. Of the substantially circular particles on the obtained binarized image, a threshold is set so that particles having an equivalent circle diameter of 10 μm or more and a circular power of 0.95 or more are extracted as entrapment air, and the binary is again obtained. The treatment was performed.

The number of gradations of each pixel of the binarized image is set so that the entrapment air on the binarized image thus obtained matches the entrapment air on the backscattered electron image after removing noise. Corrected. Thereafter, the area ratio of the entrapped air portion was calculated from the corrected image, and the area ratio was estimated as the air amount (V _air ).

(3) Estimation of water cement ratio Using a scanning electron microscope (JSM-7001F, manufactured by JEOL Ltd.), noise was removed from a reflected electron image obtained with an observation magnification of 500 by applying a moving average filter. The threshold value that can extract the aggregate part and crack part on the backscattered electron image is set, then binarization processing is performed to obtain a binary image that extracts the aggregate part and crack part, and the total area ratio (V _crack ) was calculated.

  And the binarized image which extracted the aggregate part and the crack part from the reflected electron image after removing noise was subtracted, and the mask process was performed about the reflected electron image. A threshold value capable of extracting an unhydrated cement portion on the reflected electron image after the mask processing was set and binarization processing was performed to obtain a binarized image in which the unhydrated cement portion was extracted.

  Further, a binary image obtained by extracting an aggregate portion and a crack portion was added to the reflected electron image after removing noise, and the reflected electron image was masked. A binarization process was performed by setting a threshold value for extracting a void portion on the reflected electron image after the mask processing, and a binary image obtained by extracting the void portion was obtained.

  Then, each pixel of each binarized image is visually matched so that the unhydrated cement portion and void portion on the reflected electron image and the unhydrated cement portion and void portion on each binarized image are visually matched. The gradation was corrected.

  From the corrected image, the total area ratio of the unhydrated cement part and the void part was calculated, and the area ratio of the cement hydrate was calculated according to the following formula (6).

式（６）中、Ｖ_ＨＰは「セメント水和物面積率（％）」を、Ｖ_{ｃｒａｃｋ}は「骨材部分及びひび割れ部分合計面積率（％）」を、Ｖ_ＡＨは「未水和セメント面積率（％）」を、Ｖ_ＣＰは「空隙面積率（％）」を表す。

Wherein _{(6), V HP} is the "cement hydrate area ratio (%)" _{a, V crack} the "aggregate portion and crack portions total area ratio _{(%)", V AH} is "Mimizuwa cement area “ _CP (%)”, and V _CP represents “Void area ratio (%)”.

  From the cement hydrate area ratio, the unhydrated cement area ratio, and the void area ratio calculated in this manner, a water cement ratio estimated value was calculated according to the following formula (2).

式（２）中、Ｖ_Ｗは「水体積率（％）」を、Ｖ_Ｃは「初期セメント体積率（％）」を、Ｖ_ＨＰは「セメント水和物面積率（％）」を、δ_Ｖは「セメントの水和膨張係数」を、Ｖ_ＣＰは「空隙面積率（％）」を、Ｖ_ＡＨは「未水和セメント面積率（％）」を、ρ_Ｃは「セメントの密度（ｇ／ｃｍ^３）」を表す。

In Formula (2), V _W is “water volume fraction (%)”, V _C is “initial cement volume fraction (%)”, V _HP is “cement hydrate area ratio (%)”, δ _V is “cement hydration expansion coefficient”, V _CP is “void area ratio (%)”, V _AH is “unhydrated cement area ratio (%)”, and ρ _C is “cement density (g / Cm ³ ) ”.

  Subsequently, the initial cement volume ratio was calculated from the calculated cement hydrate area ratio according to the following formula (3).

式（３）中、Ｖ_Ｃは「初期セメント体積率（％）」を、Ｖ_ＡＨは「未水和セメント面積率（％）」を、Ｖ_ＨＰは「セメント水和物面積率（％）」を、δ_Ｖは「水和膨張係数」を表す。

Wherein (3), _{V C} is the "initial cement volume ratio (%)" _{a, V AH} is "Mimizuwa cement area ratio (%)" _{a, V HP} is "cement hydrate area ratio (%)" _ΔV represents “hydration expansion coefficient”.

  Further, an estimated unit cement amount was calculated from the calculated initial cement volume ratio, aggregate area ratio, and area ratio of the entrapment air portion based on the following formula (4).

式（４）中、Ｖ_ａｇｇは「骨材面積率（％）」を、Ｖ_ａｉｒは「エントラップトエア部分の面積率（％）」を、Ｖ_Ｃは「初期セメント体積率（％）」を、ρ_Ｃは「セメント密度（ｇ／ｃｍ^３）」を表す。

In the formula _(4), the _{V agg} is "aggregate area ratio _(%)", the _{V air} is "area ratio of the entrapped air portion (%)", _{V C} is the "initial cement volume ratio (%)" , Ρ _C represents “cement density (g / cm ³ )”.

  Furthermore, the unit water amount was calculated according to the following equation (5) from the water cement ratio estimated value and the unit cement amount estimated value calculated as described above.

  Table 3 shows the composition of the hardened concrete body estimated as described above, together with the composition of the hardened concrete body.

[Comparative Example 1]
Using the concrete hardened body (samples 1 to 4) used in Example 1, the concrete committee report F-18 Joint test report on blended estimation of hardened concrete (Cement Association, September 1967) By the method, the unit volume mass and the unit water amount of each of the above samples 1 to 4 are obtained, and the method described in the unit cement amount test method of hardened concrete with sodium gluconate (Japan Nondestructive Inspection Association Standard, NDIS-3422, 2002) Thus, the unit cement amount of each of the above samples 1 to 4 was obtained. The unit aggregate amount was calculated by the following formulas (7) to (11). The results are shown in Table 3.

式（７）中において、Ｘは「セメント量（％）」を、Ｙは「骨材量（％）」を、Ｚは「水量（％）」を表す。

In the formula (7), X represents “cement amount (%)”, Y represents “aggregate amount (%)”, and Z represents “water amount (%)”.

式（８）中において、ａは「コンクリート試料の５００℃強熱減量（％）」を、αは「骨材の６００℃強熱減量（％）」を表す。なお、本比較例１においては、αを１．２％と仮定し、下記式（９）により水量（Ｚ）をコンクリート試料の５００℃強熱減量（ａ）及び骨材量（Ｙ）で表すことができるため、上記式（７）は、下記式（１０）で表すことができる。

In the formula (8), a represents “500 ° C. ignition loss (%) of concrete sample”, and α represents “600 ° C. ignition loss (%) of aggregate”. In this comparative example 1, α is assumed to be 1.2%, and the amount of water (Z) is expressed by the 500 ° C. ignition loss (a) and the amount of aggregate (Y) of the concrete sample by the following formula (9). Therefore, the above formula (7) can be expressed by the following formula (10).

  The amount of unit aggregate was calculated by substituting the calculation results by the above formulas (7) to (10), the table dry unit volume mass, the concrete absorption rate, and the aggregate absorption rate into the following equation (11). The aggregate absorption rate was assumed to be 1.8%.

式（１１）中において、Ｗは「単位容積質量（ｋｇ／ｍ^３）」を、Ｙは「骨材量（％）」を、ρ_１は「コンクリートの吸水率（％）」を、ρ_２は「骨材の吸水率（％）」を表す。

In the formula (11), W is “unit volume mass (kg / m ³ )”, Y is “aggregate amount (%)”, ρ ₁ is “concrete water absorption (%)”, ρ ₂ Represents “Aggregate water absorption (%)”.

  As shown in Table 3, it was confirmed that the blended estimated value of the hardened concrete by the method of Example 1 was closer to the actual blend than that by the method of Comparative Example 1. From this, it was confirmed that according to the method of Example 1, the blend of the hardened concrete body can be estimated with high accuracy. In particular, it was found that the amount of unit aggregate can be estimated with high accuracy even for a hardened concrete containing limestone aggregate. Moreover, it was confirmed that the air amount that could not be estimated by the conventional method can be estimated with high accuracy.

Claims (9)

A method for estimating the composition of a hardened concrete,
Based on the aggregate area ratio calculated from the binarized image obtained by binarizing the multi-valued image of the hardened concrete body using the aggregate amount estimation threshold, the following formula (1) is used. And calculating a unit aggregate amount estimated value.

In formula (1), V _agg represents “aggregate area ratio (%)”. A method for estimating the composition of a hardened concrete,
The multi-valued image of the hardened concrete body is binarized using an air amount estimation threshold, and the entrapped air portion extracted from the obtained binarized image based on the entrapment air portion determination parameter A composition estimation method, wherein the area ratio is calculated and the obtained area ratio is estimated as the amount of air in the hardened concrete body.   The non-hydrated cement part, the cement hydrate part, and the substantially circular part displayed on the lower brightness side than the aggregate part in the multi-valued image are extracted as an image of the entrapment air part. 2. The method for estimating the formulation according to 2. The entrapment air partial determination parameter is a circular power or an equivalent circle diameter,
The composition estimation method according to claim 2 or 3, wherein an image of the entrapment air portion is extracted from the binarized image based on the circular power or equivalent circle diameter. A method for estimating the composition of a hardened concrete,
The multi-valued image of the hardened concrete body is binarized using a water-cement ratio estimation threshold, and the unhydrated cement area ratio, void area ratio, and cement hydrate area calculated from the binarized image From the ratio, a water cement ratio estimated value is calculated based on the following formula (2), and a blend estimation method characterized by:

In Formula (2), V _W is “water volume fraction (%)”, V _C is “initial cement volume fraction (%)”, V _HP is “cement hydrate area ratio (%)”, δ _V is “cement hydration expansion coefficient”, V _CP is “void area ratio (%)”, V _AH is “unhydrated cement area ratio (%)”, and ρ _C is “cement density (g / Cm ³ ) ”. A method for estimating the composition of a hardened concrete,
From the unhydrated cement area ratio calculated in the blending estimation method according to claim 5, an initial cement volume ratio is calculated based on the following formula (3):
The said aggregate area ratio calculated in the mixing | blending estimation method of Claim 1, the area ratio of the said entrapment air part calculated in the mixing | blending estimation method in any one of Claims 2-4, and the said initial cement volume From the rate, a unit cement amount estimated value is calculated based on the following formula (4), and a blending estimation method characterized by:

Wherein (3), _{V C} is the "initial cement volume ratio (%)" _{a, V AH} is "Mimizuwa cement area ratio (%)" _{a, V HP} is "cement hydrate area ratio (%)" Δ _V represents “hydration expansion coefficient”, and in formula (4), V _agg represents “aggregate area ratio (%)”, and V _air represents “area ratio of entrapped air part (%)”. , V _C represents “initial cement volume fraction (%)”, and ρ _C represents “cement density (g / cm ³ )”. A method for estimating the composition of a hardened concrete,
From the water cement ratio estimated value calculated by the blending estimation method according to claim 5 and the unit cement amount estimated value calculated by the blending estimation method according to claim 6, a unit based on the following formula (5) A formulation estimation method characterized by calculating an estimated amount of water.

  The multi-value image is a multi-value image obtained by imaging one surface of a test piece obtained by cutting the hardened concrete body into a predetermined size. Method of estimating the composition of   The composition estimation method according to claim 8, wherein the multi-value image is a multi-value image obtained by imaging one surface of the polished test piece.

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