JP5610742B2 - Method for measuring activity of cement composition in uncured state, and reuse system using the method - Google Patents

Description

  The present invention relates to a method for measuring the degree of activity of an uncured cement composition, and a reuse system using the method.

  In the ready-mixed concrete factory, waste water containing cement that cleans agitator cars and batcher plants, so-called cleaning waste water, is generated. In addition, there is a residual concrete or a return concrete that is left at the delivery site. The remaining and returned containers are solidified with molds and discarded as hardened concrete, or after being crushed with water, they are separated into recovered water and aggregates using a recovered water treatment device, and these are reused. There are many cases. In addition, JIS A 5308 allows the supernatant water to be reused as part of the kneaded water, and the solid content to be used up to 3% as concrete in concrete. However, it is said that the remaining and returned containers are about 1.6% of the total shipment amount, and the absolute amount of generated sludge is large, and most of them are disposed of at the final disposal site as dehydrated and dried cake.

  In such a current situation, the residual con, the return con, or the washing waste water thereof contains cement which has not lost its activity, and these can be used again as a material for a cement composition such as concrete. Such reuse of the cement composition can be said to be the most effective method from the viewpoint of reducing the environmental load, and it is important to establish a technique for realizing it. A method of adding and reusing a retarder is disclosed in Patent Documents 2 and 3, in which a retarder or the like is added to the adhering mortar of an agitator vehicle, and the stabilized washing wastewater is reused as a concrete material. Patent Document 4 proposes a method of reusing cleaning wastewater to be used as mixing water for the next day and after adding a retarder to the cleaning wastewater.

  By the way, the activity of the cement contained in the washing waste water or the like gradually decreases as the hydration of the cement proceeds and is finally lost. When cleaning wastewater containing cement that has lost its activity is used in concrete, it adversely affects the physical properties of the concrete, such as decreased fluidity and increased shrinkage after curing. At present, the use of washing wastewater is permitted in JIS A 5308 Annex C, but since it is necessary to correct the decrease in the fluidity of the concrete, the mixing of the concrete is generally corrected.

  On the other hand, the method of reusing cement using the retarder proposed in Patent Documents 1 to 4 does not decrease the fluidity of the concrete, so it can be used without modifying the concrete mix, It is an effective recycling technology that makes it possible to increase the strength of hardened concrete.

In this way, if cleaning wastewater containing cement having activity can be used for concrete etc., concrete can be produced in the same manner as concrete using fresh water without modifying the concrete mix, but it can be said that the significance is great, For that purpose, it is necessary to confirm the activity of the cement contained in the uncured cement composition.
As a method for determining the presence or absence of cement activity in the prior art, loss on ignition (measured by the method defined in JIS R 5202) highly correlated with the activity of cement requires modification of the concrete mix. The standard is said to be 7.0% or more, and it has clear judgment criteria, but requires time and skill for measurement, and requires equipment such as a dryer, electric furnace, and high-precision measuring instrument. It cannot be said that it is a simple method to be carried out at a ready-mix factory. In addition, when using lime-based aggregates that have recently been used with the depletion of aggregates, mixing of fine lime powder contained in the sludge may cause errors and increase the value of ignition loss. It recognized.

Furthermore, in Patent Document 5, as a method for detecting the activity of cement in washing wastewater, a retarder containing a reducing sugar such as glucose as an essential component is added to the washing wastewater. For example, glucose oxidase, peroxidase and A technique has been proposed in which the presence of the reducing sugar is detected by a color reaction with a reaction reagent composed of o-tolidine, and the activity of the cement is indirectly examined. However, this method visually checks the presence or absence of coloration, and the determination is ambiguous and cannot be said to be quantitative. In addition, since the reaction reagent is also disposable, it is not a preferable method when it is applied to many samples, and it is necessary to pay attention to the management and long-term storage of the reaction reagent used, such as prevention of inactivation of the enzyme used. is there.
Furthermore, since this method is merely a technique for determining the concentration of reducing sugar, it cannot be applied to a retarder that does not contain reducing sugar as an essential component, so it lacks versatility, and has also lost the activity of cement. Even when reducing sugar is added, there is a risk of erroneous determination that the activity of the cement is present, so it cannot be said to be a method for detecting an appropriate activity.

  Patent Document 6 uses at least a pair of detection electrodes consisting of an anode and a cathode, and the detection electrode uses at least the anode using a passivated metal that easily forms an oxide film on the electrode surface. Measuring the current value flowing when a voltage is applied between the detection electrodes, and determining the activity of the cement based on a variation pattern of the current value caused by the formation of an oxide film on the electrode surface immediately after the voltage application An activity detection method has been proposed. However, this method determines the cement activity based on the fluctuation pattern of the current value resulting from the formation of an oxide film on the electrode surface immediately after voltage application. In addition, when measuring again, it is necessary to remove the oxide film on the electrode surface and recover the electrode.

  On the other hand, in Non-Patent Documents 1 to 4, the electrical conductivity of cement paste and mortar is measured, and the correlation (setting time and strength, etc.) between the electrical conductivity and the hardening properties of concrete is shown. The literature discusses structural changes in the hardening process of cement paste and mortar, especially changes in the amount of water, which is an electrically conductive medium in the matrix, and changes in electrical conductivity, and quantitatively determines the activity of cement. It does not disclose or suggest how to do it.

Accordingly, there remains a need for an accurate and simple method for determining the activity of cement contained in an uncured cement composition, particularly in the technical field of cement reuse.

Japanese Patent No. 2694883 Special Table No. 2579373 Japanese Patent No. 4150134 Japanese Patent No. 2651537 Japanese Patent No. 3384737 Japanese Patent No. 4150190

A study of the early hydration of Portland cement, The Institution of Civil Engineers-Proceedings Part 2 Research and Theory, UK, 1985, ol. An Experiment on Electrical Conductivity of Cement Paste and Mortar-Summary of Annual Conference of Architectural Institute of Japan, September 1994, 115-116 Impedance Spectroscopy of Hydrating Cement-Based Materials: Measurement, Interpretation, and Application-Journal of the American Ceramic Society, April, 1999 Correspondence between change in electrical conduction characteristics of cement paste by high temperature curing and coarse capillary void space structure-64th Annual Scientific Lecture, Japan Society of Civil Engineers, September 2009, 893-894

  Accordingly, an object of the present invention is to provide a method for accurately and simply measuring the activity of cement contained in an uncured cement composition, and further provide a cement reuse system using the method.

  The inventors of the present invention have found that the activity of the composition can be measured by measuring the electrical conductivity of the uncured cement composition in the course of diligent research to solve the above problems. As a result of further research, the present invention has been completed.

  That is, the present invention relates to a method for measuring the activity of cement contained in an uncured cement composition, wherein the activity is measured based on electrical conductivity.

  Further, the present invention provides a degree of slump reduction of the cement composition caused by the activity measured based on electrical conductivity being added to a cement composition in which an uncured cement composition is newly mixed. It is related with the said method calculated as a parameter | index.

The present invention also relates to the above method, wherein the solid content of the uncured cement composition is 60% by weight or less.
Furthermore, the present invention relates to the method, wherein the uncured cement composition is a cleaning waste water of the cement composition.

The present invention also relates to the method, wherein the uncured cement composition comprises a retarder.
Further, in the present invention, the retarder is one or more selected from phosphonic acid derivatives, oxycarboxylic acids and salts thereof, polycarboxylic acids and salts thereof, lignin sulfonic acids and salts thereof, saccharides, silicofluorides, and the like. It is related with the said method.

  The present invention also provides a cement composition reuse system that measures the activity of cement by the above method and reuses the uncured cement composition as a newly kneaded cement composition based on the measurement result. About.

  Furthermore, the present invention is based on the result of measuring the activity of cement by the above method, and the composition of the cement composition in which the uncured cement composition is newly kneaded is modified or not modified. The present invention relates to the reuse system for reusing a cement composition in a hardened state.

  According to the measurement method based on electrical conductivity disclosed by the present invention, (1) high accuracy, (2) rapid, simple and versatile (3) quantitatively and continuously, the activity of the uncured cement composition Can be measured. Furthermore, based on the measurement results obtained by the method, when the uncured cement composition is reused as a material for a cement composition to be newly mixed, it is possible to appropriately correct the cement composition. To do.

FIG. 1 is a relationship diagram between sludge concentration and electrical conductivity (Example 1). FIG. 2 is a relationship diagram of sludge concentration and electrical conductivity (Example 3). FIG. 3 is a relationship diagram between sludge concentration and electrical conductivity (Example 4).

In the present invention, the activity of cement refers to the degree of slump reduction of the cement composition that occurs when an uncured cement composition is added to a newly kneaded cement composition. If it is small, the activity is high, and if it is large, the activity is judged to be low. It is understood that the degree of slump reduction depends on the progress of the hydration reaction of the uncured cement composition that is generally added, and the degree of slump reduction increases as the hydration reaction proceeds.
Then, the present invention finds that there is a certain correlation between the degree of slump reduction and the measurement result of the electrical conductivity of the uncured cement composition, whereby the uncured cement composition This makes it possible to easily measure the activity. The mechanism of the correlation is not necessarily clear, but in an uncured cement composition that has undergone a hydration reaction, ions are eluted from the cement particles, and the electric conductivity increases as the ion concentration increases. At this time, it is considered that cement slump is generated on the surface of the cement particles, and the slump is lowered by increasing the specific surface area.

The electrical conductivity according to the present invention is also referred to as conductivity, electrical conductivity, electrical conductivity or electrical conductivity, and at 25 ° C., a sample liquid located between opposing inactive metal electrodes having a cross-sectional area of 1 cm ² and a distance of 1 cm. It is a reciprocal of the electrical resistance and is a value represented by the unit S / cm. Means for measuring the electrical conductivity of the sample liquid have been established, such as an electrode method and an electromagnetic induction method, and many measuring devices for realizing the means are commercially available. Such a device may be used.

  For the measurement of the concentration of the uncured cement composition, an ultrasonic type raw sludge densitometer marketed by Ultrasonic Industry Co., Ltd. or the method defined in JIS R 5308 (Ready Mixed Concrete) Annex C, Furthermore, a ZKT-104 recovered water concentration test method (precision test), a ZKT-105 recovered water concentration test method (simple test), and the like can be used.

  When measuring the electrical conductivity of cleaning wastewater containing cement, a flocculant may be used to settle cement solids before measurement.

  The electrical conductivity may be measured in real time for the sample liquid, or may be measured for the sample liquid sampled by an appropriate method.

  Examples of the cement in the present invention include normal, early strength, very early strength, moderate heat, low heat, sulfate-resistant Portland cement, blast furnace, fly ash, silica fume and other mixed cement.

Examples of the cement composition in the present invention include cement milk, grout, paste, mortar, adhesion mortar, concrete, residual concrete, remainder concrete, and return concrete.
The uncured cement composition in the present invention includes the cleaning wastewater itself.

  The retarder in the present invention is not limited as long as it suppresses the hydration reaction of cement contained in the cleaning solution or cleaning wastewater of the ready-mixed car, and includes phosphonic acid derivatives, oxycarboxylic acids and salts thereof, polycarboxylic acids and salts thereof, Examples thereof include lignin sulfonic acid and salts thereof, saccharides, silicofluorides and the like. Specific examples of phosphonic acid derivatives include aminodi (methylenephosphonic acid), aminotri (methylenephosphonic acid) / pentasodium salt, 1-hydroxyethylidene-1,1-diphosphonic acid / tetrasodium salt, ethylenediaminetetra (methylenephosphonic acid). Acid) / calcium sodium salt, hexamethylenediaminetetra (methylenephosphonic acid) / potassium salt, diethylenetriaminepenta (methylenephosphonic acid) / sodium salt, and other polymethoxypolyphosphonates described in JP-A-5-221700 As polycarboxylic acids and salts thereof, relatively low molecular weight polymaleic acid, polyfumaric acid, polyacrylic acid, polymethacrylic acid, styrene-maleic acid copolymer, (meth) acrylic acid ester- (meth) acrylic Acid copolymerization , Ethylenesulfonic acid-acrylic acid copolymers and their salts, oxycarboxylic acid and its salts include citric acid, gluconic acid, tartaric acid, lactic acid, malic acid, glucoheptonic acid and their salts as alkali metal salts, alkalis Examples of the earth metal salt and amine salt include glucose, maltose, saccharose, fructose, galactose, oligosaccharide, corn syrup and the like as saccharides, and examples of silicofluoride include magnesium silicofluoride. 1 type (s) or 2 or more types can be used. Generally, it can be used in an amount of about 0.01 to 0.3% by volume with respect to the washing water and about 0.1 to 10% by weight with respect to the cement in the washing waste water.

  The cleaning waste water for the cement composition according to the present invention is one in which the cement composition is crushed with water and the aggregate is removed, and the returned agitator car, fresh concrete manufacturing apparatus, hopper, mixer, etc. are cleaned. Is mentioned. To clean these, water, preferably water containing a retarder, can be used. Moreover, the sludge in this invention shows solid content contained in washing | cleaning wastewater, and can illustrate cement, fine sand, etc.

  On the other hand, when it is necessary to correct the mix of concrete, the mix is generally corrected by the method described in the “Namakon Factory Quality Control Guidebook” by the National Federation of Ready-mixed Concrete Industries Association. According to this, the blending of concrete is corrected in three items of unit water amount, fine aggregate rate and AE agent usage. Since this correction value has different properties of washing wastewater depending on various materials used in each factory, recovery equipment, etc., it is desirable to appropriately correct the mix of concrete by test mixing.

  In addition, according to the Japan Society of Civil Engineers "Concrete mix design and construction guidelines based on construction performance" (draft), the target slump should be set based on the minimum slump value of the driving, considering the change with the slump time. It is said. That is, in the case of cleaning wastewater having a large slump loss, it is necessary to confirm the fluctuation of the slump value when the cleaning wastewater is used, and to set a slump that has been refined in consideration of the slump loss with the passage of time.

In general, when cleaning wastewater is used, the slump loss is larger than when clean water is used. When using washed wastewater, the concrete that has been blended and corrected by the above-described method has improved fluidity immediately after kneading, but does not improve changes due to slump time. That is, even if the slump immediately after mixing is equivalent, the value of the slump accompanying the elapsed time such as after 15 minutes or after 30 minutes is different from the case of using fresh water. As an improvement method, there is a blend correction method in which an appropriate type and amount of admixture is selected according to the degree of slump reduction and slump loss.
More preferably, the concrete blending correction is performed so that the slump value at the time of unloading satisfies the required slump range, using the slump value when washing wastewater is used from the average transportation time of each factory as a calibration curve.

  One of the preferred embodiments of the cement recycling system of the present invention is to add the solid content of the uncured cement composition, the electrical conductivity, and the cement composition to be reused to the cement composition to be newly mixed. The relationship between the degree of slump reduction and slump loss of the cement composition caused by the above is grasped in advance, and a calibration curve is created. The activity can be evaluated. As a result, appropriate blending correction is possible, and it is possible to produce the cement composition without being deteriorated in quality.

  In addition, as described above, the reuse system can be widely applied to commonly used cement compositions, and can be applied regardless of the presence, type, and amount of added retarder. Furthermore, blending correction can be performed in consideration of slump reduction and slump loss by the method described above.

使用材料は以下のとおりである。
セメント（Ｃ）：太平洋セメント、宇部三菱セメント、住友大阪セメントの等量混合品
細骨材（Ｓ）：大井川水系陸砂：表乾密度：２．５８ｇ／ｃｍ^３、粗粒率：２．６３、吸水率：２．３４％
粗骨材（Ｇ）：青梅産硬質砂岩砕石：表乾密度：２．６６ｇ／ｃｍ^３、最大寸法：２０ｍｍ
高性能ＡＥ減水剤（ＳＰ）：レオビルドＳＰ８ＳＶ（ＢＡＳＦポゾリス（株）社製）
空気量調整剤（ＡＥ）：マイクロエア２０２（ＢＡＳＦポゾリス（株）社製）
水（Ｗ）：水道水
２０℃の条件において、配合Ｎｏ．１で練り混ぜられ２時間が経過したコンクリートを５ｍｍ篩に通して洗浄し、さらに、粒径の大きい砂を沈降させ濃度７、１５および２０重量％の洗浄廃水を得た。この洗浄廃水をある任意の時点で電気伝導度を測定し、その値の洗浄廃水を使用したコンクリートの練り混ぜ直後および３０分後のスランプを測定し、清水を使用したコンクリートのスランプと比較した。また、電気伝導度の測定には、東亜電波（株）社製ＣＭ−６０Ｓを使用して測定を行った。
なお、判定基準は以下のとおりである。
洗浄廃水を使用したコンクリートのスランプ値と清水を使用したコンクリートのスランプ値との差
○： 練り混ぜ直後＝１．５ｃｍ未満、３０分後＝１．５ｃｍ未満
△： 練り混ぜ直後＝１．５ｃｍ以上３．０ｃｍ未満、３０分後＝１．５ｃｍ以上３．０ｃｍ未満
×： 練り混ぜ直後＝３．０ｃｍ以上、３０分後＝３．０ｃｍ以上
−： 測定無し
試験結果を表２に示す。

いずれの濃度においても、電気伝導度が高くなるにつれてコンクリートの性状に影響を及ぼし、濃度ごとに影響を受けはじめる電気伝導度の値が存在する。また、電気伝導度は濃度に依存することから、濃度と電気伝導度の関係を図１に示すと判定○の線と判定×の線が図示できる。また、判定○と判定×の線の間が判定△となり洗浄廃水の濃度と電気伝導度を測定することにより、コンクリートの性状に影響を与える洗浄廃水か否かの判別が可能である。 Hereinafter, the present invention will be described in more detail based on each example, but the present invention is not limited to only the example.
[Example 1]
Table 1 shows the concrete composition.

The materials used are as follows.
Cement (C): Taiheiyo Cement, Ube Mitsubishi Cement, Sumitomo Osaka Cement Equivalent Mixture Fine Aggregate (S): Oigawa Waterland Land Sand: Surface Dry Density: 2.58 g / cm ³ , Coarse Grain Ratio: 2.63 , Water absorption: 2.34%
Coarse aggregate (G): Ome hard sandstone crushed stone: Surface dry density: 2.66 g / cm ³ , Maximum dimension: 20 mm
High-performance AE water reducing agent (SP): Leo Build SP8SV (manufactured by BASF Pozzolith Co., Ltd.)
Air amount adjusting agent (AE): Micro Air 202 (manufactured by BASF Pozzolith Co., Ltd.)
Water (W): tap water The concrete that had been kneaded in 1 and passed for 2 hours was washed through a 5 mm sieve, and further, sand having a large particle size was settled to obtain washing wastewater having concentrations of 7, 15 and 20% by weight. The electrical conductivity of this washing wastewater was measured at an arbitrary time point, the slump immediately after mixing the concrete using the washing wastewater of that value and after 30 minutes was measured, and compared with the concrete slump using fresh water. Moreover, the electrical conductivity was measured using CM-60S manufactured by Toa Radio Co., Ltd.
The criteria for determination are as follows.
Difference between slump value of concrete using washing waste water and slump value of concrete using clean water ○: Immediately after mixing = less than 1.5 cm, 30 minutes later = less than 1.5 cm Δ: Immediately after mixing = 1.5 cm or more Less than 3.0 cm, after 30 minutes = 1.5 cm or more and less than 3.0 cm ×: Immediately after kneading = 3.0 cm or more, after 30 minutes = 3.0 cm or more−: No measurement The test results are shown in Table 2.

At any concentration, there is a value of electrical conductivity that affects the properties of concrete as the electrical conductivity increases and begins to be affected for each concentration. Further, since the electric conductivity depends on the concentration, the relationship between the concentration and the electric conductivity is shown in FIG. Moreover, it becomes the determination (triangle | delta) between the line of determination (circle) and determination x, and it can be discriminate | determined whether it is washing waste water which affects the property of concrete by measuring the density | concentration and electrical conductivity of washing waste water.

Ａ：ホスホン酸誘導体（ディクエスト２０００、サーモフォス社製）
Ｂ：オキシカルボン酸塩（グルコン酸ナトリウム、関東化学）
Ｃ：糖類（マルトース、関東化学）
Ｄ：ポリカルボン酸塩（レオビルドＳＰ８Ｎ、ＢＡＳＦポゾリス社製）
Ｅ：リグニンスルホン酸塩（ポゾリスＮｏ．８、ＢＡＳＦポゾリス社製）
Ｆ：ケイ弗化物（レオリタード、ＢＡＳＦポゾリス社製）
また、遅延剤の組合せと添加量は、以下の通り洗浄廃水に対する容積％とした。
Ａ、ＢおよびＣは０．１２５、０．２５および０．５０容積％
Ｄ、Ｅ、Ｆ、Ａ＋Ｂ、Ａ＋Ｃ、Ａ＋Ｂ＋ＣおよびＢ＋Ｄ＋Ｅは０．２５容積％
また、遅延剤は、２０℃の条件において、配合Ｎｏ．１で練り混ぜられ２時間が経過したコンクリートを５ｍｍ篩に通して洗浄する際に添加した。その後、粒径の大きい砂を沈降させ濃度１０重量％の洗浄廃水について、任意の時点で電気伝導度を測定しコンクリート試験を実施した。なお、電気伝導度の測定および評価判定は実施例１と同様である。
試験結果を表４に示す。

いずれの遅延剤においても、電気伝導度が高くなるにつれてコンクリートの性状に影響を及ぼし、電気伝導度を測定することにより、コンクリートの性状に影響を与える洗浄廃水か否かの判別が可能である。 [Example 2]
The cleaning wastewater when the retarder shown in Table 3 was added was evaluated in the same manner as in Example 1.
The retarders used were adjusted to 20% by weight for the types shown below.

A: Phosphonic acid derivative (Diquest 2000, manufactured by Thermophos)
B: Oxycarboxylate (sodium gluconate, Kanto Chemical)
C: Sugar (Maltose, Kanto Chemical)
D: Polycarboxylate (Reobuild SP8N, manufactured by BASF Pozzolith)
E: Lignin sulfonate (Pozoris No. 8, manufactured by BASF Pozzolith)
F: Silica fluoride (Leotard, manufactured by BASF Pozzolith)
In addition, the combination and addition amount of the retarder were set to volume% with respect to the washing waste water as follows.
A, B and C are 0.125, 0.25 and 0.50 vol%
D, E, F, A + B, A + C, A + B + C and B + D + E are 0.25% by volume
In addition, the retarder was blended No. at 20 ° C. The concrete which was kneaded in 1 and passed for 2 hours was added when washed through a 5 mm sieve. Thereafter, sand having a large particle size was settled, and the electrical conductivity was measured at an arbitrary time for a washing wastewater having a concentration of 10% by weight, and a concrete test was performed. Note that the measurement and evaluation of electrical conductivity are the same as in Example 1.
The test results are shown in Table 4.

In any of the retarders, the properties of the concrete are affected as the electrical conductivity increases, and by measuring the electrical conductivity, it is possible to determine whether or not the waste water is washed waste water that affects the properties of the concrete.

いずれの濃度においても、電気伝導度が高くなるにつれてコンクリートの性状に影響を及ぼし、濃度ごとに影響を受けはじめる電気伝導度の値が存在する。また、電気伝導度は濃度に依存することから、濃度と電気伝導度の関係を図２に示すと判定○の線と判定×の線が図示できる。また、判定○と判定×の線の間が判定△となり洗浄廃水の濃度と電気伝導度を測定することにより、コンクリートの性状に影響を与える洗浄廃水か否かの判別が可能である。 [Example 3]
Next, 0.25% by volume of the retarder A is added to the cleaning wastewater by the same method to adjust the cleaning wastewater to a concentration of 5, 7, 10, 15, and 30% by weight, and the same evaluation as in Example 1 is performed. It was.
The test results are shown in Table 5.

At any concentration, there is a value of electrical conductivity that affects the properties of concrete as the electrical conductivity increases and begins to be affected for each concentration. Further, since the electrical conductivity depends on the concentration, the relationship between the concentration and the electrical conductivity is shown in FIG. Moreover, it becomes the determination (triangle | delta) between the line of determination (circle) and determination x, and it can be discriminate | determined whether it is washing waste water which affects the property of concrete by measuring the density | concentration and electrical conductivity of washing waste water.

いずれの濃度においても、電気伝導度が高くなるにつれてコンクリートの性状に影響を及ぼし、濃度ごとに影響を受けはじめる電気伝導度の値が存在する。また、電気伝導度は濃度に依存することから、濃度と電気伝導度の関係を図３に示すと判定○の線と判定×の線が図示できる。また、判定○と判定×の線の間が判定△となり洗浄廃水の濃度と電気伝導度を測定することにより、コンクリートの性状に影響を与える洗浄廃水か否かの判別が可能である。 [Example 4]
Next, 0.25 vol% of the retarder A + B is added to the washing wastewater by the same method to adjust the washing wastewater to a concentration of 5, 7, 10, 15 and 30% by weight, and the same evaluation as in Example 1 is performed. It was.
The test results are shown in Table 6.

At any concentration, there is a value of electrical conductivity that affects the properties of concrete as the electrical conductivity increases and begins to be affected for each concentration. Since the electrical conductivity depends on the concentration, the relationship between the concentration and the electrical conductivity is shown in FIG. Moreover, it becomes the determination (triangle | delta) between the line of determination (circle) and determination x, and it can be discriminate | determined whether it is washing waste water which affects the property of concrete by measuring the density | concentration and electrical conductivity of washing waste water.

その結果、○と判定されたもの（Ｎｏ．２９）は、清水で調整したもの（Ｎｏ．２８）と同様のスランプ値を示し、×と判定されたもの（Ｎｏ．３０）はいずれの時間においても、スランプ値が清水の場合より３ｃｍ以上小さい値を示した。
この結果より、電気伝導度により洗浄廃水がコンクリートの性状に影響を与える洗浄廃水か否かの判別が可能である。 [Example 5]
Next, 0.25 vol% of the retarder A + B was added to the washing wastewater by the same method to adjust the washing wastewater to a concentration of 20% by weight, and the electrical conductivity was measured. The result of the electrical conductivity was determined according to FIG. 3, and the result was confirmed by a concrete test. The test results are shown in Table 7.

As a result, what was determined as ◯ (No. 29) showed the same slump value as that adjusted with fresh water (No. 28), and what was determined as x (No. 30) at any time Also, the slump value was 3 cm or more smaller than that of fresh water.
From this result, it is possible to determine whether or not the cleaning wastewater is a cleaning wastewater that affects the properties of the concrete by electric conductivity.

使用材料は以下の通りである。
セメント（Ｃ）：宇部三菱セメント
細骨材（Ｓ）：山砂：表乾密度：２．５９ｇ／ｃｍ^３、粗粒率：２．６２、吸水率：２．１４％
粗骨材（Ｇ）：石灰砕石：表乾密度：２．６９ｇ／ｃｍ^３、最大寸法：２０ｍｍ
高性能ＡＥ減水剤（ＳＰ）：レオビルドＳＰ８ＳＶ（ＢＡＳＦポゾリス（株）社製）
空気量調整剤（ＡＥ）：マイクロエア１０１（ＢＡＳＦポゾリス（株）社製）
水（Ｗ）：水道水
表９に試験結果を示す。

石灰石微粉末が混入する場合では、強熱減量は大きな値を示し判定×となったのに対し、電気伝導度は図３から判定が○となった。この結果を元に、コンクリート評価をした結果、コンクリートの性状に影響を及ぼさない洗浄廃水であることが認められ、石灰系材料を用いた場合においても電気伝導度による判定は可能であった。なお、コンクリートの配合修正を必要とする強熱減量の値は、一般的に７．０％以上である。 [Example 6]
Washing wastewater was made from concrete using lime-based materials, and electrical conductivity, ignition loss, and fresh properties of concrete were confirmed. Further, when preparing the cleaning wastewater, the cleaning wastewater having a concentration of 30% by weight prepared using 0.25% by volume of the retarder A + B with respect to the cleaning wastewater was used. The concrete composition shown in Table 8 was used for the experiment. For mixing, a 55 liter pan type forced mixer was used to produce 30 liters of concrete. The kneading time was 90 seconds, and the physical properties of fresh concrete were measured after completion of production.
The blending conditions were as shown in Table 8.

The materials used are as follows.
Cement (C): Ube Mitsubishi Cement Fine Aggregate (S): Mountain Sand: Surface Dry Density: 2.59 g / cm ³ , Coarse Grain Ratio: 2.62, Water Absorption Rate: 2.14%
Coarse aggregate (G): Limestone: Surface dry density: 2.69 g / cm ³ , Maximum dimension: 20 mm
High-performance AE water reducing agent (SP): Leo Build SP8SV (manufactured by BASF Pozzolith Co., Ltd.)
Air amount adjusting agent (AE): Micro Air 101 (manufactured by BASF Pozzolith Co., Ltd.)
Water (W): Tap water Table 9 shows the test results.

In the case where limestone fine powder is mixed, the loss on ignition shows a large value and is judged x, whereas the electric conductivity is judged as ◯ from FIG. As a result of evaluating the concrete based on this result, it was recognized that the waste water was washed without affecting the properties of the concrete, and even when a lime-based material was used, it was possible to make a judgment based on electrical conductivity. In addition, the value of the ignition loss which requires the mix correction of concrete is generally 7.0% or more.

  The present invention measures (1) accuracy, (2) rapid, simple and versatile (3) quantitative and continuous measurement of the cement composition contained in the uncured cement composition or its washing wastewater. Provide a way to do it. Further, when the cement composition is reused as a material for a cement composition in which the cement is newly kneaded based on the measurement result of the activity of the cement, the cement composition can be appropriately mixed and modified. It is possible to apply it to a ready-mixed concrete factory that requires reuse of attached mortar, residual concrete, residual concrete, and return concrete, which have been disposed of in the past.

Claims (8)

A method for determining the activity of cement contained in an uncured cement composition, wherein the activity is slump and slump loss immediately after mixing the cement composition to which only clean water is added as mixing water. to slump after occurs, the respective differences slump after slump and slump loss immediately occurs kneading the cement composition cement composition is kneaded to the newly added uncured, unhardened The method as described above, which is determined from the measurement result of the electrical conductivity of the cement composition in an uncured state based on the correlation obtained between the electrical conductivity of the cement composition. The correlation between the solid content of the uncured cement composition, the electrical conductivity , and the slump immediately after mixing of the cement composition to which only clean water is added as the mixing water, and the slump after the slump loss occurs On the other hand, it was obtained from a calibration curve created from the difference between the slump immediately after mixing and the slump after slump loss of the cement composition to which the uncured cement composition is added and newly mixed. The method of claim 1, wherein The method according to claim 1 or 2, wherein the solid content of the uncured cement composition is 60% by weight or less. The method according to any one of claims 1 to 3, wherein the uncured cement composition is a cleaning waste water of the cement composition. The method according to claim 1, wherein the uncured cement composition contains a retarder. The retarder is one or more selected from phosphonic acid derivatives, oxycarboxylic acids and salts thereof, polycarboxylic acids and salts thereof, lignin sulfonic acids and salts thereof, saccharides, silicofluorides, and the like. The method described in 1. Cement composition which determines the activity of cement by the method according to any one of claims 1 to 6, and recycles the uncured cement composition into a newly kneaded cement composition based on the determination result. Reuse system for things. The reuse of the cement composition according to claim 7, wherein the cement composition in the uncured state is reused with or without modification based on the determination result. Usage system.

Images